// SPDX-License-Identifier: MIT

pragma solidity ^0.8.7;

import "@openzeppelin/contracts/utils/Context.sol";
import "@openzeppelin/contracts/utils/Strings.sol";

import "../interfaces/IAccessControl.sol";

/**
 * @dev This contract is fully forked from OpenZeppelin `AccessControl`.
 * The only difference is the removal of the ERC165 implementation as it's not
 * needed in Angle.
 *
 * Contract module that allows children to implement role-based access
 * control mechanisms. This is a lightweight version that doesn't allow enumerating role
 * members except through off-chain means by accessing the contract event logs. Some
 * applications may benefit from on-chain enumerability, for those cases see
 * {AccessControlEnumerable}.
 *
 * Roles are referred to by their `bytes32` identifier. These should be exposed
 * in the external API and be unique. The best way to achieve this is by
 * using `public constant` hash digests:
 *
 * ```
 * bytes32 public constant MY_ROLE = keccak256("MY_ROLE");
 * ```
 *
 * Roles can be used to represent a set of permissions. To restrict access to a
 * function call, use {hasRole}:
 *
 * ```
 * function foo() public {
 *     require(hasRole(MY_ROLE, msg.sender));
 *     ...
 * }
 * ```
 *
 * Roles can be granted and revoked dynamically via the {grantRole} and
 * {revokeRole} functions. Each role has an associated admin role, and only
 * accounts that have a role's admin role can call {grantRole} and {revokeRole}.
 *
 * By default, the admin role for all roles is `DEFAULT_ADMIN_ROLE`, which means
 * that only accounts with this role will be able to grant or revoke other
 * roles. More complex role relationships can be created by using
 * {_setRoleAdmin}.
 *
 * WARNING: The `DEFAULT_ADMIN_ROLE` is also its own admin: it has permission to
 * grant and revoke this role. Extra precautions should be taken to secure
 * accounts that have been granted it.
 */
abstract contract AccessControl is Context, IAccessControl {
    struct RoleData {
        mapping(address => bool) members;
        bytes32 adminRole;
    }

    mapping(bytes32 => RoleData) private _roles;

    bytes32 public constant DEFAULT_ADMIN_ROLE = 0x00;

    /**
     * @dev Emitted when `newAdminRole` is set as ``role``'s admin role, replacing `previousAdminRole`
     *
     * `DEFAULT_ADMIN_ROLE` is the starting admin for all roles, despite
     * {RoleAdminChanged} not being emitted signaling this.
     *
     * _Available since v3.1._
     */
    event RoleAdminChanged(bytes32 indexed role, bytes32 indexed previousAdminRole, bytes32 indexed newAdminRole);

    /**
     * @dev Emitted when `account` is granted `role`.
     *
     * `sender` is the account that originated the contract call, an admin role
     * bearer except when using {_setupRole}.
     */
    event RoleGranted(bytes32 indexed role, address indexed account, address indexed sender);

    /**
     * @dev Emitted when `account` is revoked `role`.
     *
     * `sender` is the account that originated the contract call:
     *   - if using `revokeRole`, it is the admin role bearer
     *   - if using `renounceRole`, it is the role bearer (i.e. `account`)
     */
    event RoleRevoked(bytes32 indexed role, address indexed account, address indexed sender);

    /**
     * @dev Modifier that checks that an account has a specific role. Reverts
     * with a standardized message including the required role.
     *
     * The format of the revert reason is given by the following regular expression:
     *
     *  /^AccessControl: account (0x[0-9a-f]{20}) is missing role (0x[0-9a-f]{32})$/
     *
     * _Available since v4.1._
     */
    modifier onlyRole(bytes32 role) {
        _checkRole(role, _msgSender());
        _;
    }

    /**
     * @dev Returns `true` if `account` has been granted `role`.
     */
    function hasRole(bytes32 role, address account) public view override returns (bool) {
        return _roles[role].members[account];
    }

    /**
     * @dev Revert with a standard message if `account` is missing `role`.
     *
     * The format of the revert reason is given by the following regular expression:
     *
     *  /^AccessControl: account (0x[0-9a-f]{20}) is missing role (0x[0-9a-f]{32})$/
     */
    function _checkRole(bytes32 role, address account) internal view {
        if (!hasRole(role, account)) {
            revert(
                string(
                    abi.encodePacked(
                        "AccessControl: account ",
                        Strings.toHexString(uint160(account), 20),
                        " is missing role ",
                        Strings.toHexString(uint256(role), 32)
                    )
                )
            );
        }
    }

