NFT Roles description

NFT Roles.sol

// SPDX-License-Identifier: MIT
// by dennison@tally.xyz
pragma solidity ^0.8.0;

import "@openzeppelin/contracts/access/AccessControl.sol";
import "@openzeppelin/contracts/token/ERC1155/ERC1155.sol";

contract Roles is ERC1155, AccessControl {
    // errors
    error NoDuplicateRoles();
    error TokenTransferProhibited();

    // role storage
    bytes32 public constant URI_SETTER_ROLE = keccak256("URI_SETTER_ROLE");
    mapping(bytes32 => uint256) public nftRoles;

    constructor() ERC1155("") {
        //add roles to mapping
        nftRoles[DEFAULT_ADMIN_ROLE] = 0;
        nftRoles[URI_SETTER_ROLE] = 1;

        //grant initial roles
        _grantRole(DEFAULT_ADMIN_ROLE, msg.sender);
        _grantRole(URI_SETTER_ROLE, msg.sender);
    }

    function setURI(string memory newuri) public onlyRole(URI_SETTER_ROLE) {
        _setURI(newuri);
    }

    function _grantRole(bytes32 role, address account) internal override {
        // check if users already has the role, if so don't mint or grant
        if (hasRole(role, account)) {
            revert NoDuplicateRoles();
        }

        // mint the role
        _mint(account, nftRoles[role], 1, "");

        // grant the role
        super._grantRole(role, account);
    }

    function _revokeRole(bytes32 role, address account) internal override {
        // burn the role
        _burn(account, nftRoles[role], 1);

        // revoke the role
        super._revokeRole(role, account);
    }

    function _beforeTokenTransfer(
        address operator,
        address from,
        address to,
        uint256[] memory ids,
        uint256[] memory amounts,
        bytes memory data
    ) internal override {

        // prevent roles from being transfered like NFTs
        if(from != address(0)){
            revert TokenTransferProhibited();
        }

        super._beforeTokenTransfer(operator, from, to, ids, amounts, data);
    }

    // The following functions are overrides required by Solidity.
    function supportsInterface(bytes4 interfaceId) public view override(ERC1155, AccessControl) returns (bool) {
        return super.supportsInterface(interfaceId);
    }
}