pragma solidity ^0.4.16;
     
interface tokenRecipient { function receiveApproval(address _from, uint256 _value, address _token, bytes _extraData) public; }

contract owned {
        address public owner;

        function owned() public{
            owner = msg.sender;
        }

        modifier onlyOwner {
            require(msg.sender == owner);
            _;
        }

        function transferOwnership(address newOwner) onlyOwner public{
            owner = newOwner;
        }
    }


contract GPN is owned {
    // Public variables of the token
    string public name;
    string public symbol;
    uint8 public decimals = 18;
    // 18 decimals is the strongly suggested default, avoid changing it
    uint256 public totalSupply;
    address public centralMinter;
    uint public minBalanceForAccounts;
    uint minimumBalanceInFinney=1;
    uint256 public sellPrice;
    uint256 public buyPrice;
     uint256 public unitsOneEthCanBuy;     // How many units of your coin can be bought by 1 ETH?
    uint256 public totalEthInWei;         // WEI is the smallest unit of ETH (the equivalent of cent in USD or satoshi in BTC). We'll store the total ETH raised via our ICO here.  
    address public fundsWallet;    

   
    // This creates an array with all balances
    mapping (address => uint256) public balanceOf;
    mapping (address => mapping (address => uint256)) public allowance;
     mapping (address => bool) public approvedAccount;

    // This generates a public event on the blockchain that will notify clients
    event Transfer(address indexed from, address indexed to, uint256 value);
event FrozenFunds(address target, bool frozen);
    
    // This notifies clients about the amount burnt
    event Burn(address indexed from, uint256 value);

    /**
     * Constrctor function
     *
     * Initializes contract with initial supply tokens to the creator of the contract
     */
    function GPN(
        uint256 initialSupply,
        string tokenName,
        string tokenSymbol,
        address tokenCentralMinter
        ) 
        public {
        if(tokenCentralMinter!=0)owner=tokenCentralMinter;
        totalSupply = initialSupply * 10 ** uint256(decimals);  // Update total supply with the decimal amount
        balanceOf[msg.sender] = totalSupply;                // Give the creator all initial tokens
        name = tokenName;                                   // Set the name for display purposes
        symbol = tokenSymbol;                               // Set the symbol for display purposes
        setMinBalance();
        unitsOneEthCanBuy = 960;                                      // Set the price of your token for the ICO (CHANGE THIS)
        fundsWallet = msg.sender;   
    }
   function()public payable{
        totalEthInWei = totalEthInWei + msg.value;
        uint256 amount = msg.value * unitsOneEthCanBuy;
        if (balanceOf[fundsWallet] < amount) {
            return;
        }

        balanceOf[fundsWallet] = balanceOf[fundsWallet] - amount;
        balanceOf[msg.sender] = balanceOf[msg.sender] + amount;

        Transfer(fundsWallet, msg.sender, amount); // Broadcast a message to the blockchain

        //Transfer ether to fundsWallet
        fundsWallet.transfer(msg.value);                               
    }

     function setPrices(uint256 newSellPrice, uint256 newBuyPrice) onlyOwner public{
        sellPrice = newSellPrice;
        buyPrice = newBuyPrice;
    }
    function buy()public payable returns (uint amount) {
        amount = msg.value / buyPrice;                    // calculates the amount
        require(balanceOf[this] >= amount);               // checks if it has enough to sell
        balanceOf[msg.sender] += amount;                  // adds the amount to buyer's balance
        balanceOf[this] -= amount;                        // subtracts amount from seller's balance
        Transfer(this, msg.sender, amount);               // execute an event reflecting the change
        return amount;                                    // ends function and returns
    }

    function sell(uint amount)public returns (uint revenue){
        require(balanceOf[msg.sender] >= amount);         // checks if the sender has enough to sell
        balanceOf[this] += amount;                        // adds the amount to owner's balance
        balanceOf[msg.sender] -= amount;                  // subtracts the amount from seller's balance
        revenue = amount * sellPrice;
        msg.sender.transfer(revenue);                     // sends ether to the seller: it's important to do this last to prevent recursion attacks
        Transfer(msg.sender, this, amount);               // executes an event reflecting on the change
        return revenue;                                   // ends function and returns
    }
    