    /**
     * @dev Returns the admin role that controls `role`. See {grantRole} and
     * {revokeRole}.
     *
     * To change a role's admin, use {_setRoleAdmin}.
     */
    function getRoleAdmin(bytes32 role) public view override returns (bytes32) {
        return _roles[role].adminRole;
    }

    /**
     * @dev Grants `role` to `account`.
     *
     * If `account` had not been already granted `role`, emits a {RoleGranted}
     * event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     */
    function grantRole(bytes32 role, address account) external override onlyRole(getRoleAdmin(role)) {
        _grantRole(role, account);
    }

    /**
     * @dev Revokes `role` from `account`.
     *
     * If `account` had been granted `role`, emits a {RoleRevoked} event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     */
    function revokeRole(bytes32 role, address account) external override onlyRole(getRoleAdmin(role)) {
        _revokeRole(role, account);
    }

    /**
     * @dev Revokes `role` from the calling account.
     *
     * Roles are often managed via {grantRole} and {revokeRole}: this function's
     * purpose is to provide a mechanism for accounts to lose their privileges
     * if they are compromised (such as when a trusted device is misplaced).
     *
     * If the calling account had been granted `role`, emits a {RoleRevoked}
     * event.
     *
     * Requirements:
     *
     * - the caller must be `account`.
     */
    function renounceRole(bytes32 role, address account) external override {
        require(account == _msgSender(), "71");

        _revokeRole(role, account);
    }

    /**
     * @dev Grants `role` to `account`.
     *
     * If `account` had not been already granted `role`, emits a {RoleGranted}
     * event. Note that unlike {grantRole}, this function doesn't perform any
     * checks on the calling account.
     *
     * [WARNING]
     * ====
     * This function should only be called from the constructor when setting
     * up the initial roles for the system.
     *
     * Using this function in any other way is effectively circumventing the admin
     * system imposed by {AccessControl}.
     * ====
     */
    function _setupRole(bytes32 role, address account) internal {
        _grantRole(role, account);
    }

    /**
     * @dev Sets `adminRole` as ``role``'s admin role.
     *
     * Emits a {RoleAdminChanged} event.
     */
    function _setRoleAdmin(bytes32 role, bytes32 adminRole) internal {
        emit RoleAdminChanged(role, getRoleAdmin(role), adminRole);
        _roles[role].adminRole = adminRole;
    }

    function _grantRole(bytes32 role, address account) internal {
        if (!hasRole(role, account)) {
            _roles[role].members[account] = true;
            emit RoleGranted(role, account, _msgSender());
        }
    }

    function _revokeRole(bytes32 role, address account) internal {
        if (hasRole(role, account)) {
            _roles[role].members[account] = false;
            emit RoleRevoked(role, account, _msgSender());
        }
    }
}

// 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: GPL-3.0

pragma solidity ^0.8.7;

/// @title IAccessControl
/// @author Forked from OpenZeppelin
/// @notice Interface for `AccessControl` contracts
interface IAccessControl {
    function hasRole(bytes32 role, address account) external view returns (bool);

    function getRoleAdmin(bytes32 role) external view returns (bytes32);

    function grantRole(bytes32 role, address account) external;

    function revokeRole(bytes32 role, address account) external;

    function renounceRole(bytes32 role, address account) external;
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `sender` to `recipient` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(
        address sender,
        address recipient,
        uint256 amount
    ) external returns (bool);

    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../IERC20.sol";

/**
 * @dev Interface for the optional metadata functions from the ERC20 standard.
 *
 * _Available since v4.1._
 */
interface IERC20Metadata is IERC20 {
    /**
     * @dev Returns the name of the token.
     */
    function name() external view returns (string memory);

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

    /**
     * @dev Returns the decimals places of the token.
     */
    function decimals() external view returns (uint8);
}

// SPDX-License-Identifier: GPL-3.0

pragma solidity ^0.8.7;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";

import "./IStakingRewards.sol";

