the pixels inc

// SPDX-License-Identifier: MIT

pragma solidity ^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;
        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");

        (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");

        (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");

        (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");

        (bool success, bytes memory returndata) = target.delegatecall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason using the provided one.
     *
     * _Available since v4.3._
     */
    function verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal 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

                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

// SPDX-License-Identifier: MIT

pragma solidity ^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 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) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "./IERC165.sol";

/**
 * @dev Implementation of the {IERC165} interface.
 *
 * Contracts that want to implement ERC165 should inherit from this contract and override {supportsInterface} to check
 * for the additional interface id that will be supported. For example:
 *
 * ```solidity
 * function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
 *     return interfaceId == type(MyInterface).interfaceId || super.supportsInterface(interfaceId);
 * }
 * ```
 *
 * Alternatively, {ERC165Storage} provides an easier to use but more expensive implementation.
 */
abstract contract ERC165 is IERC165 {
    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
        return interfaceId == type(IERC165).interfaceId;
    }
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "./IERC721.sol";
import "./IERC721Receiver.sol";
import "./extensions/IERC721Metadata.sol";
import "../../utils/Address.sol";
import "../../utils/Context.sol";
import "../../utils/Strings.sol";
import "../../utils/introspection/ERC165.sol";

/**
 * @dev Implementation of https://eips.ethereum.org/EIPS/eip-721[ERC721] Non-Fungible Token Standard, including
 * the Metadata extension, but not including the Enumerable extension, which is available separately as
 * {ERC721Enumerable}.
 */
contract ERC721 is Context, ERC165, IERC721, IERC721Metadata {
    using Address for address;
    using Strings for uint256;

    // Token name
    string private _name;

    // Token symbol
    string private _symbol;

    // Mapping from token ID to owner address
    mapping(uint256 => address) private _owners;

    // Mapping owner address to token count
    mapping(address => uint256) private _balances;

    // 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;

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

    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override(ERC165, IERC165) returns (bool) {
        return
            interfaceId == type(IERC721).interfaceId ||
            interfaceId == type(IERC721Metadata).interfaceId ||
            super.supportsInterface(interfaceId);
    }

    /**
     * @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 _balances[owner];
    }

    /**
     * @dev See {IERC721-ownerOf}.
     */
    function ownerOf(uint256 tokenId) public view virtual override returns (address) {
        address owner = _owners[tokenId];
        require(owner != address(0), "ERC721: owner query for nonexistent token");
        return owner;
    }

    /**
     * @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 baseURI = _baseURI();
        return bytes(baseURI).length > 0 ? string(abi.encodePacked(baseURI, tokenId.toString())) : "";
    }

    /**
     * @dev Base URI for computing {tokenURI}. If set, the resulting URI for each
     * token will be the concatenation of the `baseURI` and the `tokenId`. Empty
     * by default, can be overriden in child contracts.
     */
    function _baseURI() internal view virtual returns (string memory) {
        return "";
    }

    /**
     * @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 || 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 _owners[tokenId] != address(0);
    }

    /**
     * @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 || isApprovedForAll(owner, spender));
    }

    /**
     * @dev Safely mints `tokenId` and transfers it to `to`.
     *
     * Requirements:
     *
     * - `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);

        _balances[to] += 1;
        _owners[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);

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

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

        _balances[owner] -= 1;
        delete _owners[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");
        require(to != address(0), "ERC721: transfer to the zero address");

        _beforeTokenTransfer(from, to, tokenId);

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

        _balances[from] -= 1;
        _balances[to] += 1;
        _owners[tokenId] = to;

        emit Transfer(from, to, tokenId);
    }

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

    /**
     * @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()) {
            try IERC721Receiver(to).onERC721Received(_msgSender(), from, tokenId, _data) returns (bytes4 retval) {
                return retval == IERC721Receiver.onERC721Received.selector;
            } catch (bytes memory reason) {
                if (reason.length == 0) {
                    revert("ERC721: transfer to non ERC721Receiver implementer");
                } else {
                    assembly {
                        revert(add(32, reason), mload(reason))
                    }
                }
            }
        } else {
            return true;
        }
    }

