pragma solidity >=0.4.22 <0.7.0;







/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");

        return c;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b <= a, "SafeMath: subtraction overflow");
        uint256 c = a - b;

        return c;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        // Solidity only automatically asserts when dividing by 0
        require(b > 0, "SafeMath: division by zero");
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b != 0, "SafeMath: modulo by zero");
        return a % b;
    }
}


library StringUtils {
  /// @dev Does a byte-by-byte lexicographical comparison of two strings.
  /// @return a negative number if `_a` is smaller, zero if they are equal
  /// and a positive numbe if `_b` is smaller.
  function compare(string memory _a, string memory _b) internal pure returns(int) {
    bytes memory a = bytes(_a);
    bytes memory b = bytes(_b);
    uint minLength = a.length;
    if (b.length < minLength) { 
      minLength = b.length;
    }
    //@todo unroll the loop into increments of 32 and do full 32 byte comparisons
    for (uint i = 0; i < minLength; i++) {
      if (a[i] < b[i]) return -1;
      else if (a[i] > b[i]) return 1;
    }

    if (a.length < b.length) {
      return -1;
    } else if (a.length > b.length) {
      return 1;
    } else {
      return 0;
    }
  }

  /// @dev Compares two strings and returns true iff they are equal.
  function equal(string memory _a, string memory _b) internal pure returns(bool) {
    return compare(_a, _b) == 0;
  }

  /// @dev Finds the index of the first occurrence of _needle in _haystack
  function indexOf(string memory _haystack, string memory _needle) internal pure returns(int) {
    bytes memory h = bytes(_haystack);
    bytes memory n = bytes(_needle);
    if (h.length < 1 || n.length < 1 || (n.length > h.length)) {
      return -1;
    } else if (h.length > (2 ** 128 - 1)) {
      // since we have to be able to return -1 (if the char isn't found or input error), 
      // this function must return an "int" type with a max length of (2^128 - 1)
      return -1;
    } else {
      uint subindex = 0;
      for (uint i = 0; i < h.length; i++) {
        if (h[i] == n[0]) { // found the first char of b
          subindex = 1;
          while (
            subindex < n.length 
            && (i + subindex) < h.length 
            && h[i + subindex] == n[subindex]
          ) { // search until the chars don't match or until we reach the end of a or b
            subindex++;
          }
          
          if (subindex == n.length)
            return int(i);
        }
      }
      return -1;
    }
  }
}


/**
 * A library for only submit hash string to blockchain
 *
 */
library HashOperateLib {
  using SafeMath for uint256;
  using StringUtils for string;

  struct ExInfo {
    address saver;
    string saverName;
    uint256 saveTime;
  }

  struct Info {
    mapping(string => ExInfo) hashInfo;
    string[] hashLib;
  }

  /**
   * @dev insertHash,insert method
   * @param  _self is where the data will be saved
   * @param  _hash is input value of hash
   * @return bool,true is successful and false is failed
   */
  function insertHash(Info storage _self, string memory _hash, string memory _saverName) 
    internal 
    returns (bool) 
  {
    if (_self.hashInfo[_hash].saveTime > 0) {
      return false;
    } else {
      _self.hashInfo[_hash].saver = msg.sender; // not msg.sender, we need the origin TX submitter;
      _self.hashInfo[_hash].saveTime = now;
      _self.hashInfo[_hash].saverName = _saverName;
      _self.hashLib.push(_hash);

      return true;
    }
  }

  /**
   * @dev deleteHash,delete method
   * @param  _self is where the data will be saved
   *         _hash is input value of hash
   * @return bool,true is successful and false is failed
   */
  function deleteHash(Info storage _self, string memory _hash) internal returns (bool) {
    require(!_hash.equal(""));
    if (_self.hashInfo[_hash].saveTime > 0) {
      delete _self.hashInfo[_hash];
      removeHash(_self, _hash);
      return true;
    } else {
      return false;
    }
  }

  /**
   * @dev selectHash,select method
   * @param  _self is where the data will be saved
   *         _hash is input value of hash
   * @return true/false,saver,save time
   */
  function selectHash(Info storage _self, string memory _hash) 
    internal 
    view 
    returns (bool, address, string memory, uint256) 
  {
    if (_self.hashInfo[_hash].saveTime > 0) {
      return (
        true, 
        _self.hashInfo[_hash].saver,
        _self.hashInfo[_hash].saverName, 
        _self.hashInfo[_hash].saveTime
      );
    } else {
      return (false, address(0), "", 0);
    }
  }

