pragma solidity ^0.4.21;

/**
 * @title SafeMath
 * @dev Math operations with safety checks that throw on error
 */
library SafeMath {

    /**
    * @dev Multiplies two numbers, throws on overflow.
    */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        if (a == 0) {
            return 0;
        }
        uint256 c = a * b;
        assert(c / a == b);
        return c;
    }

    /**
    * @dev Integer division of two numbers, truncating the quotient.
    */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        // assert(b > 0); // Solidity automatically throws when dividing by 0
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold
        return c;
    }

    /**
    * @dev Substracts two numbers, throws on overflow (i.e. if subtrahend is greater than minuend).
    */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        assert(b <= a);
        return a - b;
    }

    /**
    * @dev Adds two numbers, throws on overflow.
    */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        assert(c >= a);
        return c;
    }
}

/**
 * @title ERC20Basic
 * @dev Simpler version of ERC20 interface
 * @dev see https://github.com/ethereum/EIPs/issues/179
 */
contract ERC20Basic {
    function totalSupply() public view returns (uint256);
    function balanceOf(address who) public view returns (uint256);
    function transfer(address to, uint256 value) public returns (bool);
    event Transfer(address indexed from, address indexed to, uint256 value);
}
/**
 * @title Basic token
 * @dev Basic version of StandardToken, with no allowances.
 */
contract BasicToken is ERC20Basic {
    using SafeMath for uint256;

    mapping(address => uint256) balances;

    uint256 totalSupply_;

    /**
    * @dev total number of tokens in existence
    */
    function totalSupply() public view returns (uint256) {
        return totalSupply_;
    }

    /**
    * @dev transfer token for a specified address
    * @param _to The address to transfer to.
    * @param _value The amount to be transferred.
    */
    function transfer(address _to, uint256 _value) public returns (bool) {
        require(_to != address(0));
        require(_value <= balances[msg.sender]);

        // SafeMath.sub will throw if there is not enough balance.
        balances[msg.sender] = balances[msg.sender].sub(_value);
        balances[_to] = balances[_to].add(_value);
        emit Transfer(msg.sender, _to, _value);
        return true;
    }

    /**
    * @dev Gets the balance of the specified address.
    * @param _owner The address to query the the balance of.
    * @return An uint256 representing the amount owned by the passed address.
    */
    function balanceOf(address _owner) public view returns (uint256 balance) {
        return balances[_owner];
    }

}



/**
 * @title ERC20 interface
 * @dev see https://github.com/ethereum/EIPs/issues/20
 */
contract ERC20 is ERC20Basic {
    function allowance(address owner, address spender) public view returns (uint256);
    function transferFrom(address from, address to, uint256 value) public returns (bool);
    function approve(address spender, uint256 value) public returns (bool);
    event Approval(address indexed owner, address indexed spender, uint256 value);
}


/**
 * @title Standard ERC20 token
 *
 * @dev Implementation of the basic standard token.
 * @dev https://github.com/ethereum/EIPs/issues/20
 * @dev Based on code by FirstBlood: https://github.com/Firstbloodio/token/blob/master/smart_contract/FirstBloodToken.sol
 */
contract StandardToken is ERC20, BasicToken {

    mapping (address => mapping (address => uint256)) internal allowed;


    /**
    * @dev Transfer tokens from one address to another
    * @param _from address The address which you want to send tokens from
    * @param _to address The address which you want to transfer to
    * @param _value uint256 the amount of tokens to be transferred
    */
    function transferFrom(address _from, address _to, uint256 _value) public returns (bool) {
        require(_to != address(0));
        require(_value <= balances[_from]);
        require(_value <= allowed[_from][msg.sender]);

        balances[_from] = balances[_from].sub(_value);
        balances[_to] = balances[_to].add(_value);
        allowed[_from][msg.sender] = allowed[_from][msg.sender].sub(_value);
        Transfer(_from, _to, _value);
        return true;
    }

