Enso NFT Smart Contract

This repository contains the Solidity smart contract of Enso, a detailed list of features and deployment instructions.

We strongly believe in giving back to the community and the NFT space as a whole. Advancements in smart contracts can only be made through open collaboration.

When we started our journey with Enso, there was no single comprehensive resource for building all the features that have made it into this smart contract. We hope that this repository can serve as a building block and guideline for future projects.

Enso

Don´t close the circle.

Features

This smart contract is based on the ERC721 token standard and it includes the ERC721Enumerable, ERC721Royalty and ERC721Burnable extensions. The contract governance is implemented via the Ownable policy.
For more information about these standards visit the Openzeppelin documentation.

Additionally, we have implemented the following features:

• Withdrawal
  The contract owner can withdraw the mint revenue to any address.
• Whitelist
  The whitelist is customizable with a discounted price, separate launch and an arbitrary amount of spots per address.
• Free Mint List
  Similar to the whitelist, one can assign an arbitrary amount of free mint spots to certain addresses. The free mint launch is aligned with the whitelist launch.
• Batch Functions
  A variety of batch functions are included for the mint types and for other purposes like setting the whitelist.
• Token Enumeration
  The ERC721Enumerable extension provides methods to build further enumeration utilities like listing all token Ids and tokens held by any address. The implementation is inspired by BCG's contract.
• Lowering of Maximum Collectible Supply
  One can lower the maximum collectible supply, but not increase it.
• Adjustment of Whitelist and Public Mint Price
  As long as the mint has not concluded, the whitelist price and the public price may be adjusted.
• Metadata Change & Lock
  One can change various metadata items in the contract after launch. These include the name, symbol, baseURI and contractURI. This functionality may be irreversibly locked. Please read the disclaimer below on usage and risk.

All of these features are extensively tested in the included test suite with around 1300 lines of code.

Disclaimer: Note that some of the features are very powerful in what they grant to the contract owner. Notably, the ability to change the metadata has proven to be a big risk factor in other projects and to their community members. The use of each and every functionality must be openly communicated.

For example, the metadata can be changed, but one should only do so before any minting is made publicly available. To secure the metadata from further tampering during and after the mint, there is a metadata lock which irrevocably locks it to its state. The engagement of the metadata lock can be proven via the blockchain transactions.

Getting Started

Make sure to install and use node version 16.14.2.

Install the Dependencies

npm i

Run the Test Suite

npx hardhat test

Deploy the Smart Contract

Create a .env file in the root of the repository with the following structure.

SCAN_API_KEY="<SCAN_API_KEY>"         # Fantomscan / Etherscan or similar api key
PRIVATE_KEY="<PRIVATE_KEY>"           # Private key of contract owner

Fill in the blanks and be careful not to leak them. The .env file is present in .gitignore. If you are uncomfortable in having these values in the repository you may also provide them via environment variables.

Check the hardhat.config.ts file that your desired networks are defined. For Enso these are Fantom related.

Next, adjust the deployment script variables in scripts/test-deploy.ts to your liking. The contract variables provided are designed for test networks, but can easily be adjusted for production networks. Ideally, one would create a separate script called scripts/prod-deploy.ts.

Finally, the deployment can be made via:

npx hardhat run --network "<YOUR_DESIRED_NETWORK>" "scripts/<YOUR_DESIRED_SCRIPT>"

Verify the Smart Contract

After deploying the smart contract it is important to verify it. This discloses and links the source code of the deployed smart contract. The verification guarantees to any third party that nothing malicious is going on.

For this, we provide a script scripts/test-verify.ts which is pre-filled with the constructor variables of scripts/test-deploy.ts. Adjust as necessary and provide the deployed contract address.

Further Improvements

The smart contract itself could be further improved by separating the functions into individual abstract contracts. Initial steps have been made by providing internally callable functions as private variable wrappers.

The provided testing suite is not fully orthogonal, that is some tests overlap in their testing responsibility. Such tests should be further modularized.

License

This repository is licensed under the MIT License and a copy is included.