RELICS Season 1

// SPDX-License-Identifier: MIT

pragma solidity >=0.6.2 <0.8.0;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        uint256 size;
        // solhint-disable-next-line no-inline-assembly
        assembly { size := extcodesize(account) }
        return size > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
        (bool success, ) = recipient.call{ value: amount }("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain`call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
      return functionCall(target, data, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value, string memory errorMessage) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        require(isContract(target), "Address: call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.call{ value: value }(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data, string memory errorMessage) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.staticcall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        require(isContract(target), "Address: delegate call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    function _verifyCallResult(bool success, bytes memory returndata, string memory errorMessage) private pure returns(bytes memory) {
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/*
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with GSN meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address payable) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}

// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

import "./IERC165.sol";

/**
 * @dev Implementation of the {IERC165} interface.
 *
 * Contracts may inherit from this and call {_registerInterface} to declare
 * their support of an interface.
 */
abstract contract ERC165 is IERC165 {
    /*
     * bytes4(keccak256('supportsInterface(bytes4)')) == 0x01ffc9a7
     */
    bytes4 private constant _INTERFACE_ID_ERC165 = 0x01ffc9a7;

    /**
     * @dev Mapping of interface ids to whether or not it's supported.
     */
    mapping(bytes4 => bool) private _supportedInterfaces;

    constructor () internal {
        // Derived contracts need only register support for their own interfaces,
        // we register support for ERC165 itself here
        _registerInterface(_INTERFACE_ID_ERC165);
    }

    /**
     * @dev See {IERC165-supportsInterface}.
     *
     * Time complexity O(1), guaranteed to always use less than 30 000 gas.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
        return _supportedInterfaces[interfaceId];
    }

    /**
     * @dev Registers the contract as an implementer of the interface defined by
     * `interfaceId`. Support of the actual ERC165 interface is automatic and
     * registering its interface id is not required.
     *
     * See {IERC165-supportsInterface}.
     *
     * Requirements:
     *
     * - `interfaceId` cannot be the ERC165 invalid interface (`0xffffffff`).
     */
    function _registerInterface(bytes4 interfaceId) internal virtual {
        require(interfaceId != 0xffffffff, "ERC165: invalid interface id");
        _supportedInterfaces[interfaceId] = true;
    }
}

// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

import "../../utils/Context.sol";
import "./IERC721.sol";
import "./IERC721Metadata.sol";
import "./IERC721Enumerable.sol";
import "./IERC721Receiver.sol";
import "../../introspection/ERC165.sol";
import "../../math/SafeMath.sol";
import "../../utils/Address.sol";
import "../../utils/EnumerableSet.sol";
import "../../utils/EnumerableMap.sol";
import "../../utils/Strings.sol";

/**
 * @title ERC721 Non-Fungible Token Standard basic implementation
 * @dev see https://eips.ethereum.org/EIPS/eip-721
 */
contract ERC721 is Context, ERC165, IERC721, IERC721Metadata, IERC721Enumerable {
    using SafeMath for uint256;
    using Address for address;
    using EnumerableSet for EnumerableSet.UintSet;
    using EnumerableMap for EnumerableMap.UintToAddressMap;
    using Strings for uint256;

    // Equals to `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`
    // which can be also obtained as `IERC721Receiver(0).onERC721Received.selector`
    bytes4 private constant _ERC721_RECEIVED = 0x150b7a02;

    // Mapping from holder address to their (enumerable) set of owned tokens
    mapping (address => EnumerableSet.UintSet) private _holderTokens;

    // Enumerable mapping from token ids to their owners
    EnumerableMap.UintToAddressMap private _tokenOwners;

    // Mapping from token ID to approved address
    mapping (uint256 => address) private _tokenApprovals;

    // Mapping from owner to operator approvals
    mapping (address => mapping (address => bool)) private _operatorApprovals;

    // Token name
    string private _name;

    // Token symbol
    string private _symbol;

    // Optional mapping for token URIs
    mapping (uint256 => string) private _tokenURIs;

    // Base URI
    string private _baseURI;

    /*
     *     bytes4(keccak256('balanceOf(address)')) == 0x70a08231
     *     bytes4(keccak256('ownerOf(uint256)')) == 0x6352211e
     *     bytes4(keccak256('approve(address,uint256)')) == 0x095ea7b3
     *     bytes4(keccak256('getApproved(uint256)')) == 0x081812fc
     *     bytes4(keccak256('setApprovalForAll(address,bool)')) == 0xa22cb465
     *     bytes4(keccak256('isApprovedForAll(address,address)')) == 0xe985e9c5
     *     bytes4(keccak256('transferFrom(address,address,uint256)')) == 0x23b872dd
     *     bytes4(keccak256('safeTransferFrom(address,address,uint256)')) == 0x42842e0e
     *     bytes4(keccak256('safeTransferFrom(address,address,uint256,bytes)')) == 0xb88d4fde
     *
     *     => 0x70a08231 ^ 0x6352211e ^ 0x095ea7b3 ^ 0x081812fc ^
     *        0xa22cb465 ^ 0xe985e9c5 ^ 0x23b872dd ^ 0x42842e0e ^ 0xb88d4fde == 0x80ac58cd
     */
    bytes4 private constant _INTERFACE_ID_ERC721 = 0x80ac58cd;

    /*
     *     bytes4(keccak256('name()')) == 0x06fdde03
     *     bytes4(keccak256('symbol()')) == 0x95d89b41
     *     bytes4(keccak256('tokenURI(uint256)')) == 0xc87b56dd
     *
     *     => 0x06fdde03 ^ 0x95d89b41 ^ 0xc87b56dd == 0x5b5e139f
     */
    bytes4 private constant _INTERFACE_ID_ERC721_METADATA = 0x5b5e139f;

    /*
     *     bytes4(keccak256('totalSupply()')) == 0x18160ddd
     *     bytes4(keccak256('tokenOfOwnerByIndex(address,uint256)')) == 0x2f745c59
     *     bytes4(keccak256('tokenByIndex(uint256)')) == 0x4f6ccce7
     *
     *     => 0x18160ddd ^ 0x2f745c59 ^ 0x4f6ccce7 == 0x780e9d63
     */
    bytes4 private constant _INTERFACE_ID_ERC721_ENUMERABLE = 0x780e9d63;

    /**
     * @dev Initializes the contract by setting a `name` and a `symbol` to the token collection.
     */
    constructor (string memory name_, string memory symbol_) public {
        _name = name_;
        _symbol = symbol_;

        // register the supported interfaces to conform to ERC721 via ERC165
        _registerInterface(_INTERFACE_ID_ERC721);
        _registerInterface(_INTERFACE_ID_ERC721_METADATA);
        _registerInterface(_INTERFACE_ID_ERC721_ENUMERABLE);
    }

    /**
     * @dev See {IERC721-balanceOf}.
     */
    function balanceOf(address owner) public view virtual override returns (uint256) {
        require(owner != address(0), "ERC721: balance query for the zero address");
        return _holderTokens[owner].length();
    }

    /**
     * @dev See {IERC721-ownerOf}.
     */
    function ownerOf(uint256 tokenId) public view virtual override returns (address) {
        return _tokenOwners.get(tokenId, "ERC721: owner query for nonexistent token");
    }

    /**
     * @dev See {IERC721Metadata-name}.
     */
    function name() public view virtual override returns (string memory) {
        return _name;
    }

    /**
     * @dev See {IERC721Metadata-symbol}.
     */
    function symbol() public view virtual override returns (string memory) {
        return _symbol;
    }

    /**
     * @dev See {IERC721Metadata-tokenURI}.
     */
    function tokenURI(uint256 tokenId) public view virtual override returns (string memory) {
        require(_exists(tokenId), "ERC721Metadata: URI query for nonexistent token");

        string memory _tokenURI = _tokenURIs[tokenId];
        string memory base = baseURI();

        // If there is no base URI, return the token URI.
        if (bytes(base).length == 0) {
            return _tokenURI;
        }
        // If both are set, concatenate the baseURI and tokenURI (via abi.encodePacked).
        if (bytes(_tokenURI).length > 0) {
            return string(abi.encodePacked(base, _tokenURI));
        }
        // If there is a baseURI but no tokenURI, concatenate the tokenID to the baseURI.
        return string(abi.encodePacked(base, tokenId.toString()));
    }

    /**
    * @dev Returns the base URI set via {_setBaseURI}. This will be
    * automatically added as a prefix in {tokenURI} to each token's URI, or
    * to the token ID if no specific URI is set for that token ID.
    */
    function baseURI() public view virtual returns (string memory) {
        return _baseURI;
    }

    /**
     * @dev See {IERC721Enumerable-tokenOfOwnerByIndex}.
     */
    function tokenOfOwnerByIndex(address owner, uint256 index) public view virtual override returns (uint256) {
        return _holderTokens[owner].at(index);
    }

    /**
     * @dev See {IERC721Enumerable-totalSupply}.
     */
    function totalSupply() public view virtual override returns (uint256) {
        // _tokenOwners are indexed by tokenIds, so .length() returns the number of tokenIds
        return _tokenOwners.length();
    }

    /**
     * @dev See {IERC721Enumerable-tokenByIndex}.
     */
    function tokenByIndex(uint256 index) public view virtual override returns (uint256) {
        (uint256 tokenId, ) = _tokenOwners.at(index);
        return tokenId;
    }

    /**
     * @dev See {IERC721-approve}.
     */
    function approve(address to, uint256 tokenId) public virtual override {
        address owner = ERC721.ownerOf(tokenId);
        require(to != owner, "ERC721: approval to current owner");

        require(_msgSender() == owner || ERC721.isApprovedForAll(owner, _msgSender()),
            "ERC721: approve caller is not owner nor approved for all"
        );

        _approve(to, tokenId);
    }

    /**
     * @dev See {IERC721-getApproved}.
     */
    function getApproved(uint256 tokenId) public view virtual override returns (address) {
        require(_exists(tokenId), "ERC721: approved query for nonexistent token");

        return _tokenApprovals[tokenId];
    }

    /**
     * @dev See {IERC721-setApprovalForAll}.
     */
    function setApprovalForAll(address operator, bool approved) public virtual override {
        require(operator != _msgSender(), "ERC721: approve to caller");

