The ethereum tamagotchi-like smart contract

doroidotchiBasuketto.sol

pragma solidity ^0.4.17;

contract doroidotchiBasuketto {

  int constant hungerPerBlock = 1;
  int constant boredomPerBlock = 2;
  int constant energyPerBlock = 2;    


  int constant hungerPerFeed = 4000;
  int constant boredomPerEntertainment = 2000;
  int constant energyPerSleep = 8000;  

  struct DoroidotchiStruct {
    string doroidotchiName;
    
    int fed;
    uint fedBlock;

    int entertained;
    uint entertainedBlock;

    int rested;
    uint restedBlock;

    uint blockBorn;
    
    bool initiated;

  }

  mapping (address => DoroidotchiStruct) public doroidotchi;
  
  uint doroidotchiCount = 1;
  mapping (uint => address) public doroidotchiMap; 

  function createDoroidotchi(string doroidotchiName) external {
        
      address parent = msg.sender;
      require (!doroidotchi[parent].initiated);
      require (bytes(doroidotchiName).length > 0);
        
      doroidotchi[parent].initiated = true;
        
      doroidotchi[parent].doroidotchiName = doroidotchiName;

      doroidotchi[parent].fed = 5000;
      doroidotchi[parent].fedBlock = block.number;
      
      doroidotchi[parent].entertained = 7000;
      doroidotchi[parent].entertainedBlock = block.number;
      
      doroidotchi[parent].rested = 90000;
      doroidotchi[parent].restedBlock  = block.number;

      doroidotchi[parent].blockBorn = block.number;
      
      doroidotchiMap[doroidotchiCount++] = msg.sender;
  }
  
  function destroyDoroidotchi() public {
    require (doroidotchi[msg.sender].initiated);
    
    delete doroidotchi[msg.sender];
  }
      
  function feed() external {
    require (doroidotchi[msg.sender].initiated);
    require(!hasDoroidotchiDied(msg.sender));
    
    doroidotchi[msg.sender].fed = hungerPerFeed + doroidotchi[msg.sender].fed - calcHungerSince(msg.sender);
    doroidotchi[msg.sender].fedBlock = block.number;
  }
  
  function play() external {
    require (doroidotchi[msg.sender].initiated);
    require(!hasDoroidotchiDied(msg.sender));

    doroidotchi[msg.sender].entertained = boredomPerEntertainment + doroidotchi[msg.sender].entertained - calcBoredomSince(msg.sender);
    doroidotchi[msg.sender].entertainedBlock = block.number;
  }

  function sleep() external {
    require (doroidotchi[msg.sender].initiated);
    require(!hasDoroidotchiDied(msg.sender));
    
    doroidotchi[msg.sender].rested = energyPerSleep + doroidotchi[msg.sender].rested - calcEnergySince(msg.sender);
    doroidotchi[msg.sender].restedBlock = block.number;
  }
  
  function getDoroidotchi(address parent) public view 
    returns (
      string doroidotchiName, 
      int fed, 
      int entertained, 
      int rested, 
      uint age, 
      bool isDead
    ) {
    require (doroidotchi[parent].initiated);

    return (
      doroidotchi[parent].doroidotchiName, 
      doroidotchi[parent].fed - calcHungerSince(parent), 
      doroidotchi[parent].entertained - calcBoredomSince(parent), 
      doroidotchi[parent].rested - calcEnergySince(parent), 
      block.number - doroidotchi[parent].blockBorn, 
      hasDoroidotchiDied(parent)
     ); 
    
  }
  
  function calcHungerSince(address parent) public view returns (int amount){
  	return int(block.number - doroidotchi[parent].fedBlock) * hungerPerBlock;
  }

  function calcBoredomSince(address parent) public view returns (int amount){
  	return int(block.number - doroidotchi[parent].entertainedBlock) * boredomPerBlock;
  }
  
  function calcEnergySince(address parent) public view returns (int amount){
  	return int(block.number - doroidotchi[parent].restedBlock) * energyPerBlock;
  }

  function hasDoroidotchiDied(address parent) public view returns (bool isDead) {
    require (doroidotchi[parent].initiated);
    
    int fed = doroidotchi[parent].fed - calcHungerSince(parent);
    
    int entertained = doroidotchi[parent].entertained - calcBoredomSince(parent);
    
    int rested = doroidotchi[parent].rested - calcEnergySince(parent);
    
    if ((fed <= 0)  || (entertained <= 0)  || (rested <= 0) ) {
      return true;
    } else {
      return false;
    }
  }
    
  function transferDoroidotchi(address newParent) public returns (bool isTransfered) {
    require (doroidotchi[msg.sender].initiated);
    require (!doroidotchi[newParent].initiated);

    doroidotchi[newParent] = doroidotchi[msg.sender];
    delete doroidotchi[msg.sender];

    return true; 
  }
  
  function getDoroidotchiListElement(uint listPosition) public view returns (address doroidotchiAddress){
  	return doroidotchiMap[listPosition];
  }
      
}