/// @title IRewardsDistributor
/// @author Angle Core Team, inspired from Fei protocol
/// (https://github.com/fei-protocol/fei-protocol-core/blob/master/contracts/staking/IRewardsDistributor.sol)
/// @notice Rewards Distributor interface
interface IRewardsDistributor {
    // ========================= Public Parameter Getter ===========================

    function rewardToken() external view returns (IERC20);

    // ======================== External User Available Function ===================

    function drip(IStakingRewards stakingContract) external returns (uint256);

    // ========================= Governor Functions ================================

    function governorWithdrawRewardToken(uint256 amount, address governance) external;

    function governorRecover(
        address tokenAddress,
        address to,
        uint256 amount,
        IStakingRewards stakingContract
    ) external;

    function setUpdateFrequency(uint256 _frequency, IStakingRewards stakingContract) external;

    function setIncentiveAmount(uint256 _incentiveAmount, IStakingRewards stakingContract) external;

    function setAmountToDistribute(uint256 _amountToDistribute, IStakingRewards stakingContract) external;

    function setDuration(uint256 _duration, IStakingRewards stakingContract) external;

    function setStakingContract(
        address _stakingContract,
        uint256 _duration,
        uint256 _incentiveAmount,
        uint256 _dripFrequency,
        uint256 _amountToDistribute
    ) external;

    function setNewRewardsDistributor(address newRewardsDistributor) external;

    function removeStakingContract(IStakingRewards stakingContract) external;
}

// SPDX-License-Identifier: GPL-3.0

pragma solidity ^0.8.7;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";

/// @title IStakingRewardsFunctions
/// @author Angle Core Team
/// @notice Interface for the staking rewards contract that interact with the `RewardsDistributor` contract
interface IStakingRewardsFunctions {
    function notifyRewardAmount(uint256 reward) external;

    function recoverERC20(
        address tokenAddress,
        address to,
        uint256 tokenAmount
    ) external;

    function setNewRewardsDistribution(address newRewardsDistribution) external;
}

/// @title IStakingRewards
/// @author Angle Core Team
/// @notice Previous interface with additionnal getters for public variables
interface IStakingRewards is IStakingRewardsFunctions {
    function rewardToken() external view returns (IERC20);
}

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Standard math utilities missing in the Solidity language.
 */
library Math {
    /**
     * @dev Returns the largest of two numbers.
     */
    function max(uint256 a, uint256 b) internal pure returns (uint256) {
        return a >= b ? a : b;
    }

    /**
     * @dev Returns the smallest of two numbers.
     */
    function min(uint256 a, uint256 b) internal pure returns (uint256) {
        return a < b ? a : b;
    }

    /**
     * @dev Returns the average of two numbers. The result is rounded towards
     * zero.
     */
    function average(uint256 a, uint256 b) internal pure returns (uint256) {
        // (a + b) / 2 can overflow.
        return (a & b) + (a ^ b) / 2;
    }

    /**
     * @dev Returns the ceiling of the division of two numbers.
     *
     * This differs from standard division with `/` in that it rounds up instead
     * of rounding down.
     */
    function ceilDiv(uint256 a, uint256 b) internal pure returns (uint256) {
        // (a + b - 1) / b can overflow on addition, so we distribute.
        return a / b + (a % b == 0 ? 0 : 1);
    }
}

// SPDX-License-Identifier: MIT

pragma solidity ^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() {
        _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 ^0.8.0;

import "../IERC20.sol";
import "../../../utils/Address.sol";

/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using Address for address;

    function safeTransfer(
        IERC20 token,
        address to,
        uint256 value
    ) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    function safeTransferFrom(
        IERC20 token,
        address from,
        address to,
        uint256 value
    ) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    /**
     * @dev Deprecated. This function has issues similar to the ones found in
     * {IERC20-approve}, and its usage is discouraged.
     *
     * Whenever possible, use {safeIncreaseAllowance} and
     * {safeDecreaseAllowance} instead.
     */
    function safeApprove(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        // safeApprove should only be called when setting an initial allowance,
        // or when resetting it to zero. To increase and decrease it, use
        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
        require(
            (value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }

    function safeIncreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        uint256 newAllowance = token.allowance(address(this), spender) + value;
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        unchecked {
            uint256 oldAllowance = token.allowance(address(this), spender);
            require(oldAllowance >= value, "SafeERC20: decreased allowance below zero");
            uint256 newAllowance = oldAllowance - value;
            _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
        }
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
        // the target address contains contract code and also asserts for success in the low-level call.

        bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
        if (returndata.length > 0) {
            // Return data is optional
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}

// SPDX-License-Identifier: GPL-3.0

pragma solidity ^0.8.7;

import "./StakingRewardsEvents.sol";

/// @title StakingRewards
/// @author Forked form SetProtocol
/// https://github.com/SetProtocol/index-coop-contracts/blob/master/contracts/staking/StakingRewards.sol
/// @notice The `StakingRewards` contracts allows to stake an ERC20 token to receive as reward another ERC20
/// @dev This contracts is managed by the reward distributor and implements the staking interface
contract StakingRewards is StakingRewardsEvents, IStakingRewards, ReentrancyGuard {
    using SafeERC20 for IERC20;

    /// @notice Checks to see if it is the `rewardsDistribution` calling this contract
    /// @dev There is no Access Control here, because it can be handled cheaply through these modifiers
    modifier onlyRewardsDistribution() {
        require(msg.sender == rewardsDistribution, "1");
        _;
    }

    // ============================ References to contracts ========================

    /// @notice ERC20 token given as reward
    IERC20 public immutable override rewardToken;

    /// @notice ERC20 token used for staking
    IERC20 public immutable stakingToken;

    /// @notice Base of the staked token, it is going to be used in the case of sanTokens
    /// which are not in base 10**18
    uint256 public immutable stakingBase;

    /// @notice Rewards Distribution contract for this staking contract
    address public rewardsDistribution;

    // ============================ Staking parameters =============================

    /// @notice Time at which distribution ends
    uint256 public periodFinish;

    /// @notice Reward per second given to the staking contract, split among the staked tokens
    uint256 public rewardRate;

    /// @notice Duration of the reward distribution
    uint256 public rewardsDuration;

    /// @notice Last time `rewardPerTokenStored` was updated
    uint256 public lastUpdateTime;

    /// @notice Helps to compute the amount earned by someone
    /// Cumulates rewards accumulated for one token since the beginning.
    /// Stored as a uint so it is actually a float times the base of the reward token
    uint256 public rewardPerTokenStored;

    /// @notice Stores for each account the `rewardPerToken`: we do the difference
    /// between the current and the old value to compute what has been earned by an account
    mapping(address => uint256) public userRewardPerTokenPaid;

    /// @notice Stores for each account the accumulated rewards
    mapping(address => uint256) public rewards;

    uint256 private _totalSupply;

    mapping(address => uint256) private _balances;

    // ============================ Constructor ====================================

    /// @notice Initializes the staking contract with a first set of parameters
    /// @param _rewardsDistribution Address owning the rewards token
    /// @param _rewardToken ERC20 token given as reward
    /// @param _stakingToken ERC20 token used for staking
    /// @param _rewardsDuration Duration of the staking contract
    constructor(
        address _rewardsDistribution,
        address _rewardToken,
        address _stakingToken,
        uint256 _rewardsDuration
    ) {
        require(_stakingToken != address(0) && _rewardToken != address(0) && _rewardsDistribution != address(0), "0");

        // We are not checking the compatibility of the reward token between the distributor and this contract here
        // because it is checked by the `RewardsDistributor` when activating the staking contract
        // Parameters
        rewardToken = IERC20(_rewardToken);
        stakingToken = IERC20(_stakingToken);
        rewardsDuration = _rewardsDuration;
        rewardsDistribution = _rewardsDistribution;

        stakingBase = 10**IERC20Metadata(_stakingToken).decimals();
    }

    // ============================ Modifiers ======================================

    /// @notice Checks to see if the calling address is the zero address
    /// @param account Address to check
    modifier zeroCheck(address account) {
        require(account != address(0), "0");
        _;
    }

    /// @notice Called frequently to update the staking parameters associated to an address
    /// @param account Address of the account to update
    modifier updateReward(address account) {
        rewardPerTokenStored = rewardPerToken();
        lastUpdateTime = lastTimeRewardApplicable();
        if (account != address(0)) {
            rewards[account] = earned(account);
            userRewardPerTokenPaid[account] = rewardPerTokenStored;
        }
        _;
    }

