<?php
declare(strict_types=1);

/**
 * Provide useful methods to generate files to export.
 */
class FreshRSS_Export_Service {

	private readonly FreshRSS_CategoryDAO $category_dao;

	private readonly FreshRSS_FeedDAO $feed_dao;

	private readonly FreshRSS_EntryDAO $entry_dao;

	private readonly FreshRSS_TagDAO $tag_dao;

	final public const FRSS_NAMESPACE = 'https://freshrss.org/opml';
	final public const TYPE_HTML_XPATH = 'HTML+XPath';
	final public const TYPE_XML_XPATH = 'XML+XPath';
	final public const TYPE_RSS_ATOM = 'rss';
	final public const TYPE_JSON_DOTPATH = 'JSON+DotPath';	// Legacy 1.24.0-dev
	final public const TYPE_JSON_DOTNOTATION = 'JSON+DotNotation';
	final public const TYPE_JSONFEED = 'JSONFeed';
	final public const TYPE_HTML_XPATH_JSON_DOTNOTATION = 'HTML+XPath+JSON+DotNotation';

	final public const PRIORITY_IMPORTANT = 'important';
	final public const PRIORITY_MAIN_STREAM = 'main';
	final public const PRIORITY_CATEGORY = 'category';
	final public const PRIORITY_FEED = 'feed';
	final public const PRIORITY_HIDDEN = 'hidden';

	/**
	 * Initialize the service for the given user.
	 */
	public function __construct(private readonly string $username) {
		$this->category_dao = FreshRSS_Factory::createCategoryDao($this->username);
		$this->feed_dao = FreshRSS_Factory::createFeedDao($this->username);
		$this->entry_dao = FreshRSS_Factory::createEntryDao($this->username);
		$this->tag_dao = FreshRSS_Factory::createTagDao();
	}

	/**
	 * Generate OPML file.
	 * @return array{0:string,1:string} First item is the filename, second item is the path of a temporary file with the content
	 * @throws Minz_PermissionDeniedException
	 */
	public function generateOpml(): array {
		$view = new FreshRSS_View();
		$day = date('Y-m-d');
		$view->categories = $this->category_dao->listSortedCategories(prePopulateFeeds: true, details: true);
		$view->excludeMutedFeeds = false;
		$view->includeSensitiveCurlParams = true;

		return [
			"feeds_{$day}.opml.xml",
			self::helperToTempFile($view, 'export/opml'),
		];
	}

	/**
	 * Generate the starred and labelled entries file.
	 *
	 * Both starred and labelled entries are put into a "starred" file, that’s
	 * why there is only one method for both.
	 *
	 * @phpstan-param 'S'|'T'|'ST' $type
	 * @param string $type must be one of:
	 *     'S' (starred/favourite),
	 *     'T' (taggued/labelled),
	 *     'ST' (starred or labelled)
	 * @return array{0:string,1:string} First item is the filename, second item is the path of a temporary file with the content
	 * @throws Minz_PermissionDeniedException
	 */
	public function generateStarredEntries(string $type): array {
		$view = new FreshRSS_View();
		$view->categories = $this->category_dao->listCategories(prePopulateFeeds: true);
		$day = date('Y-m-d');

		$view->list_title = _t('sub.import_export.starred_list');
		$view->type = 'starred';
		$entriesId = $this->entry_dao->listIdsWhere($type, 0, FreshRSS_Entry::STATE_ALL, order: 'ASC', limit: -1) ?? [];
		$view->entryIdsTagNames = $this->tag_dao->getEntryIdsTagNames($entriesId);
		// The following is a streamable query, i.e. must be last
		$view->entries = $this->entry_dao->listWhere(
			$type, 0, FreshRSS_Entry::STATE_ALL, order: 'ASC', limit: -1
		);

		return [
			"starred_{$day}.json",
			self::helperToTempFile($view, 'export/articles'),
		];
	}

	/**
	 * Generate the entries file for the given feed.
	 * @return array{0:string,1:string}|null First item is the filename, second item is the path of a temporary file with the content.
	 *                    It also can return null if the feed doesn’t exist.
	 * @throws Minz_PermissionDeniedException
	 */
	public function generateFeedEntries(int $feed_id, int $max_number_entries): ?array {
		$view = new FreshRSS_View();
		$view->categories = $this->category_dao->listCategories(prePopulateFeeds: true);

		$feed = FreshRSS_Category::findFeed($view->categories, $feed_id);
		if ($feed === null) {
			return null;
		}
		$view->feed = $feed;

		$day = date('Y-m-d');
		$filename = "feed_{$day}_" . $feed->categoryId() . '_' . $feed->id() . '.json';

		$view->list_title = _t('sub.import_export.feed_list', $feed->name());
		$view->type = 'feed/' . $feed->id();
		$entriesId = $this->entry_dao->listIdsWhere(
			'f', $feed->id(), FreshRSS_Entry::STATE_ALL, order: 'ASC', limit: $max_number_entries
		) ?? [];
		$view->entryIdsTagNames = $this->tag_dao->getEntryIdsTagNames($entriesId);
		// The following is a streamable query, i.e. must be last
		$view->entries = $this->entry_dao->listWhere(
			'f', $feed->id(), FreshRSS_Entry::STATE_ALL, order: 'ASC', limit: $max_number_entries
		);

		return [
			$filename,
			self::helperToTempFile($view, 'export/articles'),
		];
	}

	/**
	 * Generate the entries files for all the feeds.
	 * @return array<string,string> Keys are filenames and values are paths of temporary files with the contents.
	 * @throws Minz_PermissionDeniedException
	 */
	public function generateAllFeedEntries(int $max_number_entries): array {
		$feed_ids = $this->feed_dao->listFeedsIds();

		$exported_files = [];
		foreach ($feed_ids as $feed_id) {
			$result = $this->generateFeedEntries($feed_id, $max_number_entries);
			if ($result === null) {
				continue;
			}

			[$filename, $path] = $result;
			$exported_files[$filename] = $path;
		}

		return $exported_files;
	}

	/**
	 * Compress several files in a Zip file.
	 * @param array<string,string> $files where the key is the filename, the value is the path of the file
	 * @return array{0:string,1:string|false} First item is the zip filename, second item is the path of a temporary zip file, or false in case of error
	 * @throws Minz_PermissionDeniedException
	 */
	public function zip(array $files): array {
		$day = date('Y-m-d');
		$zip_filename = 'freshrss_' . $this->username . '_' . $day . '_export.zip';

		$zip_file = self::tempFile();
		$zip_archive = new ZipArchive();
		$zip_archive->open($zip_file, ZipArchive::OVERWRITE);

		foreach ($files as $filename => $path) {
			$zip_archive->addFile($path, $filename);
		}

		return [
			$zip_filename,
			$zip_archive->close() ? $zip_file : false,
		];
	}

	/**
	 * Create a temporary file, which is deleted at the end of the script.
	 * @throws Minz_PermissionDeniedException
	 */
	private static function tempFile(): string {
		$filename = tempnam(TMP_PATH, 'export');
		if ($filename === false) {
			throw new Minz_PermissionDeniedException(TMP_PATH);
		}
		register_shutdown_function(static fn() => @unlink($filename));
		return $filename;
	}

	/**
	 * Render a view helper into a temporary file, instead of keeping the whole content in memory.
	 * @return string The path of the temporary file
	 * @throws Minz_PermissionDeniedException
	 */
	private static function helperToTempFile(FreshRSS_View $view, string $helper): string {
		$filename = self::tempFile();
		$view->helperToFile($helper, $filename);
		return $filename;
	}
}