pragma solidity ^0.4.15;

contract Owned {

    address public owner;

    function Owned() public {
        owner = msg.sender;
    }

    modifier onlyOwner() {
        require(msg.sender == owner);
        _;
    }

    function setOwner(address _newOwner) onlyOwner public {
        owner = _newOwner;
    }
}

library SafeMath {
  function mul(uint256 a, uint256 b) internal pure returns (uint256) {
    uint256 c = a * b;
    assert(a == 0 || c / a == b);
    return c;
  }

  function div(uint256 a, uint256 b) internal pure returns (uint256) {
    // assert(b > 0); // Solidity automatically throws when dividing by 0
    uint256 c = a / b;
    // assert(a == b * c + a % b); // There is no case in which this doesn't hold
    return c;
  }

  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) {
    uint256 c = a + b;
    assert(c >= a);
    return c;
  }

  function toUINT112(uint256 a) internal pure returns(uint112) {
    assert(uint112(a) == a);
    return uint112(a);
  }

  function toUINT120(uint256 a) internal pure returns(uint120) {
    assert(uint120(a) == a);
    return uint120(a);
  }

  function toUINT128(uint256 a) internal pure returns(uint128) {
    assert(uint128(a) == a);
    return uint128(a);
  }
}

contract ERC20Basic {
  uint256 public totalSupply;
  function balanceOf(address who) public constant returns (uint256);
  function transfer(address to, uint256 value) public returns (bool);
  event Transfer(address indexed from, address indexed to, uint256 value);
}

contract ERC20 is ERC20Basic {
  function allowance(address owner, address spender) public constant 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 BasicToken is ERC20Basic, Owned {
  event SetLock(bool _locked);
  using SafeMath for uint256;

  bool locked;
  address impl;
  mapping(address => uint256) balances;

  /**
  * @dev transfer token for a specified address
  * @param _to The address to transfer to.
  * @param _value The amount to be transferred.
  */
  function transfer(address _to, uint256 _value) public returns (bool) {
    require(!locked);
    require(_to != address(0));
    require(_value <= balances[msg.sender]);

    // SafeMath.sub will throw if there is not enough balance.
    balances[msg.sender] = balances[msg.sender].sub(_value);
    balances[_to] = balances[_to].add(_value);
    emit Transfer(msg.sender, _to, _value);
    return true;
  }

  /**
  * @dev Gets the balance of the specified address.
  * @param _owner The address to query the the balance of.
  * @return An uint256 representing the amount owned by the passed address.
  */
  function balanceOf(address _owner) public constant returns (uint256 balance) {
    return balances[_owner];
  }

  function burn(uint256 _value) public returns (bool) {
    require(_value <= balances[msg.sender]);
    balances[msg.sender] -= _value;            // Subtract from the sender
    totalSupply -= _value;                      // Updates totalSupply
    emit Transfer(msg.sender, address(0), _value);
    return true;
  }
  
  function setLocked(bool _locked) public onlyOwner
  {
    locked = _locked;
    emit SetLock(_locked);
  }
  
  function getLocked() public constant returns (bool) {
    return locked;
  }
  
  function SetImpl(address _address) public onlyOwner {
    impl = _address;
  }

  function getImpl() public constant returns (address) {
    return impl;
  }
  
  /**
   * for o2 exchange
  */
  function transferOrigin(address _to, uint256 _value) public returns (bool) {
    require(!locked);
    require(_to != address(0));
    require(msg.sender == impl);
    require(_value <= balances[tx.origin]);

    // SafeMath.sub will throw if there is not enough balance.
    balances[tx.origin] = balances[tx.origin].sub(_value);
    balances[_to] = balances[_to].add(_value);
    emit Transfer(tx.origin, _to, _value);
    return true;
  }
    
}

contract StandardToken is ERC20, BasicToken {

  mapping (address => mapping (address => uint256)) internal allowed;


  /**
   * @dev Transfer tokens from one address to another
   * @param _from address The address which you want to send tokens from
   * @param _to address The address which you want to transfer to
   * @param _value uint256 the amount of tokens to be transferred
   */
  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;
  }

  /**
   * @dev Approve the passed address to spend the specified amount of tokens on behalf of msg.sender.
   *
   * Beware that changing an allowance with this method brings the risk that someone may use both the old
   * and the new allowance by unfortunate transaction ordering. One possible solution to mitigate this
   * race condition is to first reduce the spender's allowance to 0 and set the desired value afterwards:
   * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
   * @param _spender The address which will spend the funds.
   * @param _value The amount of tokens to be spent.
   */
  function approve(address _spender, uint256 _value) public returns (bool) {
    require((_value == 0) || (allowed[msg.sender][_spender] == 0 ));
    allowed[msg.sender][_spender] = _value;
    emit Approval(msg.sender, _spender, _value);
    return true;
  }

  /**
   * @dev Function to check the amount of tokens that an owner allowed to a spender.
   * @param _owner address The address which owns the funds.
   * @param _spender address The address which will spend the funds.
   * @return A uint256 specifying the amount of tokens still available for the spender.
   */
  function allowance(address _owner, address _spender) public constant returns (uint256 remaining) {
    return allowed[_owner][_spender];
  }

}

contract O2Token is StandardToken {

  string public constant name = "O2 Token";
  string public constant symbol = "O2";
  uint8 public constant decimals = 18;


  uint256 public constant INITIAL_SUPPLY = 1000000000 * (10 ** uint256(decimals));

  /**
   * @dev Constructor that gives msg.sender all of existing tokens.
   */
  constructor() public {
    locked = false;
    setOwner(msg.sender);
    totalSupply = INITIAL_SUPPLY;
    balances[0xE60a38E821C2868e54Fa4388cFf6F8844E046c8C] = 1000000000 * (10 ** uint256(decimals));
    emit Transfer(msg.sender, 0xE60a38E821C2868e54Fa4388cFf6F8844E046c8C, 1000000000 * (10 ** uint256(decimals)));
  }
  
  function () public payable {        
    msg.sender.transfer(msg.value);
  }

}