pragma solidity ^0.4.15;

/**
 * Standard ERC20 token
 *
 * https://github.com/ethereum/EIPs/issues/20
 * Based on code by FirstBlood:
 * https://github.com/Firstbloodio/token/blob/master/smart_contract/FirstBloodToken.sol
 *
 * This is the token contract for trade.io, join the trading revolution.
 * It utilizes Majoolr's TokenLib library to reduce custom source code surface
 * area and increase overall security. Majoolr provides smart contract services
 * and security reviews for contract deployments in addition to working on open
 * source projects in the Ethereum community.
 * For further information: trade.io, majoolr.io
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

contract TIOToken {
  using TokenLib for TokenLib.TokenStorage;

  TokenLib.TokenStorage token;

  function TIOToken(address owner,
                    string name, //TradeToken
                    string symbol, //TIO
                    uint8 decimals, //18
                    uint256 initialSupply, // 555000000000000000000000000
                    bool allowMinting) //false
  {
    token.init(owner, name, symbol, decimals, initialSupply, allowMinting);
  }

  function owner() constant returns (address) {
    return token.owner;
  }

  function name() constant returns (string) {
    return token.name;
  }

  function symbol() constant returns (string) {
    return token.symbol;
  }

  function decimals() constant returns (uint8) {
    return token.decimals;
  }

  function initialSupply() constant returns (uint256) {
    return token.INITIAL_SUPPLY;
  }

  function totalSupply() constant returns (uint256) {
    return token.totalSupply;
  }

  function balanceOf(address who) constant returns (uint256) {
    return token.balanceOf(who);
  }

  function allowance(address owner, address spender) constant returns (uint256) {
    return token.allowance(owner, spender);
  }

  function transfer(address to, uint value) returns (bool ok) {
    return token.transfer(to, value);
  }

  function transferFrom(address from, address to, uint value) returns (bool ok) {
    return token.transferFrom(from, to, value);
  }

  function approve(address spender, uint value) returns (bool ok) {
    return token.approve(spender, value);
  }

  function changeOwner(address newOwner) returns (bool ok) {
    return token.changeOwner(newOwner);
  }

  function burnToken(uint256 amount) returns (bool ok) {
    return token.burnToken(amount);
  }
}

library TokenLib {
  using BasicMathLib for uint256;

  struct TokenStorage {
    mapping (address => uint256) balances;
    mapping (address => mapping (address => uint256)) allowed;

    string name;
    string symbol;
    uint256 totalSupply;
    uint256 INITIAL_SUPPLY;
    address owner;
    uint8 decimals;
    bool stillMinting;
  }

  event Transfer(address indexed from, address indexed to, uint256 value);
  event Approval(address indexed owner, address indexed spender, uint256 value);
  event OwnerChange(address from, address to);
  event Burn(address indexed burner, uint256 value);
  event MintingClosed(bool mintingClosed);

  /// @dev Called by the Standard Token upon creation.
  /// @param self Stored token from token contract
  /// @param _name Name of the new token
  /// @param _symbol Symbol of the new token
  /// @param _decimals Decimal places for the token represented
  /// @param _initial_supply The initial token supply
  /// @param _allowMinting True if additional tokens can be created, false otherwise
  function init(TokenStorage storage self,
                address _owner,
                string _name,
                string _symbol,
                uint8 _decimals,
                uint256 _initial_supply,
                bool _allowMinting)
  {
    require(self.INITIAL_SUPPLY == 0);
    self.name = _name;
    self.symbol = _symbol;
    self.totalSupply = _initial_supply;
    self.INITIAL_SUPPLY = _initial_supply;
    self.decimals = _decimals;
    self.owner = _owner;
    self.stillMinting = _allowMinting;
    self.balances[_owner] = _initial_supply;
  }

  /// @dev Transfer tokens from caller's account to another account.
  /// @param self Stored token from token contract
  /// @param _to Address to send tokens
  /// @param _value Number of tokens to send
  /// @return True if completed
  function transfer(TokenStorage storage self, address _to, uint256 _value) returns (bool) {
    bool err;
    uint256 balance;

