Contract Source Code:

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

interface IERC721A {
    function ownerOf(uint256 tokenId) external view returns (address);
    function approve(address to, uint256 tokenId) external;
    function transferFrom(address from, address to, uint256 tokenId) external;
}

contract TransferToNull {
    address public nftContractAddress;

    // Track the number of NFTs burned by each address
    mapping(address => uint256) public burnedNFTs;

    // Enum for tier levels
    enum Tier { None, Tier1, Tier2, Tier3 }

    // Mapping to store user's tier level
    mapping(address => Tier) public userTier;

    // Arrays to store addresses by tier
    address[] public tier1Addresses;
    address[] public tier2Addresses;
    address[] public tier3Addresses;

    // Constructor to set the NFT contract address
    constructor(address _nftContractAddress) {
        nftContractAddress = _nftContractAddress;
    }

    // Function to get the current tier of an address
    function getTier(address user) public view returns (Tier) {
        return userTier[user];
    }

    // Function to transfer multiple NFTs to the null address (0x0)
    function transferToNull(uint256[] calldata tokenIds) external {
        IERC721A nft = IERC721A(nftContractAddress);

        for (uint256 i = 0; i < tokenIds.length; i++) {
            uint256 tokenId = tokenIds[i];
            // Ensure the caller owns the token
            address owner = nft.ownerOf(tokenId);
            require(owner == msg.sender, "You must own the token to transfer it");

            // Approve the transfer to this contract
            nft.approve(address(this), tokenId);

            // Transfer the token to the null address (0x0)
            nft.transferFrom(owner, address(0), tokenId);

            // Track the number of NFTs burned by the caller
            burnedNFTs[msg.sender]++;

            // Update the user's tier based on the number of NFTs burned
            updateTier(msg.sender);
        }
    }

    // Function to update the tier of the user based on the number of NFTs burned
    function updateTier(address user) internal {
        uint256 burnedCount = burnedNFTs[user];

        // Check if the user needs to be moved to a higher or lower tier
        if (burnedCount >= 25) {
            if (userTier[user] != Tier.Tier1) {
                removeFromTier(userTier[user], user);
                tier1Addresses.push(user);
                userTier[user] = Tier.Tier1;
            }
        } else if (burnedCount >= 15) {
            if (userTier[user] != Tier.Tier2) {
                removeFromTier(userTier[user], user);
                tier2Addresses.push(user);
                userTier[user] = Tier.Tier2;
            }
        } else if (burnedCount >= 5) {
            if (userTier[user] != Tier.Tier3) {
                removeFromTier(userTier[user], user);
                tier3Addresses.push(user);
                userTier[user] = Tier.Tier3;
            }
        } else {
            if (userTier[user] != Tier.None) {
                removeFromTier(userTier[user], user);
                userTier[user] = Tier.None;
            }
        }
    }

    // Helper function to remove an address from the previous tier array
    function removeFromTier(Tier oldTier, address user) internal {
        if (oldTier == Tier.Tier1) {
            removeAddressFromArray(tier1Addresses, user);
        } else if (oldTier == Tier.Tier2) {
            removeAddressFromArray(tier2Addresses, user);
        } else if (oldTier == Tier.Tier3) {
            removeAddressFromArray(tier3Addresses, user);
        }
    }

    // Helper function to remove an address from an array
    function removeAddressFromArray(address[] storage tierArray, address user) internal {
        for (uint256 i = 0; i < tierArray.length; i++) {
            if (tierArray[i] == user) {
                tierArray[i] = tierArray[tierArray.length - 1];
                tierArray.pop();
                break;
            }
        }
    }

    // Function to get all addresses of users in Tier 1
    function getTier1Addresses() public view returns (address[] memory) {
        return tier1Addresses;
    }

    // Function to get all addresses of users in Tier 2
    function getTier2Addresses() public view returns (address[] memory) {
        return tier2Addresses;
    }

    // Function to get all addresses of users in Tier 3
    function getTier3Addresses() public view returns (address[] memory) {
        return tier3Addresses;
    }
}