<?php
/**
 * Feed file manager.
 *
 * Handles writing feed files to the uploads directory, managing
 * file paths/URLs, and cleaning up stale feeds. Protects the feed
 * directory with .htaccess (Options -Indexes) and uses LOCK_EX
 * for atomic writes.
 *
 * @package AICommerce\Feed
 */

declare(strict_types=1);

namespace AICommerce\Feed;

/**
 * Manages feed file storage in wp-content/uploads/aicommerce/feeds/.
 */
class FeedFileManager {

	/**
	 * Base directory for feed files relative to uploads.
	 *
	 * @var string
	 */
	private const FEED_DIR = 'aicommerce/feeds';

	/**
	 * Get the WordPress uploads directory info.
	 *
	 * @return array WordPress upload directory data.
	 */
	public function get_upload_dir(): array {
		return wp_upload_dir();
	}

	/**
	 * Get the absolute path to the feed directory.
	 *
	 * @return string Absolute directory path (with trailing slash).
	 */
	public function get_feed_dir(): string {
		$upload_dir = $this->get_upload_dir();
		return trailingslashit( $upload_dir['basedir'] ) . self::FEED_DIR . '/';
	}

	/**
	 * Get the absolute path for a specific feed file.
	 *
	 * @param string $filename The feed filename.
	 *
	 * @return string Absolute file path.
	 */
	public function get_feed_path( string $filename ): string {
		return $this->get_feed_dir() . sanitize_file_name( $filename );
	}

	/**
	 * Get the public URL to the feed directory.
	 *
	 * @return string Public URL (with trailing slash).
	 */
	public function get_feed_url( string $filename = '' ): string {
		$upload_dir = $this->get_upload_dir();
		$base       = trailingslashit( $upload_dir['baseurl'] ) . self::FEED_DIR . '/';

		if ( '' !== $filename ) {
			return $base . sanitize_file_name( $filename );
		}

		return $base;
	}

	/**
	 * Ensure the feed directory exists and is protected.
	 *
	 * Creates .htaccess with Options -Indexes and index.php.
	 *
	 * @return bool True if directory is ready.
	 */
	public function ensure_directory(): bool {
		$dir = $this->get_feed_dir();

		if ( ! file_exists( $dir ) ) {
			wp_mkdir_p( $dir );
		}

		$filesystem = $this->filesystem();
		if ( null === $filesystem ) {
			return is_dir( $dir ) && wp_is_writable( $dir );
		}

		// Add index.php to prevent directory listing.
		$index_file = $dir . 'index.php';
		if ( ! file_exists( $index_file ) ) {
			$filesystem->put_contents( $index_file, "<?php\n// Silence is golden.\n", FS_CHMOD_FILE );
		}

		// Add .htaccess to disable directory listing on Apache.
		$htaccess_file = $dir . '.htaccess';
		if ( ! file_exists( $htaccess_file ) ) {
			$filesystem->put_contents( $htaccess_file, "Options -Indexes\n", FS_CHMOD_FILE );
		}

		return is_dir( $dir ) && wp_is_writable( $dir );
	}

	/**
	 * Initialize and return the WordPress filesystem abstraction.
	 *
	 * @return \WP_Filesystem_Base|null The filesystem, or null if unavailable.
	 */
	private function filesystem(): ?\WP_Filesystem_Base {
		global $wp_filesystem;

		if ( ! $wp_filesystem instanceof \WP_Filesystem_Base ) {
			require_once ABSPATH . 'wp-admin/includes/file.php';
			WP_Filesystem();
		}

		return $wp_filesystem instanceof \WP_Filesystem_Base ? $wp_filesystem : null;
	}

	/**
	 * Write feed content to a file with LOCK_EX.
	 *
	 * Uses atomic write: writes to a temp file first, then renames.
	 *
	 * @param string $filename The filename (e.g., 'google-feed.xml').
	 * @param string $content  The feed content.
	 *
	 * @return array{path: string, url: string, size: int}|false File info or false on failure.
	 */
	public function write_feed( string $filename, string $content ) {
		if ( ! $this->ensure_directory() ) {
			return false;
		}

		$filesystem = $this->filesystem();
		if ( null === $filesystem ) {
			return false;
		}

		$file_path = $this->get_feed_path( $filename );
		$temp_path = $file_path . '.tmp';

		// Atomic write: write to a temp file, then move it into place.
		if ( ! $filesystem->put_contents( $temp_path, $content, FS_CHMOD_FILE ) ) {
			return false;
		}

		if ( ! $filesystem->move( $temp_path, $file_path, true ) ) {
			$filesystem->delete( $temp_path );
			return false;
		}

		return array(
			'path' => $file_path,
			'url'  => $this->get_feed_url( $filename ),
			'size' => (int) $filesystem->size( $file_path ),
		);
	}

	/**
	 * Delete a feed file.
	 *
	 * @param string $filename The filename to delete.
	 *
	 * @return bool True if deleted or didn't exist.
	 */
	public function delete_feed( string $filename ): bool {
		$file_path = $this->get_feed_path( $filename );

		if ( file_exists( $file_path ) ) {
			return wp_delete_file( $file_path ) !== false;
		}

		return true;
	}

	/**
	 * Get the filename for a feed type.
	 *
	 * @param string $feed_type The feed type identifier.
	 * @param string $extension File extension (default: xml).
	 *
	 * @return string The filename.
	 */
	public function get_filename( string $feed_type, string $extension = 'xml' ): string {
		return sanitize_file_name( $feed_type . '-feed.' . $extension );
	}

	/**
	 * Get file hash for integrity checks.
	 *
	 * @param string $filename The filename.
	 *
	 * @return string|null SHA-256 hash or null if file doesn't exist.
	 */
	public function get_file_hash( string $filename ): ?string {
		$file_path = $this->get_feed_path( $filename );

		if ( ! file_exists( $file_path ) ) {
			return null;
		}

		return hash_file( 'sha256', $file_path );
	}

	/**
	 * List all feed files in the directory.
	 *
	 * @return array Array of file info arrays.
	 */
	public function list_feeds(): array {
		$dir = $this->get_feed_dir();
		if ( ! is_dir( $dir ) ) {
			return array();
		}

		$feeds = array();
		$files = glob( $dir . '*-feed.*' );

		if ( ! is_array( $files ) ) {
			return array();
		}

		foreach ( $files as $file ) {
			$filename = basename( $file );
			$feeds[]  = array(
				'filename' => $filename,
				'path'     => $file,
				'url'      => $this->get_feed_url( $filename ),
				'size'     => filesize( $file ),
				'modified' => gmdate( 'c', filemtime( $file ) ),
			);
		}

		return $feeds;
	}
}