// ----------------------------------------------------------------------------
// META SYSTEM Contract
// Name        : META SYSTEM
// Symbol      : MSYS
// Decimals    : 18
// InitialSupply : 500,000,000 MSYS
// ----------------------------------------------------------------------------

pragma solidity 0.5.8;

interface IERC20 {

    function totalSupply() external view returns (uint256);

    function balanceOf(address account) external view returns (uint256);

    function transfer(address recipient, uint256 amount) external returns (bool);

    function allowance(address owner, address spender) external view returns (uint256);

    function approve(address spender, uint256 amount) external returns (bool);

    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);

    event Transfer(address indexed from, address indexed to, uint256 value);

    event Approval(address indexed owner, address indexed spender, uint256 value);
}

library SafeMath {

    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");

        return c;
    }

    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b <= a, "SafeMath: subtraction overflow");
        uint256 c = a - b;

        return c;
    }

    function mul(uint256 a, uint256 b) internal pure returns (uint256) {

        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }

    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b > 0, "SafeMath: division by zero");
        uint256 c = a / b;

        return c;
    }

    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b != 0, "SafeMath: modulo by zero");
        return a % b;
    }
}

contract ERC20 is IERC20 {
    using SafeMath for uint256;

    mapping (address => uint256) internal _balances;

    mapping (address => mapping (address => uint256)) private _allowances;

    uint256 private _totalSupply;

    function totalSupply() public view returns (uint256) {
        return _totalSupply;
    }

    function balanceOf(address account) public view returns (uint256) {
        return _balances[account];
    }

    function transfer(address recipient, uint256 amount) public returns (bool) {
        _transfer(msg.sender, recipient, amount);
        return true;
    }

    function allowance(address owner, address spender) public view returns (uint256) {
        return _allowances[owner][spender];
    }

    function approve(address spender, uint256 value) public returns (bool) {
        _approve(msg.sender, spender, value);
        return true;
    }

    function transferFrom(address sender, address recipient, uint256 amount) public returns (bool) {
        _transfer(sender, recipient, amount);
        _approve(sender, msg.sender, _allowances[sender][msg.sender].sub(amount));
        return true;
    }

    function increaseAllowance(address spender, uint256 addedValue) public returns (bool) {
        _approve(msg.sender, spender, _allowances[msg.sender][spender].add(addedValue));
        return true;
    }

    function decreaseAllowance(address spender, uint256 subtractedValue) public returns (bool) {
        _approve(msg.sender, spender, _allowances[msg.sender][spender].sub(subtractedValue));
        return true;
    }

    function _transfer(address sender, address recipient, uint256 amount) internal {
        require(sender != address(0), "ERC20: transfer from the zero address");
        require(recipient != address(0), "ERC20: transfer to the zero address");

        _balances[sender] = _balances[sender].sub(amount);
        _balances[recipient] = _balances[recipient].add(amount);
        emit Transfer(sender, recipient, amount);
    }

    function _mint(address account, uint256 amount) internal {
        require(account != address(0), "ERC20: mint to the zero address");

        _totalSupply = _totalSupply.add(amount);
        _balances[account] = _balances[account].add(amount);
        emit Transfer(address(0), account, amount);
    }

    function _burn(address owner, uint256 value) internal {
        require(owner != address(0), "ERC20: burn from the zero address");

        _totalSupply = _totalSupply.sub(value);
        _balances[owner] = _balances[owner].sub(value);
        emit Transfer(owner, address(0), value);
    }

    function _approve(address owner, address spender, uint256 value) internal {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");

        _allowances[owner][spender] = value;
        emit Approval(owner, spender, value);
    }

    function _burnFrom(address owner, uint256 amount) internal {
        _burn(owner, amount);
        _approve(owner, msg.sender, _allowances[owner][msg.sender].sub(amount));
    }
}

contract METASYSTEM is ERC20 {
    string public constant name = "META SYSTEM";
    string public constant symbol = "MSYS"; 
    uint8 public constant decimals = 18; 
    uint256 public constant initialSupply = 500000000 * (10 ** uint256(decimals));
    
    constructor() public {
        super._mint(msg.sender, initialSupply);
        owner = msg.sender;
    }

    address public owner;

    event OwnershipRenounced(address indexed previousOwner);
    event OwnershipTransferred(
    address indexed previousOwner,
    address indexed newOwner
    );

