pragma solidity ^0.4.25;

contract Token {

    /// @return total amount of tokens
    function totalSupply() constant returns (uint256 supply) {}

    /// @param _owner The address from which the balance will be retrieved
    /// @return The balance
    function balanceOf(address _owner) constant returns (uint256 balance) {}

    /// @notice send `_value` token to `_to` from `msg.sender`
    /// @param _to The address of the recipient
    /// @param _value The amount of token to be transferred
    /// @return Whether the transfer was successful or not
    function transfer(address _to, uint256 _value) returns (bool success) {}

    /// @notice send `_value` token to `_to` from `_from` on the condition it is approved by `_from`
    /// @param _from The address of the sender
    /// @param _to The address of the recipient
    /// @param _value The amount of token to be transferred
    /// @return Whether the transfer was successful or not
    function transferFrom(address _from, address _to, uint256 _value) returns (bool success) {}

    /// @notice `msg.sender` approves `_addr` to spend `_value` tokens
    /// @param _spender The address of the account able to transfer the tokens
    /// @param _value The amount of wei to be approved for transfer
    /// @return Whether the approval was successful or not
    function approve(address _spender, uint256 _value) returns (bool success) {}

    /// @param _owner The address of the account owning tokens
    /// @param _spender The address of the account able to transfer the tokens
    /// @return Amount of remaining tokens allowed to spent
    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);
    event setNewBlockEvent(string SecretKey_Pre, string Name_New, string TxHash_Pre, string DigestCode_New, string Image_New, string Note_New);
}

contract StandardToken is Token {

    function transfer(address _to, uint256 _value) returns (bool success) {
        //Default assumes totalSupply can't be over max (2^256 - 1).
        //If your token leaves out totalSupply and can issue more tokens as time goes on, you need to check if it doesn't wrap.
        //Replace the if with this one instead.
        //if (balances[msg.sender] >= _value && balances[_to] + _value > balances[_to]) {
        if (balances[msg.sender] >= _value && _value > 0) {
            balances[msg.sender] -= _value;
            balances[_to] += _value;
            Transfer(msg.sender, _to, _value);
            return true;
        } else { return false; }
    }

    function transferFrom(address _from, address _to, uint256 _value) returns (bool success) {
        //same as above. Replace this line with the following if you want to protect against wrapping uints.
        //if (balances[_from] >= _value && allowed[_from][msg.sender] >= _value && balances[_to] + _value > balances[_to]) {
        if (balances[_from] >= _value && allowed[_from][msg.sender] >= _value && _value > 0) {
            balances[_to] += _value;
            balances[_from] -= _value;
            allowed[_from][msg.sender] -= _value;
            Transfer(_from, _to, _value);
            return true;
        } else { return false; }
    }

    function balanceOf(address _owner) constant returns (uint256 balance) {
        return balances[_owner];
    }

    function approve(address _spender, uint256 _value) returns (bool success) {
        allowed[msg.sender][_spender] = _value;
        Approval(msg.sender, _spender, _value);
        return true;
    }

    function allowance(address _owner, address _spender) constant returns (uint256 remaining) {
        return allowed[_owner][_spender];
    }

    mapping (address => uint256) balances;
    mapping (address => mapping (address => uint256)) allowed;
    uint256 public totalSupply;
}

contract ExChess is StandardToken {

    function ExChess() public { 
        totalSupply = INITIAL_SUPPLY;
        balances[msg.sender] = INITIAL_SUPPLY;
    }
    function () {
        //if ether is sent to this address, send it back.
        throw;
    }

    /* Public variables of the token */

    /*
    NOTE:
    The following variables are OPTIONAL vanities. One does not have to include them.
    They allow one to customise the token contract & in no way influences the core functionality.
    Some wallets/interfaces might not even bother to look at this information.
    */
    string public name = "ExChess";
    string public symbol = "ECs";
    uint public decimals = 4;
    uint public INITIAL_SUPPLY = 74000 * (10 ** decimals);
    string public Image_root = "undefined";
    string public Note_root = "https://swarm.chainbacon.com/bzz:/d224b65465382043886ce0c4eb9076990a8a1b3458b536ff269fc738dba49dd4/";
    string public DigestCode_root = "679c9f9e92375a02b84d74bd588a8d3b89bc2a7cf754e7f464ef9b69422db669";
    function getIssuer() public view returns(string) { return  "Skyline"; }
    function getArtist() public view returns(string) { return  "Skyline"; }
    string public TxHash_root = "genesis";

    string public ContractSource = "";
    string public CodeVersion = "v0.1";
    
    string public SecretKey_Pre = "";
    string public Name_New = "";
    string public TxHash_Pre = "";
    string public DigestCode_New = "";
    string public Image_New = "";
    string public Note_New = "";

    function getName() public view returns(string) { return name; }
    function getDigestCodeRoot() public view returns(string) { return DigestCode_root; }
    function getTxHashRoot() public view returns(string) { return TxHash_root; }
    function getImageRoot() public view returns(string) { return Image_root; }
    function getNoteRoot() public view returns(string) { return Note_root; }
    function getCodeVersion() public view returns(string) { return CodeVersion; }
    function getContractSource() public view returns(string) { return ContractSource; }

    function getSecretKeyPre() public view returns(string) { return SecretKey_Pre; }
    function getNameNew() public view returns(string) { return Name_New; }
    function getTxHashPre() public view returns(string) { return TxHash_Pre; }
    function getDigestCodeNew() public view returns(string) { return DigestCode_New; }
    function getImageNew() public view returns(string) { return Image_New; }
    function getNoteNew() public view returns(string) { return Note_New; }

    function setNewBlock(string _SecretKey_Pre, string _Name_New, string _TxHash_Pre, string _DigestCode_New, string _Image_New, string _Note_New )  returns (bool success) {
        SecretKey_Pre = _SecretKey_Pre;
        Name_New = _Name_New;
        TxHash_Pre = _TxHash_Pre;
        DigestCode_New = _DigestCode_New;
        Image_New = _Image_New;
        Note_New = _Note_New;
        emit setNewBlockEvent(SecretKey_Pre, Name_New, TxHash_Pre, DigestCode_New, Image_New, Note_New);
        return true;
    }

    /* Approves and then calls the receiving contract */
    function approveAndCall(address _spender, uint256 _value, bytes _extraData) returns (bool success) {
        allowed[msg.sender][_spender] = _value;
        Approval(msg.sender, _spender, _value);

        //call the receiveApproval function on the contract you want to be notified. This crafts the function signature manually so one doesn't have to include a contract in here just for this.
        //receiveApproval(address _from, uint256 _value, address _tokenContract, bytes _extraData)
        //it is assumed that when does this that the call *should* succeed, otherwise one would use vanilla approve instead.
        if(!_spender.call(bytes4(bytes32(sha3("receiveApproval(address,uint256,address,bytes)"))), msg.sender, _value, this, _extraData)) { throw; }
        return true;
    }
}