🖼️ Advanced NFT Contract

This project implements an advanced NFT smart contract on Ethereum using Solidity. It features a Merkle-tree-based whitelist, gas optimization with BitMaps, commit-reveal randomness, a multicall interface, and a secure pull-based withdrawal system.

🚀 Features

✅ Merkle Tree Whitelist Airdrop

• Only addresses in the Merkle Tree can mint.
• Leaf format: keccak256(abi.encodePacked(index, address)).
• Prevents double claiming using BitMaps and Mapping for gas comparison.

🔬 Gas Comparison

• Two minting methods:
  • merkleMintWithMapping(): Tracks claims with a mapping.
  • merkleMintWithBitmap(): Tracks claims with a BitMap.
• Compare gas usage between both.

🎲 Commit-Reveal NFT Randomness

• Users commit a hash of a secret and salt.
• After 10 blocks, users reveal the secret to mint a random NFT ID.

🧩 Multicall Support

• Batch multiple transferFrom() or other safe actions in a single transaction.
• Minting is protected from abuse via multicall.

🧠 Sale State Machine

• Sale phases:
  • CLOSED
  • PRESALE
  • PUBLIC
  • SOLD_OUT
• Contract logic is restricted based on sale phase.

💸 Pull-Based Withdrawals

• Secure pull pattern for fund distribution.
• Owner can deposit ETH to contributors.
• Each address can withdraw their allocated amount independently.

🧪 Testing

Recommended testing with Hardhat:

npm install
npx hardhat test