pragma solidity ^0.4.18;

/**
 * Math operations with safety checks
 */
contract SafeMath {
  function safeMult(uint256 a, uint256 b) internal returns (uint256) {
    uint256 c = a * b;
    assert(a == 0 || c / a == b);
    return c;
  }

  function safeDiv(uint256 a, uint256 b) internal returns (uint256) {
    assert(b > 0);
    uint256 c = a / b;
    assert(a == b * c + a % b);
    return c;
  }

  function safeSub(uint256 a, uint256 b) internal returns (uint256) {
    assert(b <= a);
    return a - b;
  }

  function safeAdd(uint256 a, uint256 b) internal returns (uint256) {
    uint256 c = a + b;
    assert(c>=a && c>=b);
    return c;
  }
}

contract TokenERC20 {
     function balanceOf(address _owner) constant returns (uint256  balance);
     function transfer(address _to, uint256  _value) returns (bool success);
     function transferFrom(address _from, address _to, uint256  _value) returns (bool success);
     function approve(address _spender, uint256  _value) returns (bool success);
     function allowance(address _owner, address _spender) constant returns (uint256 remaining);
     event Transfer(address indexed _from, address indexed _to, uint256  _value);
     event Approval(address indexed _owner, address indexed _spender, uint256 _value);
}

contract MMMToken is SafeMath, TokenERC20{ 
    string public name = "MMM";
    string public symbol = "MMM";
    uint8 public decimals = 18;
    uint256 public totalSupply = 4204800;
	address public owner = 0x0;
	string  public version = "1.0";	
	
    bool public locked = false;	
    uint256 public currentSupply;           
    uint256 public tokenRaised = 0;    
    uint256 public tokenExchangeRate = 500; 

    /* This creates an array with all balances */
    mapping (address => uint256) public balanceOf;
	mapping (address => uint256) public freezeOf;
    mapping (address => mapping (address => uint256)) public allowance;
	
	/* IssueToken*/
    event IssueToken(address indexed to, uint256 value);

    /* Initializes contract with initial supply tokens to the creator of the contract */
    function MMMToken(
        uint256 initialSupply,
        string tokenName,
        string tokenSymbol
        ) {
        totalSupply = formatDecimals(initialSupply);      			 //  Update total supply
        balanceOf[msg.sender] = totalSupply;              			 //  Give the creator all initial tokens
        name = tokenName;                                   		 //  Set the name for display purposes
		currentSupply = totalSupply;
        symbol = tokenSymbol;                                        //  Set the symbol for display purposes
		owner = msg.sender;
    }
	
	modifier onlyOwner()  { 
		require(msg.sender == owner); 
		_; 
	}
	
	modifier validAddress()  {
        require(address(0) != msg.sender);
        _;
    }
	
    modifier unlocked() {
        require(!locked);
        _;
    }
	
    function formatDecimals(uint256 _value) internal returns (uint256 ) {
        return _value * 10 ** uint256(decimals);
	}
	
	function balanceOf(address _owner) constant returns (uint256 balance) {
        return balanceOf[_owner];
    }

    /* Allow another contract to spend some tokens in your behalf */
    function approve(address _spender, uint256 _value) validAddress unlocked returns (bool success) {
        require(_value > 0);
        allowance[msg.sender][_spender] = _value;
		Approval(msg.sender, _spender, _value);
        return true;
    }
	
	/*Function to check the amount of tokens that an owner allowed to a spender.*/
	function allowance(address _owner, address _spender) constant returns (uint256 remaining) {
		return allowance[_owner][_spender];
	}	

	  /**
	   * @dev Increase the amount of tokens that an owner allowance to a spender.
	   * approve should be called when allowance[_spender] == 0. To increment
	   * allowance value is better to use this function to avoid 2 calls (and wait until
	   * the first transaction is mined)
	   * @param _spender The address which will spend the funds.
	   * @param _addedValue The amount of tokens to increase the allowance by.
	   */
	  function increaseApproval(address _spender, uint256 _addedValue) validAddress unlocked public returns (bool success)
	  {
		allowance[msg.sender][_spender] = SafeMath.safeAdd(allowance[msg.sender][_spender], _addedValue);
		Approval(msg.sender, _spender, allowance[msg.sender][_spender]);
		return true;
	  }

	  /**
	   * @dev Decrease the amount of tokens that an owner allowance to a spender.
	   * approve should be called when allowance[_spender] == 0. To decrement
	   * allowance value is better to use this function to avoid 2 calls (and wait until
	   * the first transaction is mined)
	   * @param _spender The address which will spend the funds.
	   * @param _subtractedValue The amount of tokens to decrease the allowance by.
	   */
	  function decreaseApproval(address _spender, uint256 _subtractedValue) validAddress unlocked public returns (bool success)
	  {
		uint256 oldValue = allowance[msg.sender][_spender];
		if (_subtractedValue > oldValue) {
		  allowance[msg.sender][_spender] = 0;
		} else {
		  allowance[msg.sender][_spender] = SafeMath.safeSub(oldValue, _subtractedValue);
		}
		Approval(msg.sender, _spender, allowance[msg.sender][_spender]);
		return true;
	  }

    /* Send coins */
    function transfer(address _to, uint256 _value) validAddress unlocked returns (bool success) {	
        _transfer(msg.sender, _to, _value);
    }
	
	/**
     * Internal transfer, only can be called by this contract
     */
    function _transfer(address _from, address _to, uint _value) internal {
        // Prevent transfer to 0x0 address. Use burn() instead
        require(_to != address(0));
        require(_value > 0);
        // 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];
        balanceOf[_from] = SafeMath.safeSub(balanceOf[_from], _value);   // Subtract from the sender
        balanceOf[_to] = SafeMath.safeAdd(balanceOf[_to], _value);       // Add the same to the recipient
        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);
    }

    /* A contract attempts to get the coins */
    function transferFrom(address _from, address _to, uint256 _value) validAddress unlocked returns (bool success) {	
        require(_value <= allowance[_from][msg.sender]);     		// Check allowance
        require(_value > 0);
        allowance[_from][msg.sender] = SafeMath.safeSub(allowance[_from][msg.sender], _value);
        _transfer(_from, _to, _value);
        return true;
    }
}