pragma solidity ^0.4.24;

contract ERC20Basic {
  function totalSupply() public view returns (uint256);
  function balanceOf(address who) public view returns (uint256);
  function transfer(address to, uint256 value) public returns (bool);
  event Transfer(address indexed from, address indexed to, uint256 value);
}

library SafeMath {

  function mul(uint256 a, uint256 b) internal pure returns (uint256 c) {
    if (a == 0) {
      return 0;
    }

    c = a * b;
    assert(c / a == b);
    return c;
  }

  function div(uint256 a, uint256 b) internal pure returns (uint256) {
    return a / b;
  }

  function sub(uint256 a, uint256 b) internal pure returns (uint256) {
    assert(b <= a);
    return a - b;
  }

  function add(uint256 a, uint256 b) internal pure returns (uint256 c) {
    c = a + b;
    assert(c >= a);
    return c;
  }
}

contract BasicToken is ERC20Basic {
  using SafeMath for uint256;

  mapping(address => uint256) balances;

  uint256 totalSupply_;

  function totalSupply() public view returns (uint256) {
    return totalSupply_;
  }

  function transfer(address _to, uint256 _value) public returns (bool) {
    require(_to != address(0));
    require(_value <= balances[msg.sender]);
    balances[msg.sender] = balances[msg.sender].sub(_value);
    balances[_to] = balances[_to].add(_value);
    emit Transfer(msg.sender, _to, _value);
    return true;
  }

  function balanceOf(address _owner) public view returns (uint256) {
    return balances[_owner];
  }

}

contract ERC20 is ERC20Basic {
  function allowance(address owner, address spender)
    public view returns (uint256);

  function transferFrom(address from, address to, uint256 value)
    public returns (bool);

  function approve(address spender, uint256 value) public returns (bool);
  event Approval(
    address indexed owner,
    address indexed spender,
    uint256 value
  );
}

contract StandardToken is ERC20, BasicToken {

  mapping (address => mapping (address => uint256)) internal allowed;

  function transferFrom(
    address _from,
    address _to,
    uint256 _value
  )
    public
    returns (bool)
  {
    require(_to != address(0));
    require(_value <= balances[_from]);
    require(_value <= allowed[_from][msg.sender]);

    balances[_from] = balances[_from].sub(_value);
    balances[_to] = balances[_to].add(_value);
    allowed[_from][msg.sender] = allowed[_from][msg.sender].sub(_value);
    emit Transfer(_from, _to, _value);
    return true;
  }

  function approve(address _spender, uint256 _value) public returns (bool) {
    allowed[msg.sender][_spender] = _value;
    emit Approval(msg.sender, _spender, _value);
    return true;
  }

  function allowance(
    address _owner,
    address _spender
   )
    public
    view
    returns (uint256)
  {
    return allowed[_owner][_spender];
  }

  function increaseApproval(
    address _spender,
    uint _addedValue
  )
    public
    returns (bool)
  {
    allowed[msg.sender][_spender] = (
      allowed[msg.sender][_spender].add(_addedValue));
    emit Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
    return true;
  }

  function decreaseApproval(
    address _spender,
    uint _subtractedValue
  )
    public
    returns (bool)
  {
    uint oldValue = allowed[msg.sender][_spender];
    if (_subtractedValue > oldValue) {
      allowed[msg.sender][_spender] = 0;
    } else {
      allowed[msg.sender][_spender] = oldValue.sub(_subtractedValue);
    }
    emit Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
    return true;
  }

}

contract Ownable {
  address public owner;

  event OwnershipRenounced(address indexed previousOwner);
  event OwnershipTransferred(
    address indexed previousOwner,
    address indexed newOwner
  );

  constructor() public {
    owner = msg.sender;
  }

  modifier onlyOwner() {
    require(msg.sender == owner);
    _;
  }

  function renounceOwnership() public onlyOwner {
    emit OwnershipRenounced(owner);
    owner = address(0);
  }

  function transferOwnership(address _newOwner) public onlyOwner {
    _transferOwnership(_newOwner);
  }

  function _transferOwnership(address _newOwner) internal {
    require(_newOwner != address(0));
    emit OwnershipTransferred(owner, _newOwner);
    owner = _newOwner;
  }
}