    /**
     * @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` and `to` are never both zero.
     *
     * 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 ^0.8.0;

import "../ERC721.sol";
import "./IERC721Enumerable.sol";

/**
 * @dev This implements an optional extension of {ERC721} defined in the EIP that adds
 * enumerability of all the token ids in the contract as well as all token ids owned by each
 * account.
 */
abstract contract ERC721Enumerable is ERC721, IERC721Enumerable {
    // Mapping from owner to list of owned token IDs
    mapping(address => mapping(uint256 => uint256)) private _ownedTokens;

    // Mapping from token ID to index of the owner tokens list
    mapping(uint256 => uint256) private _ownedTokensIndex;

    // Array with all token ids, used for enumeration
    uint256[] private _allTokens;

    // Mapping from token id to position in the allTokens array
    mapping(uint256 => uint256) private _allTokensIndex;

    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override(IERC165, ERC721) returns (bool) {
        return interfaceId == type(IERC721Enumerable).interfaceId || super.supportsInterface(interfaceId);
    }

    /**
     * @dev See {IERC721Enumerable-tokenOfOwnerByIndex}.
     */
    function tokenOfOwnerByIndex(address owner, uint256 index) public view virtual override returns (uint256) {
        require(index < ERC721.balanceOf(owner), "ERC721Enumerable: owner index out of bounds");
        return _ownedTokens[owner][index];
    }

    /**
     * @dev See {IERC721Enumerable-totalSupply}.
     */
    function totalSupply() public view virtual override returns (uint256) {
        return _allTokens.length;
    }

    /**
     * @dev See {IERC721Enumerable-tokenByIndex}.
     */
    function tokenByIndex(uint256 index) public view virtual override returns (uint256) {
        require(index < ERC721Enumerable.totalSupply(), "ERC721Enumerable: global index out of bounds");
        return _allTokens[index];
    }

    /**
     * @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 override {
        super._beforeTokenTransfer(from, to, tokenId);

        if (from == address(0)) {
            _addTokenToAllTokensEnumeration(tokenId);
        } else if (from != to) {
            _removeTokenFromOwnerEnumeration(from, tokenId);
        }
        if (to == address(0)) {
            _removeTokenFromAllTokensEnumeration(tokenId);
        } else if (to != from) {
            _addTokenToOwnerEnumeration(to, tokenId);
        }
    }

    /**
     * @dev Private function to add a token to this extension's ownership-tracking data structures.
     * @param to address representing the new owner of the given token ID
     * @param tokenId uint256 ID of the token to be added to the tokens list of the given address
     */
    function _addTokenToOwnerEnumeration(address to, uint256 tokenId) private {
        uint256 length = ERC721.balanceOf(to);
        _ownedTokens[to][length] = tokenId;
        _ownedTokensIndex[tokenId] = length;
    }

    /**
     * @dev Private function to add a token to this extension's token tracking data structures.
     * @param tokenId uint256 ID of the token to be added to the tokens list
     */
    function _addTokenToAllTokensEnumeration(uint256 tokenId) private {
        _allTokensIndex[tokenId] = _allTokens.length;
        _allTokens.push(tokenId);
    }

    /**
     * @dev Private function to remove a token from this extension's ownership-tracking data structures. Note that
     * while the token is not assigned a new owner, the `_ownedTokensIndex` mapping is _not_ updated: this allows for
     * gas optimizations e.g. when performing a transfer operation (avoiding double writes).
     * This has O(1) time complexity, but alters the order of the _ownedTokens array.
     * @param from address representing the previous owner of the given token ID
     * @param tokenId uint256 ID of the token to be removed from the tokens list of the given address
     */
    function _removeTokenFromOwnerEnumeration(address from, uint256 tokenId) private {
        // To prevent a gap in from's tokens array, we store the last token in the index of the token to delete, and
        // then delete the last slot (swap and pop).

        uint256 lastTokenIndex = ERC721.balanceOf(from) - 1;
        uint256 tokenIndex = _ownedTokensIndex[tokenId];

        // When the token to delete is the last token, the swap operation is unnecessary
        if (tokenIndex != lastTokenIndex) {
            uint256 lastTokenId = _ownedTokens[from][lastTokenIndex];

