// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.5.0) (proxy/utils/UUPSUpgradeable.sol)

pragma solidity ^0.8.0;

import "@openzeppelin/contracts/interfaces/draft-IERC1822.sol";
import {DoubleLogicERC1967Upgrade} from "./AdminFallbackProxy.sol";

/**
 * @dev UUPSUpgradeable by OpenZeppelin but not upgradeable. This is expected to be used on the secondary
 * logic slot behind a DoubleLogicERC1967Upgrade proxy
 */
abstract contract UUPSNotUpgradeable is IERC1822Proxiable, DoubleLogicERC1967Upgrade {
    /// @custom:oz-upgrades-unsafe-allow state-variable-immutable state-variable-assignment
    address private immutable __self = address(this);

    /**
     * @dev Check that the execution is being performed through a delegatecall call and that the execution context is
     * a proxy contract with an implementation (as defined in ERC1967) pointing to self. This should only be the case
     * for UUPS and transparent proxies that are using the current contract as their implementation. Execution of a
     * function through ERC1167 minimal proxies (clones) would not normally pass this test, but is not guaranteed to
     * fail.
     */
    modifier onlyProxy() {
        require(address(this) != __self, "Function must be called through delegatecall");
        require(
            _getSecondaryImplementation() == __self,
            "Function must be called through active proxy"
        );
        _;
    }

    /**
     * @dev Check that the execution is not being performed through a delegate call. This allows a function to be
     * callable on the implementing contract but not through proxies.
     */
    modifier notDelegated() {
        require(
            address(this) == __self,
            "UUPSNotUpgradeable: must not be called through delegatecall"
        );
        _;
    }

    /**
     * @dev Implementation of the ERC1822 {proxiableUUID} function. This returns the storage slot used by the
     * implementation. It is used to validate that the this implementation remains valid after an upgrade.
     *
     * IMPORTANT: A proxy pointing at a proxiable contract should not be considered proxiable itself, because this risks
     * bricking a proxy that upgrades to it, by delegating to itself until out of gas. Thus it is critical that this
     * function revert if invoked through a proxy. This is guaranteed by the `notDelegated` modifier.
     */
    function proxiableUUID() external view virtual override notDelegated returns (bytes32) {
        return _IMPLEMENTATION_SECONDARY_SLOT;
    }
}