    // ============================ View functions =================================

    /// @notice Accesses the total supply
    /// @dev Used instead of having a public variable to respect the ERC20 standard
    function totalSupply() external view returns (uint256) {
        return _totalSupply;
    }

    /// @notice Accesses the number of token staked by an account
    /// @param account Account to query the balance of
    /// @dev Used instead of having a public variable to respect the ERC20 standard
    function balanceOf(address account) external view returns (uint256) {
        return _balances[account];
    }

    /// @notice Queries the last timestamp at which a reward was distributed
    /// @dev Returns the current timestamp if a reward is being distributed and the end of the staking
    /// period if staking is done
    function lastTimeRewardApplicable() public view returns (uint256) {
        return Math.min(block.timestamp, periodFinish);
    }

    /// @notice Used to actualize the `rewardPerTokenStored`
    /// @dev It adds to the reward per token: the time elapsed since the `rewardPerTokenStored` was
    /// last updated multiplied by the `rewardRate` divided by the number of tokens
    function rewardPerToken() public view returns (uint256) {
        if (_totalSupply == 0) {
            return rewardPerTokenStored;
        }
        return
            rewardPerTokenStored +
            (((lastTimeRewardApplicable() - lastUpdateTime) * rewardRate * stakingBase) / _totalSupply);
    }

    /// @notice Returns how much a given account earned rewards
    /// @param account Address for which the request is made
    /// @return How much a given account earned rewards
    /// @dev It adds to the rewards the amount of reward earned since last time that is the difference
    /// in reward per token from now and last time multiplied by the number of tokens staked by the person
    function earned(address account) public view returns (uint256) {
        return
            (_balances[account] * (rewardPerToken() - userRewardPerTokenPaid[account])) /
            stakingBase +
            rewards[account];
    }

    // ======================== Mutative functions forked ==========================

    /// @notice Lets someone stake a given amount of `stakingTokens`
    /// @param amount Amount of ERC20 staking token that the `msg.sender` wants to stake
    function stake(uint256 amount) external nonReentrant updateReward(msg.sender) {
        _stake(amount, msg.sender);
    }

    /// @notice Lets a user withdraw a given amount of collateral from the staking contract
    /// @param amount Amount of the ERC20 staking token that the `msg.sender` wants to withdraw
    function withdraw(uint256 amount) public nonReentrant updateReward(msg.sender) {
        require(amount > 0, "89");
        _totalSupply = _totalSupply - amount;
        _balances[msg.sender] = _balances[msg.sender] - amount;
        stakingToken.safeTransfer(msg.sender, amount);
        emit Withdrawn(msg.sender, amount);
    }

    /// @notice Triggers a payment of the reward earned to the msg.sender
    function getReward() public nonReentrant updateReward(msg.sender) {
        uint256 reward = rewards[msg.sender];
        if (reward > 0) {
            rewards[msg.sender] = 0;
            rewardToken.safeTransfer(msg.sender, reward);
            emit RewardPaid(msg.sender, reward);
        }
    }

    /// @notice Exits someone
    /// @dev This function lets the caller withdraw its staking and claim rewards
    // Attention here, there may be reentrancy attacks because of the following call
    // to an external contract done before other things are modified, yet since the `rewardToken`
    // is mostly going to be a trusted contract controlled by governance (namely the ANGLE token),
    // this is not an issue. If the `rewardToken` changes to an untrusted contract, this need to be updated.
    function exit() external {
        withdraw(_balances[msg.sender]);
        getReward();
    }

    // ====================== Functions added by Angle Core Team ===================

    /// @notice Allows to stake on behalf of another address
    /// @param amount Amount to stake
    /// @param onBehalf Address to stake onBehalf of
    function stakeOnBehalf(uint256 amount, address onBehalf)
        external
        nonReentrant
        zeroCheck(onBehalf)
        updateReward(onBehalf)
    {
        _stake(amount, onBehalf);
    }

