// 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;
    }
}

// File: contracts/tokens/TokenVesting.sol



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

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


contract TokenVesting is Ownable{

    IERC20 public token;
    uint256 public startTime; 

    struct UserVesting {
        uint256 totalTokens; 
        uint256 initialUnlockPercentage; 
        uint256 delayAfterStart; 
        uint256 linearVestingDuration; 
        uint256 claimedTokens; 
    }

    mapping(address => UserVesting) public vestingSchedules;

    constructor() {}


    function init (address _token, uint256 _startTime)  external onlyOwner{
        token = IERC20(_token);
        startTime = _startTime;
    }
     function setStartTime ( uint256 _startTime)   external onlyOwner{
        startTime = _startTime;
    }

    function setMultipleUserVesting(
            address[] calldata _users,
            uint256[] calldata _totalTokens,
            uint256[] calldata _initialUnlockPercentages,
            uint256[] calldata _delaysAfterStart,
            uint256[] calldata _linearVestingDurations,
            uint256[] calldata _claimedTokens
        ) external onlyOwner {
            require(
                _users.length == _totalTokens.length &&
                _users.length == _initialUnlockPercentages.length
                && _users.length == _delaysAfterStart.length 
                && _users.length == _linearVestingDurations.length,
                "Array lengths must be equal"
                );

        for (uint256 i = 0; i < _users.length; i++) {
            setUserVesting( _users[i],  _totalTokens[i],  _initialUnlockPercentages[i], 
             _delaysAfterStart[i],  _linearVestingDurations[i],_claimedTokens[i]);
        }
    }

    function setUserVesting(address _user, uint256 _totalTokens, uint256 _initialUnlockPercentage,
     uint256 _delayAfterStart, uint256 _linearVestingDuration,uint256 _claimedTokens) public onlyOwner {
        vestingSchedules[_user] = UserVesting({
            totalTokens: _totalTokens,
            initialUnlockPercentage: _initialUnlockPercentage,
            delayAfterStart: _delayAfterStart,
            linearVestingDuration: _linearVestingDuration,
            claimedTokens: _claimedTokens
        });
    }
     
    
    function calculateClaimableTokens(address _user) public view returns (uint256) {
        UserVesting storage vesting = vestingSchedules[_user];
        if (block.timestamp < startTime) {
            return 0; 
        }

        uint256 timeElapsed = block.timestamp - startTime;
        uint256 initUnlockClaimable = 0;
        uint256 linearClaimable = 0;

        if (timeElapsed >= 0) {
            initUnlockClaimable = (vesting.totalTokens * vesting.initialUnlockPercentage) / 1000;
        }

        if (timeElapsed > vesting.delayAfterStart) {
            uint256 timeSinceStartOfLinearVesting = timeElapsed - (vesting.delayAfterStart );
            uint256 linearVestingPeriodInSeconds = vesting.linearVestingDuration ;
            uint256 totalLinearVestingTokens = vesting.totalTokens - initUnlockClaimable; 
            uint256 canClaimable = (totalLinearVestingTokens * timeSinceStartOfLinearVesting) / linearVestingPeriodInSeconds;
            linearClaimable = canClaimable > totalLinearVestingTokens ? totalLinearVestingTokens : canClaimable;
        }

        return initUnlockClaimable + linearClaimable - vesting.claimedTokens;
    }
    
    function claimTokens() external {
        uint256 claimable = calculateClaimableTokens(msg.sender);
        require(claimable > 0, "No claimable tokens");

        vestingSchedules[msg.sender].claimedTokens += claimable;
        require(token.transfer(msg.sender, claimable), "Token transfer failed");
        
    }

    function withdrawTokens(address _token,uint256 amount)  external onlyOwner {
        uint256 contractBalance = IERC20(_token).balanceOf(address(this));
        require(amount <= contractBalance, "Insufficient balance in contract");

        require(IERC20(_token).transfer(msg.sender, amount), "Token transfer failed");
    }

}