Embryo NFT

SPEN Contract (SuperPiccellEmbryoNFT)

This documentation is for a prototype contract and the specifications may be updated.

Overview

The SPEN contract is designed to mint full on-chain NFTs using content data retrieved from the SuperPiccellCore contract. The content stored in the core contract is minted as a unique NFT, ensuring that each piece of content can only be minted once. This contract supports both free and paid minting, and can accept either Ether (ETH) or ERC20 tokens as payment. The contract also includes features for managing minting configurations, checking content protection, and burning tokens.

This contract is highly flexible, allowing it to be customized and adapted for other NFT minting processes. It can be easily integrated into a wide range of projects, making it an ideal solution for decentralized content management and NFT minting.

You can view the contract on the Sepolia testnet at the following links:

• SPEN Contract GitHub repository

• SPEN Contract on Sepolia Etherscan

Frontend Application (DApp)

The frontend application (DApp) provides an intuitive interface for minting NFTs directly from content stored in the SuperPiccellCore contract. Users can browse and select content from the core contract, and mint it as a full on-chain NFT. Additionally, the DApp performs necessary checks to ensure that the selected content:

• Is not already minted.

• Is not locked or protected.

• Complies with the minting configuration set in the contract.

If all conditions are met, users can proceed with minting the NFT, either for free or by paying with Ether or ERC20 tokens.

You can also interact with the contract using our Frontend Application (DApp) which is available at SuperPiccell Embryo NFT DApp.

Features of the DApp

• Content Retrieval: The DApp retrieves content from the SuperPiccellCore contract and displays it to users for minting.

• Minting Checks: The application ensures that the content has not already been minted and that it is not protected by the core contract’s content protection mechanism.

• Customization: The DApp can be customized to modify the user interface, design, and minting logic. This flexibility makes it easy to adapt the application to other NFT minting use cases or projects.

• Reusable Architecture: The DApp can be reused for different content or NFT minting projects by simply swapping out the core contract or modifying the minting logic.

Interaction with the DApp

To interact with the DApp, users will need a browser extension such as MetaMask that allows their browser to connect to the Ethereum blockchain. Users must switch their MetaMask network to the Sepolia testnet and ensure that they have enough Ether or the configured ERC20 tokens in their wallet to pay for minting if applicable.

You can add the Sepolia network to MetaMask by using chainlist or manually adding it from the settings menu in MetaMask.

The DApp is built using the React JavaScript library and communicates with the Ethereum blockchain using ethers.js, providing a seamless and efficient user experience.

Environment Requirements for the DApp

• PC: MetaMask, Trust Wallet, Coinbase Wallet

• Smartphone: MetaMask

Features

Function Name	Description
setMintingEnabled	Enables or disables minting. This function can only be called by the owner of the contract.
setMintPrice	Sets the price for minting an NFT. This function can only be called by the owner of the contract.
setPaymentToken	Sets the ERC20 token to be used for minting payments. If not set, ETH will be used as the payment currency. This function can only be called by the owner of the contract.
mintNFT	Mints a new NFT with the specified content. Can be done for free or with payment based on the configuration. Each content ID can only be minted once.
getMintConfig	Retrieves the current minting configuration, including minting status, price, payment token, and whether free minting is allowed.
paymentTokenSymbol	Returns the symbol of the payment token (ERC20). If no payment token is set, returns "ETH" for Ether.
totalSupply	Returns the total number of minted NFTs.
tokenURI	Returns the URI of a specific token ID, as long as it has not been burned.
withdraw	Allows the owner to withdraw Ether that was sent to the contract.
withdrawToken	Allows the owner to withdraw ERC20 tokens from the contract.
receiveToken	Allows the owner to receive ERC20 tokens sent to the contract.

Security Features

Function Name	Description
burn	Burns an NFT and invalidates its associated content. It also unlocks the content ID, allowing it to be minted again.
withdraw	Allows the contract owner to withdraw Ether from the contract.
withdrawToken	Allows the contract owner to withdraw ERC20 tokens from the contract.
receiveToken	Allows the owner to receive ERC20 tokens from the contract.

Minting Process

Minting Conditions

The minting process is subject to the following conditions:

1. Minting must be enabled (mintingEnabled == true).

2. The content ID must not have been minted before (_mintedContentIds[contentId] == false).

3. If minting is not free (isFreeMint() == false):

   • Ether Payments: If no payment token is set (paymentToken == address(0)), the caller must send the required Ether (msg.value >= mintPrice).

   • ERC20 Payments: If a payment token is set (paymentToken != address(0)), the caller must transfer the required ERC20 tokens to the contract (paymentToken.transferFrom()).

Free Mint

The isFreeMint() function checks whether minting is free. If the mint price is set to 0, minting is considered free.

Mint Configuration

The minting configuration is accessible via the getMintConfig() function, which returns:

• mintingEnabled: Whether minting is currently enabled.

• mintPrice: The price of minting in either Ether or ERC20 tokens.

• paymentTokenAddress: The address of the ERC20 token used for minting, or 0x0 for Ether.

• isFreeMint: Whether minting is free.

• paymentTokenSymbol: The symbol of the payment token used for minting (e.g., "ETH", "DAI").

Token Transfers

The contract supports withdrawing Ether and ERC20 tokens. The owner can:

1. Withdraw Ether: Using the withdraw() function, the contract owner can transfer any Ether held in the contract to their own address.

2. Withdraw ERC20 Tokens: Using the withdrawToken(IERC20 _token) function, the contract owner can transfer ERC20 tokens held in the contract to their own address.

3. Receive ERC20 Tokens: The owner can receive ERC20 tokens by calling the receiveToken(IERC20 _token, uint256 _amount) function.

Burn Mechanism

When an NFT is burned using the burn(uint256 tokenId) function:

• The NFT is permanently removed.

• The content ID associated with the burned NFT is reset, allowing it to be minted again in the future.

• The token is marked as burned in the _burnedTokens mapping to ensure that its URI can no longer be accessed.

Data Structure

• Token IDs: The token IDs are auto-incremented starting from 0 and are unique to each NFT minted.

• Content IDs: Each token is associated with a content ID, which must be unique across minted tokens.

• Minted Content IDs: A mapping _mintedContentIds is used to track whether a content ID has been minted or not.

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Important Notes:

• This contract uses ERC721URIStorage, which allows storing token metadata on-chain.

• The contract is equipped with ERC721Burnable to allow burning of tokens, and Ownable to manage ownership and security.

• Minting can be configured to either use Ether or an ERC20 token for payments.

• The contract supports fallback and receive functions to handle incoming Ether and tokens, but Ether cannot be used for minting when an ERC20 payment token is set.