            _ownedTokens[from][tokenIndex] = lastTokenId; // Move the last token to the slot of the to-delete token
            _ownedTokensIndex[lastTokenId] = tokenIndex; // Update the moved token's index
        }

        // This also deletes the contents at the last position of the array
        delete _ownedTokensIndex[tokenId];
        delete _ownedTokens[from][lastTokenIndex];
    }

    /**
     * @dev Private function to remove a token from this extension's token tracking data structures.
     * This has O(1) time complexity, but alters the order of the _allTokens array.
     * @param tokenId uint256 ID of the token to be removed from the tokens list
     */
    function _removeTokenFromAllTokensEnumeration(uint256 tokenId) private {
        // To prevent a gap in the tokens array, we store the last token in the index of the token to delete, and
        // then delete the last slot (swap and pop).

        uint256 lastTokenIndex = _allTokens.length - 1;
        uint256 tokenIndex = _allTokensIndex[tokenId];

        // When the token to delete is the last token, the swap operation is unnecessary. However, since this occurs so
        // rarely (when the last minted token is burnt) that we still do the swap here to avoid the gas cost of adding
        // an 'if' statement (like in _removeTokenFromOwnerEnumeration)
        uint256 lastTokenId = _allTokens[lastTokenIndex];

        _allTokens[tokenIndex] = lastTokenId; // Move the last token to the slot of the to-delete token
        _allTokensIndex[lastTokenId] = tokenIndex; // Update the moved token's index

        // This also deletes the contents at the last position of the array
        delete _allTokensIndex[tokenId];
        _allTokens.pop();
    }
}

// SPDX-License-Identifier: MIT

pragma solidity ^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 ^0.8.0;

import "../../utils/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 ^0.8.0;

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 ^0.8.0;

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 ^0.8.0;

/**
 * @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

// ______  __  __   ______       _____    __  __   _____    ______
// /\__  _\/\ \_\ \ /\  ___\     /\  __-. /\ \/\ \ /\  __-. /\  ___\
// \/_/\ \/\ \  __ \\ \  __\     \ \ \/\ \\ \ \_\ \\ \ \/\ \\ \  __\
//   \ \_\ \ \_\ \_\\ \_____\    \ \____- \ \_____\\ \____- \ \_____\
//    \/_/  \/_/\/_/ \/_____/     \/____/  \/_____/ \/____/  \/_____/
//

pragma solidity ^0.8.0;

interface IThePixelsDNAUpdater {
  function canUpdateDNAExtension(
    address _owner,
    uint256 _tokenId,
    uint256 _dna,
    uint256 _dnaExtension
  ) external view returns (bool);

  function getUpdatedDNAExtension(
    address _owner,
    uint256 _tokenId,
    uint256 _dna,
    uint256 _dnaExtension
  ) external returns (uint256);
}

// SPDX-License-Identifier: MIT

// ______  __  __   ______       _____    __  __   _____    ______
// /\__  _\/\ \_\ \ /\  ___\     /\  __-. /\ \/\ \ /\  __-. /\  ___\
// \/_/\ \/\ \  __ \\ \  __\     \ \ \/\ \\ \ \_\ \\ \ \/\ \\ \  __\
//   \ \_\ \ \_\ \_\\ \_____\    \ \____- \ \_____\\ \____- \ \_____\
//    \/_/  \/_/\/_/ \/_____/     \/____/  \/_____/ \/____/  \/_____/
//

pragma solidity ^0.8.0;

interface IThePixelsMetadataProvider {
  function getMetadata(
    uint256 tokenId,
    uint256 dna,
    uint256 dnaExtension
  ) external view returns (string memory);
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../utils/Context.sol";

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor() {
        _setOwner(_msgSender());
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        _setOwner(address(0));
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _setOwner(newOwner);
    }

    function _setOwner(address newOwner) private {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev String operations.
 */
library Strings {
    bytes16 private constant _HEX_SYMBOLS = "0123456789abcdef";