  /**
   * @dev getHashByInd,get one hash string by its index
   * @param  _self is where the data will be saved
   *         _ind is input value of the index
   * @return string, the hash string
   */
  function getHashByInd(Info storage _self, uint _ind) internal view returns (string memory) {
    return (_self.hashLib[_ind]);
  }

  /**
   * @dev getHashByInd,get one hash string by its index
   * @param  _self is where the data will be saved
   *         _ind is input value of the index
   * @return string, the hash string
   */
  function isHashExisted(Info storage _self, string memory _hash) 
    internal 
    view 
    returns (bool) 
  {
    return (_self.hashInfo[_hash].saveTime > 0);
  }

  /**
   * @dev remove a hash value from hash info storage
   *
   * @param _hashStr the account address in the list
   */
  function removeHash(Info storage _self, string memory _hashStr) internal returns (bool) {
    uint i = 0;
    for (; i < _self.hashLib.length; i = i.add(1)) {
      if (_self.hashLib[i].equal(_hashStr)) 
        break;
    }

    if (i >= _self.hashLib.length)
      return false;

    uint lastInd = _self.hashLib.length.sub(1);
    while (i < lastInd) {
      _self.hashLib[i] = _self.hashLib[i.add(1)];
      i = i.add(1);
    }

    delete _self.hashLib[lastInd];
    _self.hashLib.length = lastInd;

    return true;
  }

}

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be aplied to your functions to restrict their use to
 * the owner.
 */
contract Ownable {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor () internal {
        _owner = msg.sender;
        emit OwnershipTransferred(address(0), _owner);
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(isOwner(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Returns true if the caller is the current owner.
     */
    function isOwner() public view returns (bool) {
        return msg.sender == _owner;
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * > Note: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public onlyOwner {
        emit OwnershipTransferred(_owner, address(0));
        _owner = address(0);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public onlyOwner {
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     */
    function _transferOwnership(address newOwner) internal {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}
/*
 * @title String & slice utility library for Solidity contracts.
 * @author Nick Johnson <arachnid@notdot.net>
 *
 * @dev Functionality in this library is largely implemented using an
 *      abstraction called a 'slice'. A slice represents a part of a string -
 *      anything from the entire string to a single character, or even no
 *      characters at all (a 0-length slice). Since a slice only has to specify
 *      an offset and a length, copying and manipulating slices is a lot less
 *      expensive than copying and manipulating the strings they reference.
 *
 *      To further reduce gas costs, most functions on slice that need to return
 *      a slice modify the original one instead of allocating a new one; for
 *      instance, `s.split(".")` will return the text up to the first '.',
 *      modifying s to only contain the remainder of the string after the '.'.
 *      In situations where you do not want to modify the original slice, you
 *      can make a copy first with `.copy()`, for example:
 *      `s.copy().split(".")`. Try and avoid using this idiom in loops; since
 *      Solidity has no memory management, it will result in allocating many
 *      short-lived slices that are later discarded.
 *
 *      Functions that return two slices come in two versions: a non-allocating
 *      version that takes the second slice as an argument, modifying it in
 *      place, and an allocating version that allocates and returns the second
 *      slice; see `nextRune` for example.
 *
 *      Functions that have to copy string data will return strings rather than
 *      slices; these can be cast back to slices for further processing if
 *      required.
 *
 *      For convenience, some functions are provided with non-modifying
 *      variants that create a new slice and return both; for instance,
 *      `s.splitNew('.')` leaves s unmodified, and returns two values
 *      corresponding to the left and right parts of the string.
 */


library strings {
    struct slice {
        uint _len;
        uint _ptr;
    }

    function memcpy(uint dest, uint src, uint len) private pure {
        // Copy word-length chunks while possible
        for(; len >= 32; len -= 32) {
            assembly {
                mstore(dest, mload(src))
            }
            dest += 32;
            src += 32;
        }

        // Copy remaining bytes
        uint mask = 256 ** (32 - len) - 1;
        assembly {
            let srcpart := and(mload(src), not(mask))
            let destpart := and(mload(dest), mask)
            mstore(dest, or(destpart, srcpart))
        }
    }

    /*
     * @dev Returns a slice containing the entire string.
     * @param self The string to make a slice from.
     * @return A newly allocated slice containing the entire string.
     */
    function toSlice(string memory self) internal pure returns (slice memory) {
        uint ptr;
        assembly {
            ptr := add(self, 0x20)
        }
        return slice(bytes(self).length, ptr);
    }