        _operatorApprovals[_msgSender()][operator] = approved;
        emit ApprovalForAll(_msgSender(), operator, approved);
    }

    /**
     * @dev See {IERC721-isApprovedForAll}.
     */
    function isApprovedForAll(address owner, address operator) public view virtual override returns (bool) {
        return _operatorApprovals[owner][operator];
    }

    /**
     * @dev See {IERC721-transferFrom}.
     */
    function transferFrom(address from, address to, uint256 tokenId) public virtual override {
        //solhint-disable-next-line max-line-length
        require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: transfer caller is not owner nor approved");

        _transfer(from, to, tokenId);
    }

    /**
     * @dev See {IERC721-safeTransferFrom}.
     */
    function safeTransferFrom(address from, address to, uint256 tokenId) public virtual override {
        safeTransferFrom(from, to, tokenId, "");
    }

    /**
     * @dev See {IERC721-safeTransferFrom}.
     */
    function safeTransferFrom(address from, address to, uint256 tokenId, bytes memory _data) public virtual override {
        require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: transfer caller is not owner nor approved");
        _safeTransfer(from, to, tokenId, _data);
    }

    /**
     * @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients
     * are aware of the ERC721 protocol to prevent tokens from being forever locked.
     *
     * `_data` is additional data, it has no specified format and it is sent in call to `to`.
     *
     * This internal function is equivalent to {safeTransferFrom}, and can be used to e.g.
     * implement alternative mechanisms to perform token transfer, such as signature-based.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must exist and be owned by `from`.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function _safeTransfer(address from, address to, uint256 tokenId, bytes memory _data) internal virtual {
        _transfer(from, to, tokenId);
        require(_checkOnERC721Received(from, to, tokenId, _data), "ERC721: transfer to non ERC721Receiver implementer");
    }

    /**
     * @dev Returns whether `tokenId` exists.
     *
     * Tokens can be managed by their owner or approved accounts via {approve} or {setApprovalForAll}.
     *
     * Tokens start existing when they are minted (`_mint`),
     * and stop existing when they are burned (`_burn`).
     */
    function _exists(uint256 tokenId) internal view virtual returns (bool) {
        return _tokenOwners.contains(tokenId);
    }

    /**
     * @dev Returns whether `spender` is allowed to manage `tokenId`.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function _isApprovedOrOwner(address spender, uint256 tokenId) internal view virtual returns (bool) {
        require(_exists(tokenId), "ERC721: operator query for nonexistent token");
        address owner = ERC721.ownerOf(tokenId);
        return (spender == owner || getApproved(tokenId) == spender || ERC721.isApprovedForAll(owner, spender));
    }

    /**
     * @dev Safely mints `tokenId` and transfers it to `to`.
     *
     * Requirements:
     d*
     * - `tokenId` must not exist.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function _safeMint(address to, uint256 tokenId) internal virtual {
        _safeMint(to, tokenId, "");
    }

    /**
     * @dev Same as {xref-ERC721-_safeMint-address-uint256-}[`_safeMint`], with an additional `data` parameter which is
     * forwarded in {IERC721Receiver-onERC721Received} to contract recipients.
     */
    function _safeMint(address to, uint256 tokenId, bytes memory _data) internal virtual {
        _mint(to, tokenId);
        require(_checkOnERC721Received(address(0), to, tokenId, _data), "ERC721: transfer to non ERC721Receiver implementer");
    }

    /**
     * @dev Mints `tokenId` and transfers it to `to`.
     *
     * WARNING: Usage of this method is discouraged, use {_safeMint} whenever possible
     *
     * Requirements:
     *
     * - `tokenId` must not exist.
     * - `to` cannot be the zero address.
     *
     * Emits a {Transfer} event.
     */
    function _mint(address to, uint256 tokenId) internal virtual {
        require(to != address(0), "ERC721: mint to the zero address");
        require(!_exists(tokenId), "ERC721: token already minted");

        _beforeTokenTransfer(address(0), to, tokenId);

        _holderTokens[to].add(tokenId);

        _tokenOwners.set(tokenId, to);

        emit Transfer(address(0), to, tokenId);
    }

    /**
     * @dev Destroys `tokenId`.
     * The approval is cleared when the token is burned.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     *
     * Emits a {Transfer} event.
     */
    function _burn(uint256 tokenId) internal virtual {
        address owner = ERC721.ownerOf(tokenId); // internal owner

        _beforeTokenTransfer(owner, address(0), tokenId);

        // Clear approvals
        _approve(address(0), tokenId);

        // Clear metadata (if any)
        if (bytes(_tokenURIs[tokenId]).length != 0) {
            delete _tokenURIs[tokenId];
        }

        _holderTokens[owner].remove(tokenId);

        _tokenOwners.remove(tokenId);

        emit Transfer(owner, address(0), tokenId);
    }

    /**
     * @dev Transfers `tokenId` from `from` to `to`.
     *  As opposed to {transferFrom}, this imposes no restrictions on msg.sender.
     *
     * Requirements:
     *
     * - `to` cannot be the zero address.
     * - `tokenId` token must be owned by `from`.
     *
     * Emits a {Transfer} event.
     */
    function _transfer(address from, address to, uint256 tokenId) internal virtual {
        require(ERC721.ownerOf(tokenId) == from, "ERC721: transfer of token that is not own"); // internal owner
        require(to != address(0), "ERC721: transfer to the zero address");

        _beforeTokenTransfer(from, to, tokenId);

        // Clear approvals from the previous owner
        _approve(address(0), tokenId);

        _holderTokens[from].remove(tokenId);
        _holderTokens[to].add(tokenId);

        _tokenOwners.set(tokenId, to);

        emit Transfer(from, to, tokenId);
    }

    /**
     * @dev Sets `_tokenURI` as the tokenURI of `tokenId`.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function _setTokenURI(uint256 tokenId, string memory _tokenURI) internal virtual {
        require(_exists(tokenId), "ERC721Metadata: URI set of nonexistent token");
        _tokenURIs[tokenId] = _tokenURI;
    }

    /**
     * @dev Internal function to set the base URI for all token IDs. It is
     * automatically added as a prefix to the value returned in {tokenURI},
     * or to the token ID if {tokenURI} is empty.
     */
    function _setBaseURI(string memory baseURI_) internal virtual {
        _baseURI = baseURI_;
    }

    /**
     * @dev Internal function to invoke {IERC721Receiver-onERC721Received} on a target address.
     * The call is not executed if the target address is not a contract.
     *
     * @param from address representing the previous owner of the given token ID
     * @param to target address that will receive the tokens
     * @param tokenId uint256 ID of the token to be transferred
     * @param _data bytes optional data to send along with the call
     * @return bool whether the call correctly returned the expected magic value
     */
    function _checkOnERC721Received(address from, address to, uint256 tokenId, bytes memory _data)
        private returns (bool)
    {
        if (!to.isContract()) {
            return true;
        }
        bytes memory returndata = to.functionCall(abi.encodeWithSelector(
            IERC721Receiver(to).onERC721Received.selector,
            _msgSender(),
            from,
            tokenId,
            _data
        ), "ERC721: transfer to non ERC721Receiver implementer");
        bytes4 retval = abi.decode(returndata, (bytes4));
        return (retval == _ERC721_RECEIVED);
    }

    /**
     * @dev Approve `to` to operate on `tokenId`
     *
     * Emits an {Approval} event.
     */
    function _approve(address to, uint256 tokenId) internal virtual {
        _tokenApprovals[tokenId] = to;
        emit Approval(ERC721.ownerOf(tokenId), to, tokenId); // internal owner
    }

    /**
     * @dev Hook that is called before any token transfer. This includes minting
     * and burning.
     *
     * Calling conditions:
     *
     * - When `from` and `to` are both non-zero, ``from``'s `tokenId` will be
     * transferred to `to`.
     * - When `from` is zero, `tokenId` will be minted for `to`.
     * - When `to` is zero, ``from``'s `tokenId` will be burned.
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _beforeTokenTransfer(address from, address to, uint256 tokenId) internal virtual { }
}

// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev Library for managing an enumerable variant of Solidity's
 * https://solidity.readthedocs.io/en/latest/types.html#mapping-types[`mapping`]
 * type.
 *
 * Maps have the following properties:
 *
 * - Entries are added, removed, and checked for existence in constant time
 * (O(1)).
 * - Entries are enumerated in O(n). No guarantees are made on the ordering.
 *
 * ```
 * contract Example {
 *     // Add the library methods
 *     using EnumerableMap for EnumerableMap.UintToAddressMap;
 *
 *     // Declare a set state variable
 *     EnumerableMap.UintToAddressMap private myMap;
 * }
 * ```
 *
 * As of v3.0.0, only maps of type `uint256 -> address` (`UintToAddressMap`) are
 * supported.
 */
library EnumerableMap {
    // To implement this library for multiple types with as little code
    // repetition as possible, we write it in terms of a generic Map type with
    // bytes32 keys and values.
    // The Map implementation uses private functions, and user-facing
    // implementations (such as Uint256ToAddressMap) are just wrappers around
    // the underlying Map.
    // This means that we can only create new EnumerableMaps for types that fit
    // in bytes32.

    struct MapEntry {
        bytes32 _key;
        bytes32 _value;
    }

    struct Map {
        // Storage of map keys and values
        MapEntry[] _entries;

        // Position of the entry defined by a key in the `entries` array, plus 1
        // because index 0 means a key is not in the map.
        mapping (bytes32 => uint256) _indexes;
    }

    /**
     * @dev Adds a key-value pair to a map, or updates the value for an existing
     * key. O(1).
     *
     * Returns true if the key was added to the map, that is if it was not
     * already present.
     */
    function _set(Map storage map, bytes32 key, bytes32 value) private returns (bool) {
        // We read and store the key's index to prevent multiple reads from the same storage slot
        uint256 keyIndex = map._indexes[key];

        if (keyIndex == 0) { // Equivalent to !contains(map, key)
            map._entries.push(MapEntry({ _key: key, _value: value }));
            // The entry is stored at length-1, but we add 1 to all indexes
            // and use 0 as a sentinel value
            map._indexes[key] = map._entries.length;
            return true;
        } else {
            map._entries[keyIndex - 1]._value = value;
            return false;
        }
    }

    /**
     * @dev Removes a key-value pair from a map. O(1).
     *
     * Returns true if the key was removed from the map, that is if it was present.
     */
    function _remove(Map storage map, bytes32 key) private returns (bool) {
        // We read and store the key's index to prevent multiple reads from the same storage slot
        uint256 keyIndex = map._indexes[key];

        if (keyIndex != 0) { // Equivalent to contains(map, key)
            // To delete a key-value pair from the _entries array in O(1), we swap the entry to delete with the last one
            // in the array, and then remove the last entry (sometimes called as 'swap and pop').
            // This modifies the order of the array, as noted in {at}.

            uint256 toDeleteIndex = keyIndex - 1;
            uint256 lastIndex = map._entries.length - 1;

            // When the entry to delete is the last one, the swap operation is unnecessary. However, since this occurs
            // so rarely, we still do the swap anyway to avoid the gas cost of adding an 'if' statement.

