One Piece Personality dApp - Backend

Overview

The backend of the One Piece Personality dApp is powered by a Solidity smart contract that integrates with the Core Blockchain. This contract enables users to discover their One Piece personality match and mint a unique NFT representing their assigned character. This README details the contract's structure, functionality, and deployment.

Smart Contract Details

Contract Name: OnePieceMint

License: MIT

Solidity Version: ^0.8.20

Dependencies:

• @openzeppelin/contracts/token/ERC721/extensions/ERC721URIStorage.sol
• @openzeppelin/contracts/access/Ownable.sol
• @openzeppelin/contracts/token/ERC721/ERC721.sol

Key Features

• Token Counter: Keeps track of the number of NFTs minted.
• Character Token URIs: A list of URIs pointing to the metadata for different One Piece characters.
• User Mappings: Tracks which character a user is assigned, if they have minted an NFT, and the token ID of their NFT.
• Events: Emits events when an NFT is requested, a character trait is determined, and an NFT is minted.
• Minting Functionality: Allows users to mint an NFT representing their One Piece personality match.
• Randomness: Utilizes Keccak hashing and block.prevrandao to ensure fair and transparent random character assignment.
• Soulbound Tokens: Overrides transfer functionality to make tokens non-transferable, ensuring they remain unique to the user.

Functions

mintNFT(address recipient, uint256 characterId)

Mints a new NFT for the specified recipient with the given character ID.

Parameters:

• recipient: The address receiving the NFT.
• characterId: The ID of the character assigned to the NFT.

Emits: NftMinted(characterId, recipient)

requestNFT(uint256[5] memory answers)

Allows a user to request an NFT by submitting their answers to the personality quiz.

Parameters:

• answers: An array of 5 answers from the user's quiz.

Emits: NftRequested(msg.sender)

determineCharacter(uint256[5] memory answers)

Determines the character ID based on the user's quiz answers.

Parameters:

• answers: An array of 5 answers from the user's quiz.

Returns: characterId (the determined character ID)

Emits: CharacterTraitDetermined(characterId)

_getRandomNumber(uint256 seed)

Generates a random number using Keccak hashing and block.prevrandao.

Parameters:

• seed: A seed value for the random number generation.

Returns: A random number.

_beforeTokenTransfer(address from, address to, uint256 firstTokenId, uint256 batchSize)

Overrides the transfer functionality to make tokens non-transferable (soulbound).

Parameters:

• from: The address transferring the token.
• to: The address receiving the token.
• firstTokenId: The ID of the first token in the transfer batch.
• batchSize: The size of the transfer batch.

Requires: Tokens can only be transferred to or from the zero address.

tokenURI(uint256 tokenId)

Overrides the default tokenURI function to provide the correct metadata URI.

Parameters:

• tokenId: The ID of the token.

Returns: The URI of the token's metadata.

supportsInterface(bytes4 interfaceId)

Overrides the supportsInterface function to indicate the supported interfaces.

Parameters:

• interfaceId: The ID of the interface.

Returns: true if the interface is supported, false otherwise.

_burn(uint256 tokenId)

Overrides the default _burn function to handle token burning.

Parameters:

• tokenId: The ID of the token to be burned.

Deployment

To deploy the contract, follow these steps:

1. Install Dependencies: Ensure you have OpenZeppelin contracts installed.

   npm install @openzeppelin/contracts

2. Compile the Contract: Compile the Solidity code using your preferred tool (e.g., Hardhat, Truffle).

   npx hardhat compile

3. Deploy the Contract: Deploy the contract to the Core Blockchain.

   npx hardhat ignition deploy ./ignition/modules/deploy.js

Events

• NftRequested: Emitted when a user requests an NFT.
• CharacterTraitDetermined: Emitted when a user's character trait is determined.
• NftMinted: Emitted when an NFT is minted for a user.

Security and Best Practices

• Ensure proper access controls with the Ownable contract to restrict certain functions to the contract owner.
• Use require statements to validate inputs and prevent unauthorized actions.
• Follow best practices for Solidity development, such as ensuring proper use of visibility specifiers.

Future Enhancements

• Expanded Character Pool: Add more character URIs to increase the variety of NFTs.
• Enhanced Randomness: Explore additional sources of randomness to further improve fairness.
• Interactivity: Introduce interactive features allowing users to engage with their NFTs in new ways.