// File: contracts/stake.sol



/**
 *Submitted for verification at Etherscan.io on 2022-09-07
*/

// SPDX-License-Identifier: MIT

pragma solidity 0.8.13;


abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

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

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 () {
        address msgSender = _msgSender();
        _owner = msgSender;
        emit OwnershipTransferred(address(0), 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 {
        emit OwnershipTransferred(_owner, address(0));
        _owner = 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");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}

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);
}

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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;
    }
}

contract BlocksVolunteerStaking is Ownable, ReentrancyGuard {

    struct User {
        uint256 stakeTime;
        uint256 claimTime;
        uint256 allocatedBalance;
    }

    mapping(address => User) public userAccount;
    uint256 public totalClaimed;
    uint256 public totalAllocated;
    uint256 public stakeRewardFactor;
    uint256 public stakeRewardEndTime; // time in seconds when the reward scheme will end
    uint256 public stakeRewardStartTime;
    address public token = 0x8a6D4C8735371EBAF8874fBd518b56Edd66024eB;

    event Allocated(uint256 totalAllocated);
    event ClaimedChanged(uint256 totalUnclaimed);
    event ERC20TokensRemoved(address indexed tokenAddress, address indexed receiver, uint256 amount);
    event StakeRewardFactorChanged(uint256 stakeRewardFactor);
    event StakeRewardEndTimeChanged(uint256 stakeRewardEndTime);
    event RewardsLoaded(address from, uint256 amount);

    constructor() {
        stakeRewardStartTime = 1688198400;
        stakeRewardEndTime = 1719817199;
        stakeRewardFactor = 365 * 1 days; // default : a user has to stake 365 tokens for 1 day to receive 1 reward token
    }

    function manuallyAllocateRewards(address[] calldata _beneficiaries, uint256[] calldata _earnings) external onlyOwner {
        require(_beneficiaries.length == _earnings.length, "Invalid array length");
        require(block.timestamp < stakeRewardEndTime, "Staking rewards have expired.");

        uint256 _sum = 0;
        for (uint256 i = 0; i < _beneficiaries.length; i++) {
            address _beneficiary = _beneficiaries[i];
            uint256 _totalEarned = _earnings[i];
            uint256 _totalReceived = userAccount[_beneficiary].allocatedBalance;

            userAccount[_beneficiary].allocatedBalance = _totalEarned + _totalReceived;

            if(userAccount[_beneficiary].stakeTime == 0){
                userAccount[_beneficiary].stakeTime = stakeRewardStartTime;
            }
            if(userAccount[_beneficiary].claimTime == 0){
                userAccount[_beneficiary].claimTime = stakeRewardStartTime;
            }
            _sum += _totalEarned;
        }
        _increaseAllocation(_sum);
    }

    function _fetchUserReward(address _account) internal view returns (uint256 rewards){
        // If rewards have ended, pay from reward end time.
        if(block.timestamp > stakeRewardEndTime) {
           uint256 _timeSinceClaim = stakeRewardEndTime - userAccount[_account].claimTime;
           uint256 _userStakeFactor = _timeSinceClaim * userAccount[_account].allocatedBalance;
           uint256 _stakeReward = _userStakeFactor / stakeRewardFactor;
           return _stakeReward;
        } else {
           uint256 _timeSinceClaim = block.timestamp - userAccount[_account].claimTime;
           uint256 _userStakeFactor = _timeSinceClaim * userAccount[_account].allocatedBalance;
           uint256 _stakeReward = _userStakeFactor / stakeRewardFactor;
           return _stakeReward;
        }
    }

    function getAccumulatedRewards(address _userAddress) external view returns (uint256 rewards){
        return _fetchUserReward(_userAddress);
    }

    function _contractBalance() internal view returns (uint256 balance) {
        uint256 blocksBalance = IERC20(token).balanceOf(address(this));
        return blocksBalance;
    }

    function getContractBalance() external view returns (uint256 balance) {
        return _contractBalance();
    }

    function claimRewards() external nonReentrant {
        require(userAccount[msg.sender].allocatedBalance > 0, "Balance must be > 0");

        uint256 _claimAmount = _fetchUserReward(msg.sender);
        require(_claimAmount <= _contractBalance(), "Contract balance too low.");

        // Update user claim time
        if(block.timestamp >= stakeRewardEndTime){
            userAccount[msg.sender].claimTime = stakeRewardEndTime;
        } else {
            userAccount[msg.sender].claimTime = block.timestamp;
        }

        _increaseClaimed(_claimAmount);

        IERC20(token).transfer(msg.sender, _claimAmount);
    }

    function withdrawAll() external nonReentrant {
        require(userAccount[msg.sender].allocatedBalance > 0, "Balance must be > 0");

        uint256 _withdrawalAmount = userAccount[msg.sender].allocatedBalance;
        require(_withdrawalAmount <= _contractBalance(), "Contract balance too low.");

        uint256 reward = _fetchUserReward(msg.sender);

        // Update user
        userAccount[msg.sender].stakeTime = 0;
        userAccount[msg.sender].claimTime = 0;
        userAccount[msg.sender].allocatedBalance = 0;

        _reduceAllocation(_withdrawalAmount);

        IERC20(token).transfer(msg.sender, _withdrawalAmount + reward);
    }

    function withdrawAmount(uint256 _amount) external nonReentrant {
        require(userAccount[msg.sender].allocatedBalance > 0, "Balance must be > 0");
        require(userAccount[msg.sender].allocatedBalance >= _amount, "Balance must be > amount");
        require(_amount <= _contractBalance(), "Contract balance too low.");

        uint256 _balance = userAccount[msg.sender].allocatedBalance;

         uint256 reward = _fetchUserReward(msg.sender);

        // Update user allocation
        _balance -= _amount;
        userAccount[msg.sender].allocatedBalance = _balance;

        _reduceAllocation(_amount);

        IERC20(token).transfer(msg.sender, _amount + reward);
    }

    function setStakeRewardFactor(uint256 _stakeRewardFactor) external onlyOwner{
        stakeRewardFactor = _stakeRewardFactor;
        emit StakeRewardFactorChanged(_stakeRewardFactor);
    }

    function setStakeRewardEndTime(uint256 _stakeRewardEndTime) external onlyOwner{
        require(_stakeRewardEndTime > block.timestamp, "End time must be > current time.");
        stakeRewardEndTime = _stakeRewardEndTime;
        emit StakeRewardEndTimeChanged(_stakeRewardEndTime);
    }

    function removeTokens(address _tokenAddress) external onlyOwner {
        uint256 balance = IERC20(_tokenAddress).balanceOf(address(this));
        IERC20(_tokenAddress).transfer(msg.sender, balance);
        emit ERC20TokensRemoved(_tokenAddress, msg.sender, balance);
    }

    function _reduceAllocation(uint256 _amount) internal {
        totalAllocated -= _amount;
        emit Allocated(totalAllocated);
    }

    function _increaseAllocation(uint256 _amount) internal {
        totalAllocated += _amount;
        emit Allocated(totalAllocated);
    }

    function _increaseClaimed(uint256 delta) internal {
        totalClaimed = totalClaimed + delta;
        emit ClaimedChanged(totalClaimed);
    }
}