creation_sourcecode: /**
   *Submitted for verification at Etherscan.io on 2023-02-04
  */
  
  // File: @openzeppelin/contracts/token/ERC20/IERC20.sol
  
  
  // OpenZeppelin Contracts (last updated v4.6.0) (token/ERC20/IERC20.sol)
  
  pragma solidity ^0.8.0;
  
  /**
   * @dev Interface of the ERC20 standard as defined in the EIP.
   */
  interface IERC20 {
      /**
       * @dev Emitted when `value` tokens are moved from one account (`from`) to
       * another (`to`).
       *
       * Note that `value` may be zero.
       */
      event Transfer(address indexed from, address indexed to, uint256 value);
  
      /**
       * @dev Emitted when the allowance of a `spender` for an `owner` is set by
       * a call to {approve}. `value` is the new allowance.
       */
      event Approval(address indexed owner, address indexed spender, uint256 value);
  
      /**
       * @dev Returns the amount of tokens in existence.
       */
      function totalSupply() external view returns (uint256);
  
      /**
       * @dev Returns the amount of tokens owned by `account`.
       */
      function balanceOf(address account) external view returns (uint256);
  
      /**
       * @dev Moves `amount` tokens from the caller's account to `to`.
       *
       * Returns a boolean value indicating whether the operation succeeded.
       *
       * Emits a {Transfer} event.
       */
      function transfer(address to, uint256 amount) external returns (bool);
  
      /**
       * @dev Returns the remaining number of tokens that `spender` will be
       * allowed to spend on behalf of `owner` through {transferFrom}. This is
       * zero by default.
       *
       * This value changes when {approve} or {transferFrom} are called.
       */
      function allowance(address owner, address spender) external view returns (uint256);
  
      /**
       * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
       *
       * Returns a boolean value indicating whether the operation succeeded.
       *
       * IMPORTANT: Beware that changing an allowance with this method brings the risk
       * that someone may use both the old and the new allowance by unfortunate
       * transaction ordering. One possible solution to mitigate this race
       * condition is to first reduce the spender's allowance to 0 and set the
       * desired value afterwards:
       * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
       *
       * Emits an {Approval} event.
       */
      function approve(address spender, uint256 amount) external returns (bool);
  
      /**
       * @dev Moves `amount` tokens from `from` to `to` using the
       * allowance mechanism. `amount` is then deducted from the caller's
       * allowance.
       *
       * Returns a boolean value indicating whether the operation succeeded.
       *
       * Emits a {Transfer} event.
       */
      function transferFrom(
          address from,
          address to,
          uint256 amount
      ) external returns (bool);
  }
  
  // File: @openzeppelin/contracts/utils/Context.sol
  
  
  // OpenZeppelin Contracts v4.4.1 (utils/Context.sol)
  
  pragma solidity ^0.8.0;
  
  /**
   * @dev Provides information about the current execution context, including the
   * sender of the transaction and its data. While these are generally available
   * via msg.sender and msg.data, they should not be accessed in such a direct
   * manner, since when dealing with meta-transactions the account sending and
   * paying for execution may not be the actual sender (as far as an application
   * is concerned).
   *
   * This contract is only required for intermediate, library-like contracts.
   */
  abstract contract Context {
      function _msgSender() internal view virtual returns (address) {
          return msg.sender;
      }
  
      function _msgData() internal view virtual returns (bytes calldata) {
          return msg.data;
      }
  }
  
  // File: @openzeppelin/contracts/access/Ownable.sol
  
  
  // OpenZeppelin Contracts (last updated v4.7.0) (access/Ownable.sol)
  
  pragma solidity ^0.8.0;
  
  
  /**
   * @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.
   *
   * By default, the owner account will be the one that deploys the contract. This
   * can later be changed with {transferOwnership}.
   *
   * This module is used through inheritance. It will make available the modifier
   * `onlyOwner`, which can be applied to your functions to restrict their use to
   * the owner.
   */
  abstract contract Ownable is Context {
      address private _owner;
  
      event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
  
      /**
       * @dev Initializes the contract setting the deployer as the initial owner.
       */
      constructor() {
          _transferOwnership(_msgSender());
      }
  
