pragma solidity ^0.4.16;

 

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;

    }

}

 

interface tokenRecipient { function receiveApproval(address _from, uint256 _value, address _token, bytes _extraData) public; }

 

contract TokenERC20 {

    // Public variables of the token

    string public name;

    string public symbol;

    uint8 public decimals = 8;

    // 18 decimals is the strongly suggested default, avoid changing it

    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);

 

    /**

     * Constrctor function

     *

     * Initializes contract with initial supply tokens to the creator of the contract

     */

    function TokenERC20(

        uint256 initialSupply,

        string tokenName,

        string tokenSymbol

    ) public {

        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

    }

 

    /**

     * 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 {

        _transfer(msg.sender, _to, _value);

    }

 

    /**

     * Transfer tokens from other address

     *

     * 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) 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 in 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 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)

        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;

    }

}

 

/******************************************/

/*       ADVANCED TOKEN STARTS HERE       */

/******************************************/

 

contract MyAdvancedToken is owned, TokenERC20 {

 

    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,

        string tokenSymbol

    ) TokenERC20(initialSupply, tokenName, tokenSymbol) public {}

 

    /* 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 public {

        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 public {

        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 public {

        sellPrice = newSellPrice;

        buyPrice = newBuyPrice;

    }

 

    /// @notice Buy tokens from contract by sending ether

    function buy() payable public {

        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) public {

        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

    }

}