    /*
     * @dev Returns the length of a null-terminated bytes32 string.
     * @param self The value to find the length of.
     * @return The length of the string, from 0 to 32.
     */
    function len(bytes32 self) internal pure returns (uint) {
        uint ret;
        if (self == 0)
            return 0;
        if (uint(self) & 0xffffffffffffffffffffffffffffffff == 0) {
            ret += 16;
            self = bytes32(uint(self) / 0x100000000000000000000000000000000);
        }
        if (uint(self) & 0xffffffffffffffff == 0) {
            ret += 8;
            self = bytes32(uint(self) / 0x10000000000000000);
        }
        if (uint(self) & 0xffffffff == 0) {
            ret += 4;
            self = bytes32(uint(self) / 0x100000000);
        }
        if (uint(self) & 0xffff == 0) {
            ret += 2;
            self = bytes32(uint(self) / 0x10000);
        }
        if (uint(self) & 0xff == 0) {
            ret += 1;
        }
        return 32 - ret;
    }

    /*
     * @dev Returns a slice containing the entire bytes32, interpreted as a
     *      null-terminated utf-8 string.
     * @param self The bytes32 value to convert to a slice.
     * @return A new slice containing the value of the input argument up to the
     *         first null.
     */
    function toSliceB32(bytes32 self) internal pure returns (slice memory ret) {
        // Allocate space for `self` in memory, copy it there, and point ret at it
        assembly {
            let ptr := mload(0x40)
            mstore(0x40, add(ptr, 0x20))
            mstore(ptr, self)
            mstore(add(ret, 0x20), ptr)
        }
        ret._len = len(self);
    }

    /*
     * @dev Returns a new slice containing the same data as the current slice.
     * @param self The slice to copy.
     * @return A new slice containing the same data as `self`.
     */
    function copy(slice memory self) internal pure returns (slice memory) {
        return slice(self._len, self._ptr);
    }

    /*
     * @dev Copies a slice to a new string.
     * @param self The slice to copy.
     * @return A newly allocated string containing the slice's text.
     */
    function toString(slice memory self) internal pure returns (string memory) {
        string memory ret = new string(self._len);
        uint retptr;
        assembly { retptr := add(ret, 32) }

        memcpy(retptr, self._ptr, self._len);
        return ret;
    }

    /*
     * @dev Returns the length in runes of the slice. Note that this operation
     *      takes time proportional to the length of the slice; avoid using it
     *      in loops, and call `slice.empty()` if you only need to know whether
     *      the slice is empty or not.
     * @param self The slice to operate on.
     * @return The length of the slice in runes.
     */
    function len(slice memory self) internal pure returns (uint l) {
        // Starting at ptr-31 means the LSB will be the byte we care about
        uint ptr = self._ptr - 31;
        uint end = ptr + self._len;
        for (l = 0; ptr < end; l++) {
            uint8 b;
            assembly { b := and(mload(ptr), 0xFF) }
            if (b < 0x80) {
                ptr += 1;
            } else if(b < 0xE0) {
                ptr += 2;
            } else if(b < 0xF0) {
                ptr += 3;
            } else if(b < 0xF8) {
                ptr += 4;
            } else if(b < 0xFC) {
                ptr += 5;
            } else {
                ptr += 6;
            }
        }
    }

    /*
     * @dev Returns true if the slice is empty (has a length of 0).
     * @param self The slice to operate on.
     * @return True if the slice is empty, False otherwise.
     */
    function empty(slice memory self) internal pure returns (bool) {
        return self._len == 0;
    }

    /*
     * @dev Returns a positive number if `other` comes lexicographically after
     *      `self`, a negative number if it comes before, or zero if the
     *      contents of the two slices are equal. Comparison is done per-rune,
     *      on unicode codepoints.
     * @param self The first slice to compare.
     * @param other The second slice to compare.
     * @return The result of the comparison.
     */
    function compare(slice memory self, slice memory other) internal pure returns (int) {
        uint shortest = self._len;
        if (other._len < self._len)
            shortest = other._len;

        uint selfptr = self._ptr;
        uint otherptr = other._ptr;
        for (uint idx = 0; idx < shortest; idx += 32) {
            uint a;
            uint b;
            assembly {
                a := mload(selfptr)
                b := mload(otherptr)
            }
            if (a != b) {
                // Mask out irrelevant bytes and check again
                uint256 mask = uint256(-1); // 0xffff...
                if(shortest < 32) {
                  mask = ~(2 ** (8 * (32 - shortest + idx)) - 1);
                }
                uint256 diff = (a & mask) - (b & mask);
                if (diff != 0)
                    return int(diff);
            }
            selfptr += 32;
            otherptr += 32;
        }
        return int(self._len) - int(other._len);
    }