    /**
     * @dev Converts a `uint256` to its ASCII `string` decimal 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);
        while (value != 0) {
            digits -= 1;
            buffer[digits] = bytes1(uint8(48 + uint256(value % 10)));
            value /= 10;
        }
        return string(buffer);
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
     */
    function toHexString(uint256 value) internal pure returns (string memory) {
        if (value == 0) {
            return "0x00";
        }
        uint256 temp = value;
        uint256 length = 0;
        while (temp != 0) {
            length++;
            temp >>= 8;
        }
        return toHexString(value, length);
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation with fixed length.
     */
    function toHexString(uint256 value, uint256 length) internal pure returns (string memory) {
        bytes memory buffer = new bytes(2 * length + 2);
        buffer[0] = "0";
        buffer[1] = "x";
        for (uint256 i = 2 * length + 1; i > 1; --i) {
            buffer[i] = _HEX_SYMBOLS[value & 0xf];
            value >>= 4;
        }
        require(value == 0, "Strings: hex length insufficient");
        return string(buffer);
    }
}

// SPDX-License-Identifier: MIT

// ______  __  __   ______       _____    __  __   _____    ______
// /\__  _\/\ \_\ \ /\  ___\     /\  __-. /\ \/\ \ /\  __-. /\  ___\
// \/_/\ \/\ \  __ \\ \  __\     \ \ \/\ \\ \ \_\ \\ \ \/\ \\ \  __\
//   \ \_\ \ \_\ \_\\ \_____\    \ \____- \ \_____\\ \____- \ \_____\
//    \/_/  \/_/\/_/ \/_____/     \/____/  \/_____/ \/____/  \/_____/
//

pragma solidity ^0.8.0;
pragma experimental ABIEncoderV2;

import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/token/ERC721/extensions/ERC721Enumerable.sol";
import "@openzeppelin/contracts/token/ERC721/IERC721.sol";

import "./ThePixelsDNAFactory.sol";
import "./IThePixelsMetadataProvider.sol";
import "./IThePixelsDNAUpdater.sol";

contract ThePixels is Ownable, ERC721Enumerable, ThePixelsDNAFactory {
  uint256 public maxPixels;
  uint256 constant public MAX_SPECIAL_PIXELS = 5;

  address public salesContractAddress;
  address public metadataProviderContractAddress;
  address public DNAUpdaterContractAddress;

  mapping (uint256 => bool) public foundDNAs;
  mapping (uint256 => bool) public mintedSpecialDNAs;
  mapping (uint256 => uint256) public pixelDNAs;
  mapping (uint256 => uint256) public pixelDNAExtensions;

  constructor (uint256 _maxPixels) ERC721("the pixels", "TPIX") {
    maxPixels = _maxPixels;
    _setTraitTable();
  }

  function setSalesContract(address _salesContractAddress) external onlyOwner {
    salesContractAddress = _salesContractAddress;
  }

  function setMetadataProviderContract(address _metadataProviderContractAddress) external onlyOwner {
    metadataProviderContractAddress = _metadataProviderContractAddress;
  }

  function setDNAUpdaterContract(address _DNAUpdaterContractAddress) external onlyOwner {
    DNAUpdaterContractAddress = _DNAUpdaterContractAddress;
  }

  function mintSpecialPixelDNA(uint256 index, uint256 _salt) external onlyOwner {
    require(index >= 0 && index < MAX_SPECIAL_PIXELS, "Invalid index");
    require(!mintedSpecialDNAs[index], "Already minted");
    uint256 totalSupply = totalSupply();
    uint256 winnerTokenIndex = _rnd(_salt, index) % totalSupply;
    address winnerAddress = ownerOf(winnerTokenIndex);
    pixelDNAs[totalSupply] = index;
    mintedSpecialDNAs[index] = true;
    _safeMint(winnerAddress, totalSupply);
  }

  function mint(address to, uint256 salt, uint256 _nonce) external {
    require(msg.sender == salesContractAddress, "Well, there is a reason only sale contract can do this.");
    uint256 totalSupply = totalSupply();
    require(totalSupply < maxPixels, "Hit the limit");
    _mintWithUniqueDNA(to, totalSupply, salt, _nonce);
  }

  function _mintWithUniqueDNA(address _to, uint256 _tokenId, uint256 _salt, uint256 _nonce) internal {
    uint256 uniqueDNA = _getUniqueDNA(_salt, _nonce);
    pixelDNAs[_tokenId] = uniqueDNA;
    _safeMint(_to, _tokenId);
  }