contract MintableToken is StandardToken, Ownable {
  event Mint(address indexed to, uint256 amount);
  event MintFinished();

  bool public mintingFinished = false;

  modifier canMint() {
    require(!mintingFinished);
    _;
  }

  modifier hasMintPermission() {
    require(msg.sender == owner);
    _;
  }

  function mint(
    address _to,
    uint256 _amount
  )
    hasMintPermission
    canMint
    public
    returns (bool)
  {
    totalSupply_ = totalSupply_.add(_amount);
    balances[_to] = balances[_to].add(_amount);
    emit Mint(_to, _amount);
    emit Transfer(address(0), _to, _amount);
    return true;
  }

  function finishMinting() onlyOwner canMint public returns (bool) {
    mintingFinished = true;
    emit MintFinished();
    return true;
  }
}


contract FreezableToken is StandardToken {

    mapping (bytes32 => uint64) internal chains;
    mapping (bytes32 => uint) internal freezings;
    mapping (address => uint) internal freezingBalance;

    event Freezed(address indexed to, uint64 release, uint amount);
    event Released(address indexed owner, uint amount);

    function balanceOf(address _owner) public view returns (uint256 balance) {
        return super.balanceOf(_owner) + freezingBalance[_owner];
    }

    function actualBalanceOf(address _owner) public view returns (uint256 balance) {
        return super.balanceOf(_owner);
    }

    function freezingBalanceOf(address _owner) public view returns (uint256 balance) {
        return freezingBalance[_owner];
    }

    function freezingCount(address _addr) public view returns (uint count) {
        uint64 release = chains[toKey(_addr, 0)];
        while (release != 0) {
            count++;
            release = chains[toKey(_addr, release)];
        }
    }

    function getFreezing(address _addr, uint _index) public view returns (uint64 _release, uint _balance) {
        for (uint i = 0; i < _index + 1; i++) {
            _release = chains[toKey(_addr, _release)];
            if (_release == 0) {
                return;
            }
        }
        _balance = freezings[toKey(_addr, _release)];
    }

    function freezeTo(address _to, uint _amount, uint64 _until) public {
        require(_to != address(0));
        require(_amount <= balances[msg.sender]);

        balances[msg.sender] = balances[msg.sender].sub(_amount);

        bytes32 currentKey = toKey(_to, _until);
        freezings[currentKey] = freezings[currentKey].add(_amount);
        freezingBalance[_to] = freezingBalance[_to].add(_amount);

        freeze(_to, _until);
        emit Transfer(msg.sender, _to, _amount);
        emit Freezed(_to, _until, _amount);
    }

    function releaseOnce() public {
        bytes32 headKey = toKey(msg.sender, 0);
        uint64 head = chains[headKey];
        require(head != 0);
        require(uint64(block.timestamp) > head);
        bytes32 currentKey = toKey(msg.sender, head);

        uint64 next = chains[currentKey];

        uint amount = freezings[currentKey];
        delete freezings[currentKey];

        balances[msg.sender] = balances[msg.sender].add(amount);
        freezingBalance[msg.sender] = freezingBalance[msg.sender].sub(amount);

        if (next == 0) {
            delete chains[headKey];
        } else {
            chains[headKey] = next;
            delete chains[currentKey];
        }
        emit Released(msg.sender, amount);
    }

    function releaseAll() public returns (uint tokens) {
        uint release;
        uint balance;
        (release, balance) = getFreezing(msg.sender, 0);
        while (release != 0 && block.timestamp > release) {
            releaseOnce();
            tokens += balance;
            (release, balance) = getFreezing(msg.sender, 0);
        }
    }

    function toKey(address _addr, uint _release) internal pure returns (bytes32 result) {
        result = 0x5749534800000000000000000000000000000000000000000000000000000000;
        assembly {
            result := or(result, mul(_addr, 0x10000000000000000))
            result := or(result, _release)
        }
    }

    function freeze(address _to, uint64 _until) internal {
        require(_until > block.timestamp);
        bytes32 key = toKey(_to, _until);
        bytes32 parentKey = toKey(_to, uint64(0));
        uint64 next = chains[parentKey];

