library ObjectLib32 {

  using SafeMath for uint256;
  enum Operations { ADD, SUB, REPLACE }
  // Constants regarding bin or chunk sizes for balance packing
  uint256 constant TYPES_BITS_SIZE   = 32;                     // Max size of each object
  uint256 constant TYPES_PER_UINT256 = 256 / TYPES_BITS_SIZE; // Number of types per uint256


  //
  // Objects and Tokens Functions
  //

  /**
  * @dev Return the bin number and index within that bin where ID is
  * @param _tokenId Object type
  * @return (Bin number, ID's index within that bin)
  */
  function getTokenBinIndex(uint256 _tokenId) internal pure returns (uint256 bin, uint256 index) {
     bin = _tokenId * TYPES_BITS_SIZE / 256;
     index = _tokenId % TYPES_PER_UINT256;
     return (bin, index);
  }


  /**
  * @dev update the balance of a type provided in _binBalances
  * @param _binBalances Uint256 containing the balances of objects
  * @param _index Index of the object in the provided bin
  * @param _amount Value to update the type balance
  * @param _operation Which operation to conduct :
  *     Operations.REPLACE : Replace type balance with _amount
  *     Operations.ADD     : ADD _amount to type balance
  *     Operations.SUB     : Substract _amount from type balance
  */
  function updateTokenBalance(
    uint256 _binBalances,
    uint256 _index,
    uint256 _amount,
    Operations _operation) internal pure returns (uint256 newBinBalance)
  {
    uint256 objectBalance = 0;
    if (_operation == Operations.ADD) {
        objectBalance = getValueInBin(_binBalances, _index);
        newBinBalance = writeValueInBin(_binBalances, _index, objectBalance.add(_amount));
    } else if (_operation == Operations.SUB) {
        objectBalance = getValueInBin(_binBalances, _index);
        newBinBalance = writeValueInBin(_binBalances, _index, objectBalance.sub(_amount));
    } else if (_operation == Operations.REPLACE) {
        newBinBalance = writeValueInBin(_binBalances, _index, _amount);
    } else {
      revert("Invalid operation"); // Bad operation
    }

    return newBinBalance;
  }
  /*
  * @dev return value in _binValue at position _index
  * @param _binValue uint256 containing the balances of TYPES_PER_UINT256 types
  * @param _index index at which to retrieve value
  * @return Value at given _index in _bin
  */
  function getValueInBin(uint256 _binValue, uint256 _index) internal pure returns (uint256) {

    // Mask to retrieve data for a given binData
    uint256 mask = (uint256(1) << TYPES_BITS_SIZE) - 1;

    // Shift amount
    uint256 rightShift = 256 - TYPES_BITS_SIZE * (_index + 1);
    return (_binValue >> rightShift) & mask;
  }

  /**
  * @dev return the updated _binValue after writing _amount at _index
  * @param _binValue uint256 containing the balances of TYPES_PER_UINT256 types
  * @param _index Index at which to retrieve value
  * @param _amount Value to store at _index in _bin
  * @return Value at given _index in _bin
  */
  function writeValueInBin(uint256 _binValue, uint256 _index, uint256 _amount) internal pure returns (uint256) {
    require(_amount < 2**TYPES_BITS_SIZE, "Amount to write in bin is too large");

    // Mask to retrieve data for a given binData
    uint256 mask = (uint256(1) << TYPES_BITS_SIZE) - 1;

    // Shift amount
    uint256 leftShift = 256 - TYPES_BITS_SIZE * (_index + 1);
    return (_binValue & ~(mask << leftShift) ) | (_amount << leftShift);
  }

}
function writeValueInBin(uint256 _binValue, uint256 _index, uint256 _amount) internal pure returns (uint256) {
    require(_amount < 2**TYPES_BITS_SIZE, "Amount to write in bin is too large");

    // Mask to retrieve data for a given binData
    uint256 mask = (uint256(1) << TYPES_BITS_SIZE) - 1;

    // Shift amount
    uint256 leftShift = 256 - TYPES_BITS_SIZE * (_index + 1);
    return (_binValue & ~(mask << leftShift) ) | (_amount << leftShift);
  }
/**
 * @dev return the updated _binValue after writing _amount at _index
 * @param _binValue uint256 containing the balances of TYPES_PER_UINT256 types
 * @param _index Index at which to retrieve value
 * @param _amount Value to store at _index in _bin
 * @return Value at given _index in _bin
 */