  function _getUniqueDNA(uint256 _salt, uint256 _nonce) internal returns (uint256) {
    uint256 generationAttempt = 0;
    while(true) {
      uint256 extendedDNA = getEncodedRandomDNA(_salt, _nonce + generationAttempt);
      if (foundDNAs[extendedDNA] == false) {
        foundDNAs[extendedDNA] = true;
        return extendedDNA;
      }
      generationAttempt++;
    }
  }

  function getEncodedRandomDNA(uint256 _salt, uint256 _nonce) internal view returns (uint256) {
    uint8[11] memory foundDNA = _getRandomDNA(_salt, _nonce);
    uint256 encodedDNA = 10 ** (foundDNA.length * 2 + 1);
    for(uint256 i=0; i<foundDNA.length; i++) {
      encodedDNA += foundDNA[i] * (10 ** ((foundDNA.length - i) * 2));
    }
    return encodedDNA;
  }

  function tokenURI(uint256 _tokenId) public view virtual override returns (string memory) {
    require(_exists(_tokenId), "ERC721Metadata: URI query for nonexistent token");
    require(metadataProviderContractAddress != address(0), "Invalid metadata provider address");

    return IThePixelsMetadataProvider(metadataProviderContractAddress)
      .getMetadata(
        _tokenId,
        pixelDNAs[_tokenId],
        pixelDNAExtensions[_tokenId]
      );
  }

  function tokensOfOwner(address _owner) public view returns (uint256[] memory) {
    uint256 tokenCount = balanceOf(_owner);
    if (tokenCount == 0) {
      return new uint256[](0);
    } else {
      uint256[] memory result = new uint256[](tokenCount);
      uint256 index;
      for (index = 0; index < tokenCount; index++) {
        result[index] = tokenOfOwnerByIndex(_owner, index);
      }
      return result;
    }
  }

  function updateDNAExtension(uint256 _tokenId) external {
    require(DNAUpdaterContractAddress != address(0), "Invalid updater address");
    require(msg.sender == ownerOf(_tokenId), "You need to own the token to update");

    uint256 newDNAExtension = IThePixelsDNAUpdater(DNAUpdaterContractAddress).getUpdatedDNAExtension(
      msg.sender,
      _tokenId,
      pixelDNAs[_tokenId],
      pixelDNAExtensions[_tokenId]
    );
    pixelDNAExtensions[_tokenId] = newDNAExtension;
  }
}

// SPDX-License-Identifier: MIT

// ______  __  __   ______       _____    __  __   _____    ______
// /\__  _\/\ \_\ \ /\  ___\     /\  __-. /\ \/\ \ /\  __-. /\  ___\
// \/_/\ \/\ \  __ \\ \  __\     \ \ \/\ \\ \ \_\ \\ \ \/\ \\ \  __\
//   \ \_\ \ \_\ \_\\ \_____\    \ \____- \ \_____\\ \____- \ \_____\
//    \/_/  \/_/\/_/ \/_____/     \/____/  \/_____/ \/____/  \/_____/
//

pragma solidity ^0.8.0;
pragma experimental ABIEncoderV2;

contract ThePixelsDNAFactory {
  uint8 constant internal maxRarityScore = 101;

  uint8 constant internal themePastelRarity = 0;
  uint8 constant internal themeZombieRarity = 80;
  uint8 constant internal themeAlienRarity = 95;

  uint8 constant internal baseDNARarity = 99;
  uint8 constant internal costumeDNARarity = 10;

  mapping (uint8 => uint8[]) public traitTable;
  // Base DNA parts:
  uint8[3] internal themes;
  uint8[18] internal bodies;
  uint8[5] internal faces;
  uint8[8] internal eyes;
  uint8[11] internal noses;
  uint8[9] internal mouths;
  // Dynamic DNA parts:
  uint8[5] internal costumes;           //6 - 1
  uint8[46] internal headAccessories;   //7 - 2
  uint8[18] internal hairs;             //8 - 3
  uint8[25] internal sunglasses;        //9 - 4
  uint8[7] internal facialHairs;        //10 - 5

