// File: contracts/tokenvending.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

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

contract TokenVesting is Ownable {
    address public tokenContractAddress;
    address public beneficiary;
    uint256 public startDate;
    uint256 public periodCount;
    uint256 public unlockedAmountPerPeriod;
    uint256 public lastClaimedPeriod;

    modifier onlyBeneficiary() {
        require(msg.sender == beneficiary, "Only the beneficiary can call this function.");
        _;
    }

    constructor(
        address _tokenContractAddress,
        address _beneficiary,
        uint256 _startDate,
        uint256 _periodCount,
        uint256 _unlockedAmountPerPeriod
    ) {
        require(_tokenContractAddress != address(0), "Invalid token contract address.");
        require(_beneficiary != address(0), "Invalid beneficiary address.");
        require(_startDate >= block.timestamp, "Start date should be in the future.");
        require(_periodCount > 0, "Period count must be greater than 0.");
        require(_unlockedAmountPerPeriod > 0, "Unlocked amount per period must be greater than 0.");

        tokenContractAddress = _tokenContractAddress;
        beneficiary = _beneficiary;
        startDate = _startDate;
        periodCount = _periodCount;
        unlockedAmountPerPeriod = _unlockedAmountPerPeriod * 10 ** 18;
        lastClaimedPeriod = 0;
    }

    function unlockedAmount() internal view returns (uint256) {
        if (block.timestamp <= startDate) return 0;
        uint256 passedPeriods = (block.timestamp - startDate) / 30 days;
        uint256 unlocked = passedPeriods * unlockedAmountPerPeriod;
        if (unlocked > periodCount * unlockedAmountPerPeriod) {
            unlocked = periodCount * unlockedAmountPerPeriod;
        }
        return unlocked - (lastClaimedPeriod * unlockedAmountPerPeriod);
    }

    function claim() external onlyBeneficiary {
        uint256 claimable = unlockedAmount();
        require(claimable > 0, "No tokens available for claim.");

        IERC20 tokenContract = IERC20(tokenContractAddress);
        uint256 balanceBefore = tokenContract.balanceOf(address(this));
        require(tokenContract.transfer(beneficiary, claimable), "Token transfer failed.");
        uint256 balanceAfter = tokenContract.balanceOf(address(this));
        require(balanceAfter == balanceBefore - claimable, "Token transfer amount mismatch.");

        lastClaimedPeriod = (block.timestamp - startDate) /30 days;
    }

    function getUnlockedAmount() external view returns (uint256) {
        return unlockedAmount();
    }

    function setBeneficiary(address _beneficiary) external onlyOwner {
        require(_beneficiary != address(0), "Invalid beneficiary address.");
        beneficiary = _beneficiary;
    }
}

// File: @openzeppelin/contracts/access/Ownable.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (access/Ownable.sol)

pragma solidity ^0.8.0;

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

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

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

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

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        _checkOwner();
        _;
    }

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

    /**
     * @dev Throws if the sender is not the owner.
     */
    function _checkOwner() internal view virtual {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
    }

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

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @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);

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

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)

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;
    }
}