    /*
     * @dev Returns true if the two slices contain the same text.
     * @param self The first slice to compare.
     * @param self The second slice to compare.
     * @return True if the slices are equal, false otherwise.
     */
    function equals(slice memory self, slice memory other) internal pure returns (bool) {
        return compare(self, other) == 0;
    }

    /*
     * @dev Extracts the first rune in the slice into `rune`, advancing the
     *      slice to point to the next rune and returning `self`.
     * @param self The slice to operate on.
     * @param rune The slice that will contain the first rune.
     * @return `rune`.
     */
    function nextRune(slice memory self, slice memory rune) internal pure returns (slice memory) {
        rune._ptr = self._ptr;

        if (self._len == 0) {
            rune._len = 0;
            return rune;
        }

        uint l;
        uint b;
        // Load the first byte of the rune into the LSBs of b
        assembly { b := and(mload(sub(mload(add(self, 32)), 31)), 0xFF) }
        if (b < 0x80) {
            l = 1;
        } else if(b < 0xE0) {
            l = 2;
        } else if(b < 0xF0) {
            l = 3;
        } else {
            l = 4;
        }

        // Check for truncated codepoints
        if (l > self._len) {
            rune._len = self._len;
            self._ptr += self._len;
            self._len = 0;
            return rune;
        }

        self._ptr += l;
        self._len -= l;
        rune._len = l;
        return rune;
    }

    /*
     * @dev Returns the first rune in the slice, advancing the slice to point
     *      to the next rune.
     * @param self The slice to operate on.
     * @return A slice containing only the first rune from `self`.
     */
    function nextRune(slice memory self) internal pure returns (slice memory ret) {
        nextRune(self, ret);
    }

    /*
     * @dev Returns the number of the first codepoint in the slice.
     * @param self The slice to operate on.
     * @return The number of the first codepoint in the slice.
     */
    function ord(slice memory self) internal pure returns (uint ret) {
        if (self._len == 0) {
            return 0;
        }

        uint word;
        uint length;
        uint divisor = 2 ** 248;

        // Load the rune into the MSBs of b
        assembly { word:= mload(mload(add(self, 32))) }
        uint b = word / divisor;
        if (b < 0x80) {
            ret = b;
            length = 1;
        } else if(b < 0xE0) {
            ret = b & 0x1F;
            length = 2;
        } else if(b < 0xF0) {
            ret = b & 0x0F;
            length = 3;
        } else {
            ret = b & 0x07;
            length = 4;
        }

        // Check for truncated codepoints
        if (length > self._len) {
            return 0;
        }

        for (uint i = 1; i < length; i++) {
            divisor = divisor / 256;
            b = (word / divisor) & 0xFF;
            if (b & 0xC0 != 0x80) {
                // Invalid UTF-8 sequence
                return 0;
            }
            ret = (ret * 64) | (b & 0x3F);
        }

        return ret;
    }

    /*
     * @dev Returns the keccak-256 hash of the slice.
     * @param self The slice to hash.
     * @return The hash of the slice.
     */
    function keccak(slice memory self) internal pure returns (bytes32 ret) {
        assembly {
            ret := keccak256(mload(add(self, 32)), mload(self))
        }
    }

    /*
     * @dev Returns true if `self` starts with `needle`.
     * @param self The slice to operate on.
     * @param needle The slice to search for.
     * @return True if the slice starts with the provided text, false otherwise.
     */
    function startsWith(slice memory self, slice memory needle) internal pure returns (bool) {
        if (self._len < needle._len) {
            return false;
        }

        if (self._ptr == needle._ptr) {
            return true;
        }

        bool equal;
        assembly {
            let length := mload(needle)
            let selfptr := mload(add(self, 0x20))
            let needleptr := mload(add(needle, 0x20))
            equal := eq(keccak256(selfptr, length), keccak256(needleptr, length))
        }
        return equal;
    }

