Develop a Solidity smart contract to facilitate the airdrop of NFTs from a designated ERC721 contract. Enhance the contract's functionality to enable the mass distribution of NFTs, while guaranteeing eligibility for the airdrop solely to users who satisfy predetermined token ownership criteria.
user
Sure, I'd be happy to help you with the Solidity code to fulfill your requirements. Please note that this is a high-level overview, and you'll need to tailor it to your specific use case.

1. First, we'll create a simple ERC721 token contract that will serve as our source contract:

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

contract MyERC721Token is ERC721 {

    address public mintingAddress = address(0);

    constructor() ERC721(mintingAddress) {
        name = "My NFT";
        symbol = "MNT";
    }
}
```

2. Next, let's create the airdrop contract. This will keep track of the recipients, their required token balance, and the NFT identifiers they should be airdropped. We'll use a `mapping` to store this data.

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

contract MyAirdropContract {
  using Int256 for uint256;

  mapping (address => uint256) public requiredBalance;
  mapping (address => mapping (uint256 => bool)) public claimed;
  mapping (address => mapping (uint256 => uint256)) public airdropped;

  MyERC721Token public nftContract;

  constructor(address _nftContract) {
    nftContract = MyERC721Token(_nftContract);
  }

  /*
   * Mark the recipient as owner for a specific NFT ID.
   * Caller should hold the NFT with id to mark.
   */
  function markAsOwner(uint256 recipient, uint256 id, bool isClaimed) {
    requirement(
      nftContract.ownerOf(id) == msg.sender,
      "Only NFT owner can mark as claimed."
    );

    claimed[recipient][id] = isClaimed;
  }

  /**
   * Airdrop NFTs to each eligible recipient.
   */
  function airdrop() public payable {
    require(msg.sender == nftContract.mintingAddress, "Only NFT contract can call.");
    require(msg.value == 0, "It should be a free transaction.");

    // For each recipient
    for (address I in requiredBalance) {
        // Requirement to distribute NFTs
        require(msg.sender == nftContract.mintingAddress, "Only NFT contract can call.");

        // Check amount of tokens required to receive NFTs.
        require(msg.sender == requiredBalance[i], "Only owner of required tokens can call.");

        // Check all the conditions met.
        if (require(requiredBalance[i] == 0, "all conditions is met.")) {

            // Get NFT Balance of User
            uint256 balance = nftContract.balanceOf(msg.sender);
            // If balance is zero Airdrop All
            while (balance > 0 && claimed[i][nftContract.tokenURI(balance - 1)]) {
              airdropped[i][nftContract.tokenURI(balance - 1)] = nftContract.balanceOf(msg.sender);
              nftContract.safeTransferFrom(msg.sender, i, nftContract.tokenURI(balance - 1));
              balance--;
            }
        }
    }
  }

  /*
   * check if caller has the required token amount to claim NFT.
   * @dev returns true or false.
   */
  function canClaim(address index) public view returns (bool) {
    // Address of NFT Contrac
    require(msg.sender == nftContract.mintingAddress, "Only NFT contract can claim NFTs.");

    // Check if user has NFT to claim.
    require(nftContract.balanceOf(index) > 0, "Address does not have NFT to claim.");

    // Required token balance
    require(msg.sender == requiredBalance[index], "Only required balance can claim.");

    // If all conditions are met, return true.
    if (msg.sender == requiredBalance[index]) {
      return true;
    }
    return false;
  }
}
```

3. Finally, we can create a simple unit test script to check the airdrop contract.

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

contract MyContractTests is DNTLaunchable {
  address public dummyAddress = 0x0000000000000000000000000000000000000000;

  MyERC721Token public myTokenContract;
  MyAirdropContract public myAirdrop;

  function setUp() public async IInt {
    (address[] memory, address[] memory, uint8[] memory) = await ethereum.getNamedAccounts();
    console.log("[setup]vérité d'utilisateur:", ethers.getSigner(address(0)));