            MapEntry storage lastEntry = map._entries[lastIndex];

            // Move the last entry to the index where the entry to delete is
            map._entries[toDeleteIndex] = lastEntry;
            // Update the index for the moved entry
            map._indexes[lastEntry._key] = toDeleteIndex + 1; // All indexes are 1-based

            // Delete the slot where the moved entry was stored
            map._entries.pop();

            // Delete the index for the deleted slot
            delete map._indexes[key];

            return true;
        } else {
            return false;
        }
    }

    /**
     * @dev Returns true if the key is in the map. O(1).
     */
    function _contains(Map storage map, bytes32 key) private view returns (bool) {
        return map._indexes[key] != 0;
    }

    /**
     * @dev Returns the number of key-value pairs in the map. O(1).
     */
    function _length(Map storage map) private view returns (uint256) {
        return map._entries.length;
    }

   /**
    * @dev Returns the key-value pair stored at position `index` in the map. O(1).
    *
    * Note that there are no guarantees on the ordering of entries inside the
    * array, and it may change when more entries are added or removed.
    *
    * Requirements:
    *
    * - `index` must be strictly less than {length}.
    */
    function _at(Map storage map, uint256 index) private view returns (bytes32, bytes32) {
        require(map._entries.length > index, "EnumerableMap: index out of bounds");

        MapEntry storage entry = map._entries[index];
        return (entry._key, entry._value);
    }

    /**
     * @dev Tries to returns the value associated with `key`.  O(1).
     * Does not revert if `key` is not in the map.
     */
    function _tryGet(Map storage map, bytes32 key) private view returns (bool, bytes32) {
        uint256 keyIndex = map._indexes[key];
        if (keyIndex == 0) return (false, 0); // Equivalent to contains(map, key)
        return (true, map._entries[keyIndex - 1]._value); // All indexes are 1-based
    }

    /**
     * @dev Returns the value associated with `key`.  O(1).
     *
     * Requirements:
     *
     * - `key` must be in the map.
     */
    function _get(Map storage map, bytes32 key) private view returns (bytes32) {
        uint256 keyIndex = map._indexes[key];
        require(keyIndex != 0, "EnumerableMap: nonexistent key"); // Equivalent to contains(map, key)
        return map._entries[keyIndex - 1]._value; // All indexes are 1-based
    }

    /**
     * @dev Same as {_get}, with a custom error message when `key` is not in the map.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {_tryGet}.
     */
    function _get(Map storage map, bytes32 key, string memory errorMessage) private view returns (bytes32) {
        uint256 keyIndex = map._indexes[key];
        require(keyIndex != 0, errorMessage); // Equivalent to contains(map, key)
        return map._entries[keyIndex - 1]._value; // All indexes are 1-based
    }

    // UintToAddressMap

    struct UintToAddressMap {
        Map _inner;
    }

    /**
     * @dev Adds a key-value pair to a map, or updates the value for an existing
     * key. O(1).
     *
     * Returns true if the key was added to the map, that is if it was not
     * already present.
     */
    function set(UintToAddressMap storage map, uint256 key, address value) internal returns (bool) {
        return _set(map._inner, bytes32(key), bytes32(uint256(uint160(value))));
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the key was removed from the map, that is if it was present.
     */
    function remove(UintToAddressMap storage map, uint256 key) internal returns (bool) {
        return _remove(map._inner, bytes32(key));
    }

    /**
     * @dev Returns true if the key is in the map. O(1).
     */
    function contains(UintToAddressMap storage map, uint256 key) internal view returns (bool) {
        return _contains(map._inner, bytes32(key));
    }

    /**
     * @dev Returns the number of elements in the map. O(1).
     */
    function length(UintToAddressMap storage map) internal view returns (uint256) {
        return _length(map._inner);
    }

   /**
    * @dev Returns the element stored at position `index` in the set. O(1).
    * Note that there are no guarantees on the ordering of values inside the
    * array, and it may change when more values are added or removed.
    *
    * Requirements:
    *
    * - `index` must be strictly less than {length}.
    */
    function at(UintToAddressMap storage map, uint256 index) internal view returns (uint256, address) {
        (bytes32 key, bytes32 value) = _at(map._inner, index);
        return (uint256(key), address(uint160(uint256(value))));
    }

    /**
     * @dev Tries to returns the value associated with `key`.  O(1).
     * Does not revert if `key` is not in the map.
     *
     * _Available since v3.4._
     */
    function tryGet(UintToAddressMap storage map, uint256 key) internal view returns (bool, address) {
        (bool success, bytes32 value) = _tryGet(map._inner, bytes32(key));
        return (success, address(uint160(uint256(value))));
    }

    /**
     * @dev Returns the value associated with `key`.  O(1).
     *
     * Requirements:
     *
     * - `key` must be in the map.
     */
    function get(UintToAddressMap storage map, uint256 key) internal view returns (address) {
        return address(uint160(uint256(_get(map._inner, bytes32(key)))));
    }

    /**
     * @dev Same as {get}, with a custom error message when `key` is not in the map.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryGet}.
     */
    function get(UintToAddressMap storage map, uint256 key, string memory errorMessage) internal view returns (address) {
        return address(uint160(uint256(_get(map._inner, bytes32(key), errorMessage))));
    }
}

// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev Library for managing
 * https://en.wikipedia.org/wiki/Set_(abstract_data_type)[sets] of primitive
 * types.
 *
 * Sets have the following properties:
 *
 * - Elements are added, removed, and checked for existence in constant time
 * (O(1)).
 * - Elements are enumerated in O(n). No guarantees are made on the ordering.
 *
 * ```
 * contract Example {
 *     // Add the library methods
 *     using EnumerableSet for EnumerableSet.AddressSet;
 *
 *     // Declare a set state variable
 *     EnumerableSet.AddressSet private mySet;
 * }
 * ```
 *
 * As of v3.3.0, sets of type `bytes32` (`Bytes32Set`), `address` (`AddressSet`)
 * and `uint256` (`UintSet`) are supported.
 */
library EnumerableSet {
    // To implement this library for multiple types with as little code
    // repetition as possible, we write it in terms of a generic Set type with
    // bytes32 values.
    // The Set implementation uses private functions, and user-facing
    // implementations (such as AddressSet) are just wrappers around the
    // underlying Set.
    // This means that we can only create new EnumerableSets for types that fit
    // in bytes32.

    struct Set {
        // Storage of set values
        bytes32[] _values;

        // Position of the value in the `values` array, plus 1 because index 0
        // means a value is not in the set.
        mapping (bytes32 => uint256) _indexes;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function _add(Set storage set, bytes32 value) private returns (bool) {
        if (!_contains(set, value)) {
            set._values.push(value);
            // The value is stored at length-1, but we add 1 to all indexes
            // and use 0 as a sentinel value
            set._indexes[value] = set._values.length;
            return true;
        } else {
            return false;
        }
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function _remove(Set storage set, bytes32 value) private returns (bool) {
        // We read and store the value's index to prevent multiple reads from the same storage slot
        uint256 valueIndex = set._indexes[value];

        if (valueIndex != 0) { // Equivalent to contains(set, value)
            // To delete an element from the _values array in O(1), we swap the element to delete with the last one in
            // the array, and then remove the last element (sometimes called as 'swap and pop').
            // This modifies the order of the array, as noted in {at}.

            uint256 toDeleteIndex = valueIndex - 1;
            uint256 lastIndex = set._values.length - 1;

            // When the value to delete is the last one, the swap operation is unnecessary. However, since this occurs
            // so rarely, we still do the swap anyway to avoid the gas cost of adding an 'if' statement.

            bytes32 lastvalue = set._values[lastIndex];

            // Move the last value to the index where the value to delete is
            set._values[toDeleteIndex] = lastvalue;
            // Update the index for the moved value
            set._indexes[lastvalue] = toDeleteIndex + 1; // All indexes are 1-based

            // Delete the slot where the moved value was stored
            set._values.pop();

            // Delete the index for the deleted slot
            delete set._indexes[value];

            return true;
        } else {
            return false;
        }
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function _contains(Set storage set, bytes32 value) private view returns (bool) {
        return set._indexes[value] != 0;
    }

    /**
     * @dev Returns the number of values on the set. O(1).
     */
    function _length(Set storage set) private view returns (uint256) {
        return set._values.length;
    }

   /**
    * @dev Returns the value stored at position `index` in the set. O(1).
    *
    * Note that there are no guarantees on the ordering of values inside the
    * array, and it may change when more values are added or removed.
    *
    * Requirements:
    *
    * - `index` must be strictly less than {length}.
    */
    function _at(Set storage set, uint256 index) private view returns (bytes32) {
        require(set._values.length > index, "EnumerableSet: index out of bounds");
        return set._values[index];
    }