    (err,balance) = self.balances[msg.sender].minus(_value);
    require(!err);
    self.balances[msg.sender] = balance;
    //It's not possible to overflow token supply
    self.balances[_to] = self.balances[_to] + _value;
    Transfer(msg.sender, _to, _value);
    return true;
  }

  /// @dev Authorized caller transfers tokens from one account to another
  /// @param self Stored token from token contract
  /// @param _from Address to send tokens from
  /// @param _to Address to send tokens to
  /// @param _value Number of tokens to send
  /// @return True if completed
  function transferFrom(TokenStorage storage self,
                        address _from,
                        address _to,
                        uint256 _value)
                        returns (bool)
  {
    var _allowance = self.allowed[_from][msg.sender];
    bool err;
    uint256 balanceOwner;
    uint256 balanceSpender;

    (err,balanceOwner) = self.balances[_from].minus(_value);
    require(!err);

    (err,balanceSpender) = _allowance.minus(_value);
    require(!err);

    self.balances[_from] = balanceOwner;
    self.allowed[_from][msg.sender] = balanceSpender;
    self.balances[_to] = self.balances[_to] + _value;

    Transfer(_from, _to, _value);
    return true;
  }

  /// @dev Retrieve token balance for an account
  /// @param self Stored token from token contract
  /// @param _owner Address to retrieve balance of
  /// @return balance The number of tokens in the subject account
  function balanceOf(TokenStorage storage self, address _owner) constant returns (uint256 balance) {
    return self.balances[_owner];
  }

  /// @dev Authorize an account to send tokens on caller's behalf
  /// @param self Stored token from token contract
  /// @param _spender Address to authorize
  /// @param _value Number of tokens authorized account may send
  /// @return True if completed
  function approve(TokenStorage storage self, address _spender, uint256 _value) returns (bool) {
    self.allowed[msg.sender][_spender] = _value;
    Approval(msg.sender, _spender, _value);
    return true;
  }

  /// @dev Remaining tokens third party spender has to send
  /// @param self Stored token from token contract
  /// @param _owner Address of token holder
  /// @param _spender Address of authorized spender
  /// @return remaining Number of tokens spender has left in owner's account
  function allowance(TokenStorage storage self, address _owner, address _spender) constant returns (uint256 remaining) {
    return self.allowed[_owner][_spender];
  }

  /// @dev Authorize third party transfer by increasing/decreasing allowed rather than setting it
  /// @param self Stored token from token contract
  /// @param _spender Address to authorize
  /// @param _valueChange Increase or decrease in number of tokens authorized account may send
  /// @param _increase True if increasing allowance, false if decreasing allowance
  /// @return True if completed
  function approveChange (TokenStorage storage self, address _spender, uint256 _valueChange, bool _increase)
                          returns (bool)
  {
    uint256 _newAllowed;
    bool err;

    if(_increase) {
      (err, _newAllowed) = self.allowed[msg.sender][_spender].plus(_valueChange);
      require(!err);

      self.allowed[msg.sender][_spender] = _newAllowed;
    } else {
      if (_valueChange > self.allowed[msg.sender][_spender]) {
        self.allowed[msg.sender][_spender] = 0;
      } else {
        _newAllowed = self.allowed[msg.sender][_spender] - _valueChange;
        self.allowed[msg.sender][_spender] = _newAllowed;
      }
    }

    Approval(msg.sender, _spender, _newAllowed);
    return true;
  }

  /// @dev Change owning address of the token contract, specifically for minting
  /// @param self Stored token from token contract
  /// @param _newOwner Address for the new owner
  /// @return True if completed
  function changeOwner(TokenStorage storage self, address _newOwner) returns (bool) {
    require((self.owner == msg.sender) && (_newOwner > 0));

    self.owner = _newOwner;
    OwnerChange(msg.sender, _newOwner);
    return true;
  }

