contract BeaconProxy is Proxy {
    /**
     * @dev The storage slot of the UpgradeableBeacon contract which defines the implementation for this proxy.
     * This is bytes32(uint256(keccak256('eip1967.proxy.beacon')) - 1)) and is validated in the constructor.
     */
    bytes32 private constant _BEACON_SLOT =
        0xa3f0ad74e5423aebfd80d3ef4346578335a9a72aeaee59ff6cb3582b35133d50;

    /**
     * @dev Initializes the proxy with `beacon`.
     *
     * If `data` is nonempty, it's used as data in a delegate call to the implementation returned by the beacon. This
     * will typically be an encoded function call, and allows initializating the storage of the proxy like a Solidity
     * constructor.
     *
     * Requirements:
     *
     * - `beacon` must be a contract with the interface {IBeacon}.
     */
    constructor(address beacon, bytes memory data) public payable {
        assert(
            _BEACON_SLOT ==
                bytes32(uint256(keccak256("eip1967.proxy.beacon")) - 1)
        );
        _setBeacon(beacon, data);
    }

    /**
     * @dev Returns the current beacon address.
     */
    function _beacon() internal view virtual returns (address beacon) {
        bytes32 slot = _BEACON_SLOT;
        // solhint-disable-next-line no-inline-assembly
        assembly {
            beacon := sload(slot)
        }
    }

    /**
     * @dev Returns the current implementation address of the associated beacon.
     */
    function _implementation()
        internal
        view
        virtual
        override
        returns (address)
    {
        return IBeacon(_beacon()).implementation();
    }

    /**
     * @dev Changes the proxy to use a new beacon.
     *
     * If `data` is nonempty, it's used as data in a delegate call to the implementation returned by the beacon.
     *
     * Requirements:
     *
     * - `beacon` must be a contract.
     * - The implementation returned by `beacon` must be a contract.
     */
    function _setBeacon(address beacon, bytes memory data) internal virtual {
        require(
            Address.isContract(beacon),
            "BeaconProxy: beacon is not a contract"
        );
        require(
            Address.isContract(IBeacon(beacon).implementation()),
            "BeaconProxy: beacon implementation is not a contract"
        );
        bytes32 slot = _BEACON_SLOT;

        // solhint-disable-next-line no-inline-assembly
        assembly {
            sstore(slot, beacon)
        }

        if (data.length > 0) {
            Address.functionDelegateCall(
                _implementation(),
                data,
                "BeaconProxy: function call failed"
            );
        }
    }
}
/**
 * @dev This contract implements a proxy that gets the implementation address for each call from a {UpgradeableBeacon}.
 *
 * The beacon address is stored in storage slot `uint256(keccak256('eip1967.proxy.beacon')) - 1`, so that it doesn't
 * conflict with the storage layout of the implementation behind the proxy.
 *
 * _Available since v3.4._
 */
function _implementation()
    internal
    view
    virtual
    override
    returns (address)
{
    return IBeacon(_beacon()).implementation();
}

/**
 * @dev Returns the current implementation address of the associated beacon.
 */