    /// @notice Internal function to stake called by `stake` and `stakeOnBehalf`
    /// @param amount Amount to stake
    /// @param onBehalf Address to stake on behalf of
    /// @dev Before calling this function, it has already been verified whether this address was a zero address or not
    function _stake(uint256 amount, address onBehalf) internal {
        require(amount > 0, "90");
        stakingToken.safeTransferFrom(msg.sender, address(this), amount);
        _totalSupply = _totalSupply + amount;
        _balances[onBehalf] = _balances[onBehalf] + amount;
        emit Staked(onBehalf, amount);
    }

    // ====================== Restricted Functions =================================

    /// @notice Adds rewards to be distributed
    /// @param reward Amount of reward tokens to distribute
    /// @dev This reward will be distributed during `rewardsDuration` set previously
    function notifyRewardAmount(uint256 reward)
        external
        override
        onlyRewardsDistribution
        nonReentrant
        updateReward(address(0))
    {
        if (block.timestamp >= periodFinish) {
            // If no reward is currently being distributed, the new rate is just `reward / duration`
            rewardRate = reward / rewardsDuration;
        } else {
            // Otherwise, cancel the future reward and add the amount left to distribute to reward
            uint256 remaining = periodFinish - block.timestamp;
            uint256 leftover = remaining * rewardRate;
            rewardRate = (reward + leftover) / rewardsDuration;
        }

        // Ensures the provided reward amount is not more than the balance in the contract.
        // This keeps the reward rate in the right range, preventing overflows due to
        // very high values of `rewardRate` in the earned and `rewardsPerToken` functions;
        // Reward + leftover must be less than 2^256 / 10^18 to avoid overflow.
        uint256 balance = rewardToken.balanceOf(address(this));
        require(rewardRate <= balance / rewardsDuration, "91");

        lastUpdateTime = block.timestamp;
        periodFinish = block.timestamp + rewardsDuration; // Change the duration
        emit RewardAdded(reward);
    }

    /// @notice Withdraws ERC20 tokens that could accrue on this contract
    /// @param tokenAddress Address of the ERC20 token to withdraw
    /// @param to Address to transfer to
    /// @param amount Amount to transfer
    /// @dev A use case would be to claim tokens if the staked tokens accumulate rewards
    function recoverERC20(
        address tokenAddress,
        address to,
        uint256 amount
    ) external override onlyRewardsDistribution {
        require(tokenAddress != address(stakingToken) && tokenAddress != address(rewardToken), "20");

        IERC20(tokenAddress).safeTransfer(to, amount);
        emit Recovered(tokenAddress, to, amount);
    }

    /// @notice Changes the rewards distributor associated to this contract
    /// @param _rewardsDistribution Address of the new rewards distributor contract
    /// @dev This function was also added by Angle Core Team
    /// @dev A compatibility check of the reward token is already performed in the current `RewardsDistributor` implementation
    /// which has right to call this function
    function setNewRewardsDistribution(address _rewardsDistribution) external override onlyRewardsDistribution {
        rewardsDistribution = _rewardsDistribution;
        emit RewardsDistributionUpdated(_rewardsDistribution);
    }
}

// SPDX-License-Identifier: GPL-3.0

pragma solidity ^0.8.7;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/token/ERC20/extensions/IERC20Metadata.sol";
import "@openzeppelin/contracts/utils/math/Math.sol";
import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import "@openzeppelin/contracts/security/ReentrancyGuard.sol";

import "../external/AccessControl.sol";

import "../interfaces/IRewardsDistributor.sol";
import "../interfaces/IStakingRewards.sol";

/// @title StakingRewardsEvents
/// @author Angle Core Team
/// @notice All the events used in `StakingRewards` contract
contract StakingRewardsEvents {
    event RewardAdded(uint256 reward);

    event Staked(address indexed user, uint256 amount);

    event Withdrawn(address indexed user, uint256 amount);

    event RewardPaid(address indexed user, uint256 reward);

    event Recovered(address indexed tokenAddress, address indexed to, uint256 amount);

    event RewardsDistributionUpdated(address indexed _rewardsDistribution);
}

// 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);
    }
}

{
  "compilationTarget": {
    "contracts/staking/StakingRewards.sol": "StakingRewards"
  },
  "evmVersion": "london",
  "libraries": {},
  "metadata": {
    "bytecodeHash": "ipfs",
    "useLiteralContent": true
  },
  "optimizer": {
    "enabled": true,
    "runs": 1000000
  },
  "remappings": []
}