riddle

pragma solidity ^0.4.24;

/**
* @title Ownable
* @dev The Ownable contract has an owner address, and provides basic authorization control
* functions, this simplifies the implementation of "user permissions".
*/

//Le contract Ownable permet simplement de restreindre l'accès à certaines fonctions au créateur du contrat
contract Ownable {
  address private _owner;

  event OwnershipTransferred(
    address indexed previousOwner,
    address indexed newOwner
  );

  /**
  * @dev The Ownable constructor sets the original `owner` of the contract to the sender
  * account.
  */
  constructor() internal {
    _owner = msg.sender;
    emit OwnershipTransferred(address(0), _owner);
  }

  /**
  * @return the address of the owner.
  */
  function owner() public view returns(address) {
    return _owner;
  }

  /**
  * @dev Throws if called by any account other than the owner.
  */
  modifier onlyOwner() {
    require(isOwner());
    _;
  }

  /**
  * @return true if `msg.sender` is the owner of the contract.
  */
  function isOwner() public view returns(bool) {
    return msg.sender == _owner;
  }

  /**
  * @dev Allows the current owner to relinquish control of the contract.
  * @notice Renouncing to ownership will leave the contract without an owner.
  * It will not be possible to call the functions with the `onlyOwner`
  * modifier anymore.
  */
  function renounceOwnership() public onlyOwner {
    emit OwnershipTransferred(_owner, address(0));
    _owner = address(0);
  }

  /**
  * @dev Allows the current owner to transfer control of the contract to a newOwner.
  * @param newOwner The address to transfer ownership to.
  */
  function transferOwnership(address newOwner) public onlyOwner {
    _transferOwnership(newOwner);
  }

  /**
  * @dev Transfers control of the contract to a newOwner.
  * @param newOwner The address to transfer ownership to.
  */
  function _transferOwnership(address newOwner) internal {
    require(newOwner != address(0));
    emit OwnershipTransferred(_owner, newOwner);
    _owner = newOwner;
  }
}

contract Riddle is Ownable {
    
    event NewRiddle(string text, string answer, uint reward);
    
    string text = "Enigme";
    string answer = "42";
    uint reward = 1;
    
    
   Riddle[] public riddles;
   
   //on commence par créer l'énigme
    function setRiddle(string _text, string _answer, uint _reward) onlyOwner {
        text = _text;
        answer = _answer;
        reward = _reward;
        emit NewRiddle(_text, _answer, _reward);
    }
    
    //puis une fonction pour y répondre, et on reçoit la récompense si la réponse est juste
    //on notera que Solidity ne permet pas de comparer deux chaînes de caractères, donc ce qu'on fait ici c'est qu'on compare leurs hashes par keccak256
    function answerRiddle(string givenAnswer) public {
        if (keccak256(abi.encodePacked(givenAnswer)) == keccak256(abi.encodePacked(answer))){
            sendReward(msg.sender);
        } 
    }
    
    function sendReward(address _address) public payable {
        _address.transfer(reward);
    }
}