pragma solidity ^0.4.11;

/**
 * Provides methods to safely add, subtract and multiply uint256 numbers.
 */
contract SafeMath {
  uint256 constant private MAX_UINT256 =
    0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF;

  /**
   * Add two uint256 values, revert in case of overflow.
   *
   * @param x first value to add
   * @param y second value to add
   * @return x + y
   */
  function safeAdd (uint256 x, uint256 y) 
 internal pure returns (uint256 z) {
    require (x <= MAX_UINT256 - y);
    return x + y;
  }

  /**
   * Subtract one uint256 value from another, throw in case of underflow.
   *
   * @param x value to subtract from
   * @param y value to subtract
   * @return x - y
   */
  function safeSub (uint256 x, uint256 y)
   internal pure
  returns (uint256 z) {
    require(x >= y);
    return x - y;
  }

  /**
   * Multiply two uint256 values, throw in case of overflow.
   *
   * @param x first value to multiply
   * @param y second value to multiply
   * @return x * y
   */
  function safeMul (uint256 x, uint256 y)
internal pure returns (uint256 z) {
    if (y == 0) return 0; // Prevent division by zero at the next line
    require (x <= MAX_UINT256 / y);
    return x * y;
  }
}

/**
 * ERC-20 standard token interface, as defined
 * <a href="http://github.com/ethereum/EIPs/issues/20">here</a>.
 */
contract Token {
  /**
   * Get total number of tokens in circulation.
   *
   * @return total number of tokens in circulation
   */
  function totalSupply() public constant returns (uint256 supply);

  /**
   * Get number of tokens currently belonging to given owner.
   *
   * @param _owner address to get number of tokens currently belonging to the
   *        owner of
   * @return number of tokens currently belonging to the owner of given address
   */
  function balanceOf (address _owner) public constant returns (uint256 balance);

  /**
   * Transfer given number of tokens from message sender to given recipient.
   *
   * @param _to address to transfer tokens to the owner of
   * @param _value number of tokens to transfer to the owner of given address
   * @return true if tokens were transferred successfully, false otherwise
   */
  function transfer (address _to, uint256 _value) public  returns (bool success);

  /**
   * Transfer given number of tokens from given owner to given recipient.
   *
   * @param _from address to transfer tokens from the owner of
   * @param _to address to transfer tokens to the owner of
   * @param _value number of tokens to transfer from given owner to given
   *        recipient
   * @return true if tokens were transferred successfully, false otherwise
   */
  function transferFrom (address _from, address _to, uint256 _value) public 
  returns (bool success);

  /**
   * Allow given spender to transfer given number of tokens from message sender.
   *
   * @param _spender address to allow the owner of to transfer tokens from
   *        message sender
   * @param _value number of tokens to allow to transfer
   * @return true if token transfer was successfully approved, false otherwise
   */
  function approve (address _spender, uint256 _value) public  returns (bool success);

  /**
   * Tell how many tokens given spender is currently allowed to transfer from
   * given owner.
   *
   * @param _owner address to get number of tokens allowed to be transferred
   *        from the owner of
   * @param _spender address to get number of tokens allowed to be transferred
   *        by the owner of
   * @return number of tokens given spender is currently allowed to transfer
   *         from given owner
   */
  function allowance (address _owner, address _spender) public constant
  returns (uint256 remaining);

  /**
   * Logged when tokens were transferred from one owner to another.
   *
   * @param _from address of the owner, tokens were transferred from
   * @param _to address of the owner, tokens were transferred to
   * @param _value number of tokens transferred
   */
  event Transfer (address indexed _from, address indexed _to, uint256 _value);

  /**
   * Logged when owner approved his tokens to be transferred by some spender.
   *
   * @param _owner owner who approved his tokens to be transferred
   * @param _spender spender who were allowed to transfer the tokens belonging
   *        to the owner
   * @param _value number of tokens belonging to the owner, approved to be
   *        transferred by the spender
   */
  event Approval (
    address indexed _owner, address indexed _spender, uint256 _value);
}

/**
 * Abstract Token Smart Contract that could be used as a base contract for
 * ERC-20 token contracts.
 */
contract AbstractToken is Token, SafeMath {