    /**
    * @dev Approve the passed address to spend the specified amount of tokens on behalf of msg.sender.
    *
    * Beware that changing an allowance with this method brings the risk that someone may use both the old
    * and the new allowance by unfortunate transaction ordering. One possible solution to mitigate this
    * race condition is to first reduce the spender's allowance to 0 and set the desired value afterwards:
    * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
    * @param _spender The address which will spend the funds.
    * @param _value The amount of tokens to be spent.
    */
    function approve(address _spender, uint256 _value) public returns (bool) {
        allowed[msg.sender][_spender] = _value;
        Approval(msg.sender, _spender, _value);
        return true;
    }

    /**
    * @dev Function to check the amount of tokens that an owner allowed to a spender.
    * @param _owner address The address which owns the funds.
    * @param _spender address The address which will spend the funds.
    * @return A uint256 specifying the amount of tokens still available for the spender.
    */
    function allowance(address _owner, address _spender) public view returns (uint256) {
        return allowed[_owner][_spender];
    }

    /**
    * @dev Increase the amount of tokens that an owner allowed to a spender.
    *
    * approve should be called when allowed[_spender] == 0. To increment
    * allowed value is better to use this function to avoid 2 calls (and wait until
    * the first transaction is mined)
    * From MonolithDAO Token.sol
    * @param _spender The address which will spend the funds.
    * @param _addedValue The amount of tokens to increase the allowance by.
    */
    function increaseApproval(address _spender, uint _addedValue) public returns (bool) {
        allowed[msg.sender][_spender] = allowed[msg.sender][_spender].add(_addedValue);
        Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
        return true;
    }

    /**
    * @dev Decrease the amount of tokens that an owner allowed to a spender.
    *
    * approve should be called when allowed[_spender] == 0. To decrement
    * allowed value is better to use this function to avoid 2 calls (and wait until
    * the first transaction is mined)
    * From MonolithDAO Token.sol
    * @param _spender The address which will spend the funds.
    * @param _subtractedValue The amount of tokens to decrease the allowance by.
    */
    function decreaseApproval(address _spender, uint _subtractedValue) public returns (bool) {
        uint oldValue = allowed[msg.sender][_spender];
        if (_subtractedValue > oldValue) {
            allowed[msg.sender][_spender] = 0;
        } else {
            allowed[msg.sender][_spender] = oldValue.sub(_subtractedValue);
        }
        Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
        return true;
    }

}

contract Usable {
    function use(address to, uint256 value, uint256 useType, uint256 param1, uint256 param2, uint256 param3, string param4) external;
    function setUseAddr(address addr) external;
    function setFee(uint256 useType, uint16 feeType, uint256 fee) external;
    event UseSucc(address indexed from, address indexed to, uint256 useType, uint256 value, uint256 fee, uint256 param1, uint256 param2, uint256 param3, string param4);
    event UseFail(address indexed from, address indexed to, uint256 useType, uint256 value, uint256 fee, uint256 param1, uint256 param2, uint256 param3, string param4);
}

contract DragonCoin is StandardToken, Usable {
    using SafeMath for uint256;
    
    event Mint(address indexed to, uint256 value);
    event Burn(address indexed burner, uint256 value);
    
    string public name = "DragonSeriesToken"; 
    string public symbol = "DST";
    uint public decimals = 18;
    uint public INITIAL_SUPPLY = 1100000 * (10 ** decimals);     
    uint public MAX_SUPPLY = 10 * 100000000 * (10 ** decimals); 
    address public ceo;
    address public coo;
    address public cfo;

    UseInterface public useAddr;