    /*
     * @dev If `self` starts with `needle`, `needle` is removed from the
     *      beginning of `self`. Otherwise, `self` is unmodified.
     * @param self The slice to operate on.
     * @param needle The slice to search for.
     * @return `self`
     */
    function beyond(slice memory self, slice memory needle) internal pure returns (slice memory) {
        if (self._len < needle._len) {
            return self;
        }

        bool equal = true;
        if (self._ptr != needle._ptr) {
            assembly {
                let length := mload(needle)
                let selfptr := mload(add(self, 0x20))
                let needleptr := mload(add(needle, 0x20))
                equal := eq(keccak256(selfptr, length), keccak256(needleptr, length))
            }
        }

        if (equal) {
            self._len -= needle._len;
            self._ptr += needle._len;
        }

        return self;
    }

    /*
     * @dev Returns true if the slice ends with `needle`.
     * @param self The slice to operate on.
     * @param needle The slice to search for.
     * @return True if the slice starts with the provided text, false otherwise.
     */
    function endsWith(slice memory self, slice memory needle) internal pure returns (bool) {
        if (self._len < needle._len) {
            return false;
        }

        uint selfptr = self._ptr + self._len - needle._len;

        if (selfptr == needle._ptr) {
            return true;
        }

        bool equal;
        assembly {
            let length := mload(needle)
            let needleptr := mload(add(needle, 0x20))
            equal := eq(keccak256(selfptr, length), keccak256(needleptr, length))
        }

        return equal;
    }

    /*
     * @dev If `self` ends with `needle`, `needle` is removed from the
     *      end of `self`. Otherwise, `self` is unmodified.
     * @param self The slice to operate on.
     * @param needle The slice to search for.
     * @return `self`
     */
    function until(slice memory self, slice memory needle) internal pure returns (slice memory) {
        if (self._len < needle._len) {
            return self;
        }

        uint selfptr = self._ptr + self._len - needle._len;
        bool equal = true;
        if (selfptr != needle._ptr) {
            assembly {
                let length := mload(needle)
                let needleptr := mload(add(needle, 0x20))
                equal := eq(keccak256(selfptr, length), keccak256(needleptr, length))
            }
        }

        if (equal) {
            self._len -= needle._len;
        }

        return self;
    }

    // Returns the memory address of the first byte of the first occurrence of
    // `needle` in `self`, or the first byte after `self` if not found.
    function findPtr(uint selflen, uint selfptr, uint needlelen, uint needleptr) private pure returns (uint) {
        uint ptr = selfptr;
        uint idx;

        if (needlelen <= selflen) {
            if (needlelen <= 32) {
                bytes32 mask = bytes32(~(2 ** (8 * (32 - needlelen)) - 1));

                bytes32 needledata;
                assembly { needledata := and(mload(needleptr), mask) }

                uint end = selfptr + selflen - needlelen;
                bytes32 ptrdata;
                assembly { ptrdata := and(mload(ptr), mask) }

                while (ptrdata != needledata) {
                    if (ptr >= end)
                        return selfptr + selflen;
                    ptr++;
                    assembly { ptrdata := and(mload(ptr), mask) }
                }
                return ptr;
            } else {
                // For long needles, use hashing
                bytes32 hash;
                assembly { hash := keccak256(needleptr, needlelen) }

                for (idx = 0; idx <= selflen - needlelen; idx++) {
                    bytes32 testHash;
                    assembly { testHash := keccak256(ptr, needlelen) }
                    if (hash == testHash)
                        return ptr;
                    ptr += 1;
                }
            }
        }
        return selfptr + selflen;
    }

    // Returns the memory address of the first byte after the last occurrence of
    // `needle` in `self`, or the address of `self` if not found.
    function rfindPtr(uint selflen, uint selfptr, uint needlelen, uint needleptr) private pure returns (uint) {
        uint ptr;

        if (needlelen <= selflen) {
            if (needlelen <= 32) {
                bytes32 mask = bytes32(~(2 ** (8 * (32 - needlelen)) - 1));

                bytes32 needledata;
                assembly { needledata := and(mload(needleptr), mask) }

                ptr = selfptr + selflen - needlelen;
                bytes32 ptrdata;
                assembly { ptrdata := and(mload(ptr), mask) }

                while (ptrdata != needledata) {
                    if (ptr <= selfptr)
                        return selfptr;
                    ptr--;
                    assembly { ptrdata := and(mload(ptr), mask) }
                }
                return ptr + needlelen;
            } else {
                // For long needles, use hashing
                bytes32 hash;
                assembly { hash := keccak256(needleptr, needlelen) }
                ptr = selfptr + (selflen - needlelen);
                while (ptr >= selfptr) {
                    bytes32 testHash;
                    assembly { testHash := keccak256(ptr, needlelen) }
                    if (hash == testHash)
                        return ptr + needlelen;
                    ptr -= 1;
                }
            }
        }
        return selfptr;
    }