    modifier onlyOwner() {
        require(msg.sender == owner, "Not owner");
        _;
    }

    function transferOwnership(address _newOwner) public onlyOwner {
        _transferOwnership(_newOwner);
    }

    function _transferOwnership(address _newOwner) internal {
        require(_newOwner != address(0), "Already Owner");
        emit OwnershipTransferred(owner, _newOwner);
        owner = _newOwner;
    }

    function transfer(
        address _to,
        uint256 _value
    )
      public

      returns (bool)
    {
        releaseLock(msg.sender);
        return super.transfer(_to, _value);
    }

    function transferFrom(
        address _from,
        address _to,
        uint256 _value
    )
      public

      returns (bool)
    {
        releaseLock(_from);
        return super.transferFrom(_from, _to, _value);
    }

    event Burn(address indexed burner, uint256 value);

    function burn(uint256 _value) public onlyOwner {
        require(_value <= super.balanceOf(owner), "Balance is too small.");

        _burn(owner, _value);
        emit Burn(owner, _value);
    }

    struct LockInfo {
        uint256 releaseTime;
        uint256 balance;
    }
    mapping(address => LockInfo[]) internal lockInfo;

    event Lock(address indexed holder, uint256 value, uint256 releaseTime);
    event Unlock(address indexed holder, uint256 value);

    function balanceOf(address _holder) public view returns (uint256 balance) {
        uint256 lockedBalance = 0;
        for(uint256 i = 0; i < lockInfo[_holder].length ; i++ ) {
            lockedBalance = lockedBalance.add(lockInfo[_holder][i].balance);
        }
        return super.balanceOf(_holder).add(lockedBalance);
    }

    function releaseLock(address _holder) internal {

        for(uint256 i = 0; i < lockInfo[_holder].length ; i++ ) {
            if (lockInfo[_holder][i].releaseTime <= now) {
                _balances[_holder] = _balances[_holder].add(lockInfo[_holder][i].balance);
                emit Unlock(_holder, lockInfo[_holder][i].balance);
                lockInfo[_holder][i].balance = 0;

                if (i != lockInfo[_holder].length - 1) {
                    lockInfo[_holder][i] = lockInfo[_holder][lockInfo[_holder].length - 1];
                    i--;
                }
                lockInfo[_holder].length--;

            }
        }
    }
    function lockCount(address _holder) public view returns (uint256) {
        return lockInfo[_holder].length;
    }
    function lockState(address _holder, uint256 _idx) public view returns (uint256, uint256) {
        return (lockInfo[_holder][_idx].releaseTime, lockInfo[_holder][_idx].balance);
    }

    function lock(address _holder, uint256 _amount, uint256 _releaseTime) public onlyOwner {
        require(super.balanceOf(_holder) >= _amount, "Balance is too small.");
        require(block.timestamp <= _releaseTime, "TokenTimelock: release time is before current time");
        
        _balances[_holder] = _balances[_holder].sub(_amount);
        lockInfo[_holder].push(
            LockInfo(_releaseTime, _amount)
        );
        emit Lock(_holder, _amount, _releaseTime);
    }

    function unlock(address _holder, uint256 i) public onlyOwner {
        require(i < lockInfo[_holder].length, "No lock information.");

        _balances[_holder] = _balances[_holder].add(lockInfo[_holder][i].balance);
        emit Unlock(_holder, lockInfo[_holder][i].balance);
        lockInfo[_holder][i].balance = 0;

        if (i != lockInfo[_holder].length - 1) {
            lockInfo[_holder][i] = lockInfo[_holder][lockInfo[_holder].length - 1];
        }
        lockInfo[_holder].length--;
    }

    function transferWithLock(address _to, uint256 _value, uint256 _releaseTime) public onlyOwner returns (bool) {
        require(_to != address(0), "wrong address");
        require(_value <= super.balanceOf(owner), "Not enough balance");
        require(block.timestamp <= _releaseTime, "TokenTimelock: release time is before current time");

        _balances[owner] = _balances[owner].sub(_value);
        lockInfo[_to].push(
            LockInfo(_releaseTime, _value)
        );
        emit Transfer(owner, _to, _value);
        emit Lock(_to, _value, _releaseTime);

        return true;
    }

}