    // Bytes32Set

    struct Bytes32Set {
        Set _inner;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function add(Bytes32Set storage set, bytes32 value) internal returns (bool) {
        return _add(set._inner, value);
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function remove(Bytes32Set storage set, bytes32 value) internal returns (bool) {
        return _remove(set._inner, value);
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function contains(Bytes32Set storage set, bytes32 value) internal view returns (bool) {
        return _contains(set._inner, value);
    }

    /**
     * @dev Returns the number of values in the set. O(1).
     */
    function length(Bytes32Set storage set) internal view returns (uint256) {
        return _length(set._inner);
    }

   /**
    * @dev Returns the value stored at position `index` in the set. O(1).
    *
    * Note that there are no guarantees on the ordering of values inside the
    * array, and it may change when more values are added or removed.
    *
    * Requirements:
    *
    * - `index` must be strictly less than {length}.
    */
    function at(Bytes32Set storage set, uint256 index) internal view returns (bytes32) {
        return _at(set._inner, index);
    }

    // AddressSet

    struct AddressSet {
        Set _inner;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function add(AddressSet storage set, address value) internal returns (bool) {
        return _add(set._inner, bytes32(uint256(uint160(value))));
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function remove(AddressSet storage set, address value) internal returns (bool) {
        return _remove(set._inner, bytes32(uint256(uint160(value))));
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function contains(AddressSet storage set, address value) internal view returns (bool) {
        return _contains(set._inner, bytes32(uint256(uint160(value))));
    }

    /**
     * @dev Returns the number of values in the set. O(1).
     */
    function length(AddressSet storage set) internal view returns (uint256) {
        return _length(set._inner);
    }

   /**
    * @dev Returns the value stored at position `index` in the set. O(1).
    *
    * Note that there are no guarantees on the ordering of values inside the
    * array, and it may change when more values are added or removed.
    *
    * Requirements:
    *
    * - `index` must be strictly less than {length}.
    */
    function at(AddressSet storage set, uint256 index) internal view returns (address) {
        return address(uint160(uint256(_at(set._inner, index))));
    }


    // UintSet

    struct UintSet {
        Set _inner;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function add(UintSet storage set, uint256 value) internal returns (bool) {
        return _add(set._inner, bytes32(value));
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function remove(UintSet storage set, uint256 value) internal returns (bool) {
        return _remove(set._inner, bytes32(value));
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function contains(UintSet storage set, uint256 value) internal view returns (bool) {
        return _contains(set._inner, bytes32(value));
    }

    /**
     * @dev Returns the number of values on the set. O(1).
     */
    function length(UintSet storage set) internal view returns (uint256) {
        return _length(set._inner);
    }

   /**
    * @dev Returns the value stored at position `index` in the set. O(1).
    *
    * Note that there are no guarantees on the ordering of values inside the
    * array, and it may change when more values are added or removed.
    *
    * Requirements:
    *
    * - `index` must be strictly less than {length}.
    */
    function at(UintSet storage set, uint256 index) internal view returns (uint256) {
        return uint256(_at(set._inner, index));
    }
}

// SPDX-License-Identifier: MIT
// Written by Tim Kang <> illestrater
// Thought innovation by Monstercat
// Product by universe.xyz

pragma solidity >=0.6.0 <0.8.0;
pragma experimental ABIEncoderV2;

library HelperFunctions {
    function toString(uint256 value) internal pure returns (string memory) {
    if (value == 0) {
        return "0";
    }
    uint256 temp = value;
    uint256 digits;
    while (temp != 0) {
        digits++;
        temp /= 10;
    }
    bytes memory buffer = new bytes(digits);
    uint256 index = digits - 1;
    temp = value;
    while (temp != 0) {
        buffer[index--] = bytes1(uint8(48 + temp % 10));
        temp /= 10;
    }
    return string(buffer);
  }

  function safeParseInt(string memory _a) internal pure returns (uint _parsedInt) {
    return safeParseInt(_a, 0);
  }

  function safeParseInt(string memory _a, uint _b) internal pure returns (uint _parsedInt) {
    bytes memory bresult = bytes(_a);
    uint mint = 0;
    bool decimals = false;
    for (uint i = 0; i < bresult.length; i++) {
      if ((uint(uint8(bresult[i])) >= 48) && (uint(uint8(bresult[i])) <= 57)) {
        if (decimals) {
            if (_b == 0) break;
            else _b--;
        }
        mint *= 10;
        mint += uint(uint8(bresult[i])) - 48;
      } else if (uint(uint8(bresult[i])) == 46) {
        require(!decimals, 'ERR: More than one decimal');
        decimals = true;
      } else {
        revert("ERR: Non-numeral character");
      }
    }
    if (_b > 0) {
      mint *= 10 ** _b;
    }
    return mint;
  }

  function substring(string memory str, uint startIndex, uint endIndex) internal pure returns (string memory) {
    bytes memory strBytes = bytes(str);
    bytes memory result = new bytes(endIndex-startIndex);
    for(uint i = startIndex; i < endIndex; i++) {
        result[i-startIndex] = strBytes[i];
    }
    return string(result);
  }

  function addressToString(address _address) internal pure returns(string memory) {
    bytes32 _bytes = bytes32(uint256(_address));
    bytes memory HEX = "0123456789abcdef";
    bytes memory _string = new bytes(42);
    _string[0] = '0';
    _string[1] = 'x';
    for(uint i = 0; i < 20; i++) {
        _string[2+i*2] = HEX[uint8(_bytes[i + 12] >> 4)];
        _string[3+i*2] = HEX[uint8(_bytes[i + 12] & 0x0f)];
    }
    return string(_string);
  }
}

// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev Interface of the ERC165 standard, as defined in the
 * https://eips.ethereum.org/EIPS/eip-165[EIP].
 *
 * Implementers can declare support of contract interfaces, which can then be
 * queried by others ({ERC165Checker}).
 *
 * For an implementation, see {ERC165}.
 */
interface IERC165 {
    /**
     * @dev Returns true if this contract implements the interface defined by
     * `interfaceId`. See the corresponding
     * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
     * to learn more about how these ids are created.
     *
     * This function call must use less than 30 000 gas.
     */
    function supportsInterface(bytes4 interfaceId) external view returns (bool);
}

// SPDX-License-Identifier: MIT

pragma solidity >=0.6.2 <0.8.0;

import "../../introspection/IERC165.sol";

/**
 * @dev Required interface of an ERC721 compliant contract.
 */
interface IERC721 is IERC165 {
    /**
     * @dev Emitted when `tokenId` token is transferred from `from` to `to`.
     */
    event Transfer(address indexed from, address indexed to, uint256 indexed tokenId);

    /**
     * @dev Emitted when `owner` enables `approved` to manage the `tokenId` token.
     */
    event Approval(address indexed owner, address indexed approved, uint256 indexed tokenId);

    /**
     * @dev Emitted when `owner` enables or disables (`approved`) `operator` to manage all of its assets.
     */
    event ApprovalForAll(address indexed owner, address indexed operator, bool approved);

    /**
     * @dev Returns the number of tokens in ``owner``'s account.
     */
    function balanceOf(address owner) external view returns (uint256 balance);

    /**
     * @dev Returns the owner of the `tokenId` token.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function ownerOf(uint256 tokenId) external view returns (address owner);

    /**
     * @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients
     * are aware of the ERC721 protocol to prevent tokens from being forever locked.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must exist and be owned by `from`.
     * - If the caller is not `from`, it must be have been allowed to move this token by either {approve} or {setApprovalForAll}.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function safeTransferFrom(address from, address to, uint256 tokenId) external;

    /**
     * @dev Transfers `tokenId` token from `from` to `to`.
     *
     * WARNING: Usage of this method is discouraged, use {safeTransferFrom} whenever possible.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must be owned by `from`.
     * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address from, address to, uint256 tokenId) external;

    /**
     * @dev Gives permission to `to` to transfer `tokenId` token to another account.
     * The approval is cleared when the token is transferred.
     *
     * Only a single account can be approved at a time, so approving the zero address clears previous approvals.
     *
     * Requirements:
     *
     * - The caller must own the token or be an approved operator.
     * - `tokenId` must exist.
     *
     * Emits an {Approval} event.
     */
    function approve(address to, uint256 tokenId) external;

    /**
     * @dev Returns the account approved for `tokenId` token.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function getApproved(uint256 tokenId) external view returns (address operator);

    /**
     * @dev Approve or remove `operator` as an operator for the caller.
     * Operators can call {transferFrom} or {safeTransferFrom} for any token owned by the caller.
     *
     * Requirements:
     *
     * - The `operator` cannot be the caller.
     *
     * Emits an {ApprovalForAll} event.
     */
    function setApprovalForAll(address operator, bool _approved) external;

    /**
     * @dev Returns if the `operator` is allowed to manage all of the assets of `owner`.
     *
     * See {setApprovalForAll}
     */
    function isApprovedForAll(address owner, address operator) external view returns (bool);

    /**
      * @dev Safely transfers `tokenId` token from `from` to `to`.
      *
      * Requirements:
      *
      * - `from` cannot be the zero address.
      * - `to` cannot be the zero address.
      * - `tokenId` token must exist and be owned by `from`.
      * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
      * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
      *
      * Emits a {Transfer} event.
      */
    function safeTransferFrom(address from, address to, uint256 tokenId, bytes calldata data) external;
}

// SPDX-License-Identifier: MIT

pragma solidity >=0.6.2 <0.8.0;

import "./IERC721.sol";

/**
 * @title ERC-721 Non-Fungible Token Standard, optional enumeration extension
 * @dev See https://eips.ethereum.org/EIPS/eip-721
 */
interface IERC721Enumerable is IERC721 {

    /**
     * @dev Returns the total amount of tokens stored by the contract.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns a token ID owned by `owner` at a given `index` of its token list.
     * Use along with {balanceOf} to enumerate all of ``owner``'s tokens.
     */
    function tokenOfOwnerByIndex(address owner, uint256 index) external view returns (uint256 tokenId);

