/**
 * Source Code first verified at https://etherscan.io on Saturday, April 20, 2019
 (UTC) */

pragma solidity 0.5.2;

// File: openzeppelin-solidity/contracts/ownership/Ownable.sol

/**
 * @title Ownable
 * @dev The Ownable contract has an owner address, and provides basic authorization control
 * functions, this simplifies the implementation of "user permissions".
 */
contract Ownable {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev The Ownable constructor sets the original `owner` of the contract to the sender
     * account.
     */
    constructor () internal {
        _owner = msg.sender;
        emit OwnershipTransferred(address(0), _owner);
    }

    /**
     * @return the address of the owner.
     */
    function owner() public view returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(isOwner());
        _;
    }

    /**
     * @return true if `msg.sender` is the owner of the contract.
     */
    function isOwner() public view returns (bool) {
        return msg.sender == _owner;
    }

    /**
     * @dev Allows the current owner to relinquish control of the contract.
     * @notice Renouncing to ownership will leave the contract without an owner.
     * It will not be possible to call the functions with the `onlyOwner`
     * modifier anymore.
     */
    function renounceOwnership() public onlyOwner {
        emit OwnershipTransferred(_owner, address(0));
        _owner = address(0);
    }

    /**
     * @dev Allows the current owner to transfer control of the contract to a newOwner.
     * @param newOwner The address to transfer ownership to.
     */
    function transferOwnership(address newOwner) public onlyOwner {
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers control of the contract to a newOwner.
     * @param newOwner The address to transfer ownership to.
     */
    function _transferOwnership(address newOwner) internal {
        require(newOwner != address(0));
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}

// File: openzeppelin-solidity/contracts/math/SafeMath.sol

/**
 * @title SafeMath
 * @dev Unsigned math operations with safety checks that revert on error
 */
library SafeMath {
    /**
    * @dev Multiplies two unsigned integers, reverts on overflow.
    */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b);

        return c;
    }

    /**
    * @dev Integer division of two unsigned integers truncating the quotient, reverts on division by zero.
    */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        // Solidity only automatically asserts when dividing by 0
        require(b > 0);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    /**
    * @dev Subtracts two unsigned integers, reverts on overflow (i.e. if subtrahend is greater than minuend).
    */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b <= a);
        uint256 c = a - b;

        return c;
    }

    /**
    * @dev Adds two unsigned integers, reverts on overflow.
    */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a);

        return c;
    }

    /**
    * @dev Divides two unsigned integers and returns the remainder (unsigned integer modulo),
    * reverts when dividing by zero.
    */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b != 0);
        return a % b;
    }
}

// File: openzeppelin-solidity/contracts/token/ERC20/IERC20.sol

/**
 * @title ERC20 interface
 * @dev see https://github.com/ethereum/EIPs/issues/20
 */
interface IERC20 {
    function transfer(address to, uint256 value) external returns (bool);

    function approve(address spender, uint256 value) external returns (bool);

    function transferFrom(address from, address to, uint256 value) external returns (bool);

    function totalSupply() external view returns (uint256);

    function balanceOf(address who) external view returns (uint256);

    function allowance(address owner, address spender) external view returns (uint256);

    event Transfer(address indexed from, address indexed to, uint256 value);

    event Approval(address indexed owner, address indexed spender, uint256 value);
}

// File: openzeppelin-solidity/contracts/token/ERC20/SafeERC20.sol

/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure.
 * To use this library you can add a `using SafeERC20 for ERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using SafeMath for uint256;

    function safeTransfer(IERC20 token, address to, uint256 value) internal {
        require(token.transfer(to, value));
    }

    function safeTransferFrom(IERC20 token, address from, address to, uint256 value) internal {
        require(token.transferFrom(from, to, value));
    }

    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(msg.sender, spender) == 0));
        require(token.approve(spender, value));
    }

    function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender).add(value);
        require(token.approve(spender, newAllowance));
    }

    function safeDecreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender).sub(value);
        require(token.approve(spender, newAllowance));
    }
}