    /*
     * @dev Modifies `self` to contain everything from the first occurrence of
     *      `needle` to the end of the slice. `self` is set to the empty slice
     *      if `needle` is not found.
     * @param self The slice to search and modify.
     * @param needle The text to search for.
     * @return `self`.
     */
    function find(slice memory self, slice memory needle) internal pure returns (slice memory) {
        uint ptr = findPtr(self._len, self._ptr, needle._len, needle._ptr);
        self._len -= ptr - self._ptr;
        self._ptr = ptr;
        return self;
    }

    /*
     * @dev Modifies `self` to contain the part of the string from the start of
     *      `self` to the end of the first occurrence of `needle`. If `needle`
     *      is not found, `self` is set to the empty slice.
     * @param self The slice to search and modify.
     * @param needle The text to search for.
     * @return `self`.
     */
    function rfind(slice memory self, slice memory needle) internal pure returns (slice memory) {
        uint ptr = rfindPtr(self._len, self._ptr, needle._len, needle._ptr);
        self._len = ptr - self._ptr;
        return self;
    }

    /*
     * @dev Splits the slice, setting `self` to everything after the first
     *      occurrence of `needle`, and `token` to everything before it. If
     *      `needle` does not occur in `self`, `self` is set to the empty slice,
     *      and `token` is set to the entirety of `self`.
     * @param self The slice to split.
     * @param needle The text to search for in `self`.
     * @param token An output parameter to which the first token is written.
     * @return `token`.
     */
    function split(slice memory self, slice memory needle, slice memory token) internal pure returns (slice memory) {
        uint ptr = findPtr(self._len, self._ptr, needle._len, needle._ptr);
        token._ptr = self._ptr;
        token._len = ptr - self._ptr;
        if (ptr == self._ptr + self._len) {
            // Not found
            self._len = 0;
        } else {
            self._len -= token._len + needle._len;
            self._ptr = ptr + needle._len;
        }
        return token;
    }

    /*
     * @dev Splits the slice, setting `self` to everything after the first
     *      occurrence of `needle`, and returning everything before it. If
     *      `needle` does not occur in `self`, `self` is set to the empty slice,
     *      and the entirety of `self` is returned.
     * @param self The slice to split.
     * @param needle The text to search for in `self`.
     * @return The part of `self` up to the first occurrence of `delim`.
     */
    function split(slice memory self, slice memory needle) internal pure returns (slice memory token) {
        split(self, needle, token);
    }

    /*
     * @dev Splits the slice, setting `self` to everything before the last
     *      occurrence of `needle`, and `token` to everything after it. If
     *      `needle` does not occur in `self`, `self` is set to the empty slice,
     *      and `token` is set to the entirety of `self`.
     * @param self The slice to split.
     * @param needle The text to search for in `self`.
     * @param token An output parameter to which the first token is written.
     * @return `token`.
     */
    function rsplit(slice memory self, slice memory needle, slice memory token) internal pure returns (slice memory) {
        uint ptr = rfindPtr(self._len, self._ptr, needle._len, needle._ptr);
        token._ptr = ptr;
        token._len = self._len - (ptr - self._ptr);
        if (ptr == self._ptr) {
            // Not found
            self._len = 0;
        } else {
            self._len -= token._len + needle._len;
        }
        return token;
    }

    /*
     * @dev Splits the slice, setting `self` to everything before the last
     *      occurrence of `needle`, and returning everything after it. If
     *      `needle` does not occur in `self`, `self` is set to the empty slice,
     *      and the entirety of `self` is returned.
     * @param self The slice to split.
     * @param needle The text to search for in `self`.
     * @return The part of `self` after the last occurrence of `delim`.
     */
    function rsplit(slice memory self, slice memory needle) internal pure returns (slice memory token) {
        rsplit(self, needle, token);
    }

    /*
     * @dev Counts the number of nonoverlapping occurrences of `needle` in `self`.
     * @param self The slice to search.
     * @param needle The text to search for in `self`.
     * @return The number of occurrences of `needle` found in `self`.
     */
    function count(slice memory self, slice memory needle) internal pure returns (uint cnt) {
        uint ptr = findPtr(self._len, self._ptr, needle._len, needle._ptr) + needle._len;
        while (ptr <= self._ptr + self._len) {
            cnt++;
            ptr = findPtr(self._len - (ptr - self._ptr), ptr, needle._len, needle._ptr) + needle._len;
        }
    }

    /*
     * @dev Returns True if `self` contains `needle`.
     * @param self The slice to search.
     * @param needle The text to search for in `self`.
     * @return True if `needle` is found in `self`, false otherwise.
     */
    function contains(slice memory self, slice memory needle) internal pure returns (bool) {
        return rfindPtr(self._len, self._ptr, needle._len, needle._ptr) != self._ptr;
    }

