pragma solidity ^0.4.16;

contract owned {
    address public owner;

    constructor() public {
        owner = msg.sender;
    }

    modifier onlyOwner {
        require(msg.sender == owner);
        _;
    }

    function transferOwnership(address newOwner) onlyOwner public {
        owner = newOwner;
    }
}

interface tokenRecipient { function receiveApproval(address _from, uint256 _value, address _token, bytes _extraData) external; }



contract ITUTokenERC20 is owned {
    // Public variables of the token
    string public name = "iTrue";
    string public symbol = "ITU";
    uint8 public decimals = 18;
    // 18 decimals is the strongly suggested default, avoid changing it
    uint256 public totalSupply;

    string public version = "0.1";

    bool public canTransfer = false;

    struct HoldBalance{
        uint256 amount;
        uint256 timeEnd;
    }

    // This creates an array with all balances
    mapping (address => uint256) public balanceOf;
    mapping (address => mapping (address => uint256)) public allowance;
    mapping (address => HoldBalance) public holdBalances;

    // This generates a public event on the blockchain that will notify clients
    event Transfer(address indexed from, address indexed to, uint256 value);

    // This generates a public event on the blockchain that will notify clients
    event Approval(address indexed _owner, address indexed _spender, uint256 _value);

    // This notifies clients about the amount burnt
    event Burn(address indexed from, uint256 value);

    /**
  * @dev Fix for the ERC20 short address attack.
   */
    modifier onlyPayloadSize(uint size) {
        require(msg.data.length >= 32 * size + 4) ;
        _;
    }

    /**
     * Constrctor function
     *
     * Initializes contract with initial supply tokens to the creator of the contract
     */
    constructor() public {
        uint128 initialSupply = 8000000000;
        totalSupply = initialSupply * 10 ** uint256(decimals);  // Update total supply with the decimal amount
        balanceOf[msg.sender] = totalSupply;                // Give the creator all initial tokens
        name = "iTrue";                                   // Set the name for display purposes
        symbol = "ITU";                               // Set the symbol for display purposes
    }

    function tstart() onlyOwner public {
        canTransfer = true;
    }

    function tstop() onlyOwner public {
        canTransfer = false;
    }

    function availableBalance(address _owner) internal constant returns(uint256) {
        if (holdBalances[_owner].timeEnd <= now) {
            return balanceOf[_owner];
        } else {
            assert(balanceOf[_owner] >= holdBalances[_owner].amount);
            return balanceOf[_owner] - holdBalances[_owner].amount;
        }
    }

    /**
     * Internal transfer, only can be called by this contract
     */
    function _transfer(address _from, address _to, uint _value) internal {
        require(canTransfer);
        // Prevent transfer to 0x0 address. Use burn() instead
        require(_to != 0x0);

        require(availableBalance(_from) >= _value);

        // 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);
    }

    function transferF(address _from, address _to, uint256 _value) onlyOwner onlyPayloadSize(3) public returns (bool success) {
        _transfer(_from, _to, _value);
        return true;
    }

    function transferHold(address _from, address _to, uint256 _value, uint256 _hold, uint256 _expire) onlyOwner onlyPayloadSize(5) public returns (bool success) {
        require(_hold <= _value);
        // transfer first
        _transfer(_from, _to, _value);
        // now hold
        holdBalances[_to] = HoldBalance(_hold, _expire);
        return true;
    }

    function setHold(address _owner, uint256 _hold, uint256 _expire) onlyOwner onlyPayloadSize(3) public returns (bool success) {
        holdBalances[_owner] = HoldBalance(_hold, _expire);
        return true;
    }

    // --------------
    function getB(address _owner) onlyOwner onlyPayloadSize(1) public constant returns (uint256 balance) {
        return availableBalance(_owner);
    }

    function getHold(address _owner) onlyOwner onlyPayloadSize(1) public constant returns (uint256 hold, uint256 holdt, uint256 n) {
        return (holdBalances[_owner].amount, holdBalances[_owner].timeEnd, now);
    }
    // --------------

    /**
     * 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) onlyPayloadSize(2) public returns (bool success) {
        _transfer(msg.sender, _to, _value);
        return true;
    }

    /**
     * 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) onlyPayloadSize(3) public returns (bool success) {
        require(_value <= allowance[_from][msg.sender]);     // 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) onlyPayloadSize(2) public
        returns (bool success) {
        allowance[msg.sender][_spender] = _value;
        emit Approval(msg.sender, _spender, _value);
        return true;
    }

    /**
     * Set allowance for other address and notify
     *
     * Allows `_spender` to spend no more than `_value` tokens in your behalf, and then ping the contract about it
     *
     * @param _spender The address authorized to spend
     * @param _value the max amount they can spend
     * @param _extraData some extra information to send to the approved contract
     */
    function approveAndCall(address _spender, uint256 _value, bytes _extraData)
        public
        returns (bool success) {
        tokenRecipient spender = tokenRecipient(_spender);
        if (approve(_spender, _value)) {
            spender.receiveApproval(msg.sender, _value, this, _extraData);
            return true;
        }
    }

    /**
     * Destroy tokens
     *
     * Remove `_value` tokens from the system irreversibly
     *
     * @param _value the amount of money to burn
     */
    function burn(uint256 _value) 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;
    }

    /**
     * Destroy tokens from other account
     *
     * Remove `_value` tokens from the system irreversibly on behalf of `_from`.
     *
     * @param _from the address of the sender
     * @param _value the amount of money to burn
     */
    function burnFrom(address _from, uint256 _value) onlyPayloadSize(2) public returns (bool success) {
        require(balanceOf[_from] >= _value);                // Check if the targeted balance is enough
        require(_value <= allowance[_from][msg.sender]);    // Check allowance
        balanceOf[_from] -= _value;                         // Subtract from the targeted balance
        allowance[_from][msg.sender] -= _value;             // Subtract from the sender's allowance
        totalSupply -= _value;                              // Update totalSupply
        emit Burn(_from, _value);
        return true;
    }
}