CryptoRandomBlockhash

CryptoRandomBlockhash.sol

pragma solidity >=0.4.0 <0.7.0;

contract CryptoRandomBlockhash {
  bool waitForRandom;
  uint deadline;

  function debug_queryLastRskBlockHash() public view returns (bytes32) {
    return rskHeaderHash(block.number - 1);
  }
    
  function isRandomSeedReady() public view returns (bool) {
      if (!waitForRandom)
        return false;
      
      require(block.number<deadline+256);
      
      // Assure the deadline block has been mined, and it has 60
      // confirmations (30 minutes)
      return block.number>=deadline+60;
  }
  
  function getRandomSeed() public returns (bytes32) {
      require(isRandomSeedReady());
      waitForRandom = false;
      return rskHeaderHash(deadline);
  }
  
  function startWaitForRandomValue() public {
     
    // Wait approximately one hour 
    deadline =  block.number+120;
    waitForRandom = true;
  }
  
  function rskHeaderHash(uint bdeadline) public view returns (bytes32) {
      bytes32 x =blockhash(bdeadline);
      return x;
  }
}