// File: contracts/TFBTokenAirdropVesting.sol

/**
 * @title TokenVesting
 * @dev A token holder contract that can release its token balance gradually like a
 * typical vesting scheme, with a cliff and vesting period. Optionally revocable by the
 * owner.
 */
contract TFBTokenAirdropVesting is Ownable {
    using SafeMath for uint256;
    using SafeERC20 for IERC20;

    IERC20 private TFBToken;
    uint256 private tokensToVest = 0;
    uint256 private vestingId = 0;

    string private constant INSUFFICIENT_BALANCE = "Insufficient balance";
    string private constant INVALID_VESTING_ID = "Invalid vesting id";
    string private constant VESTING_ALREADY_RELEASED = "Vesting already released";
    string private constant INVALID_BENEFICIARY = "Invalid beneficiary address";
    string private constant NOT_VESTED = "Tokens have not vested yet";

    struct Vesting {
        uint256 releaseTime;
        uint256 amount;
        address beneficiary;
        bool released;
    }
    mapping(uint256 => Vesting) public vestings;

    event TokenVestingReleased(uint256 indexed vestingId, address indexed beneficiary, uint256 amount);
    event TokenVestingAdded(uint256 indexed vestingId, address indexed beneficiary, uint256 amount);
    event TokenVestingRemoved(uint256 indexed vestingId, address indexed beneficiary, uint256 amount);

    constructor(IERC20 _token) public {
        require(address(_token) != address(0x0), "TFB token address is not valid");
        TFBToken = _token;

        uint256 SCALING_FACTOR = 10 ** 18;
        uint256 day = 1 days;

        addVesting(0x2eB7Df352621FE6F14188AC5A50ada4252925b86, now + 62 * day, 1000000000 * SCALING_FACTOR);
    }

    function token() public view returns (IERC20) {
        return TFBToken;
    }

    function beneficiary(uint256 _vestingId) public view returns (address) {
        return vestings[_vestingId].beneficiary;
    }

    function releaseTime(uint256 _vestingId) public view returns (uint256) {
        return vestings[_vestingId].releaseTime;
    }

    function vestingAmount(uint256 _vestingId) public view returns (uint256) {
        return vestings[_vestingId].amount;
    }

    function removeVesting(uint256 _vestingId) public onlyOwner {
        Vesting storage vesting = vestings[_vestingId];
        require(vesting.beneficiary != address(0x0), INVALID_VESTING_ID);
        require(!vesting.released , VESTING_ALREADY_RELEASED);
        vesting.released = true;
        tokensToVest = tokensToVest.sub(vesting.amount);
        emit TokenVestingRemoved(_vestingId, vesting.beneficiary, vesting.amount);
    }

    function addVesting(address _beneficiary, uint256 _releaseTime, uint256 _amount) public onlyOwner {
        require(_beneficiary != address(0x0), INVALID_BENEFICIARY);
        tokensToVest = tokensToVest.add(_amount);
        vestingId = vestingId.add(1);
        vestings[vestingId] = Vesting({
            beneficiary: _beneficiary,
            releaseTime: _releaseTime,
            amount: _amount,
            released: false
        });
        emit TokenVestingAdded(vestingId, _beneficiary, _amount);
    }

    function release(uint256 _vestingId) public {
        Vesting storage vesting = vestings[_vestingId];
        require(vesting.beneficiary != address(0x0), INVALID_VESTING_ID);
        require(!vesting.released , VESTING_ALREADY_RELEASED);
        // solhint-disable-next-line not-rely-on-time
        require(block.timestamp >= vesting.releaseTime, NOT_VESTED);

        require(TFBToken.balanceOf(address(this)) >= vesting.amount, INSUFFICIENT_BALANCE);
        vesting.released = true;
        tokensToVest = tokensToVest.sub(vesting.amount);
        TFBToken.safeTransfer(vesting.beneficiary, vesting.amount);
        emit TokenVestingReleased(_vestingId, vesting.beneficiary, vesting.amount);
    }

    function retrieveExcessTokens(uint256 _amount) public onlyOwner {
        require(_amount <= TFBToken.balanceOf(address(this)).sub(tokensToVest), INSUFFICIENT_BALANCE);
        TFBToken.safeTransfer(owner(), _amount);
    }
}