contract-16cdfb3744.sol

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.9;

import "@openzeppelin/contracts-upgradeable@4.8.0/token/ERC721/ERC721Upgradeable.sol";
import "@openzeppelin/contracts-upgradeable@4.8.0/security/PausableUpgradeable.sol";
import "@openzeppelin/contracts-upgradeable@4.8.0/access/AccessControlUpgradeable.sol";
import "@openzeppelin/contracts-upgradeable@4.8.0/token/ERC721/extensions/ERC721BurnableUpgradeable.sol";
import "@openzeppelin/contracts-upgradeable@4.8.0/proxy/utils/Initializable.sol";
import "@openzeppelin/contracts-upgradeable@4.8.0/proxy/utils/UUPSUpgradeable.sol";
import "@openzeppelin/contracts-upgradeable@4.8.0/utils/CountersUpgradeable.sol";

contract CySBT is Initializable, ERC721Upgradeable, PausableUpgradeable, AccessControlUpgradeable, ERC721BurnableUpgradeable, UUPSUpgradeable {
    using CountersUpgradeable for CountersUpgradeable.Counter;

    bytes32 public constant PAUSER_ROLE = keccak256("PAUSER_ROLE");
    bytes32 public constant MINTER_ROLE = keccak256("MINTER_ROLE");
    CountersUpgradeable.Counter private _tokenIdCounter;
    bytes32 public constant UPGRADER_ROLE = keccak256("UPGRADER_ROLE");

    /// @custom:oz-upgrades-unsafe-allow constructor
    constructor() {
        _disableInitializers();
    }

    function initialize() initializer public {
        __ERC721_init("CySBT", "CSBT");
        __Pausable_init();
        __AccessControl_init();
        __ERC721Burnable_init();
        __UUPSUpgradeable_init();

        _grantRole(DEFAULT_ADMIN_ROLE, msg.sender);
        _grantRole(PAUSER_ROLE, msg.sender);
        _grantRole(MINTER_ROLE, msg.sender);
        _grantRole(UPGRADER_ROLE, msg.sender);
    }

    function pause() public onlyRole(PAUSER_ROLE) {
        _pause();
    }

    function unpause() public onlyRole(PAUSER_ROLE) {
        _unpause();
    }

    function safeMint(address to) public onlyRole(MINTER_ROLE) {
        uint256 tokenId = _tokenIdCounter.current();
        _tokenIdCounter.increment();
        _safeMint(to, tokenId);
    }

    function _beforeTokenTransfer(address from, address to, uint256 tokenId, uint256 batchSize)
        internal
        whenNotPaused
        //require(from == address(0), "Err: token is SOUL BOUND");
        override
    {
        super._beforeTokenTransfer(from, to, tokenId, batchSize);
    }

    function _authorizeUpgrade(address newImplementation)
        internal
        onlyRole(UPGRADER_ROLE)
        override
    {}
    //This function burns/revokes a token/certificate with tokenId
    //TODO: We need to either override burn or not expose it as burn can be executed by the owner or approved address. Student is the owner in our case
    //Revoke works fine on the other hand as it can only be executed by the admin
    function revoke(uint256 tokenId) public onlyRole(DEFAULT_ADMIN_ROLE) {
        //require(_isApprovedOrOwner(msg.sender, tokenId));
        _burn(tokenId);          
    }

    // The following functions are overrides required by Solidity.

    function supportsInterface(bytes4 interfaceId)
        public
        view
        override(ERC721Upgradeable, AccessControlUpgradeable)
        returns (bool)
    {
        return super.supportsInterface(interfaceId);
    }
}