// SPDX-License-Identifier: Apache-2.0
pragma solidity >=0.5.0 <0.9.0;

import {HederaResponseCodes} from "../../common/HederaResponseCodes.sol";
import {HederaTokenService} from "../../token-service/HederaTokenService.sol";
import {IHederaTokenService} from "../../token-service/IHederaTokenService.sol";
pragma experimental ABIEncoderV2;

// @title Cancel Airdrop Contract
// @notice Facilitates cancellation of pending token airdrops on the Hedera network
// @dev Implements HRC-904 standard for cancelling pending airdrops
//
// Pending airdrops can be cancelled in these cases:
// - When receiver has "receiver signature required" enabled
// - When receiver has no available auto-association slots
// - Before the receiver claims the airdrop
contract CancelAirdrop is HederaTokenService {

    // @notice Cancels a pending fungible token airdrop from a sender to a receiver
    // @dev Builds pending airdrop struct and submits cancelAirdrops system contract call
    // @param sender The address that sent the tokens
    // @param receiver The address that was to receive the tokens
    // @param token The token address of the pending airdrop
    // @return responseCode The response code from the cancel operation (22 = success)
    function cancelAirdrop(address sender, address receiver, address token) public returns(int64 responseCode){
        IHederaTokenService.PendingAirdrop[] memory pendingAirdrops = new IHederaTokenService.PendingAirdrop[](1);

        IHederaTokenService.PendingAirdrop memory pendingAirdrop;
        pendingAirdrop.sender = sender;
        pendingAirdrop.receiver = receiver;
        pendingAirdrop.token = token;

        pendingAirdrops[0] = pendingAirdrop;

        responseCode = cancelAirdrops(pendingAirdrops);
        if (responseCode != HederaResponseCodes.SUCCESS) {
            revert();
        }
        return responseCode;
    }

    // @notice Cancels a pending non-fungible token airdrop from a sender to a receiver
    // @dev Builds pending NFT airdrop struct and submits cancelAirdrops system contract call
    // @param sender The address that sent the NFT
    // @param receiver The address that was to receive the NFT
    // @param token The NFT token address
    // @param serial The serial number of the NFT
    // @return responseCode The response code from the cancel operation (22 = success)
    function cancelNFTAirdrop(address sender, address receiver, address token, int64 serial) public returns(int64 responseCode){
        IHederaTokenService.PendingAirdrop[] memory pendingAirdrops = new IHederaTokenService.PendingAirdrop[](1);

        IHederaTokenService.PendingAirdrop memory pendingAirdrop;
        pendingAirdrop.sender = sender;
        pendingAirdrop.receiver = receiver;
        pendingAirdrop.token = token;
        pendingAirdrop.serial = serial;

        pendingAirdrops[0] = pendingAirdrop;

        responseCode = cancelAirdrops(pendingAirdrops);
        if (responseCode != HederaResponseCodes.SUCCESS) {
            revert();
        }
        return responseCode;
    }

    // @notice Cancels multiple pending airdrops in a single transaction
    // @dev Builds array of pending airdrop structs and submits batch cancelAirdrops call
    // @param senders Array of addresses that sent the tokens/NFTs
    // @param receivers Array of addresses that were to receive the tokens/NFTs
    // @param tokens Array of token addresses for the pending airdrops
    // @param serials Array of serial numbers for NFT airdrops (use 0 for fungible tokens)
    // @return responseCode The response code from the batch cancel operation (22 = success)
    function cancelMultipleAirdrops(address[] memory senders, address[] memory receivers, address[] memory tokens, int64[] memory serials) public returns (int64 responseCode) {
        uint length = senders.length;
        IHederaTokenService.PendingAirdrop[] memory pendingAirdrops = new IHederaTokenService.PendingAirdrop[](length);
        for (uint i = 0; i < length; i++) {
            IHederaTokenService.PendingAirdrop memory pendingAirdrop;
            pendingAirdrop.sender = senders[i];
            pendingAirdrop.receiver = receivers[i];
            pendingAirdrop.token = tokens[i];
            pendingAirdrop.serial = serials[i];

            pendingAirdrops[i] = pendingAirdrop;
        }

        responseCode = cancelAirdrops(pendingAirdrops);
        if (responseCode != HederaResponseCodes.SUCCESS) {
            revert();
        }
        return responseCode;
    }
}