  /// @dev Mints additional tokens, new tokens go to owner
  /// @param self Stored token from token contract
  /// @param _amount Number of tokens to mint
  /// @return True if completed
  function mintToken(TokenStorage storage self, uint256 _amount) returns (bool) {
    require((self.owner == msg.sender) && self.stillMinting);
    uint256 _newAmount;
    bool err;

    (err, _newAmount) = self.totalSupply.plus(_amount);
    require(!err);

    self.totalSupply =  _newAmount;
    self.balances[self.owner] = self.balances[self.owner] + _amount;
    Transfer(0x0, self.owner, _amount);
    return true;
  }

  /// @dev Permanent stops minting
  /// @param self Stored token from token contract
  /// @return True if completed
  function closeMint(TokenStorage storage self) returns (bool) {
    require(self.owner == msg.sender);

    self.stillMinting = false;
    MintingClosed(true);
    return true;
  }

  /// @dev Permanently burn tokens
  /// @param self Stored token from token contract
  /// @param _amount Amount of tokens to burn
  /// @return True if completed
  function burnToken(TokenStorage storage self, uint256 _amount) returns (bool) {
      uint256 _newBalance;
      bool err;

      (err, _newBalance) = self.balances[msg.sender].minus(_amount);
      require(!err);

      self.balances[msg.sender] = _newBalance;
      self.totalSupply = self.totalSupply - _amount;
      Burn(msg.sender, _amount);
      Transfer(msg.sender, 0x0, _amount);
      return true;
  }
}

library BasicMathLib {
  event Err(string typeErr);

  /// @dev Multiplies two numbers and checks for overflow before returning.
  /// Does not throw but rather logs an Err event if there is overflow.
  /// @param a First number
  /// @param b Second number
  /// @return err False normally, or true if there is overflow
  /// @return res The product of a and b, or 0 if there is overflow
  function times(uint256 a, uint256 b) constant returns (bool err,uint256 res) {
    assembly{
      res := mul(a,b)
      switch or(iszero(b), eq(div(res,b), a))
      case 0 {
        err := 1
        res := 0
      }
    }
    if (err)
      Err("times func overflow");
  }

  /// @dev Divides two numbers but checks for 0 in the divisor first.
  /// Does not throw but rather logs an Err event if 0 is in the divisor.
  /// @param a First number
  /// @param b Second number
  /// @return err False normally, or true if `b` is 0
  /// @return res The quotient of a and b, or 0 if `b` is 0
  function dividedBy(uint256 a, uint256 b) constant returns (bool err,uint256 res) {
    assembly{
      switch iszero(b)
      case 0 {
        res := div(a,b)
        mstore(add(mload(0x40),0x20),res)
        return(mload(0x40),0x40)
      }
    }
    Err("tried to divide by zero");
    return (true, 0);
  }

  /// @dev Adds two numbers and checks for overflow before returning.
  /// Does not throw but rather logs an Err event if there is overflow.
  /// @param a First number
  /// @param b Second number
  /// @return err False normally, or true if there is overflow
  /// @return res The sum of a and b, or 0 if there is overflow
  function plus(uint256 a, uint256 b) constant returns (bool err, uint256 res) {
    assembly{
      res := add(a,b)
      switch and(eq(sub(res,b), a), or(gt(res,b),eq(res,b)))
      case 0 {
        err := 1
        res := 0
      }
    }
    if (err)
      Err("plus func overflow");
  }

  /// @dev Subtracts two numbers and checks for underflow before returning.
  /// Does not throw but rather logs an Err event if there is underflow.
  /// @param a First number
  /// @param b Second number
  /// @return err False normally, or true if there is underflow
  /// @return res The difference between a and b, or 0 if there is underflow
  function minus(uint256 a, uint256 b) constant returns (bool err,uint256 res) {
    assembly{
      res := sub(a,b)
      switch eq(and(eq(add(res,b), a), or(lt(res,a), eq(res,a))), 1)
      case 0 {
        err := 1
        res := 0
      }
    }
    if (err)
      Err("minus func underflow");
  }
}