    /**
     * @dev Returns a token ID at a given `index` of all the tokens stored by the contract.
     * Use along with {totalSupply} to enumerate all tokens.
     */
    function tokenByIndex(uint256 index) external view returns (uint256);
}

// SPDX-License-Identifier: MIT

pragma solidity >=0.6.2 <0.8.0;

import "./IERC721.sol";

/**
 * @title ERC-721 Non-Fungible Token Standard, optional metadata extension
 * @dev See https://eips.ethereum.org/EIPS/eip-721
 */
interface IERC721Metadata is IERC721 {

    /**
     * @dev Returns the token collection name.
     */
    function name() external view returns (string memory);

    /**
     * @dev Returns the token collection symbol.
     */
    function symbol() external view returns (string memory);

    /**
     * @dev Returns the Uniform Resource Identifier (URI) for `tokenId` token.
     */
    function tokenURI(uint256 tokenId) external view returns (string memory);
}

// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/**
 * @title ERC721 token receiver interface
 * @dev Interface for any contract that wants to support safeTransfers
 * from ERC721 asset contracts.
 */
interface IERC721Receiver {
    /**
     * @dev Whenever an {IERC721} `tokenId` token is transferred to this contract via {IERC721-safeTransferFrom}
     * by `operator` from `from`, this function is called.
     *
     * It must return its Solidity selector to confirm the token transfer.
     * If any other value is returned or the interface is not implemented by the recipient, the transfer will be reverted.
     *
     * The selector can be obtained in Solidity with `IERC721.onERC721Received.selector`.
     */
    function onERC721Received(address operator, address from, uint256 tokenId, bytes calldata data) external returns (bytes4);
}

// SPDX-License-Identifier: MIT
// Written by Tim Kang <> illestrater
// Thought innovation by Monstercat
// Product by universe.xyz

pragma solidity >=0.6.0 <0.8.0;
pragma experimental ABIEncoderV2;

import './LibPackStorage.sol';
import "@openzeppelin/contracts/token/ERC721/IERC721Enumerable.sol";

/// @title Creators can release NFTs with multiple collectibles, across multiple collections/drops, and buyers will receive a random tokenID
/// @notice This interface should be implemented by the Packs contract
/// @dev This interface should be implemented by the Packs contract
interface IPacks is IERC721Enumerable {

  /* 
   * cID refers to collection ID
   * Should not have more than 1000 editions of the same collectible (gas limit recommended, technically can support ~4000 editions)
  */

  /// @notice Transfers contract ownership to DAO / different address
  /// @param _daoAddress The new address
  function transferDAOownership(address payable _daoAddress) external;

  /// @notice Creates a new collection / drop (first collection is created via constructor)
  /// @param _baseURI Base URI (e.g. https://arweave.net/)
  /// @param _editioned Toggle to show edition # in returned metadata
  /// @param _initParams Initialization parameters in array [token price, bulk buy max quantity, start time of sale]
  /// @param _licenseURI Global license URI of collection / drop
  /// @param _mintPass ERC721 contract address to allow 1 free mint prior to sale start time
  /// @param _mintPassDuration Duration before sale start time allowing free mints
  /// @param _mintPassParams Array of params for mintPass [One Per Wallet, Mint Pass ONLY, Mint Pass Free Mint, Mint Pass Burn]
  function createNewCollection(string memory _baseURI, bool _editioned, uint256[] memory _initParams, string[] memory _metadataKeys, string memory _licenseURI, address _mintPass, uint256 _mintPassDuration, bool[] memory _mintPassParams) external;
  
  /// @notice Add multiple collectibles in one function call, same parameters as addCollectible but in array
  /// @param cID Collection ID
  /// @param _coreData Array of parameters [title, description, # of NFTs, current artwork version index starting 1]
  /// @param _editions Number of NFTs per asset
  /// @param _assets Array of artwork assets, starting index 0 indicative of version 1
  /// @param _metadataValues Array of key value pairs for property name and value
  /// @param _fees Array of different percentage payout splits on secondary sales
  function bulkAddCollectible(uint256 cID, string[][] memory _coreData, uint16[] memory _editions, string[][] memory _assets, LibPackStorage.MetadataStore[][] memory _metadataValues, LibPackStorage.Fee[][] memory _fees) external;
  
  /// @notice Mints an NFT with random token ID
  /// @param cID Collection ID
  /// @param mintPassTokenId Provide token ID to use as mint pass if appicable
  function mintPack(uint256 cID, uint256 mintPassTokenId) external payable;

  /// @notice Mints multiple NFTs with random token IDs
  /// @param cID Collection ID
  /// @param amount # of NFTs to mint
  function bulkMintPack(uint256 cID, uint256 amount) external payable;

  /// @notice Returns if an NFT was used as mint pass claim
  /// @param cID Collection ID
  /// @param tokenId NFT tokenID
  function mintPassClaimed(uint256 cID, uint256 tokenId) external view returns (bool);

  /// @notice Returns remaining NFTs available to purchase
  /// @param cID Collection ID
  function remainingTokens(uint256 cID) external view returns (uint256);

  /// @notice Updates metadata value given property is editable
  /// @param cID Collection ID
  /// @param collectibleId Collectible index (value 1 is index 0)
  /// @param propertyIndex Index of property to update (value 0 is index 0)
  /// @param value Value of property to update
  function updateMetadata(uint256 cID, uint256 collectibleId, uint256 propertyIndex, string memory value) external;

  /// @notice Adds new URI version with provided asset
  /// @param cID Collection ID
  /// @param collectibleId Collectible index (value 1 is index 0)
  /// @param asset Asset hash without baseURI included
  function addVersion(uint256 cID, uint256 collectibleId, string memory asset) external;

  /// @notice Adds new license URL for collection, auto increments license version number
  /// @param cID Collection ID
  /// @param _license Full URL of license
  function addNewLicense(uint256 cID, string memory _license) external;

  /// @notice Gets license given a license version
  /// @param cID Collection ID
  /// @param versionNumber Version number of license
  function getLicense(uint256 cID, uint256 versionNumber) external view returns (string memory);

  /// @notice Returns number of collections
  function getCollectionCount() external view returns (uint256);

    /// @notice Returns collection configured settings
  function getCollectionInfo(uint256 cID) external view returns (string memory);

  /// @notice Dynamically generates tokenURI as base64 encoded JSON of on-chain metadata
  /// @param tokenId NFT/Token ID number
  function tokenURI(uint256 tokenId) external view returns (string memory);

  /// @notice Returns addresses of secondary sale fees (Rarible Royalties Standard)
  /// @param tokenId NFT/Token ID number
  function getFeeRecipients(uint256 tokenId) external view returns (address payable[] memory);

  /// @notice Returns basis point values of secondary sale fees (Rarible Royalties Standard)
  /// @param tokenId NFT/Token ID number
  function getFeeBps(uint256 tokenId) external view returns (uint256[] memory);

  /// @notice Returns address and value of secondary sale fee (EIP-2981 royalties standard)
  /// @param tokenId NFT/Token ID number
  /// @param value ETH/ERC20 value to calculate from
  function royaltyInfo(uint256 tokenId, uint256 value) external view returns (address recipient, uint256 amount);
}

// SPDX-License-Identifier: MIT
// Written by Tim Kang <> illestrater
// Thought innovation by Monstercat
// Product by universe.xyz

pragma solidity >=0.6.0 <0.8.0;
pragma experimental ABIEncoderV2;

import "@openzeppelin/contracts/math/SafeMath.sol";
import "@openzeppelin/contracts/token/ERC721/ERC721.sol";
import 'base64-sol/base64.sol';
import './HelperFunctions.sol';

library LibPackStorage {
  using SafeMath for uint256;

  bytes32 constant STORAGE_POSITION = keccak256("com.universe.packs.storage");

  struct Fee {
    address payable recipient;
    uint256 value;
  }

  struct SingleCollectible {
    uint16 count; // Amount of editions per collectible
    uint16 totalVersionCount; // Total number of existing states
    uint16 currentVersion; // Current existing state
    string title; // Collectible name
    string description; // Collectible description
    string[] assets; // Each asset in array is a version
  }

  struct Metadata {
    uint8[] name; // Trait or attribute property field name
    string[] value; // Trait or attribute property value
    bool[] modifiable; // Can owner modify the value of field
    uint16 propertyCount; // Tracker of total attributes
  }

  struct MetadataStore {
    uint8 propertyKey;
    string value;
    bool modifiable;
  }

  struct Collection {
    uint16 collectibleCount; // Total unique assets count
    uint16 bulkBuyLimit;
    uint16 licenseVersion; // Tracker of latest license
    uint256 totalTokenCount; // Total NFT count to be minted
    uint256 tokenPrice;
    uint256 saleStartTime;

    string baseURI; // Token ID base URL

    bool initialized;
    bool editioned; // Display edition # in token name
    bool mintPass;
    bool mintPassOnly;
    bool mintPassFree;
    bool mintPassBurn;
    uint256 mintPassDuration;

    address mintPassAddress;
    ERC721 mintPassContract;
    uint32[] shuffleIDs;

    uint16 metadataKeysLength;

    mapping (uint256 => SingleCollectible) collectibles; // Unique assets
    mapping (uint256 => string) metadataKeys;
    mapping (uint256 => Metadata) metadata; // Trait & property attributes, indexes should be coupled with 'collectibles'
    mapping (uint256 => Fee[]) secondaryFees;
    mapping (uint256 => string) licenseURI; // URL to external license or file
    mapping (uint256 => bool) mintPassClaims;
  }

  struct Storage {
    address relicsAddress;
    address payable daoAddress;
    bool daoInitialized;

    uint256 collectionCount;

    mapping (uint256 => Collection) collection;
  }

  function packStorage() internal pure returns (Storage storage ds) {
    bytes32 position = STORAGE_POSITION;
    assembly {
      ds.slot := position
    }
  }

  event LogMintPack(
    address minter,
    uint256 tokenID
  );

  event LogCreateNewCollection(
    uint256 index
  );

  event LogAddCollectible(
    uint256 cID,
    string title
  );

  event LogUpdateMetadata(
    uint256 cID,
    uint256 collectibleId,
    uint256 propertyIndex,
    string value
  );

  event LogAddVersion(
    uint256 cID,
    uint256 collectibleId,
    string asset
  );

  event LogUpdateVersion(
    uint256 cID,
    uint256 collectibleId,
    uint256 versionNumber
  );

  event LogAddNewLicense(
    uint256 cID,
    string license
  );

  function random(uint256 cID) internal view returns (uint) {
    return uint(keccak256(abi.encodePacked(block.difficulty, block.timestamp, packStorage().collection[cID].totalTokenCount)));
  }

  function randomTokenID(address relics, uint256 cID) external relicSafety(relics) returns (uint256, uint256) {
    Storage storage ds = packStorage();

    uint256 randomID = random(cID) % ds.collection[cID].shuffleIDs.length;
    uint256 tokenID = ds.collection[cID].shuffleIDs[randomID];

    emit LogMintPack(msg.sender, tokenID);

    return (randomID, tokenID);
  }

  modifier onlyDAO() {
    require(msg.sender == packStorage().daoAddress, "Wrong address");
    _;
  }

  modifier relicSafety(address relics) {
    Storage storage ds = packStorage();
    require(relics == ds.relicsAddress);
    _;
  }

