pragma solidity ^0.4.17;


contract owned {
    address public owner;

    function owned() {
        owner = msg.sender;
    }

    modifier onlyOwner {
        require(msg.sender == owner);
        _;
    }

    function transferOwnership(address newOwner) onlyOwner {
        owner = newOwner;
    }
}


contract tokenRecipient {function receiveApproval(address _from, uint256 _value, address _token, bytes _extraData);}


contract token {
    /* Public variables of the token */
    string public name;
    string public symbol;
    uint8 public decimals;
    uint256 public totalSupply;

    /* This creates an array with all balances */
    mapping (address => uint256) public balanceOf;

    mapping (address => mapping (address => uint256)) public allowance;

    /* This generates a public event on the blockchain that will notify clients */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /* This notifies clients about the amount burnt */
    event Burn(address indexed from, uint256 value);

    /* Initializes contract with initial supply tokens to the creator of the contract */
    function token(
    uint256 initialSupply,
    string tokenName,
    uint8 decimalUnits,
    string tokenSymbol
    ) {
        balanceOf[address(this)] = initialSupply; // Give the contract all initial tokens
        totalSupply = initialSupply; // Update total supply
        name = tokenName; // Set the name for display purposes
        symbol = tokenSymbol; // Set the symbol for display purposes
        decimals = decimalUnits; // Amount of decimals for display purposes
    }

    /* Internal transfer, only can be called by this contract */
    function _transfer(address _from, address _to, uint _value) internal {
        require(_to != 0x0); // Prevent transfer to 0x0 address. Use burn() instead
        require(balanceOf[_from] > _value); // Check if the sender has enough
        require(balanceOf[_to] + _value > balanceOf[_to]); // Check for overflows
        balanceOf[_from] -= _value; // Subtract from the sender
        balanceOf[_to] += _value; // Add the same to the recipient
        Transfer(_from, _to, _value);
    }

    /// @notice 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) {
        _transfer(msg.sender, _to, _value);
    }

    /// @notice Send `_value` tokens to `_to` in 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) returns (bool success) {
        require(_value < allowance[_from][msg.sender]); // Check allowance
        allowance[_from][msg.sender] -= _value;
        _transfer(_from, _to, _value);
        return true;
    }

    /// @notice Allows `_spender` to spend no more than `_value` tokens in your behalf
    /// @param _spender The address authorized to spend
    /// @param _value the max amount they can spend
    function approve(address _spender, uint256 _value)
    returns (bool success) {
        allowance[msg.sender][_spender] = _value;
        return true;
    }

    /// @notice Allows `_spender` to spend no more than `_value` tokens in 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)
    returns (bool success) {
        tokenRecipient spender = tokenRecipient(_spender);
        if (approve(_spender, _value)) {
            spender.receiveApproval(msg.sender, _value, this, _extraData);
            return true;
        }
    }

    /// @notice Remove `_value` tokens from the system irreversibly
    /// @param _value the amount of money to burn
    function burn(uint256 _value) 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;
    }

    function burnFrom(address _from, uint256 _value) 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;
    }
}


contract MyAdvancedToken is owned, token {
    uint256 public sellPrice;
    uint256 public buyPrice;
    mapping (address => bool) public frozenAccount;

    /* This generates a public event on the blockchain that will notify clients */
    event FrozenFunds(address target, bool frozen);

    /* Initializes contract with initial supply tokens to the creator of the contract */
    function MyAdvancedToken(
    uint256 initialSupply,
    string tokenName,
    uint8 decimalUnits,
    string tokenSymbol
    ) token(initialSupply, tokenName, decimalUnits, tokenSymbol) {}

    /* Internal transfer, only can be called by this contract */
    function _transfer(address _from, address _to, uint _value) internal {
        require(_to != 0x0); // Prevent transfer to 0x0 address. Use burn() instead
        require(balanceOf[_from] > _value); // Check if the sender has enough
        require(balanceOf[_to] + _value > balanceOf[_to]); // Check for overflows
        require(!frozenAccount[_from]); // Check if sender is frozen
        require(!frozenAccount[_to]); // Check if recipient is frozen
        balanceOf[_from] -= _value; // Subtract from the sender
        balanceOf[_to] += _value; // Add the same to the recipient
        Transfer(_from, _to, _value);
    }

    /// @notice Create `mintedAmount` tokens and send it to `target`
    /// @param target Address to receive the tokens
    /// @param mintedAmount the amount of tokens it will receive
    function mintToken(address target, uint256 mintedAmount) onlyOwner {
        balanceOf[target] += mintedAmount;
        totalSupply += mintedAmount;
        Transfer(0, this, mintedAmount);
        Transfer(this, target, mintedAmount);
    }

    /// @notice `freeze? Prevent | Allow` `target` from sending & receiving tokens
    /// @param target Address to be frozen
    /// @param freeze either to freeze it or not
    function freezeAccount(address target, bool freeze) onlyOwner {
        frozenAccount[target] = freeze;
        FrozenFunds(target, freeze);
    }

    /// @notice Allow users to buy tokens for `newBuyPrice` eth and sell tokens for `newSellPrice` eth
    /// @param newSellPrice Price the users can sell to the contract
    /// @param newBuyPrice Price users can buy from the contract
    function setPrices(uint256 newSellPrice, uint256 newBuyPrice) onlyOwner {
        sellPrice = newSellPrice;
        buyPrice = newBuyPrice;
    }

    /// @notice Buy tokens from contract by sending ether
    function buy() payable {
        uint amount = msg.value / buyPrice; // calculates the amount
        _transfer(this, msg.sender, amount); // makes the transfers
    }

    /// @notice Sell `amount` tokens to contract
    /// @param amount amount of tokens to be sold
    function sell(uint256 amount) {
        require(this.balance >= amount * sellPrice); // checks if the contract has enough ether to buy
        _transfer(msg.sender, this, amount); // makes the transfers
        msg.sender.transfer(amount * sellPrice); // sends ether to the seller. It's important to do this last to avoid recursion attacks
    }
}

contract NeuroToken is MyAdvancedToken {
    /* Public variables of the token */
    uint256 public frozenTokensSupply;

    /* Initializes contract with initial supply tokens to the creator of the contract */
    function NeuroToken() MyAdvancedToken(17500000, "NeuroToken", 0, "NRT") {
        freezeTokens(17437000);
    }

    /// @notice Freeze `frozenAmount` tokens from being sold
    /// @param frozenAmount amount of tokens to be frozen
    function freezeTokens(uint256 frozenAmount) onlyOwner {
        require(balanceOf[address(this)] >= frozenAmount); // Check if the contract has enough

        frozenTokensSupply += frozenAmount;
        balanceOf[address(this)] -= frozenAmount;
    }

    /// @notice Release `releasedAmount` tokens to contract
    /// @param releasedAmount amount of tokens to be released
    function releaseTokens(uint256 releasedAmount) onlyOwner {
        require(frozenTokensSupply >= releasedAmount); // Check if the contract has enough released tokens

        frozenTokensSupply -= releasedAmount;
        balanceOf[address(this)] += releasedAmount;
    }
}