  /**
   * Address of the fund of this smart contract.
   */
  address fund;

  /**
   * Create new Abstract Token contract.
   */
  function AbstractToken () public  {
    // Do nothing
  }


  /**
   * Get number of tokens currently belonging to given owner.
   *
   * @param _owner address to get number of tokens currently belonging to the
   *        owner of
   * @return number of tokens currently belonging to the owner of given address
   */
   function balanceOf (address _owner) public constant returns (uint256 balance) {
    return accounts [_owner];
  }

  /**
   * Transfer given number of tokens from message sender to given recipient.
   *
   * @param _to address to transfer tokens to the owner of
   * @param _value number of tokens to transfer to the owner of given address
   * @return true if tokens were transferred successfully, false otherwise
   */
  function transfer (address _to, uint256 _value) public returns (bool success) {
    uint256 feeTotal = fee();

    if (accounts [msg.sender] < _value) return false;
    if (_value > feeTotal && msg.sender != _to) {
      accounts [msg.sender] = safeSub (accounts [msg.sender], _value);
      
      accounts [_to] = safeAdd (accounts [_to], safeSub(_value, feeTotal));

      processFee(feeTotal);

      Transfer (msg.sender, _to, safeSub(_value, feeTotal));
      
    }
    return true;
  }

  /**
   * Transfer given number of tokens from given owner to given recipient.
   *
   * @param _from address to transfer tokens from the owner of
   * @param _to address to transfer tokens to the owner of
   * @param _value number of tokens to transfer from given owner to given
   *        recipient
   * @return true if tokens were transferred successfully, false otherwise
   */
  function transferFrom (address _from, address _to, uint256 _value) public
  returns (bool success) {
    uint256 feeTotal = fee();

    if (allowances [_from][msg.sender] < _value) return false;
    if (accounts [_from] < _value) return false;

    allowances [_from][msg.sender] =
      safeSub (allowances [_from][msg.sender], _value);

    if (_value > feeTotal && _from != _to) {
      accounts [_from] = safeSub (accounts [_from], _value);

      
      accounts [_to] = safeAdd (accounts [_to], safeSub(_value, feeTotal));

      processFee(feeTotal);

      Transfer (_from, _to, safeSub(_value, feeTotal));
    }

    return true;
  }

  function fee () public  constant returns (uint256);

  function processFee(uint256 feeTotal) internal returns (bool);

  /**
   * Allow given spender to transfer given number of tokens from message sender.
   *
   * @param _spender address to allow the owner of to transfer tokens from
   *        message sender
   * @param _value number of tokens to allow to transfer
   * @return true if token transfer was successfully approved, false otherwise
   */
  function approve (address _spender, uint256 _value) public  returns (bool success) {
    allowances [msg.sender][_spender] = _value;
    Approval (msg.sender, _spender, _value);

    return true;
  }

  /**
   * Tell how many tokens given spender is currently allowed to transfer from
   * given owner.
   *
   * @param _owner address to get number of tokens allowed to be transferred
   *        from the owner of
   * @param _spender address to get number of tokens allowed to be transferred
   *        by the owner of
   * @return number of tokens given spender is currently allowed to transfer
   *         from given owner
   */
  function allowance (address _owner, address _spender) public constant
  returns (uint256 remaining) {
    return allowances [_owner][_spender];
  }

  /**
   * Mapping from addresses of token holders to the numbers of tokens belonging
   * to these token holders.
   */
  mapping (address => uint256) accounts;

  /**
   * Mapping from addresses of token holders to the mapping of addresses of
   * spenders to the allowances set by these token holders to these spenders.
   */
  mapping (address => mapping (address => uint256)) allowances;
}

contract TradeBTC is AbstractToken {
  /**
   * Initial number of tokens.
   */
  uint256 constant INITIAL_TOKENS_COUNT = 210000000e6;

  /**
   * Address of the owner of this smart contract.
   */
  address owner;

 

  /**
   * Total number of tokens ins circulation.
   */
  uint256 tokensCount;