    /*
     * @dev Returns a newly allocated string containing the concatenation of
     *      `self` and `other`.
     * @param self The first slice to concatenate.
     * @param other The second slice to concatenate.
     * @return The concatenation of the two strings.
     */
    function concat(slice memory self, slice memory other) internal pure returns (string memory) {
        string memory ret = new string(self._len + other._len);
        uint retptr;
        assembly { retptr := add(ret, 32) }
        memcpy(retptr, self._ptr, self._len);
        memcpy(retptr + self._len, other._ptr, other._len);
        return ret;
    }

    /*
     * @dev Joins an array of slices, using `self` as a delimiter, returning a
     *      newly allocated string.
     * @param self The delimiter to use.
     * @param parts A list of slices to join.
     * @return A newly allocated string containing all the slices in `parts`,
     *         joined with `self`.
     */
    function join(slice memory self, slice[] memory parts) internal pure returns (string memory) {
        if (parts.length == 0)
            return "";

        uint length = self._len * (parts.length - 1);
        for(uint i = 0; i < parts.length; i++)
            length += parts[i]._len;

        string memory ret = new string(length);
        uint retptr;
        assembly { retptr := add(ret, 32) }

        for(uint i = 0; i < parts.length; i++) {
            memcpy(retptr, parts[i]._ptr, parts[i]._len);
            retptr += parts[i]._len;
            if (i < parts.length - 1) {
                memcpy(retptr, self._ptr, self._len);
                retptr += self._len;
            }
        }

        return ret;
    }
}


/**
 * This contract will take charge of submitting base hash value to blockchain
 * it will be inherited by other hash operating contracts
 */
contract DRCHashBase is Ownable {
  //import the HashOperateLib for contract
  using HashOperateLib for HashOperateLib.Info;
  using StringUtils for string;
  using strings for *;
  using SafeMath for uint256;

  HashOperateLib.Info internal hashInfoLib;
  string public memo;
  mapping(string => string) internal txHashInfo; // hash => txHash
  mapping(string => string) internal insertedHashInfo; // txHash => hash


  /**
   * @dev set the memo to describe the objective of the contract
   */
  function setMemo(string memory _memoStr) public onlyOwner returns(bool) {
    memo = _memoStr;
    return true;
  }  

  /**
   * @dev add Tx hash for the hash string uploaded to blockchain
   * @param _hash is input value of hash
   * @param _txHash is the Tx hash value generated by action of inserting hash
   * @return bool,true is successful and false is failed
   */
  function addTxIdForOnchainData(string memory _hash, string memory _txHash) 
    public 
    onlyOwner 
    returns (bool) 
  {
    require(!_hash.equal(""));

    if (!hashInfoLib.isHashExisted(_hash)) {
      return false;
    } else {
      txHashInfo[_hash] = _txHash;
      insertedHashInfo[_txHash] = _hash;
      return true;
    }
  }

  /**
   * @dev get Tx hash for the hash string uploaded to blockchain
   * @param _hash is input value of hash
   * @return is the Tx hash value generated by action of inserting hash
   */
  function getTxIdByHash(string memory _hash) public view returns (string memory) {
    require(!_hash.equal(""));
    return txHashInfo[_hash];
  }

  /**
   * @dev get inserted hash string by the Tx hash
   * @param _txHash is input value of Tx hash
   * @return is the hash string corresponding to the Tx hash
   */
  function getHashByTxId(string memory _txHash) public view returns (string memory) {
    require(!_txHash.equal(""));
    return insertedHashInfo[_txHash];
  }

  /**
   * @dev get a group of Tx hashs for the hash strings uploaded to blockchain
   * @param _indices is array of the index of the Tx hash group
   * @return is the Tx hash value generated by action of inserting hash
   */
  function getInsertedHashGroup(uint[] memory _indices) public view returns (bytes memory) {
    uint len = _indices.length;

    strings.slice[] memory hashSlices = new strings.slice[](len);
    for(uint i = 0; i < len; i = i.add(1)) {
      string memory tmpHashStr = hashInfoLib.getHashByInd(_indices[i]);
      hashSlices[i] = tmpHashStr.toSlice();
    }
    string memory hashStrs = ",".toSlice().join(hashSlices);

    return (abi.encode(hashStrs));
  }

  /**
   * @dev insertHash,insert hash into contract with bytes data
	 * @param _hash is input value of hash
   * @param _uploadedData is the data being uploaded with hash value
	 * @return bool,true is successful and false is failed
   */
  function insertHash(string memory _hash, bytes memory _uploadedData) public returns(bool);