  /**
   * Map token order w/ URI upon mints
   * Sample token ID (edition #77) with collection of 12 different assets: 1200077
   */
  function createTokenIDs(uint256 cID, uint256 collectibleCount, uint16 editions) private {
    Storage storage ds = packStorage();

    for (uint16 i = 0; i < editions; i++) {
      uint32 tokenID = uint32((cID + 1) * 100000000) + uint32((collectibleCount + 1) * 100000) + uint32(i + 1);
      ds.collection[cID].shuffleIDs.push(tokenID);
    }
  }

  function createNewCollection(
    string memory _baseURI,
    bool _editioned,
    uint256[] memory _initParams,
    string[] memory _metadataKeys,
    string memory _licenseURI,
    address _mintPass,
    uint256 _mintPassDuration,
    bool[] memory _mintPassParams
  ) external onlyDAO {
    require(_initParams[1] <= 50, "Limit of 50");
    Storage storage ds = packStorage();

    ds.collection[ds.collectionCount].baseURI = _baseURI;
    ds.collection[ds.collectionCount].editioned = _editioned;
    ds.collection[ds.collectionCount].tokenPrice = _initParams[0];
    ds.collection[ds.collectionCount].bulkBuyLimit = uint16(_initParams[1]);
    ds.collection[ds.collectionCount].saleStartTime = _initParams[2];
    ds.collection[ds.collectionCount].licenseURI[0] = _licenseURI;
    ds.collection[ds.collectionCount].licenseVersion = 1;

    if (_mintPass != address(0)) {
      ds.collection[ds.collectionCount].mintPass = true;
      ds.collection[ds.collectionCount].mintPassAddress = _mintPass;
      ds.collection[ds.collectionCount].mintPassContract = ERC721(_mintPass);
      ds.collection[ds.collectionCount].mintPassDuration = _mintPassDuration;
      ds.collection[ds.collectionCount].mintPassOnly = _mintPassParams[0];
      ds.collection[ds.collectionCount].mintPassFree = _mintPassParams[1];
      ds.collection[ds.collectionCount].mintPassBurn = _mintPassParams[2];
    } else {
      ds.collection[ds.collectionCount].mintPass = false;
      ds.collection[ds.collectionCount].mintPassDuration = 0;
      ds.collection[ds.collectionCount].mintPassOnly = false;
      ds.collection[ds.collectionCount].mintPassFree = false;
      ds.collection[ds.collectionCount].mintPassBurn = false;
    }

    for (uint8 i; i < _metadataKeys.length; i++) {
      ds.collection[ds.collectionCount].metadataKeys[i] = _metadataKeys[i];
    }

    ds.collection[ds.collectionCount].metadataKeysLength = uint16(_metadataKeys.length);

    ds.collectionCount++;

    emit LogCreateNewCollection(ds.collectionCount);
  }

  // Add single collectible asset with main info and metadata properties
  function addCollectible(uint256 cID, string[] memory _coreData, uint16 _editions, string[] memory _assets, MetadataStore[] memory _metadataValues, Fee[] memory _fees) external onlyDAO {
    Storage storage ds = packStorage();

    Collection storage collection = ds.collection[cID];
    uint256 collectibleCount = collection.collectibleCount;

    uint256 sum = 0;
    for (uint256 i = 0; i < _fees.length; i++) {
      require(_fees[i].recipient != address(0x0), "No recipient");
      require(_fees[i].value != 0, "Fee negative");
      collection.secondaryFees[collectibleCount].push(Fee({
        recipient: _fees[i].recipient,
        value: _fees[i].value
      }));
      sum = sum.add(_fees[i].value);
    }

    require(sum < 10000, "Fee GT 100%");
    require(_editions > 0, "GT 0");

    collection.collectibles[collectibleCount] = SingleCollectible({
      title: _coreData[0],
      description: _coreData[1],
      count: _editions,
      currentVersion: uint16(_assets.length),
      assets: _assets,
      totalVersionCount: uint16(_assets.length)
    });

    uint8[] memory propertyNames = new uint8[](_metadataValues.length);
    string[] memory propertyValues = new string[](_metadataValues.length);
    bool[] memory modifiables = new bool[](_metadataValues.length);
    for (uint256 i = 0; i < _metadataValues.length; i++) {
      propertyNames[i] = _metadataValues[i].propertyKey;
      propertyValues[i] = _metadataValues[i].value;
      modifiables[i] = _metadataValues[i].modifiable; // 1 is modifiable, 0 is permanent
    }

    collection.metadata[collectibleCount] = Metadata({
      name: propertyNames,
      value: propertyValues,
      modifiable: modifiables,
      propertyCount: uint16(_metadataValues.length)
    });

    uint16 editions = _editions;
    createTokenIDs(cID, collectibleCount, editions);

    collection.collectibleCount++;
    collection.totalTokenCount = collection.totalTokenCount.add(editions);

    emit LogAddCollectible(cID, _coreData[0]);
  }

  function checkTokensForMintPass(uint256 cID, uint256 mintPassTokenId, address minter) private returns (bool) {
    Storage storage ds = packStorage();
    if (ds.collection[cID].mintPassContract.ownerOf(mintPassTokenId) == minter &&
        ds.collection[cID].mintPassClaims[mintPassTokenId] != true) {
      ds.collection[cID].mintPassClaims[mintPassTokenId] = true;
      if (ds.collection[cID].mintPassBurn) ds.collection[cID].mintPassContract.safeTransferFrom(msg.sender, address(0xdEaD), mintPassTokenId);
      return true;
    } else return false;
  }

  function checkMintPass(address relics, uint256 cID, uint256 mintPassTokenId, address users) external relicSafety(relics) returns (bool) {
    Storage storage ds = packStorage();

    bool canMintPass = false;
    if (ds.collection[cID].mintPass && checkTokensForMintPass(cID, mintPassTokenId, users)) canMintPass = true;

    if (ds.collection[cID].mintPassOnly) {
      require(canMintPass, "Mint pass only");
      require(block.timestamp > ds.collection[cID].saleStartTime - ds.collection[cID].mintPassDuration, "ERR: Sale start");
    } else {
      if (canMintPass) require (block.timestamp > (ds.collection[cID].saleStartTime - ds.collection[cID].mintPassDuration), "ERR: Sale start");
      else require(block.timestamp > ds.collection[cID].saleStartTime, "ERR: Sale start");
    }

    return canMintPass;
  }

  function bulkMintChecks(uint256 cID, uint256 amount) external {
    Storage storage ds = packStorage();

    require(amount > 0, 'Missing amount');
    require(!ds.collection[cID].mintPassOnly, 'Mint pass only');
    require(amount <= ds.collection[cID].bulkBuyLimit, "Over limit");
    require(amount <= ds.collection[cID].shuffleIDs.length, "Total supply reached");
    require((block.timestamp > ds.collection[cID].saleStartTime), "ERR: Sale start");
  }

  function mintPassClaimed(uint256 cID, uint256 tokenId) public view returns (bool) {
    Storage storage ds = packStorage();
    return (ds.collection[cID].mintPassClaims[tokenId] == true);
  }

  function remainingTokens(uint256 cID) public view returns (uint256) {
    Storage storage ds = packStorage();
    return ds.collection[cID].shuffleIDs.length;
  }

  // Modify property field only if marked as updateable
  function updateMetadata(uint256 cID, uint256 collectibleId, uint256 propertyIndex, string memory value) external onlyDAO {
    Storage storage ds = packStorage();
    require(ds.collection[cID].metadata[collectibleId - 1].modifiable[propertyIndex], 'Uneditable');
    ds.collection[cID].metadata[collectibleId - 1].value[propertyIndex] = value;
    emit LogUpdateMetadata(cID, collectibleId, propertyIndex, value);
  }

  // Add new asset, does not automatically increase current version
  function addVersion(uint256 cID, uint256 collectibleId, string memory asset) public onlyDAO {
    Storage storage ds = packStorage();
    ds.collection[cID].collectibles[collectibleId - 1].assets[ds.collection[cID].collectibles[collectibleId - 1].totalVersionCount - 1] = asset;
    ds.collection[cID].collectibles[collectibleId - 1].totalVersionCount++;
    emit LogAddVersion(cID, collectibleId, asset);
  }

