// File: contracts/DAOFarm.sol



//SPDX-License-Identifier: MIT
pragma solidity =0.8.14;

import "@openzeppelin/contracts/security/ReentrancyGuard.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";

contract DAOFarm is ReentrancyGuard {
    using SafeERC20 for IERC20;

    uint constant HUNDRED_PERCENT = 1e3;
    uint constant ACC_REWARD_MULTIPLIER = 1e36;
    uint constant UPDATE_PERIOD = 60;

    struct User {
        uint shares;
        uint rewardDebt;
        uint requestedUnstakeAt;
    }
    mapping (address => User) public users;

    IERC20 immutable public stakingToken;
    IERC20 immutable public rewardToken;
    address immutable public feeCollector1;
    address immutable public feeCollector2;
    uint immutable public rewardPerPeriod;
    uint immutable public cooldownPeriod;
    uint immutable public cooldownFee;
    uint immutable public cooldownFeeSplit;
    uint immutable public startTime;
    uint immutable public endTime;

    uint public totalShares;
    uint public totalClaimed;
    uint public accRewardPerShare;
    uint public lastUpdateTimestamp;
    
    event Stake(address userAddress, uint amount);
    event RequestUnstake(address userAddress, bool withoutClaim, uint timestamp);
    event Unstake(address userAddress, uint amount, uint fee);
    event Claim(address userAddress, uint reward);
    event Update(uint periodsPassed, uint totalShares, uint totalClaimed, uint accRewardPerShare, uint timestamp);

    modifier withUpdate() {
        update();
        _;
    }

    constructor(
        IERC20 _stakingToken,
        IERC20 _rewardToken,
        address _feeCollector1,
        address _feeCollector2,
        uint _rewardPerPeriod,
        uint _cooldownPeriod,
        uint _cooldownFee,
        uint _cooldownFeeSplit,
        uint _startTime,
        uint _endTime
    ) {
        require(address(_stakingToken) != address(0));
        require(address(_rewardToken) != address(0));
        require(_feeCollector1 != address(0));
        require(_feeCollector2 != address(0));
        require(_cooldownFee <= HUNDRED_PERCENT);
        require(_cooldownFeeSplit <= HUNDRED_PERCENT);
        require(_startTime > block.timestamp);
        require(_startTime < _endTime);

        stakingToken = _stakingToken;
        rewardToken = _rewardToken;
        feeCollector1 = _feeCollector1;
        feeCollector2 = _feeCollector2;
        rewardPerPeriod = _rewardPerPeriod;
        cooldownPeriod = _cooldownPeriod;
        cooldownFee = _cooldownFee;
        cooldownFeeSplit = _cooldownFeeSplit;
        startTime = _startTime;
        endTime = _endTime;
        lastUpdateTimestamp = _startTime;
    }
    
    // =================== EXTERNAL FUNCTIONS  =================== //

    /**
        Check whether some update periods have passed and if so, increase the pending reward of all users.
     */
    function update() public {
        uint currentTimestamp = block.timestamp;
        if (currentTimestamp > endTime) {
            currentTimestamp = endTime;
        }
        require(currentTimestamp > startTime, "before startTime");

        uint periodsPassed = (currentTimestamp - lastUpdateTimestamp) / UPDATE_PERIOD;
        if (periodsPassed > 0 && totalShares > 0) {
            uint reward = rewardPerPeriod * periodsPassed;
            accRewardPerShare += ACC_REWARD_MULTIPLIER * reward / totalShares;
            lastUpdateTimestamp += periodsPassed * UPDATE_PERIOD;
        }

        emit Update(periodsPassed, totalShares, totalClaimed, accRewardPerShare, block.timestamp);
    }

    /**
        Stake tokens.
        @param amount amount to stake
     */
    function stake(uint amount) external nonReentrant withUpdate {
        User storage user = users[msg.sender];
        require(amount > 0, "0 amount");
        require(user.requestedUnstakeAt == 0, "unstake requested");

        uint balanceBefore = stakingToken.balanceOf(address(this));
        stakingToken.safeTransferFrom(msg.sender, address(this), amount);
        uint receivedAmount = stakingToken.balanceOf(address(this)) - balanceBefore;

        user.shares += receivedAmount;
        user.rewardDebt += _calculateAbsoluteReward(receivedAmount);
        totalShares += receivedAmount;

        emit Stake(msg.sender, receivedAmount);
    }

    /**
        Enter the cooldown period for unstaking without any fee after the period passes.
        Users can't stake or claim while in the cooldown period.
        @param withoutClaim in case the pending rewards can't be claimed, there's still this option to request unstake without claiming
     */
    function requestUnstake(bool withoutClaim) external nonReentrant withUpdate {
        User storage user = users[msg.sender];
        require(user.requestedUnstakeAt == 0, "unstake requested already");
        _requestUnstake(withoutClaim);
    }

