pragma solidity ^0.4.24;
// sol to LUSD token
// 
// Senior Development Engineer  CHIEH-HSUAN WANG of Lucas. 
// Jason Wang  <ixhxpns@gmail.com>
// reference https://ethereum.org/token

contract owned {
    address public owner;

    constructor()  owned() public {
        owner = msg.sender;
    }

    modifier onlyOwner {
        require(msg.sender == owner);
        _;
    }

    function transferOwnership(address newOwner) onlyOwner public {
        owner = newOwner;
    }
}

contract TokenERC20 is owned {
    address public deployer;
    // Public variables of the token
    string public name ="Lucas Credit Cooperative";
    string public symbol = "LUSD";
    uint8 public decimals = 4;
    // 18 decimals is the strongly suggested default, avoid changing it
    uint256 public totalSupply = 100000000;
    
    // This creates an array with all balances
    mapping (address => uint256) public balanceOf;
    mapping (address => mapping (address => uint256)) public allowance;

    event Approval(address indexed owner, address indexed spender, uint value);

    // This generates a public event on the blockchain that will notify clients
    event Transfer(address indexed from, address indexed to, uint256 value);

    // This notifies clients about the amount burnt
    event Burn(address indexed from, uint256 value);

    /**
     * Constrctor function
     *
     * Initializes contract with initial supply tokens to the creator of the contract
     */
    constructor()  public {
        deployer = msg.sender;
    }

    /**
     * Internal transfer, only can be called by this contract
     */
    function _transfer(address _from, address _to, uint _value) internal {
        // Prevent transfer to 0x0 address. Use burn() instead
        require(_to != 0x0);
        // Check if the sender has enough
        require(balanceOf[_from] >= _value);
        // Check for overflows
        require(balanceOf[_to] + _value >= balanceOf[_to]);
        // Save this for an assertion in the future
        uint previousBalances = balanceOf[_from] + balanceOf[_to];
        // Subtract from the sender
        balanceOf[_from] -= _value;
        // Add the same to the recipient
        balanceOf[_to] += _value;
        emit Transfer(_from, _to, _value);
        // Asserts are used to use static analysis to find bugs in your code. They should never fail
        assert(balanceOf[_from] + balanceOf[_to] == previousBalances);
    }

    /**
     * Transfer tokens
     *
     * Send `_value` tokens to `_to` from your account
     *
     * @param _to The address of the recipient
     * @param _value the amount to send
     */
    function transfer(address _to, uint256 _value) public {
        _transfer(msg.sender, _to, _value);
    }

    /**
     * Transfer tokens from other address
     *
     * Send `_value` tokens to `_to` in behalf of `_from`
     *
     * @param _from The address of the sender
     * @param _to The address of the recipient
     * @param _value the amount to send
     */
    function transferFrom(address _from, address _to, uint256 _value) public returns (bool success) {
        require(allowance[_from][msg.sender] >= _value);     // Check allowance
        allowance[_from][msg.sender] -= _value;
        _transfer(_from, _to, _value);
        return true;
    }

    /**
     * Set allowance for other address
     *
     * Allows `_spender` to spend no more than `_value` tokens in your behalf
     *
     * @param _spender The address authorized to spend
     * @param _value the max amount they can spend
     */
    function approve(address _spender, uint256 _value) public returns (bool success) {
        allowance[msg.sender][_spender] = _value;
        emit Approval(msg.sender, _spender, _value);
        return true;
    }

    /**
     * Destroy tokens
     *
     * Remove `_value` tokens from the system irreversibly
     *
     * @param _value the amount of money to burn
     */
    function burn(uint256 _value) onlyOwner public returns (bool success) {
        require(balanceOf[msg.sender] >= _value);   // Check if the sender has enough
        balanceOf[msg.sender] -= _value;            // Subtract from the sender
        totalSupply -= _value;                      // Updates totalSupply
        emit Burn(msg.sender, _value);
        return true;
    }
}


contract AdvancedToken is TokenERC20 {
    mapping (address => bool) public frozenAccount;

    /* This generates a public event on the blockchain that will notify clients */
    event FrozenFunds(address target, bool frozen);