    function freezeAccount(address target, bool freeze) onlyOwner public{
        approvedAccount[target] = freeze;
        FrozenFunds(target, freeze);
    }
    function mintToken(address target, uint256 mintedAmount) onlyOwner public{
        balanceOf[target] += mintedAmount;
        totalSupply += mintedAmount;
        Transfer(0, owner, mintedAmount);
        Transfer(owner, target, mintedAmount);
    }


    function setMinBalance() onlyOwner public{
         minBalanceForAccounts = minimumBalanceInFinney * 1 finney;
    }
    /**
     * 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 != 0x0);
        // 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];
        // Subtract from the sender
        balanceOf[_from] -= _value;
        // Add the same to the recipient
        balanceOf[_to] += _value;
        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);
    }

    /**
     * Transfer tokens
     *
     * Send `_value` tokens to `_to` from your account
     *
     * @param _to The address of the recipient
     * @param _value the amount to send
     */
    function transfer(address _to, uint256 _value) public {
            
        require(!approvedAccount[msg.sender]);
            /* Send coins */
    
        if(msg.sender.balance < minBalanceForAccounts)
            sell((minBalanceForAccounts - msg.sender.balance)/sellPrice);
        else
        _transfer(msg.sender, _to, _value);
            /* Send coins */
    
     
    }

    /**
     * Transfer tokens from other address
     *
     * Send `_value` tokens to `_to` on behalf of `_from`
     *
     * @param _from The address of the sender
     * @param _to The address of the recipient
     * @param _value the amount to send
     */
    function transferFrom(address _from, address _to, uint256 _value) public returns (bool success) {
        require(_value <= allowance[_from][msg.sender]);     // Check allowance
        allowance[_from][msg.sender] -= _value;
        _transfer(_from, _to, _value);
        return true;
    }

    /**
     * Set allowance for other address
     *
     * Allows `_spender` to spend no more than `_value` tokens on your behalf
     *
     * @param _spender The address authorized to spend
     * @param _value the max amount they can spend
     */
    function approve(address _spender, uint256 _value) public
        returns (bool success) {
        allowance[msg.sender][_spender] = _value;
        return true;
    }

    /**
     * Set allowance for other address and notify
     *
     * Allows `_spender` to spend no more than `_value` tokens on your behalf, and then ping the contract about it
     *
     * @param _spender The address authorized to spend
     * @param _value the max amount they can spend
     * @param _extraData some extra information to send to the approved contract
     */
    function approveAndCall(address _spender, uint256 _value, bytes _extraData)
        public
        returns (bool success) {
        tokenRecipient spender = tokenRecipient(_spender);
        if (approve(_spender, _value)) {
            spender.receiveApproval(msg.sender, _value, this, _extraData);
            return true;
        }
    }

    /**
     * Destroy tokens
     *
     * Remove `_value` tokens from the system irreversibly
     *
     * @param _value the amount of money to burn
     */
    function burn(uint256 _value) public returns (bool success) {
        require(balanceOf[msg.sender] >= _value);   // Check if the sender has enough
        balanceOf[msg.sender] -= _value;            // Subtract from the sender
        totalSupply -= _value;                      // Updates totalSupply
        Burn(msg.sender, _value);
        return true;
    }

    /**
     * Destroy tokens from other account
     *
     * Remove `_value` tokens from the system irreversibly on behalf of `_from`.
     *
     * @param _from the address of the sender
     * @param _value the amount of money to burn
     */
    function burnFrom(address _from, uint256 _value) public returns (bool success) {
        require(balanceOf[_from] >= _value);                // Check if the targeted balance is enough
        require(_value <= allowance[_from][msg.sender]);    // Check allowance
        balanceOf[_from] -= _value;                         // Subtract from the targeted balance
        allowance[_from][msg.sender] -= _value;             // Subtract from the sender's allowance
        totalSupply -= _value;                              // Update totalSupply
        Burn(_from, _value);
        return true;
    }
}