      /**
       * @dev Throws if called by any account other than the owner.
       */
      modifier onlyOwner() {
          _checkOwner();
          _;
      }
  
      /**
       * @dev Returns the address of the current owner.
       */
      function owner() public view virtual returns (address) {
          return _owner;
      }
  
      /**
       * @dev Throws if the sender is not the owner.
       */
      function _checkOwner() internal view virtual {
          require(owner() == _msgSender(), "Ownable: caller is not the 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 virtual onlyOwner {
          _transferOwnership(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 virtual onlyOwner {
          require(newOwner != address(0), "Ownable: new owner is the zero address");
          _transferOwnership(newOwner);
      }
  
      /**
       * @dev Transfers ownership of the contract to a new account (`newOwner`).
       * Internal function without access restriction.
       */
      function _transferOwnership(address newOwner) internal virtual {
          address oldOwner = _owner;
          _owner = newOwner;
          emit OwnershipTransferred(oldOwner, newOwner);
      }
  }
  
  // File: @openzeppelin/contracts/utils/cryptography/MerkleProof.sol
  
  
  // OpenZeppelin Contracts (last updated v4.8.0) (utils/cryptography/MerkleProof.sol)
  
  pragma solidity ^0.8.0;
  
  /**
   * @dev These functions deal with verification of Merkle Tree proofs.
   *
   * The tree and the proofs can be generated using our
   * https://github.com/OpenZeppelin/merkle-tree[JavaScript library].
   * You will find a quickstart guide in the readme.
   *
   * WARNING: You should avoid using leaf values that are 64 bytes long prior to
   * hashing, or use a hash function other than keccak256 for hashing leaves.
   * This is because the concatenation of a sorted pair of internal nodes in
   * the merkle tree could be reinterpreted as a leaf value.
   * OpenZeppelin's JavaScript library generates merkle trees that are safe
   * against this attack out of the box.
   */
  library MerkleProof {
      /**
       * @dev Returns true if a `leaf` can be proved to be a part of a Merkle tree
       * defined by `root`. For this, a `proof` must be provided, containing
       * sibling hashes on the branch from the leaf to the root of the tree. Each
       * pair of leaves and each pair of pre-images are assumed to be sorted.
       */
      function verify(
          bytes32[] memory proof,
          bytes32 root,
          bytes32 leaf
      ) internal pure returns (bool) {
          return processProof(proof, leaf) == root;
      }
  
      /**
       * @dev Calldata version of {verify}
       *
       * _Available since v4.7._
       */
      function verifyCalldata(
          bytes32[] calldata proof,
          bytes32 root,
          bytes32 leaf
      ) internal pure returns (bool) {
          return processProofCalldata(proof, leaf) == root;
      }
  
      /**
       * @dev Returns the rebuilt hash obtained by traversing a Merkle tree up
       * from `leaf` using `proof`. A `proof` is valid if and only if the rebuilt
       * hash matches the root of the tree. When processing the proof, the pairs
       * of leafs & pre-images are assumed to be sorted.
       *
       * _Available since v4.4._
       */
      function processProof(bytes32[] memory proof, bytes32 leaf) internal pure returns (bytes32) {
          bytes32 computedHash = leaf;
          for (uint256 i = 0; i < proof.length; i++) {
              computedHash = _hashPair(computedHash, proof[i]);
          }
          return computedHash;
      }
  
      /**
       * @dev Calldata version of {processProof}
       *
       * _Available since v4.7._
       */
      function processProofCalldata(bytes32[] calldata proof, bytes32 leaf) internal pure returns (bytes32) {
          bytes32 computedHash = leaf;
          for (uint256 i = 0; i < proof.length; i++) {
              computedHash = _hashPair(computedHash, proof[i]);
          }
          return computedHash;
      }
  
      /**
       * @dev Returns true if the `leaves` can be simultaneously proven to be a part of a merkle tree defined by
       * `root`, according to `proof` and `proofFlags` as described in {processMultiProof}.
       *
       * CAUTION: Not all merkle trees admit multiproofs. See {processMultiProof} for details.
       *
       * _Available since v4.7._
       */
      function multiProofVerify(
          bytes32[] memory proof,
          bool[] memory proofFlags,
          bytes32 root,
          bytes32[] memory leaves
      ) internal pure returns (bool) {
          return processMultiProof(proof, proofFlags, leaves) == root;
      }
  