    /* Initializes contract with initial supply tokens to the creator of the contract */
    constructor()  TokenERC20() public { }

    /* Internal transfer, only can be called by this contract */
    function _transfer(address _from, address _to, uint _value) internal {
        require(_to != 0x0);                               // Prevent transfer to 0x0 address. Use burn() instead
        require(balanceOf[_from] >= _value);               // Check if the sender has enough
        require(balanceOf[_to] + _value > balanceOf[_to]); // Check for overflows
        require(!frozenAccount[_from]);                     // Check if sender is frozen
        require(!frozenAccount[_to]);                       // Check if recipient is frozen
        balanceOf[_from] -= _value;                         // Subtract from the sender
        balanceOf[_to] += _value;                           // Add the same to the recipient
        emit Transfer(_from, _to, _value);
    }

    /// @notice Create `mintedAmount` tokens and send it to `target`
    /// @param target Address to receive the tokens
    /// @param mintedAmount the amount of tokens it will receive
    function mintToken(address target, uint256 mintedAmount) onlyOwner public {
        uint tempSupply = totalSupply;
        balanceOf[target] += mintedAmount;
        totalSupply += mintedAmount;
        require(totalSupply >= tempSupply);
        emit Transfer(0, this, mintedAmount);
        emit Transfer(this, target, mintedAmount);
    }

    /// @notice `freeze? Prevent | Allow` `target` from sending & receiving tokens
    /// @param target Address to be frozen
    /// @param freeze either to freeze it or not
    function freezeAccount(address target, bool freeze) onlyOwner public {
        frozenAccount[target] = freeze;
        emit FrozenFunds(target, freeze);
    }

    function () payable public {
        require(false);
    }

}

contract LUSD is AdvancedToken {
    mapping(address => uint) public lockdate;
    mapping(address => uint) public lockTokenBalance;

    event LockToken(address account, uint amount, uint unixtime);

    constructor()  AdvancedToken() public {}
    function getLockBalance(address account) internal returns(uint) {
        if(now >= lockdate[account]) {
            lockdate[account] = 0;
            lockTokenBalance[account] = 0;
        }
        return lockTokenBalance[account];
    }

    /* Internal transfer, only can be called by this contract */
    function _transfer(address _from, address _to, uint _value) internal {
        uint usableBalance = balanceOf[_from] - getLockBalance(_from);
        require(balanceOf[_from] >= usableBalance);
        require(_to != 0x0);                                // Prevent transfer to 0x0 address. Use burn() instead
        require(usableBalance >= _value);                   // Check if the sender has enough
        require(balanceOf[_to] + _value > balanceOf[_to]);  // Check for overflows
        require(!frozenAccount[_from]);                     // Check if sender is frozen
        require(!frozenAccount[_to]);                       // Check if recipient is frozen
        balanceOf[_from] -= _value;                         // Subtract from the sender
        balanceOf[_to] += _value;                           // Add the same to the recipient
        emit Transfer(_from, _to, _value);
    }


    function lockTokenToDate(address account, uint amount, uint unixtime) onlyOwner public {
        require(unixtime >= lockdate[account]);
        require(unixtime >= now);
        if(balanceOf[account] >= amount) {
            lockdate[account] = unixtime;
            lockTokenBalance[account] = amount;
            emit LockToken(account, amount, unixtime);
        }
    }

    function lockTokenDays(address account, uint amount, uint _days) public {
        uint unixtime = _days * 1 days + now;
        lockTokenToDate(account, amount, unixtime);
    }

     /**
     * Destroy tokens
     *
     * Remove `_value` tokens from the system irreversibly
     *
     * @param _value the amount of money to burn
     */
    function burn(uint256 _value) onlyOwner public returns (bool success) {
        uint usableBalance = balanceOf[msg.sender] - getLockBalance(msg.sender);
        require(balanceOf[msg.sender] >= usableBalance);
        require(usableBalance >= _value);           // Check if the sender has enough
        balanceOf[msg.sender] -= _value;            // Subtract from the sender
        totalSupply -= _value;                      // Updates totalSupply
        emit Burn(msg.sender, _value);
        return true;
    }
}