  /**
	 * @dev selectHash,select hash from contract
	 * @param _hash is input value of hash
	 * @return true/false,saver,uploadedData,save time
	 */
  function selectHash(string memory _hash) public view returns (bool, address, bytes memory, uint256, string memory);
    
	/**
	 * @dev deleteHash,delete hash into contract
	 * @param _hash is input value of hash
	 * @return bool,true is successful and false is failed
	 */
  function deleteHash(string memory _hash) public returns (bool);

}


/**
 * This contract will take charge of submitting file hash to blockchain
 *
 */
contract DRCMediaHashCon is DRCHashBase {
  enum MediaType { 
    ARTICLE, 
    AUDIO, 
    VIDEO 
  }

  struct MediaInfo {
    string mediaName; // must have a value
    string mediaUrl; // must have
    string author; // must have
    MediaType t; // must have    
  }

  mapping(string => MediaInfo) private mediaHashInfo;

  event LogInsertMediaHash(
    address indexed _operator, 
    string _hash, 
    string _mediaName, 
    string _mediaUrl, 
    string _mediaType,
    bool _bool
  );

  event LogDeleteMediaHash(
    address indexed _operator, 
    string _hash, 
    string _mediaName, 
    string _mediaUrl,
    string _mediaType, 
    bool _bool
  );

  /**
   * @dev Constructor,not used just reserved
   */
  constructor() public {
  }

  /**
   * @dev insertHash,insert hash into contract
   * @param _hash is input value of hash
   * @param _uploadedData is the additional data being uploaded to the contract
   * @return bool,true is successful and false is failed
   */
  function insertHash(string memory _hash, bytes memory _uploadedData) 
    public 
    onlyOwner 
    returns (bool) 
  {
    require(!_hash.equal(""));

    (string memory _saverName, string memory _mediaName, string memory _mediaUrl, string memory _author, uint256 _mediaType) 
      = abi.decode(_uploadedData, (string, string, string, string, uint256));

    bool res = hashInfoLib.insertHash(_hash, _saverName);
    require(res);
    mediaHashInfo[_hash] = MediaInfo(_mediaName, _mediaUrl, _author, MediaType(_mediaType)); 
    emit LogInsertMediaHash(
      msg.sender, 
      _hash, 
      mediaHashInfo[_hash].mediaName,
      mediaHashInfo[_hash].mediaUrl, 
      getMediaTypeStr(mediaHashInfo[_hash].t),
      res
    );

    return true;
  }

  /**
   * @dev selectHash,select hash from contract
   * @param _hash is input value of hash
   * @return true/false,saver,save time
   */
  function selectHash(string memory _hash) 
    public 
    view 
    returns (bool, address, bytes memory, uint256, string memory) 
  {
    bool selectRes;
    HashOperateLib.ExInfo memory exInfo;

    (selectRes, exInfo.saver, exInfo.saverName, exInfo.saveTime) = hashInfoLib.selectHash(_hash);
    string memory selectTxHash = getTxIdByHash(_hash);
    bytes memory selectData = abi.encodePacked(
      exInfo.saverName, 
      mediaHashInfo[_hash].mediaName,
      mediaHashInfo[_hash].mediaUrl,
      mediaHashInfo[_hash].author,
      uint256(mediaHashInfo[_hash].t)
    );

    return (
      selectRes, 
      exInfo.saver, 
      selectData,
      exInfo.saveTime,
      selectTxHash
    );
  }

  /**
   * @dev deleteHash,delete hash into contract
   * @param _hash is input value of hash
   * @return bool,true is successful and false is failed
   */
  function deleteHash(string memory _hash) public onlyOwner returns (bool) {
    bool res = hashInfoLib.deleteHash(_hash);
    if (res) 
      delete mediaHashInfo[_hash];

    emit LogDeleteMediaHash(
      msg.sender, 
      _hash, 
      mediaHashInfo[_hash].mediaName,
      mediaHashInfo[_hash].mediaUrl, 
      getMediaTypeStr(mediaHashInfo[_hash].t),
      res
    );

    return res;
  }

  function getMediaTypeStr(MediaType t) private pure returns (string memory) {
    if (t == MediaType.ARTICLE) {
      return "Article";
    } else if (t == MediaType.AUDIO) {
      return "Audio";
    } else if (t == MediaType.VIDEO) {
      return "Video";
    } else {
      return "";
    }
  }

}