  // Adds new license and updates version to latest
  function addNewLicense(uint256 cID, string memory _license) public onlyDAO {
    Storage storage ds = packStorage();
    require(cID < ds.collectionCount, 'ID DNE');
    ds.collection[cID].licenseURI[ds.collection[cID].licenseVersion] = _license;
    ds.collection[cID].licenseVersion++;
    emit LogAddNewLicense(cID, _license);
  }

  function getLicense(uint256 cID, uint256 versionNumber) public view returns (string memory) {
    Storage storage ds = packStorage();
    return ds.collection[cID].licenseURI[versionNumber - 1];
  }

  function getCurrentLicense(uint256 cID) public view returns (string memory) {
    Storage storage ds = packStorage();
    return ds.collection[cID].licenseURI[ds.collection[cID].licenseVersion - 1];
  }

  function getCollectionInfo(uint256 cID) public view returns (string memory) {
    Storage storage ds = packStorage();
    
    string memory encodedMetadata = '';
    for (uint i = 0; i < ds.collection[cID].metadataKeysLength; i++) {
      encodedMetadata = string(abi.encodePacked(
        encodedMetadata,
        '{"index":"',
        HelperFunctions.toString(i),
        '", "name":"',
        ds.collection[cID].metadataKeys[i],
        '"}',
        i == ds.collection[cID].metadataKeysLength - 1 ? '' : ',')
      );
    }

    return string(
      abi.encodePacked(
        '{"weiPrice": "',
        HelperFunctions.toString(ds.collection[cID].tokenPrice),
        '", "saleStart": "',
        HelperFunctions.toString(ds.collection[cID].saleStartTime),
        '", "mintPass": "',
        ds.collection[cID].mintPass ? 'true' : 'false',
        '", "passAddress": "',
        HelperFunctions.addressToString(ds.collection[cID].mintPassAddress),
        '", "passDuration": "',
        HelperFunctions.toString(ds.collection[cID].mintPassDuration),
        '", "passOnly": "',
        ds.collection[cID].mintPassOnly ? 'true' : 'false',
        '", "passBurn": "',
        ds.collection[cID].mintPassBurn ? 'true' : 'false',
        '", "metadata": [',
          encodedMetadata,
        '] }'
      )
    );
  }

  // Dynamic base64 encoded metadata generation using on-chain metadata and edition numbers
  function tokenURI(uint256 tokenId) public view returns (string memory) {
    Storage storage ds = packStorage();

    uint256 edition = HelperFunctions.safeParseInt(HelperFunctions.substring(HelperFunctions.toString(tokenId), bytes(HelperFunctions.toString(tokenId)).length - 5, bytes(HelperFunctions.toString(tokenId)).length)) - 1;
    uint256 collectibleId = HelperFunctions.safeParseInt(HelperFunctions.substring(HelperFunctions.toString(tokenId), bytes(HelperFunctions.toString(tokenId)).length - 8, bytes(HelperFunctions.toString(tokenId)).length - 5)) - 1;
    uint256 cID = ((tokenId - ((collectibleId + 1) * 100000)) - (edition + 1)) / 100000000 - 1;
    string memory encodedMetadata = '';

    Collection storage collection = ds.collection[cID];

    for (uint i = 0; i < collection.metadata[collectibleId].propertyCount; i++) {
      encodedMetadata = string(abi.encodePacked(
        encodedMetadata,
        '{"trait_type":"',
        collection.metadataKeys[collection.metadata[collectibleId].name[i]],
        '", "value":"',
        collection.metadata[collectibleId].value[i],
        '", "permanent":"',
        collection.metadata[collectibleId].modifiable[i] ? 'false' : 'true',
        '"}',
        i == collection.metadata[collectibleId].propertyCount - 1 ? '' : ',')
      );
    }

    SingleCollectible storage collectible = collection.collectibles[collectibleId];
    uint256 asset = collectible.currentVersion - 1;
    string memory encoded = string(
        abi.encodePacked(
          'data:application/json;base64,',
          Base64.encode(
            bytes(
              abi.encodePacked(
                '{"name":"',
                collectible.title,
                collection.editioned ? ' #' : '',
                collection.editioned ? HelperFunctions.toString(edition + 1) : '',
                '", "description":"',
                collectible.description,
                '", "image": "',
                collection.baseURI,
                collectible.assets[asset],
                '", "license": "',
                getCurrentLicense(cID),
                '", "attributes": [',
                encodedMetadata,
                '] }'
              )
            )
          )
        )
      );

    return encoded;
  }

  // Secondary sale fees apply to each individual collectible ID (will apply to a range of tokenIDs);
  function getFeeRecipients(uint256 tokenId) public view returns (address payable[] memory) {
    Storage storage ds = packStorage();

    uint256 edition = HelperFunctions.safeParseInt(HelperFunctions.substring(HelperFunctions.toString(tokenId), bytes(HelperFunctions.toString(tokenId)).length - 5, bytes(HelperFunctions.toString(tokenId)).length)) - 1;
    uint256 collectibleId = HelperFunctions.safeParseInt(HelperFunctions.substring(HelperFunctions.toString(tokenId), bytes(HelperFunctions.toString(tokenId)).length - 8, bytes(HelperFunctions.toString(tokenId)).length - 5)) - 1;
    uint256 cID = ((tokenId - ((collectibleId + 1) * 100000)) - (edition + 1)) / 100000000 - 1;
    Fee[] memory _fees = ds.collection[cID].secondaryFees[collectibleId];
    address payable[] memory result = new address payable[](_fees.length);
    for (uint i = 0; i < _fees.length; i++) {
      result[i] = _fees[i].recipient;
    }
    return result;
  }

  function getFeeBps(uint256 tokenId) public view returns (uint[] memory) {
    Storage storage ds = packStorage();

    uint256 edition = HelperFunctions.safeParseInt(HelperFunctions.substring(HelperFunctions.toString(tokenId), bytes(HelperFunctions.toString(tokenId)).length - 5, bytes(HelperFunctions.toString(tokenId)).length)) - 1;
    uint256 collectibleId = HelperFunctions.safeParseInt(HelperFunctions.substring(HelperFunctions.toString(tokenId), bytes(HelperFunctions.toString(tokenId)).length - 8, bytes(HelperFunctions.toString(tokenId)).length - 5)) - 1;
    uint256 cID = ((tokenId - ((collectibleId + 1) * 100000)) - (edition + 1)) / 100000000 - 1;
    Fee[] memory _fees = ds.collection[cID].secondaryFees[collectibleId];
    uint[] memory result = new uint[](_fees.length);
    for (uint i = 0; i < _fees.length; i++) {
      result[i] = _fees[i].value;
    }

    return result;
  }

  function royaltyInfo(uint256 tokenId, uint256 value) public view returns (address recipient, uint256 amount){
    address payable[] memory rec = getFeeRecipients(tokenId);
    require(rec.length <= 1, "More than 1 royalty recipient");

    if (rec.length == 0) return (address(this), 0);
    return (rec[0], getFeeBps(tokenId)[0] * value / 10000);
  }
}

// SPDX-License-Identifier: MIT
// Written by Tim Kang <> illestrater
// Thought innovation by Monstercat
// Product by universe.xyz

pragma solidity >=0.6.0 <0.8.0;
pragma experimental ABIEncoderV2;

import "@openzeppelin/contracts/math/SafeMath.sol";
import "@openzeppelin/contracts/utils/ReentrancyGuard.sol";
import "@openzeppelin/contracts/token/ERC721/ERC721.sol";
import "./IPacks.sol";
import "./LibPackStorage.sol";

contract Packs is IPacks, ERC721, ReentrancyGuard {
  using SafeMath for uint256;

  constructor(
    string memory name,
    string memory symbol,
    string memory _baseURI,
    bool _editioned,
    uint256[] memory _initParams,
    string[] memory _metadataKeys,
    string memory _licenseURI,
    address _mintPass,
    uint256 _mintPassDuration,
    bool[] memory _mintPassParams
  ) ERC721(name, symbol) {
    LibPackStorage.Storage storage ds = LibPackStorage.packStorage();

    ds.relicsAddress = address(this);
    ds.daoAddress = msg.sender;
    ds.daoInitialized = true;
    ds.collectionCount = 0;

    createNewCollection(_baseURI, _editioned, _initParams, _metadataKeys, _licenseURI, _mintPass, _mintPassDuration, _mintPassParams);

    _setBaseURI(_baseURI);
  }

  bytes4 private constant _INTERFACE_ID_ROYALTIES_RARIBLE = 0xb7799584;
  bytes4 private constant _INTERFACE_ID_ROYALTIES_EIP2981 = 0x2a55205a;

  function supportsInterface(bytes4 interfaceId) public view virtual override(ERC165, IERC165) returns (bool) {
    return interfaceId == _INTERFACE_ID_ROYALTIES_RARIBLE || interfaceId == _INTERFACE_ID_ROYALTIES_EIP2981 || super.supportsInterface(interfaceId);
  }

  modifier onlyDAO() {
    LibPackStorage.Storage storage ds = LibPackStorage.packStorage();
    require(msg.sender == ds.daoAddress, "Wrong address");
    _;
  }

  function transferDAOownership(address payable _daoAddress) public override onlyDAO {
    LibPackStorage.Storage storage ds = LibPackStorage.packStorage();
    ds.daoAddress = _daoAddress;
    ds.daoInitialized = true;
  }

  function createNewCollection(string memory _baseURI, bool _editioned, uint256[] memory _initParams, string[] memory _metadataKeys, string memory _licenseURI, address _mintPass, uint256 _mintPassDuration, bool[] memory _mintPassParams) public override onlyDAO {
    LibPackStorage.createNewCollection(_baseURI, _editioned, _initParams, _metadataKeys, _licenseURI, _mintPass, _mintPassDuration, _mintPassParams);
  }

  function bulkAddCollectible(uint256 cID, string[][] memory _coreData, uint16[] memory _editions, string[][] memory _assets, LibPackStorage.MetadataStore[][] memory _metadataValues, LibPackStorage.Fee[][] memory _fees) public override onlyDAO {
    for (uint256 i = 0; i < _coreData.length; i++) {
      LibPackStorage.addCollectible(cID, _coreData[i], _editions[i], _assets[i], _metadataValues[i], _fees[i]);
    }
  }

  function randomTokenID(uint256 cID) private returns (uint256) {
    LibPackStorage.Storage storage ds = LibPackStorage.packStorage();