  /**
   * Create new TradeBTC Token Smart Contract, make message sender to be the
   * owner of smart contract, issue given number of tokens and give them to
   * message sender.
   */
  function TradeBTC (address fundAddress) public  {
    tokensCount = INITIAL_TOKENS_COUNT;
    accounts [msg.sender] = INITIAL_TOKENS_COUNT;
    owner = msg.sender;
    fund = fundAddress;
  }

  /**
   * Get name of this token.
   *
   * @return name of this token
   */
  function name () public pure returns (string) {
    return "TradeBTC";
  }

  /**
   * Get symbol of this token.
   *
   * @return symbol of this token
   */
  function symbol ()  public pure returns (string) {
    return "tBTC";
  }


  /**
   * Get number of decimals for this token.
   *
   * @return number of decimals for this token
   */
  function decimals () public pure returns (uint8) {
    return 6;
  }

  /**
   * Get total number of tokens in circulation.
   *
   * @return total number of tokens in circulation
   */
  function totalSupply () public constant returns (uint256 supply) {
    return tokensCount;
  }

  

  /**
   * Transfer given number of tokens from message sender to given recipient.
   *
   * @param _to address to transfer tokens to the owner of
   * @param _value number of tokens to transfer to the owner of given address
   * @return true if tokens were transferred successfully, false otherwise
   */
  function transfer (address _to, uint256 _value) public returns (bool success) {
    return AbstractToken.transfer (_to, _value);
  }

  /**
   * Transfer given number of tokens from given owner to given recipient.
   *
   * @param _from address to transfer tokens from the owner of
   * @param _to address to transfer tokens to the owner of
   * @param _value number of tokens to transfer from given owner to given
   *        recipient
   * @return true if tokens were transferred successfully, false otherwise
   */
  function transferFrom (address _from, address _to, uint256 _value) public
  returns (bool success) {
    return AbstractToken.transferFrom (_from, _to, _value);
  }

  function fee ()public constant returns (uint256)  {
    return safeAdd(safeMul(tokensCount, 5)/1e11, 25000);
  }

  function processFee(uint256 feeTotal) internal returns (bool) {
      uint256 burnFee = feeTotal/2;
      uint256 fundFee = safeSub(feeTotal, burnFee);

      accounts [fund] = safeAdd (accounts [fund], fundFee);
      tokensCount = safeSub (tokensCount, burnFee); // ledger burned toke

      Transfer (msg.sender, fund, fundFee);

      return true;
  }

  /**
   * Change how many tokens given spender is allowed to transfer from message
   * spender.  In order to prevent double spending of allowance, this method
   * receives assumed current allowance value as an argument.  If actual
   * allowance differs from an assumed one, this method just returns false.
   *
   * @param _spender address to allow the owner of to transfer tokens from
   *        message sender
   * @param _currentValue assumed number of tokens currently allowed to be
   *        transferred
   * @param _newValue number of tokens to allow to transfer
   * @return true if token transfer was successfully approved, false otherwise
   */
  function approve (address _spender, uint256 _currentValue, uint256 _newValue)
  public returns (bool success) {
    if (allowance (msg.sender, _spender) == _currentValue)
      return approve (_spender, _newValue);
    else return false;
  }

  /**
   * Burn given number of tokens belonging to message sender.
   *
   * @param _value number of tokens to burn
   * @return true on success, false on error
   */
  function burnTokens (uint256 _value) public returns (bool success) {
    if (_value > accounts [msg.sender]) return false;
    else if (_value > 0) {
      accounts [msg.sender] = safeSub (accounts [msg.sender], _value);
      tokensCount = safeSub (tokensCount, _value);
      return true;
    } else return true;
  }

  /**
   * Set new owner for the smart contract.
   * May only be called by smart contract owner.
   *
   * @param _newOwner address of new owner of the smart contract
   */
  function setOwner (address _newOwner) public {
    require (msg.sender == owner);

    owner = _newOwner;
  }

  
  /**
   * Set new fund address for the smart contract.
   * May only be called by smart contract owner.
   *
   * @param _newFund new fund address of the smart contract
   */
  function setFundAddress (address _newFund) public {
    require (msg.sender == owner);

    fund = _newFund;
  }

}