PID

Overview

PID is the core NFT contract that represents Payment ID ownership as ERC-721 tokens. It handles token registration, transfers, and delegates ownership and resolver management to the PIDRegistry contract. This contract implements the tokenized representation of Payment IDs, allowing them to be transferred, approved, and managed like standard NFTs.

Key Concepts

Concept	Description
NFT Representation	Each Payment ID is represented as a unique ERC-721 token.
Registry Integration	Maintains synchronization with PIDRegistry when tokens are transferred or registered.
Controller Pattern	Only authorized controller contracts can register new Payment IDs.
Ownership Management	Extends OpenZeppelin's Ownable2Step for secure contract ownership management.

Data Structures

State Variables

Name	Type	Description
registry	IPIDRegistry	Reference to the PID Registry contract.
totalAmount	uint256	Counter for the total number of minted Payment IDs.
controller	address	Address of the authorized controller that can register new tokens.

Functions

Constructor

constructor(address _initialOwner) public

Input Parameter	Type	Description
_initialOwner	address	Address of the initial contract owner.

Initialization

init

function init(address _registry, address _controller) external onlyOwner

Input Parameter	Type	Description
_registry	address	Address of the PID Registry contract.
_controller	address	Address of the controller contract.

Reverts	Description
PID__AlreadyInitialized	Thrown when the contract has already been initialized.
PID__InvalidRegistry	Thrown when the registry address is zero.
PID__InvalidController	Thrown when the controller address is zero.

Token Registration

register

function register(uint256 id, address owner, address resolver) external onlyController returns (uint256)

Input Parameter	Type	Description
id	uint256	The token ID to register.
owner	address	The address that will own the token.
resolver	address	The resolver address for the token.

Returns	Description
uint256	The registered token ID.

Reverts	Description
PID__NameAlreadyTaken	Thrown when the token ID is already registered.
PID__OnlyController	Thrown when caller is not the controller.

Token Transfers

transferFrom

function transferFrom(address from, address to, uint256 tokenId) public override(ERC721, IERC721)

Input Parameter	Type	Description
from	address	Current owner of the token.
to	address	Address to receive the token.
tokenId	uint256	ID of the token to transfer.

Reverts	Description
PID__NotApprovedOrOwner	Thrown when caller is not token owner or approved.

safeTransferFrom

function safeTransferFrom(address from, address to, uint256 tokenId, bytes memory _data) public override(ERC721, IERC721)

Input Parameter	Type	Description
from	address	Current owner of the token.
to	address	Address to receive the token.
tokenId	uint256	ID of the token to transfer.
_data	bytes	Additional data with no specified format.

Reverts	Description
PID__NotApprovedOrOwner	Thrown when caller is not token owner or approved.

Availability Check

available

function available(uint256 id) public view returns (bool)

Input Parameter	Type	Description
id	uint256	Token ID to check availability for.

Returns	Description
bool	true if the token ID is available, false otherwise.

Internal Functions

_isApprovedOrOwner

function _isApprovedOrOwner(address spender, uint256 tokenId) internal view returns (bool)

Input Parameter	Type	Description
spender	address	Address to check for approval.
tokenId	uint256	Token ID to check.

Returns	Description
bool	true if spender is owner or approved, false otherwise.

_safeMint

function _safeMint(address _to, uint256 _tokenId, bytes memory _data) internal virtual override(ERC721)

Input Parameter	Type	Description
_to	address	Address receiving the token.
_tokenId	uint256	ID of token to mint.
_data	bytes	Additional data with no specified format.

Events

Event	Parameters	Description
RegistryUpdated	(address oldRegistry, address newRegistry)	Emitted when the registry address is updated.
ControllerUpdated	(address oldController, address newController)	Emitted when the controller address is updated.
NameRegistered	(uint256 id, address owner, address resolver)	Emitted when a new Payment ID is registered.

Errors

Error	Description
PID__AlreadyInitialized	Thrown when attempting to initialize an already initialized contract.
PID__InvalidRegistry	Thrown when providing a zero address for the registry.
PID__InvalidController	Thrown when providing a zero address for the controller.
PID__OnlyController	Thrown when a non-controller address calls a controller-only function.
PID__NameAlreadyTaken	Thrown when attempting to register an ID that is already taken.
PID__NotApprovedOrOwner	Thrown when an unauthorized address attempts to transfer a token.