Token Types Using Skucode Contract

Token Types are managed on the platform using Ethereum-based Token Management Contract named Skucode.

Overview

This contract implements a customizable ERC20 token with additional functionalities for wrapping and unwrapping tokens, attachments, and wrap ratios. The contract is based on OpenZeppelin's ERC20 implementation and includes security features like ownership and reentrancy protection.

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Imports

1. ERC20

   import {ERC20} from "@openzeppelin/contracts/token/ERC20/ERC20.sol";

   Standard ERC20 implementation from OpenZeppelin.

2. Ownable

   import {Ownable} from "@openzeppelin/contracts/access/Ownable.sol";

   Provides a basic access control mechanism for ownership.

3. UD60x18

   import {UD60x18, ud} from "@prb/math/src/UD60x18.sol";

   Implements fixed-point arithmetic operations using the UD60x18 type.

4. ReentrancyGuard

   import {ReentrancyGuard} from "@openzeppelin/contracts/utils/ReentrancyGuard.sol";

   Prevents reentrant calls to certain functions.

5. IERC20Receiver (Interface)

   interface IERC20Receiver {
       function onReceiveERC20(address from, uint256 value) external returns (bytes4);
   }

   Interface for contracts that want to handle receiving ERC20 tokens.

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Events

1. AttachmentAdded

   event AttachmentAdded(string cid, address indexed submitter);

   Emitted when an attachment (identified by a cid) is added to the contract.

2. WrapRatioAdded

   event WrapRatioAdded(address childSkucodeAddress, uint256 ratio);

   Emitted when a wrap ratio is set for a child Skucode.

3. WrapRatioReceived

   event WrapRatioReceived(address skucodeAddress, uint256 ratio);

   Emitted when the contract receives a wrap ratio from another Skucode.

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Functions

1. Constructor

   constructor(
       address _initialOwner,
       string memory _tokenName,
       string memory _tokenSymbol,
       uint256 _initialSupply,
       SkucodeType _skucodeType
   )

   Initializes the Skucode contract with an initial owner, token name, symbol, initial supply, and type.

   Parameters:

   • _initialOwner: Address of the initial owner.
   • _tokenName: Name of the token.
   • _tokenSymbol: Symbol of the token.
   • _initialSupply: Initial token supply.
   • _skucodeType: Type of the Skucode (Mintable or Wrappable).

2. mint(address account, uint256 value) → external

   function mint(address account, uint256 value) external onlyOwner

   Mints new tokens to a specified account.

   Conditions:

   • Only the owner can call this function.
   • The contract must be of type Mintable.

3. wrap(uint256 value, address wrapperSkucode, address to) → external

   function wrap(uint256 value, address wrapperSkucode, address to) external nonReentrant

   Wraps the specified token amount into another Skucode.

   Conditions:

   • Requires a valid wrap ratio for the target Skucode.
   • Transfers tokens to the target Skucode and calls onReceiveWrappedTokens.

4. unwrap(uint256 value, address wrappedSkucode, address to) → external

   function unwrap(uint256 value, address wrappedSkucode, address to) external nonReentrant onlyOwner

   Unwraps tokens from another Skucode and returns them to the specified address.

   Conditions:

   • Only the owner can call this function.
   • Requires a valid wrap ratio from the target Skucode.

5. onReceiveWrappedTokens(uint256 value, address to) → external

   function onReceiveWrappedTokens(uint256 value, address to) external nonReentrant

   Handles the receipt of wrapped tokens from another Skucode.

   Conditions:

   • Verifies the sender's contract bytecode.

6. setWrapRatio(address childSkucodeAddress, uint256 ratio) → external

   function setWrapRatio(address childSkucodeAddress, uint256 ratio) external nonReentrant

   Sets the wrap ratio for a child Skucode.

   Conditions:

   • The sender must own the target Skucode.
   • Verifies the target's contract bytecode.

7. getWrapRatio(address skucodeAddress) → external view returns (uint256)

   function getWrapRatio(address skucodeAddress) external view returns (uint256)

   Returns the wrap ratio for a specific Skucode.

8. onReceiveWrapRatio(uint256 ratio) → external

   function onReceiveWrapRatio(uint256 ratio) external

   Handles receiving a wrap ratio from a parent Skucode.

   Conditions:

   • Verifies the sender's contract bytecode.

9. transfer(address to, uint256 value) → public virtual override nonReentrant returns (bool)

   function transfer(address to, uint256 value) public virtual override nonReentrant returns (bool)

   Transfers tokens to another address. If the recipient is a contract, it performs a validation check.

   Overrides: ERC20's transfer.

10. transferFrom(address from, address to, uint256 value) → public virtual override nonReentrant returns (bool)

    function transferFrom(address from, address to, uint256 value) public virtual override nonReentrant returns (bool)

    Transfers tokens on behalf of another address. If the recipient is a contract, it performs a validation check.

    Overrides: ERC20's transferFrom.

11. addAttachment(string calldata cid) → external onlyOwner

    function addAttachment(string calldata cid) external onlyOwner

    Adds an attachment identified by cid.

    Conditions:

    • Only the owner can add attachments.
    • Emits the AttachmentAdded event.

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Custom Errors

1. MintingNotAllowed - Raised if minting is attempted on a non-mintable Skucode.
2. UnauthorizedSkucodeOwner - Raised if a wrap ratio is set by a non-owner.
3. InvalidTwinContract(address target) - Raised if the target contract bytecode does not match.
4. WrapRatioNotRegistered(address target) - Raised if a wrap ratio is not registered.
5. InsufficientBalanceForWrap(uint256 available, uint256 required) - Raised if the user lacks sufficient tokens.
6. ERC20ReceiverError(address to, bytes error) - Raised if the receiver contract rejects tokens.
7. ERC20TransferError(address to, uint256 value) - Raised if a transfer operation fails.
8. AttachmentAlreadyAdded(string cid) - Raised if an attachment already exists.