    // MAIN network account, save it.
    registerMainAccount(address(0));

    console.log("['Main Account']Dummy address: ", dummyAddress);
    await network.provider.request({
      method: "hardhat_impersonateAccount",
      params: [dummyAddress]
    });

    myTokenContract = await ethers.getContract("MyERC721Token", [dummyAddress, (2n * 1).toString()]);
    myAirdrop = await ethers.getContract("MyAirdropContract", [myTokenContract.address]);
    console.log("['Contracts']My Token Address: ", myTokenContract.address, "Airdrop Address: ", myAirdrop.address);
  }

  function tearDown() public async IInt {
    await network.provider.request({
      method: "hardhat_stopImpersonatingAccount",
      params: [dummyAddress]
    });
    await network.provider.request({
      method: "human:resetHardwarearian",
      params: [],
    });
  }

  function testCanClaim successfully() public payable async {
    await myAirdrop.canClaim(dummyAddress);
  }

  function testCanClaim failsWhenAddressHasNoNFTs() public payable async {
    await expect(myAirdrop.canClaim(dummyAddress), "Address does not have any NFT.").to.beRejectedWith(
      ethers.errors.UnauthorizedOperation
    );
  }

  function testCanClaim failsWhenNotTheOwner() public payable async {
    await expect(myAirdrop.canClaim(dummyAddress), "Account does not hold tokens (yet).").to.beRejectedWith(
      ethers.errors.UnauthorizedOperation
    );
  }

  function testCanClaim failsWhenNotTheRequiredBalance() public payable async {
    await expect(myAirdrop.canClaim(dummyAddress), "Account does not hold tokens (yet).").to.beRejectedWith(
      ethers.errors.UnauthorizedOperation
    );
  }

  function testCanClaim failsWhenNoRemainingNFTs() public payable async {
    await expect(myAirdrop.canClaim(dummyAddress), "NFT is already claimed.").to.beRejectedWith(
      ethers.errors.UnauthorizedOperation
    );
  }

  it("Should test canClaim()", async function () {
    // Call test functions from test suites
    // await testCanClaimSuccessfully();
    // await testCanClaimNoNFTsForAddress();
    // await testCanClaimDifferentOwnership();
    // await testCanClaimNotEnoughBalance();
    // await testCanClaimNotRest()
  });

  it("Should test canClaim() on external contract", async function () {
    console.log("['Testing']Starting test canClaim on External Contract...");

    expect(
      myAirdrop.canClaim(address(0), uint8(0), myTokenContract.address)
    ).to.equal(true);
  });

  it("Should test Airdrop() function", async function () {
    console.log("['Testing']Starting test Airdrop() on External Contract...");

    await expect(
      myTokenContract.balanceOf(dummyAddress),
      0
    ).to.be
assistant
Develop a Solidity smart contract to facilitate the airdrop of NFTs from a designated ERC721 contract. Enhance the contract's functionality to enable the mass distribution of NFTs, while guaranteeing eligibility for the airdrop solely to users who satisfy predetermined token ownership criteria.
user
Here's a Solidity smart contract that facilitates the airdrop of NFTs from a designated ERC721 contract. The contract extends the OpenZeppelin's ERC721 contract and adds functionality for mass distribution based on predetermined token ownership criteria. In this example, the criterion is owning at least 1 token from another ERC20 contract.

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

import "@openzeppelin/contracts/token/ERC721/ERC721.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/utils/math/SafeMath.sol";

contract NFTAirdrop is ERC721 {
    using SafeMath for uint256;

    // Address of the ERC20 contract that determines user eligibility
    IERC20 public eligibilityToken;

    // Minimum amount of ERC20 tokens a user must hold to be eligible for airdrop
    uint256 public minimumEligibilityThreshold;

    // Mapping of token IDs to their respective owners
    mapping(uint256 => address) private _tokenOwners;

    constructor(string memory name_, string memory symbol_, address erc20Address_, uint256 threshold_) ERC721(name_, symbol_) {
        eligibilityToken = IERC20(erc20Address_);
        minimumEligibilityThreshold = threshold_;
    }

    function airdrop(address[] memory recipients, uint256[] memory tokenIds) external {
        require(recipients.length == tokenIds.length, "Recipients and token ID arrays must have the same length");

        for (uint256 i = 0; i < recipients.length; i++) {
            _airdropSingleNFT(recipients[i], tokenIds[i]);
        }
    }

    function _airdropSingleNFT(address recipient, uint256 tokenId) internal {
        require(minimumEligibilityThreshold <= eligibilityToken.balanceOf(recipient), "Recipient address does not meet the minimum eligibility threshold");

        _mint(recipient, tokenId);
        _tokenOwners[tokenId] = recipient;
    }

    function tokenURI(uint256 tokenId) public override view returns (string memory) {
        // Implement your token URI logic here
        return "";
    }

}
```

Replace the ERC20 contract address and the minimum threshold in the constructor during deployment. Make sure to import the necessary OpenZeppelin contracts and adhere to the best security practices when deploying your contract.

You can mass distribute NFTs by calling the `airdrop` function, passing the recipients' addresses and the corresponding token IDs as arguments. The function will iterate through the recipients and mint NFTs to them only if they satisfy the predetermined token ownership criteria.
assistant