    (uint256 randomID, uint256 tokenID) = LibPackStorage.randomTokenID(address(this), cID);

    ds.collection[cID].shuffleIDs[randomID] = ds.collection[cID].shuffleIDs[ds.collection[cID].shuffleIDs.length - 1];
    ds.collection[cID].shuffleIDs.pop();

    return tokenID;
  }

  function mintPack(uint256 cID, uint256 mintPassTokenId) public override payable nonReentrant {
    LibPackStorage.Storage storage ds = LibPackStorage.packStorage();
    bool canMintPass = LibPackStorage.checkMintPass(address(this), cID, mintPassTokenId, msg.sender);
 
    uint256 excessAmount;
    if (canMintPass && ds.collection[cID].mintPassFree) excessAmount = msg.value.sub(0);
    else excessAmount = msg.value.sub(ds.collection[cID].tokenPrice);

    if (excessAmount > 0) {
      (bool returnExcessStatus, ) = _msgSender().call{value: excessAmount}("");
      require(returnExcessStatus, "Failed to return excess.");
    }

    uint256 tokenID = randomTokenID(cID);
    _mint(_msgSender(), tokenID);
  }

  function bulkMintPack(uint256 cID, uint256 amount) public override payable nonReentrant {
    LibPackStorage.Storage storage ds = LibPackStorage.packStorage();
    LibPackStorage.bulkMintChecks(cID, amount);

    uint256 excessAmount = msg.value.sub(ds.collection[cID].tokenPrice.mul(amount));
    if (excessAmount > 0) {
      (bool returnExcessStatus, ) = _msgSender().call{value: excessAmount}("");
      require(returnExcessStatus, "Failed to return excess.");
    }

    for (uint256 i = 0; i < amount; i++) {
      uint256 tokenID = randomTokenID(cID);
      _mint(_msgSender(), tokenID);
    }
  }

  function mintPassClaimed(uint256 cID, uint256 tokenId) public override view returns (bool) {
    return LibPackStorage.mintPassClaimed(cID, tokenId);
  }

  function remainingTokens(uint256 cID) public override view returns (uint256) {
    return LibPackStorage.remainingTokens(cID);
  }

  function updateMetadata(uint256 cID, uint256 collectibleId, uint256 propertyIndex, string memory value) public override onlyDAO {
    LibPackStorage.updateMetadata(cID, collectibleId, propertyIndex, value);
  }

  function addVersion(uint256 cID, uint256 collectibleId, string memory asset) public override onlyDAO {
    LibPackStorage.addVersion(cID, collectibleId, asset);
  }

  function addNewLicense(uint256 cID, string memory _license) public override onlyDAO {
    LibPackStorage.addNewLicense(cID, _license);
  }

  function getLicense(uint256 cID, uint256 versionNumber) public override view returns (string memory) {
    return LibPackStorage.getLicense(cID, versionNumber);
  }

  function getCollectionCount() public override view returns (uint256) {
    return LibPackStorage.packStorage().collectionCount;
  }

  function getCollectionInfo(uint256 cID) public override view returns (string memory) {
    return LibPackStorage.getCollectionInfo(cID);
  }

  function tokenURI(uint256 tokenId) public view virtual override(ERC721, IPacks) returns (string memory) {
    return LibPackStorage.tokenURI(tokenId);
  }

  function getFeeRecipients(uint256 tokenId) public override view returns (address payable[] memory) {
    require(_exists(tokenId), "Nonexistent token");
    return LibPackStorage.getFeeRecipients(tokenId);
  }

  function getFeeBps(uint256 tokenId) public override view returns (uint256[] memory) {
    require(_exists(tokenId), "Nonexistent token");
    return LibPackStorage.getFeeBps(tokenId);
  }

  function royaltyInfo(uint256 tokenId, uint256 value) public override view returns (address recipient, uint256 amount){
    require(_exists(tokenId), "Nonexistent token");
    return LibPackStorage.royaltyInfo(tokenId, value);
  }

  function withdraw(address _to, uint amount) public onlyDAO {
    payable(_to).call{value:amount, gas:200000}("");
  }
}

// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev Contract module that helps prevent reentrant calls to a function.
 *
 * Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
 * available, which can be applied to functions to make sure there are no nested
 * (reentrant) calls to them.
 *
 * Note that because there is a single `nonReentrant` guard, functions marked as
 * `nonReentrant` may not call one another. This can be worked around by making
 * those functions `private`, and then adding `external` `nonReentrant` entry
 * points to them.
 *
 * TIP: If you would like to learn more about reentrancy and alternative ways
 * to protect against it, check out our blog post
 * https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
 */
abstract contract ReentrancyGuard {
    // Booleans are more expensive than uint256 or any type that takes up a full
    // word because each write operation emits an extra SLOAD to first read the
    // slot's contents, replace the bits taken up by the boolean, and then write
    // back. This is the compiler's defense against contract upgrades and
    // pointer aliasing, and it cannot be disabled.

    // The values being non-zero value makes deployment a bit more expensive,
    // but in exchange the refund on every call to nonReentrant will be lower in
    // amount. Since refunds are capped to a percentage of the total
    // transaction's gas, it is best to keep them low in cases like this one, to
    // increase the likelihood of the full refund coming into effect.
    uint256 private constant _NOT_ENTERED = 1;
    uint256 private constant _ENTERED = 2;

    uint256 private _status;

    constructor () internal {
        _status = _NOT_ENTERED;
    }

    /**
     * @dev Prevents a contract from calling itself, directly or indirectly.
     * Calling a `nonReentrant` function from another `nonReentrant`
     * function is not supported. It is possible to prevent this from happening
     * by making the `nonReentrant` function external, and make it call a
     * `private` function that does the actual work.
     */
    modifier nonReentrant() {
        // On the first call to nonReentrant, _notEntered will be true
        require(_status != _ENTERED, "ReentrancyGuard: reentrant call");

        // Any calls to nonReentrant after this point will fail
        _status = _ENTERED;

        _;

        // By storing the original value once again, a refund is triggered (see
        // https://eips.ethereum.org/EIPS/eip-2200)
        _status = _NOT_ENTERED;
    }
}

// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        uint256 c = a + b;
        if (c < a) return (false, 0);
        return (true, c);
    }

    /**
     * @dev Returns the substraction of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b > a) return (false, 0);
        return (true, a - b);
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
        if (a == 0) return (true, 0);
        uint256 c = a * b;
        if (c / a != b) return (false, 0);
        return (true, c);
    }

    /**
     * @dev Returns the division of two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b == 0) return (false, 0);
        return (true, a / b);
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b == 0) return (false, 0);
        return (true, a % b);
    }

    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");
        return c;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b <= a, "SafeMath: subtraction overflow");
        return a - b;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        if (a == 0) return 0;
        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");
        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b > 0, "SafeMath: division by zero");
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b > 0, "SafeMath: modulo by zero");
        return a % b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {trySub}.
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        return a - b;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryDiv}.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting with custom message when dividing by zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryMod}.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        return a % b;
    }
}

// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev String operations.
 */
library Strings {
    /**
     * @dev Converts a `uint256` to its ASCII `string` representation.
     */
    function toString(uint256 value) internal pure returns (string memory) {
        // Inspired by OraclizeAPI's implementation - MIT licence
        // https://github.com/oraclize/ethereum-api/blob/b42146b063c7d6ee1358846c198246239e9360e8/oraclizeAPI_0.4.25.sol

        if (value == 0) {
            return "0";
        }
        uint256 temp = value;
        uint256 digits;
        while (temp != 0) {
            digits++;
            temp /= 10;
        }
        bytes memory buffer = new bytes(digits);
        uint256 index = digits - 1;
        temp = value;
        while (temp != 0) {
            buffer[index--] = bytes1(uint8(48 + temp % 10));
            temp /= 10;
        }
        return string(buffer);
    }
}

// SPDX-License-Identifier: MIT

/// @title Base64
/// @author Brecht Devos - <brecht@loopring.org>
/// @notice Provides a function for encoding some bytes in base64
library Base64 {
    string internal constant TABLE = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';

    function encode(bytes memory data) internal pure returns (string memory) {
        if (data.length == 0) return '';
        
        // load the table into memory
        string memory table = TABLE;

        // multiply by 4/3 rounded up
        uint256 encodedLen = 4 * ((data.length + 2) / 3);

        // add some extra buffer at the end required for the writing
        string memory result = new string(encodedLen + 32);

        assembly {
            // set the actual output length
            mstore(result, encodedLen)
            
            // prepare the lookup table
            let tablePtr := add(table, 1)
            
            // input ptr
            let dataPtr := data
            let endPtr := add(dataPtr, mload(data))
            
            // result ptr, jump over length
            let resultPtr := add(result, 32)
            
            // run over the input, 3 bytes at a time
            for {} lt(dataPtr, endPtr) {}
            {
               dataPtr := add(dataPtr, 3)
               
               // read 3 bytes
               let input := mload(dataPtr)
               
               // write 4 characters
               mstore(resultPtr, shl(248, mload(add(tablePtr, and(shr(18, input), 0x3F)))))
               resultPtr := add(resultPtr, 1)
               mstore(resultPtr, shl(248, mload(add(tablePtr, and(shr(12, input), 0x3F)))))
               resultPtr := add(resultPtr, 1)
               mstore(resultPtr, shl(248, mload(add(tablePtr, and(shr( 6, input), 0x3F)))))
               resultPtr := add(resultPtr, 1)
               mstore(resultPtr, shl(248, mload(add(tablePtr, and(        input,  0x3F)))))
               resultPtr := add(resultPtr, 1)
            }
            
            // padding with '='
            switch mod(mload(data), 3)
            case 1 { mstore(sub(resultPtr, 2), shl(240, 0x3d3d)) }
            case 2 { mstore(sub(resultPtr, 1), shl(248, 0x3d)) }
        }
        
        return result;
    }
}

{
  "compilationTarget": {
    "contracts/Packs.sol": "Packs"
  },
  "evmVersion": "istanbul",
  "libraries": {
    "LibPackStorage": "0x3e0a32e80e4dbf13c74feb384cce4fbe01d90784"
  },
  "metadata": {
    "bytecodeHash": "ipfs"
  },
  "optimizer": {
    "enabled": false,
    "runs": 200
  },
  "remappings": []
}