Ownership #32
Description
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;
// Import OpenZeppelin libraries
import "@openzeppelin/contracts/access/AccessControl.sol";
import "@openzeppelin/contracts/token/ERC721/ERC721.sol";
import "@openzeppelin/contracts/token/ERC721/extensions/ERC721URIStorage.sol";
contract OwnershipNFT is ERC721URIStorage, AccessControl {
// Define roles
bytes32 public constant ADMIN_ROLE = keccak256("ADMIN_ROLE");
// Token ID tracker
uint256 private _tokenIdCounter;
// Constructor: Initializes the contract, sets up roles, and deploys the NFT with a name and symbol
constructor() ERC721("OwnershipNFT", "ONFT") {
// Grant deployer the default admin role and admin role
_setupRole(DEFAULT_ADMIN_ROLE, msg.sender); // DEFAULT_ADMIN_ROLE is required for role management
_setupRole(ADMIN_ROLE, msg.sender); // Assign ADMIN_ROLE to deployer
}
// Modifier to restrict minting only to admins
modifier onlyAdmin() {
require(hasRole(ADMIN_ROLE, msg.sender), "Permission denied: Not an admin");
_;
}
// Function to mint a new NFT
function mintNFT(address to, string memory uri) public onlyAdmin {
_tokenIdCounter++;
uint256 tokenId = _tokenIdCounter;
_mint(to, tokenId); // Mint the token to the recipient's address
_setTokenURI(tokenId, uri); // Set metadata URI for the token
}
// Function to transfer admin role (ownership) to a new address
function transferAdminRole(address newAdmin) public {
require(hasRole(ADMIN_ROLE, msg.sender), "Permission denied: Not an admin");
require(newAdmin != address(0), "New admin cannot be the zero address");
// Revoke admin role from current admin
_revokeRole(ADMIN_ROLE, msg.sender);
// Grant admin role to the new admin
_grantRole(ADMIN_ROLE, newAdmin);
}
// Function to revoke admin privileges from an address (only by DEFAULT_ADMIN_ROLE)
function revokeAdminRole(address account) public {
require(hasRole(DEFAULT_ADMIN_ROLE, msg.sender), "Permission denied: Not a default admin");
require(account != address(0), "Cannot revoke from zero address");
_revokeRole(ADMIN_ROLE, account);
}
// Function to renounce admin privileges (self-action)
function renounceAdminRole() public {
require(hasRole(ADMIN_ROLE, msg.sender), "You are not an admin");
_revokeRole(ADMIN_ROLE, msg.sender);
}
// Internal function to set base URI (for metadata)
function _baseURI() internal pure override returns (string memory) {
return "https://example.com/metadata/";
}
}