1 files changed, 124 insertions, 0 deletions
diff --git a/lib/private/Http/Client/GuzzlePromiseAdapter.php b/lib/private/Http/Client/GuzzlePromiseAdapter.php
new file mode 100644
index 00000000000..03a9ed9a599
--- /dev/null
+++ b/lib/private/Http/Client/GuzzlePromiseAdapter.php
@@ -0,0 +1,124 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2023 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OC\Http\Client;
+
+use Exception;
+use GuzzleHttp\Exception\RequestException;
+use GuzzleHttp\Promise\PromiseInterface;
+use LogicException;
+use OCP\Http\Client\IPromise;
+use OCP\Http\Client\IResponse;
+use Psr\Http\Message\ResponseInterface;
+use Psr\Log\LoggerInterface;
+
+/**
+ * A wrapper around Guzzle's PromiseInterface
+ *
+ * @see \GuzzleHttp\Promise\PromiseInterface
+ * @since 28.0.0
+ */
+class GuzzlePromiseAdapter implements IPromise {
+	public function __construct(
+		protected PromiseInterface $promise,
+		protected LoggerInterface $logger,
+	) {
+	}
+
+	/**
+	 * Appends fulfillment and rejection handlers to the promise, and returns
+	 * a new promise resolving to the return value of the called handler.
+	 *
+	 * @param ?callable(IResponse): void $onFulfilled Invoked when the promise fulfills. Gets an \OCP\Http\Client\IResponse passed in as argument
+	 * @param ?callable(Exception): void $onRejected Invoked when the promise is rejected. Gets an \Exception passed in as argument
+	 *
+	 * @return IPromise
+	 * @since 28.0.0
+	 */
+	public function then(
+		?callable $onFulfilled = null,
+		?callable $onRejected = null,
+	): IPromise {
+		if ($onFulfilled !== null) {
+			$wrappedOnFulfilled = static function (ResponseInterface $response) use ($onFulfilled) {
+				$onFulfilled(new Response($response));
+			};
+		} else {
+			$wrappedOnFulfilled = null;
+		}
+
+		if ($onRejected !== null) {
+			$wrappedOnRejected = static function (RequestException $e) use ($onRejected) {
+				$onRejected($e);
+			};
+		} else {
+			$wrappedOnRejected = null;
+		}
+
+		$this->promise->then($wrappedOnFulfilled, $wrappedOnRejected);
+		return $this;
+	}
+
+	/**
+	 * Get the state of the promise ("pending", "rejected", or "fulfilled").
+	 *
+	 * The three states can be checked against the constants defined:
+	 * STATE_PENDING, STATE_FULFILLED, and STATE_REJECTED.
+	 *
+	 * @return IPromise::STATE_*
+	 * @since 28.0.0
+	 */
+	public function getState(): string {
+		$state = $this->promise->getState();
+		if ($state === PromiseInterface::FULFILLED) {
+			return self::STATE_FULFILLED;
+		}
+		if ($state === PromiseInterface::REJECTED) {
+			return self::STATE_REJECTED;
+		}
+		if ($state === PromiseInterface::PENDING) {
+			return self::STATE_PENDING;
+		}
+
+		$this->logger->error('Unexpected promise state "{state}" returned by Guzzle', [
+			'state' => $state,
+		]);
+		return self::STATE_PENDING;
+	}
+
+	/**
+	 * Cancels the promise if possible.
+	 *
+	 * @link https://github.com/promises-aplus/cancellation-spec/issues/7
+	 * @since 28.0.0
+	 */
+	public function cancel(): void {
+		$this->promise->cancel();
+	}
+
+	/**
+	 * Waits until the promise completes if possible.
+	 *
+	 * Pass $unwrap as true to unwrap the result of the promise, either
+	 * returning the resolved value or throwing the rejected exception.
+	 *
+	 * If the promise cannot be waited on, then the promise will be rejected.
+	 *
+	 * @param bool $unwrap
+	 *
+	 * @return mixed
+	 *
+	 * @throws LogicException if the promise has no wait function or if the
+	 *                        promise does not settle after waiting.
+	 * @since 28.0.0
+	 */
+	public function wait(bool $unwrap = true): mixed {
+		return $this->promise->wait($unwrap);
+	}
+}