  function _getRandomDNA(uint256 _seed, uint256 _nonce) internal view returns (uint8[11] memory) {
    uint256 r = _rnd(_seed, _nonce) % maxRarityScore;

    if (r > themeAlienRarity) {
      return _getAlienDNA(_seed, _nonce + 1);
    }else if (r > themeZombieRarity) {
      return _getZombieDNA(_seed, _nonce + 2);
    }else {
      return _getPastelDNA(_seed, _nonce + 3);
    }
  }

  function _getPastelDNA(uint256 _seed, uint256 _nonce) internal view returns (uint8[11] memory) {
    uint256 r = _rnd(_seed, _nonce) % maxRarityScore;
    uint8[11] memory finalDNA = _getBaseDNA(_seed, _nonce + 1, 0);
    uint256 nextNonce = _nonce + 13;

    //99 - 100
    if (r >= baseDNARarity) {
      return finalDNA;

    // 54 - 99
    }else if (r < baseDNARarity && r >= 54) {
      finalDNA[7] = _pickTrait(7, _seed, nextNonce + 2);
      finalDNA[9] = _pickTrait(9, _seed, nextNonce + 3);
      finalDNA[10] = _pickTrait(10, _seed, nextNonce + 4);

    // 54 - 32
    }else if (r < 54 && r >= 32) {
      finalDNA[7] = _pickTrait(7, _seed, nextNonce + 2);
      finalDNA[9] = _pickTrait(9, _seed, nextNonce + 3);

    // 32 - 10
    }else if (r < 32 && r >= costumeDNARarity) {
      finalDNA[8] = _pickTrait(8, _seed, nextNonce + 5);
      finalDNA[9] = _pickTrait(9, _seed, nextNonce + 6);

    // 0 - 10
    }else {
      finalDNA[6] = _pickTrait(6, _seed, nextNonce + 7);
      finalDNA[9] = _pickTrait(9, _seed, nextNonce + 8);
      finalDNA[10] = _pickTrait(10, _seed, nextNonce + 9);
    }
    return finalDNA;
  }

  function _getZombieDNA(uint256 _seed, uint256 _nonce) internal view returns (uint8[11] memory) {
    uint256 r = _rnd(_seed, _nonce) % maxRarityScore;
    uint8[11] memory finalDNA = _getBaseDNA(_seed, _nonce + 1, 1);
    uint256 nextNonce = _nonce + 13;

    if (r >= baseDNARarity) {
      return finalDNA;

    // 54 - 99
    }else if (r < baseDNARarity && r >= 54) {
      finalDNA[7] = _pickTrait(7, _seed, nextNonce + 2);
      finalDNA[9] = _pickTrait(9, _seed, nextNonce + 3);
      finalDNA[10] = _pickTrait(10, _seed, nextNonce + 4);

    // 54 - 32
    }else if (r < 54 && r >= 32) {
      finalDNA[7] = _pickTrait(7, _seed, nextNonce + 2);
      finalDNA[9] = _pickTrait(9, _seed, nextNonce + 3);

    // 32 - 10
    }else if (r < 32 && r >= costumeDNARarity) {
      finalDNA[8] = _pickTrait(8, _seed, nextNonce + 5);
      finalDNA[9] = _pickTrait(9, _seed, nextNonce + 6);

    // 0 - 10
    }else {
      finalDNA[6] = _pickTrait(6, _seed, nextNonce + 7);
      finalDNA[9] = _pickTrait(9, _seed, nextNonce + 8);
      finalDNA[10] = _pickTrait(10, _seed, nextNonce + 9);
    }
    return finalDNA;
  }

  function _getAlienDNA(uint256 _seed, uint256 _nonce) internal view returns (uint8[11] memory) {
    uint256 r = _rnd(_seed, _nonce) % maxRarityScore;
    uint8[11] memory finalDNA = _getBaseDNA(_seed, _nonce + 1, 2);
    uint256 nextNonce = _nonce + 13;

    if (r >= baseDNARarity) {
      return finalDNA;

    }else if (r < baseDNARarity && r >= 50) {
      finalDNA[7] = _pickTrait(7, _seed, nextNonce + 2);

    }else if (r < 50 && r >= costumeDNARarity) {
      finalDNA[8] = _pickTrait(8, _seed, nextNonce + 3);