      /**
       * @dev Calldata version of {multiProofVerify}
       *
       * CAUTION: Not all merkle trees admit multiproofs. See {processMultiProof} for details.
       *
       * _Available since v4.7._
       */
      function multiProofVerifyCalldata(
          bytes32[] calldata proof,
          bool[] calldata proofFlags,
          bytes32 root,
          bytes32[] memory leaves
      ) internal pure returns (bool) {
          return processMultiProofCalldata(proof, proofFlags, leaves) == root;
      }
  
      /**
       * @dev Returns the root of a tree reconstructed from `leaves` and sibling nodes in `proof`. The reconstruction
       * proceeds by incrementally reconstructing all inner nodes by combining a leaf/inner node with either another
       * leaf/inner node or a proof sibling node, depending on whether each `proofFlags` item is true or false
       * respectively.
       *
       * CAUTION: Not all merkle trees admit multiproofs. To use multiproofs, it is sufficient to ensure that: 1) the tree
       * is complete (but not necessarily perfect), 2) the leaves to be proven are in the opposite order they are in the
       * tree (i.e., as seen from right to left starting at the deepest layer and continuing at the next layer).
       *
       * _Available since v4.7._
       */
      function processMultiProof(
          bytes32[] memory proof,
          bool[] memory proofFlags,
          bytes32[] memory leaves
      ) internal pure returns (bytes32 merkleRoot) {
          // This function rebuild the root hash by traversing the tree up from the leaves. The root is rebuilt by
          // consuming and producing values on a queue. The queue starts with the `leaves` array, then goes onto the
          // `hashes` array. At the end of the process, the last hash in the `hashes` array should contain the root of
          // the merkle tree.
          uint256 leavesLen = leaves.length;
          uint256 totalHashes = proofFlags.length;
  
          // Check proof validity.
          require(leavesLen + proof.length - 1 == totalHashes, "MerkleProof: invalid multiproof");
  
          // The xxxPos values are "pointers" to the next value to consume in each array. All accesses are done using
          // `xxx[xxxPos++]`, which return the current value and increment the pointer, thus mimicking a queue's "pop".
          bytes32[] memory hashes = new bytes32[](totalHashes);
          uint256 leafPos = 0;
          uint256 hashPos = 0;
          uint256 proofPos = 0;
          // At each step, we compute the next hash using two values:
          // - a value from the "main queue". If not all leaves have been consumed, we get the next leaf, otherwise we
          //   get the next hash.
          // - depending on the flag, either another value for the "main queue" (merging branches) or an element from the
          //   `proof` array.
          for (uint256 i = 0; i < totalHashes; i++) {
              bytes32 a = leafPos < leavesLen ? leaves[leafPos++] : hashes[hashPos++];
              bytes32 b = proofFlags[i] ? leafPos < leavesLen ? leaves[leafPos++] : hashes[hashPos++] : proof[proofPos++];
              hashes[i] = _hashPair(a, b);
          }
  
          if (totalHashes > 0) {
              return hashes[totalHashes - 1];
          } else if (leavesLen > 0) {
              return leaves[0];
          } else {
              return proof[0];
          }
      }
  
      /**
       * @dev Calldata version of {processMultiProof}.
       *
       * CAUTION: Not all merkle trees admit multiproofs. See {processMultiProof} for details.
       *
       * _Available since v4.7._
       */
      function processMultiProofCalldata(
          bytes32[] calldata proof,
          bool[] calldata proofFlags,
          bytes32[] memory leaves
      ) internal pure returns (bytes32 merkleRoot) {
          // This function rebuild the root hash by traversing the tree up from the leaves. The root is rebuilt by
          // consuming and producing values on a queue. The queue starts with the `leaves` array, then goes onto the
          // `hashes` array. At the end of the process, the last hash in the `hashes` array should contain the root of
          // the merkle tree.
          uint256 leavesLen = leaves.length;
          uint256 totalHashes = proofFlags.length;
  
          // Check proof validity.
          require(leavesLen + proof.length - 1 == totalHashes, "MerkleProof: invalid multiproof");
  