        if (next == 0) {
            chains[parentKey] = _until;
            return;
        }

        bytes32 nextKey = toKey(_to, next);
        uint parent;

        while (next != 0 && _until > next) {
            parent = next;
            parentKey = nextKey;

            next = chains[nextKey];
            nextKey = toKey(_to, next);
        }

        if (_until == next) {
            return;
        }

        if (next != 0) {
            chains[key] = next;
        }

        chains[parentKey] = _until;
    }
}

contract BurnableToken is BasicToken {

  event Burn(address indexed burner, uint256 value);

  function burn(uint256 _value) public {
    _burn(msg.sender, _value);
  }

  function _burn(address _who, uint256 _value) internal {
    require(_value <= balances[_who]);

    balances[_who] = balances[_who].sub(_value);
    totalSupply_ = totalSupply_.sub(_value);
    emit Burn(_who, _value);
    emit Transfer(_who, address(0), _value);
  }
}

contract Pausable is Ownable {
  event Pause();
  event Unpause();

  bool public paused = false;

  modifier whenNotPaused() {
    require(!paused);
    _;
  }

  modifier whenPaused() {
    require(paused);
    _;
  }

  function pause() onlyOwner whenNotPaused public {
    paused = true;
    emit Pause();
  }

  function unpause() onlyOwner whenPaused public {
    paused = false;
    emit Unpause();
  }
}


contract FreezableMintableToken is FreezableToken, MintableToken {

    function mintAndFreeze(address _to, uint _amount, uint64 _until) public onlyOwner canMint returns (bool) {
        totalSupply_ = totalSupply_.add(_amount);

        bytes32 currentKey = toKey(_to, _until);
        freezings[currentKey] = freezings[currentKey].add(_amount);
        freezingBalance[_to] = freezingBalance[_to].add(_amount);

        freeze(_to, _until);
        emit Mint(_to, _amount);
        emit Freezed(_to, _until, _amount);
        emit Transfer(msg.sender, _to, _amount);
        return true;
    }
}


contract Consts {
    uint public constant TOKEN_DECIMALS = 4;
    uint8 public constant TOKEN_DECIMALS_UINT8 = 4;
    uint public constant TOKEN_DECIMAL_MULTIPLIER = 10 ** TOKEN_DECIMALS;

    string public constant TOKEN_NAME = "Vietnam Real Estate Crypto";
    string public constant TOKEN_SYMBOL = "BDS coin";
    bool public constant PAUSED = false;
    address public constant TARGET_USER = 0xbCFcB0299071Dc5f22176c17C1A2A67BA315D8a8;
    
    bool public constant CONTINUE_MINTING = false;
}

contract MainToken is Consts, FreezableMintableToken, BurnableToken, Pausable    
{  
    event Initialized();
    bool public initialized = false;

    constructor() public {
        init();
        transferOwnership(TARGET_USER);
    }
    
    function name() public pure returns (string _name) {
        return TOKEN_NAME;
    }

    function symbol() public pure returns (string _symbol) {
        return TOKEN_SYMBOL;
    }

    function decimals() public pure returns (uint8 _decimals) {
        return TOKEN_DECIMALS_UINT8;
    }

    function transferFrom(address _from, address _to, uint256 _value) public returns (bool _success) {
        require(!paused);
        return super.transferFrom(_from, _to, _value);
    }

    function transfer(address _to, uint256 _value) public returns (bool _success) {
        require(!paused);
        return super.transfer(_to, _value);
    }

    
    function init() private {
        require(!initialized);
        initialized = true;

        if (PAUSED) {
            pause();
        }

        
        address[1] memory addresses = [address(0xbCFcB0299071Dc5f22176c17C1A2A67BA315D8a8)];
        uint[1] memory amounts = [uint(10000000000000)];
        uint64[1] memory freezes = [uint64(0)];

        for (uint i = 0; i < addresses.length; i++) {
            if (freezes[i] == 0) {
                mint(addresses[i], amounts[i]);
            } else {
                mintAndFreeze(addresses[i], amounts[i], freezes[i]);
            }
        }
        

        if (!CONTINUE_MINTING) {
            finishMinting();
        }

        emit Initialized();
    }
    
}