    }else {
      finalDNA[6] = _pickTrait(6, _seed, nextNonce + 4);
    }
    return finalDNA;
  }

  function _getBaseDNA(uint256 _seed, uint256 _nonce, uint8 _theme) internal view returns (uint8[11] memory) {
    uint8[11] memory dna;
    dna[0] = _theme;
    if (_theme == 2) {
      dna[1] = _pickTrait(1, _seed, _nonce + 1);
      dna[2] = _pickTrait(2, _seed, _nonce + 2);
      dna[3] = 8;
      dna[4] = _pickTrait(4, _seed, _nonce + 4);
      dna[5] = _pickTrait(5, _seed, _nonce + 5);
    }else{
      dna[1] = _pickTrait(1, _seed, _nonce + 6);
      dna[2] = _pickTrait(2, _seed, _nonce + 7);
      dna[3] = _pickTrait(3, _seed, _nonce + 8);
      dna[4] = _pickTrait(4, _seed, _nonce + 9);
      dna[5] = _pickTrait(5, _seed, _nonce + 10);
    }
    return dna;
  }

  function _pickTrait(uint8 traitIndex, uint256 _seed, uint256 _nonce) internal view returns (uint8) {
    uint256 beginIndex = _rnd(_seed, _seed + _nonce + traitIndex);
    uint256 r = beginIndex % maxRarityScore;

    uint8[] memory _traits = traitTable[traitIndex];
    for (uint256 i=beginIndex; i<beginIndex + _traits.length; i++) {
      uint256 index = i % _traits.length;
      if (_traits[index] <= r) {
        return uint8(index);
      }
    }
    return uint8(beginIndex);
  }

  function _setBodyRarities() internal {
    bodies[0] = 0;
    bodies[1] = 0;
    bodies[2] = 10;
    bodies[3] = 95;
    bodies[4] = 15;
    bodies[5] = 0;
    bodies[6] = 5;
    bodies[7] = 0;
    bodies[8] = 0;
    bodies[9] = 35;
    bodies[10] = 0;
    bodies[11] = 15;
    bodies[12] = 25;
    bodies[13] = 25;
    bodies[14] = 20;
    bodies[15] = 30;
    bodies[16] = 20;
    bodies[17] = 30;
  }

  function _setFaceRarities() internal {
    faces[0] = 0;
    faces[1] = 0;
    faces[2] = 0;
    faces[3] = 5;
    faces[4] = 10;
  }

  function _setEyesRarities() internal {
    eyes[0] = 0;
    eyes[1] = 0;
    eyes[2] = 10;
    eyes[3] = 15;
    eyes[4] = 5;
    eyes[5] = 5;
    eyes[6] = 30;
    eyes[7] = 30;
  }

  function _setNoseRarities() internal {
    noses[0] = 15;
    noses[1] = 15;
    noses[2] = 5;
    noses[3] = 25;
    noses[4] = 0;
    noses[5] = 0;
    noses[6] = 50;
    noses[7] = 0;
    noses[8] = 0;
    noses[9] = 20;
    noses[10] = 20;
  }

  function _setMouthRarities() internal {
    mouths[0] = 0;
    mouths[1] = 10;
    mouths[2] = 15;
    mouths[3] = 20;
    mouths[4] = 80;
    mouths[5] = 40;
    mouths[6] = 30;
    mouths[7] = 65;
    mouths[8] = 25;
  }

  function _setCostumeRarities() internal {
    costumes[0] = 0;
    costumes[1] = 75;
    costumes[2] = 85;
    costumes[3] = 55;
    costumes[4] = 75;
  }

  function _setHeadAccessoryRarities() internal {
    headAccessories[0] = 0;
    headAccessories[1] = 35;
    headAccessories[2] = 50;

    headAccessories[3] = 20;
    headAccessories[4] = 20;
    headAccessories[5] = 20;
    headAccessories[6] = 20;

    headAccessories[7] = 0;
    headAccessories[8] = 0;
    headAccessories[9] = 0;

    headAccessories[10] = 90;
    headAccessories[11] = 90;
    headAccessories[12] = 90;