          // The xxxPos values are "pointers" to the next value to consume in each array. All accesses are done using
          // `xxx[xxxPos++]`, which return the current value and increment the pointer, thus mimicking a queue's "pop".
          bytes32[] memory hashes = new bytes32[](totalHashes);
          uint256 leafPos = 0;
          uint256 hashPos = 0;
          uint256 proofPos = 0;
          // At each step, we compute the next hash using two values:
          // - a value from the "main queue". If not all leaves have been consumed, we get the next leaf, otherwise we
          //   get the next hash.
          // - depending on the flag, either another value for the "main queue" (merging branches) or an element from the
          //   `proof` array.
          for (uint256 i = 0; i < totalHashes; i++) {
              bytes32 a = leafPos < leavesLen ? leaves[leafPos++] : hashes[hashPos++];
              bytes32 b = proofFlags[i] ? leafPos < leavesLen ? leaves[leafPos++] : hashes[hashPos++] : proof[proofPos++];
              hashes[i] = _hashPair(a, b);
          }
  
          if (totalHashes > 0) {
              return hashes[totalHashes - 1];
          } else if (leavesLen > 0) {
              return leaves[0];
          } else {
              return proof[0];
          }
      }
  
      function _hashPair(bytes32 a, bytes32 b) private pure returns (bytes32) {
          return a < b ? _efficientHash(a, b) : _efficientHash(b, a);
      }
  
      function _efficientHash(bytes32 a, bytes32 b) private pure returns (bytes32 value) {
          /// @solidity memory-safe-assembly
          assembly {
              mstore(0x00, a)
              mstore(0x20, b)
              value := keccak256(0x00, 0x40)
          }
      }
  }
  
  // File: contracts/airdrop.sol
  
  
  pragma solidity ^0.8.0;
  
  
  
  
  
  contract Airdrop is Ownable {
  
      bytes32 public root;
  
      address public token;
      mapping(address => uint256) public claimedAmount;
  
      uint256 public totalTokensToBeDistributed;
  
      uint256 public tokensAlreadyReceived;
      uint256 public tokensAlreadyClaimed;
  
      constructor(bytes32 _root, address _token, uint256 _totalTokensToBeDistributed) {
          root = _root;
          token = _token;
          totalTokensToBeDistributed = _totalTokensToBeDistributed;
      }
  
      function claim(bytes32[] calldata proof, uint256 amount) public {
          bytes32 leaf = keccak256(abi.encodePacked(msg.sender, amount));
          require(MerkleProof.verify(proof, root, leaf), "Invalid proof");
  
          if (tokensAlreadyReceived < tokensAlreadyClaimed + safeGetBalance(token, address(this))) {
              tokensAlreadyReceived = tokensAlreadyClaimed + safeGetBalance(token, address(this));
          }
  
          uint256 amountToClaim = amount * tokensAlreadyReceived  / totalTokensToBeDistributed;
  
          if (claimedAmount[msg.sender] < amountToClaim) {
              tokensAlreadyClaimed += amountToClaim - claimedAmount[msg.sender];
              safeTransfer(token, msg.sender, amountToClaim - claimedAmount[msg.sender]);
              claimedAmount[msg.sender] = amountToClaim;
          } else {
              revert("Already claimed");
          }
      }
  
      function setRoot(bytes32 _root) public onlyOwner {
          root = _root;
      }
  
      function setToken(address _token) public onlyOwner {
          token = _token;
      }
  
      function setTotalTokensToBeDistributed(uint256 _totalTokensToBeDistributed) public onlyOwner {
          totalTokensToBeDistributed = _totalTokensToBeDistributed;
      }
  
      //support
  
      function safeTransfer(
          address _token,
          address _to,
          uint256 _value
      ) internal {
          (bool success, bytes memory data) = _token.call(
              abi.encodeWithSelector(IERC20.transfer.selector, _to, _value)
          );
          require(success && (data.length == 0 || abi.decode(data, (bool))), 'TF');
      }
  
      function safeGetBalance(
          address _token,
          address _account
      ) internal view returns (uint256) {
          (bool success, bytes memory data) = _token.staticcall(
              abi.encodeWithSelector(IERC20.balanceOf.selector, _account)
          );
          require(success && (data.length > 0), 'SGB');
          return abi.decode(data, (uint256));
      }
  
  }