    /**
        Unstaking before the cooldown period ends causes a fee on the staked amount (it's free of charge if the farm staking has ended).
     */
    function unstake() external nonReentrant withUpdate {
        User storage user = users[msg.sender];

        if (user.requestedUnstakeAt == 0) {
            _requestUnstake(false);
        }

        uint unstakeAmount = user.shares;
        bool earlyUnstake = block.timestamp < user.requestedUnstakeAt + cooldownPeriod;
        uint fee;
        if (earlyUnstake) {
            fee = _applyPercentage(unstakeAmount, cooldownFee);
            uint feeSplit1 = _applyPercentage(fee, cooldownFeeSplit);
            uint feeSplit2 = fee - feeSplit1;
            stakingToken.safeTransfer(feeCollector1, feeSplit1);
            stakingToken.safeTransfer(feeCollector2, feeSplit2);
        }
        unstakeAmount -= fee;
    
        stakingToken.safeTransfer(msg.sender, unstakeAmount);
        delete users[msg.sender];

        emit Unstake(msg.sender, unstakeAmount, fee);
    }

    /**
        Claim all the pending rewards. 
    */
    function claim() external nonReentrant withUpdate returns (uint claimableReward) {
        claimableReward = getClaimableReward(msg.sender); 
        require(claimableReward > 0, "nothing to claim");
        _claim(msg.sender);
    }

    // =================== INTERNAL FUNCTIONS  =================== //

    function _claim(address userAddress) internal {
        User storage user = users[userAddress];

        uint claimableReward = getClaimableReward(userAddress);
        if (claimableReward > 0) {
            require(getRewardBalance() >= claimableReward, "not enough reward balance");
            user.rewardDebt += claimableReward;
            totalClaimed += claimableReward;
            rewardToken.safeTransfer(userAddress, claimableReward);
            emit Claim(userAddress, claimableReward);
        }
    }

    function _requestUnstake(bool withoutClaim) internal {
        User storage user = users[msg.sender];
        require(user.shares > 0, "nothing to unstake");

        if (!withoutClaim) {
            _claim(msg.sender);
        }

        user.requestedUnstakeAt = block.timestamp;
        totalShares -= user.shares;
        emit RequestUnstake(msg.sender, withoutClaim, block.timestamp);
    }

    // =================== VIEW FUNCTIONS  =================== //

    function getClaimableReward(address userAddress) public view returns (uint reward) {
        User storage user = users[userAddress];
        if (user.requestedUnstakeAt > 0) {
            return 0;
        }

        uint absoluteReward = _calculateAbsoluteReward(user.shares);
        reward = absoluteReward - user.rewardDebt;
    }

    function getRewardBalance() public view returns (uint rewardBalance) {
        uint balance = rewardToken.balanceOf(address(this));

        if (rewardToken != stakingToken) {
            return balance;
        } else {
            return balance - totalShares;
        }
    }

    function getFarmInfo(address userAddress) public view returns (IERC20, IERC20, uint, uint, uint, uint, uint, uint, uint, uint) {
        User storage user = users[userAddress];
        return (
            stakingToken,
            rewardToken,
            rewardPerPeriod,
            cooldownPeriod,
            cooldownFee,
            startTime,
            endTime,
            totalShares,
            user.shares,
            user.requestedUnstakeAt
        );
    }

    function _calculateAbsoluteReward(uint shares) private view returns (uint absoluteReward) {
        return accRewardPerShare * shares / ACC_REWARD_MULTIPLIER;
    }

    function _applyPercentage(uint value, uint percentage) internal pure returns (uint) {
        return value * percentage / HUNDRED_PERCENT;
    }
}
// File: @openzeppelin/contracts/security/ReentrancyGuard.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.0 (security/ReentrancyGuard.sol)

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 making 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;
    }
}

// File: @openzeppelin/contracts/token/ERC20/IERC20.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.0 (token/ERC20/IERC20.sol)

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);
}

// File: @openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.0 (token/ERC20/utils/SafeERC20.sol)

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");
        }
    }
}

// File: @openzeppelin/contracts/utils/Address.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.0 (utils/Address.sol)

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);
            }
        }
    }
}