    headAccessories[13] = 0;
    headAccessories[14] = 0;
    headAccessories[15] = 0;
    headAccessories[16] = 0;
    headAccessories[17] = 0;

    headAccessories[18] = 35;
    headAccessories[19] = 35;
    headAccessories[20] = 35;
    headAccessories[21] = 35;

    headAccessories[22] = 0;

    headAccessories[23] = 80;

    headAccessories[24] = 0;
    headAccessories[25] = 0;
    headAccessories[26] = 0;

    headAccessories[27] = 70;

    headAccessories[28] = 30;
    headAccessories[29] = 30;
    headAccessories[30] = 30;
    headAccessories[31] = 30;

    headAccessories[32] = 5;
    headAccessories[33] = 5;
    headAccessories[34] = 5;

    headAccessories[35] = 30;
    headAccessories[36] = 30;
    headAccessories[37] = 30;

    headAccessories[38] = 95;

    headAccessories[39] = 40;

    headAccessories[40] = 98;

    headAccessories[41] = 75;

    headAccessories[42] = 15;
    headAccessories[43] = 15;
    headAccessories[44] = 15;
    headAccessories[45] = 15;
  }

  function _setHairRarities() internal {
    hairs[0] = 55;
    hairs[1] = 40;
    hairs[2] = 40;
    hairs[3] = 0;
    hairs[4] = 35;
    hairs[5] = 5;
    hairs[6] = 0;
    hairs[7] = 15;
    hairs[8] = 80;
    hairs[9] = 20;
    hairs[10] = 25;
    hairs[11] = 30;
    hairs[12] = 50;
    hairs[13] = 50;
    hairs[14] = 90;
    hairs[15] = 50;
    hairs[16] = 50;
    hairs[17] = 20;
  }

  function _setSunglassesRarities() internal {
    sunglasses[0] = 0;
    sunglasses[1] = 40;
    sunglasses[2] = 55;
    sunglasses[3] = 80;
    sunglasses[4] = 25;
    sunglasses[5] = 85;
    sunglasses[6] = 25;
    sunglasses[7] = 20;
    sunglasses[8] = 35;
    sunglasses[9] = 10;
    sunglasses[10] = 95;
    sunglasses[11] = 30;
    sunglasses[12] = 70;
    sunglasses[13] = 90;

    sunglasses[14] = 70;
    sunglasses[15] = 80;
    sunglasses[16] = 60;
    sunglasses[17] = 90;
    sunglasses[18] = 60;
    sunglasses[19] = 55;
    sunglasses[20] = 70;
    sunglasses[21] = 55;
    sunglasses[22] = 60;
    sunglasses[23] = 65;
    sunglasses[24] = 85;
  }

  function _setFacialHairRarities() internal {
    facialHairs[0] = 50;
    facialHairs[1] = 0;
    facialHairs[2] = 10;
    facialHairs[3] = 20;
    facialHairs[4] = 50;
    facialHairs[5] = 60;
    facialHairs[6] = 70;
  }

  function _setTraitTable() internal {
    _setBodyRarities();
    _setFaceRarities();
    _setEyesRarities();
    _setNoseRarities();
    _setMouthRarities();

    _setCostumeRarities();
    _setHeadAccessoryRarities();
    _setHairRarities();
    _setSunglassesRarities();
    _setFaceRarities();

    traitTable[0] = themes;
    traitTable[1] = bodies;
    traitTable[2] = faces;
    traitTable[3] = eyes;
    traitTable[4] = noses;
    traitTable[5] = mouths;
    traitTable[6] = costumes;
    traitTable[7] = headAccessories;
    traitTable[8] = hairs;
    traitTable[9] = sunglasses;
    traitTable[10] = facialHairs;
  }

  function _rnd(uint256 _salt, uint256 _nonce) internal view returns (uint256) {
    return uint256(keccak256(abi.encodePacked(block.timestamp, msg.sender, _salt, _nonce)));
  }
}

{
  "compilationTarget": {
    "contracts/ThePixels.sol": "ThePixels"
  },
  "evmVersion": "istanbul",
  "libraries": {},
  "metadata": {
    "bytecodeHash": "ipfs"
  },
  "optimizer": {
    "enabled": true,
    "runs": 1000
  },
  "remappings": []
}