<?php

declare(strict_types=1);

/**
 * SPDX-FileCopyrightText: 2024 Nextcloud GmbH and Nextcloud contributors
 * SPDX-License-Identifier: AGPL-3.0-or-later
 */
namespace OCA\DAV\CalDAV\WebcalCaching;

use Exception;
use GuzzleHttp\RequestOptions;
use OCP\Http\Client\IClientService;
use OCP\Http\Client\LocalServerException;
use OCP\IAppConfig;
use Psr\Log\LoggerInterface;

class Connection {
	public function __construct(
		private IClientService $clientService,
		private IAppConfig $config,
		private LoggerInterface $logger,
	) {
	}

	/**
	 * gets webcal feed from remote server
	 *
	 * @return array{data: resource, format: string}|null
	 */
	public function queryWebcalFeed(array $subscription): ?array {
		$subscriptionId = $subscription['id'];
		$url = $this->cleanURL($subscription['source']);
		if ($url === null) {
			return null;
		}

		// ICS feeds hosted on O365 can return HTTP 500 when the UA string isn't satisfactory
		// Ref https://github.com/nextcloud/calendar/issues/7234
		$uaString = 'Nextcloud Webcal Service';
		if (parse_url($url, PHP_URL_HOST) === 'outlook.office365.com') {
			// The required format/values here are not documented.
			// Instead, this string based on research.
			// Ref https://github.com/bitfireAT/icsx5/discussions/654#discussioncomment-14158051
			$uaString = 'Nextcloud (Linux) Chrome/66';
		}

		$allowLocalAccess = $this->config->getValueString('dav', 'webcalAllowLocalAccess', 'no');

		$params = [
			'nextcloud' => [
				'allow_local_address' => $allowLocalAccess === 'yes',
			],
			RequestOptions::HEADERS => [
				'User-Agent' => $uaString,
				'Accept' => 'text/calendar, application/calendar+json, application/calendar+xml',
			],
			'stream' => true,
		];

		$user = parse_url($subscription['source'], PHP_URL_USER);
		$pass = parse_url($subscription['source'], PHP_URL_PASS);
		if ($user !== null && $pass !== null) {
			$params[RequestOptions::AUTH] = [$user, $pass];
		}

		try {
			$client = $this->clientService->newClient();
			$response = $client->get($url, $params);
		} catch (LocalServerException $ex) {
			$this->logger->warning("Subscription $subscriptionId was not refreshed because it violates local access rules", [
				'exception' => $ex,
			]);
			return null;
		} catch (Exception $ex) {
			$this->logger->warning("Subscription $subscriptionId could not be refreshed due to a network error", [
				'exception' => $ex,
			]);
			return null;
		}

		$contentType = $response->getHeader('Content-Type');
		$contentType = explode(';', $contentType, 2)[0];

		$format = match ($contentType) {
			'application/calendar+json' => 'jcal',
			'application/calendar+xml' => 'xcal',
			default => 'ical',
		};

		// With 'stream' => true, getBody() returns the underlying stream resource
		$stream = $response->getBody();
		if (!is_resource($stream)) {
			return null;
		}

		return ['data' => $stream, 'format' => $format];
	}

	/**
	 * This method will strip authentication information and replace the
	 * 'webcal' or 'webcals' protocol scheme
	 *
	 * @param string $url
	 * @return string|null
	 */
	private function cleanURL(string $url): ?string {
		$parsed = parse_url($url);
		if ($parsed === false) {
			return null;
		}

		if (isset($parsed['scheme']) && $parsed['scheme'] === 'http') {
			$scheme = 'http';
		} else {
			$scheme = 'https';
		}

		$host = $parsed['host'] ?? '';
		$port = isset($parsed['port']) ? ':' . $parsed['port'] : '';
		$path = $parsed['path'] ?? '';
		$query = isset($parsed['query']) ? '?' . $parsed['query'] : '';
		$fragment = isset($parsed['fragment']) ? '#' . $parsed['fragment'] : '';

		$cleanURL = "$scheme://$host$port$path$query$fragment";
		// parse_url is giving some weird results if no url and no :// is given,
		// so let's test the url again
		$parsedClean = parse_url($cleanURL);
		if ($parsedClean === false || !isset($parsedClean['host'])) {
			return null;
		}

		return $cleanURL;
	}
}