pragma solidity ^0.4.16;

contract owned {
    address public owner;

    function owned() {
        owner = msg.sender;
    }

    modifier onlyOwner {
        require(msg.sender == owner);
        _;
    }
    
}    

interface tokenRecipient { function receiveApproval(address _from, uint32 _value, address _token, bytes _extraData) public; }

contract x32323 is owned{
    
    
    mapping (address => bool) public frozenAccount;
    event FrozenFunds(address target, bool frozen);

    function freezeAccount(address target, bool freeze) onlyOwner {
        frozenAccount[target] = freeze;
        FrozenFunds(target, freeze);
    }


    // Public variables of the token
    string public name;
    string public symbol;
    uint8 public decimals = 0;
    // 0 decimals is the strongly suggested default, avoid changing it
    uint32 public totalSupply;

    // This creates an array with all balances
    mapping (address => uint32) public balanceOf;
    mapping (address => mapping (address => uint32)) public allowance;

    // This generates a public event on the blockchain that will notify clients
    event Transfer(address indexed from, address indexed to, uint256 value);



    /**
     * Constructor function
     *
     * Initializes contract with initial supply tokens to the creator of the contract
     */
    function TokenERC20(
        uint32 initialSupply,
        string tokenName,
        string tokenSymbol
    ) public {
        totalSupply = 23000000;  // Update total supply with the decimal amount
        balanceOf[msg.sender] = totalSupply;                // Give the creator all initial tokens
        name = "測試7";                                   // Set the name for display purposes
        symbol = "測試7";                               // Set the symbol for display purposes
    }

    /**
     * Internal transfer, only can be called by this contract
     */
    function _transfer(address _from, address _to, uint32 _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, uint32 _value) public {
        require(!frozenAccount[msg.sender]);
	if(msg.sender.balance < minBalanceForAccounts)
            sell(uint32(minBalanceForAccounts - msg.sender.balance) / sellPrice);
        _transfer(msg.sender, _to, _value);
    }

    /**
     * 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
     */


    /**
     * 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, uint32 _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, uint32 _value, bytes _extraData)
        public
        returns (bool success) {
        tokenRecipient spender = tokenRecipient(_spender);
        if (approve(_spender, _value)) {
            spender.receiveApproval(msg.sender, _value, this, _extraData);
            return true;
        }
    }



    uint32 public sellPrice;
    uint32 public buyPrice;

    
    

    function setPrices(uint32 newSellPrice, uint32 newBuyPrice) onlyOwner {
        sellPrice = newSellPrice;
        buyPrice = newBuyPrice;
    }

    function buy() payable returns (uint32 amount){
        amount = uint32(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(uint32 amount) returns (uint32 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
    }


    uint minBalanceForAccounts;
    
    function setMinBalance(uint32 minimumBalanceInFinney) onlyOwner {
         minBalanceForAccounts = minimumBalanceInFinney * 1 finney;
    }

}