    // key = useType, value = UseFee
    mapping (uint256 => UseFee) public useFees;
    uint private _maxPercentFee = 1000000;

    struct UseFee {
        uint16 feeType;     // 1: fixed, 2: percentage
        uint256 fee;        // feeType=1: DST, feeType=2: 0-1000000 (0.0000% - 100.0000%)
    }
    
    function DragonCoin() public {
        totalSupply_ = INITIAL_SUPPLY;
        balances[msg.sender] = INITIAL_SUPPLY;
        ceo = msg.sender;
        emit Transfer(0x0, msg.sender, INITIAL_SUPPLY);
    }
    
    function setCEO(address newCEO) public onlyCEO{
        require(newCEO != address(0));
        
        ceo = newCEO;
    }
    
    function setCOO(address newCOO) public onlyCEO{
        require(newCOO != address(0));
        
        coo = newCOO;
    }
    
    function setCFO(address newCFO) public onlyCEO{
        require(newCFO != address(0));
        
        cfo = newCFO;
    }

    function mint(uint256 value) public onlyCFO returns (bool) {
        require(totalSupply_.add(value) <= MAX_SUPPLY);
        
        balances[cfo] = balances[cfo].add(value);
        totalSupply_ = totalSupply_.add(value);
        
        // mint event
        emit Mint(cfo, value);
        emit Transfer(0x0, cfo, value);
        return true;
    }
    
    function burn(uint256 value) public onlyCOO returns (bool) {
        require(balances[coo] >= value); 
        
        balances[coo] = balances[coo].sub(value);
        totalSupply_ = totalSupply_.sub(value);
        
        // burn event
        emit Burn(coo, value);
        emit Transfer(coo, 0x0, value);
        return true;
    }

    // Useable

    function setUseAddr(address addr) external onlyCOO{
        useAddr = UseInterface(addr);
    }

    function setFee(uint256 useType, uint16 feeType, uint256 fee) external onlyCOO{
        require(feeType == 1 || feeType == 2);

        if(feeType == 2){
            require(fee <= _maxPercentFee);
        }

        UseFee memory ufee = UseFee({
            feeType: feeType,
            fee: fee
        });
        useFees[useType] = ufee;
    }

    function use(address to, uint256 value, uint256 useType, uint256 param1, uint256 param2, uint256 param3, string param4) external {
        require(useAddr != address(0));
        require(balances[msg.sender] >= value);
        require(to != address(0) && cfo != address(0));
        
        UseFee memory ufee = useFees[useType];

        require(ufee.feeType == 1 || ufee.feeType == 2);
        
        uint256 actualFee = 0;

        if(ufee.feeType == 1){  // fixed fee
            actualFee = ufee.fee;
        }else if(ufee.feeType == 2){  // percentage fee
            actualFee = value.mul(ufee.fee).div(_maxPercentFee);
        }

        uint256 actualVal = value.sub(actualFee);

        if(useAddr.use(msg.sender, to, value, useType, param1, param2, param3, param4)){
            // transfer token
            balances[msg.sender] = balances[msg.sender].sub(value);
            balances[to] = balances[to].add(actualVal);
            emit Transfer(msg.sender, to, actualVal);

            if(actualFee > 0){
                balances[cfo] = balances[cfo].add(actualFee);
                emit Transfer(msg.sender, cfo, actualFee);
            }

            emit UseSucc(msg.sender, to, useType, value, actualFee, param1, param2, param3, param4);
        }else{
            emit UseFail(msg.sender, to, useType, value, actualFee, param1, param2, param3, param4);
        }
    }

    /// @dev Access modifier for CEO-only functionality
    modifier onlyCEO() {
        require(msg.sender == ceo);
        _;
    }
    
    /// @dev Access modifier for CFO-only functionality
    modifier onlyCFO() {
        require(msg.sender == cfo);
        _;
    }
    
    /// @dev Access modifier for COO-only functionality
    modifier onlyCOO() {
        require(msg.sender == coo);
        _;
    }
    
}

contract UseInterface {
    function use(address from, address to, uint256 value, uint256 useType, uint256 param1, uint256 param2, uint256 param3, string param4) external returns (bool);
}