<?php
/**
 * File writer: stores and retrieves llms.txt content using WP_Filesystem.
 *
 * Files are written to two locations:
 *  1. wp-content/uploads/llmstxt/  — primary storage (WP-Filesystem compliant)
 *  2. WordPress site root (ABSPATH) — physical file so AI crawlers and tools
 *     like llmstxtgenerator.de can access /llms.txt without relying on
 *     WordPress rewrite rules or caching plugins.
 *
 * @package LLMs_Txt_Generator
 */

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * Handles reading and writing of llms.txt files via WP_Filesystem.
 */
class LLMSTXT_File_Writer {

	/**
	 * Returns the upload-based storage directory, creating it if needed.
	 */
	private static function get_dir(): string {
		$upload = wp_upload_dir();
		$dir    = trailingslashit( $upload['basedir'] ) . 'llmstxt/';
		wp_mkdir_p( $dir );
		return $dir;
	}

	/**
	 * Returns the filename for a given type.
	 */
	private static function get_filename( string $type ): string {
		return ( 'full' === $type ) ? 'llms-full.txt' : 'llms.txt';
	}

	/**
	 * Initialises and returns a WP_Filesystem instance.
	 *
	 * @return \WP_Filesystem_Base|false
	 */
	private static function get_fs() {
		global $wp_filesystem;

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

		return $wp_filesystem;
	}

	/**
	 * Writes content to both the uploads storage and the site root.
	 *
	 * @param string $content The content to write.
	 * @param string $type    'standard' or 'full'.
	 * @return bool True when at least the uploads copy was written successfully.
	 */
	public static function write( string $content, string $type = 'standard' ): bool {
		$fs       = self::get_fs();
		$filename = self::get_filename( $type );

		if ( ! $fs ) {
			return false;
		}

		// 1. Primary storage: uploads directory (WP-Filesystem compliant).
		$upload_file = self::get_dir() . $filename;
		$ok          = $fs->put_contents( $upload_file, $content, FS_CHMOD_FILE );

		// 2. Physical copy in site root so AI crawlers and external checkers
		//    can fetch /llms.txt directly without WordPress rewrite rules.
		$root_file = rtrim( ABSPATH, '/' ) . '/' . $filename;
		$fs->put_contents( $root_file, $content, FS_CHMOD_FILE );

		// 3. Ensure .htaccess declares UTF-8 charset for these files.
		//    Apache serves text/plain as ISO-8859-1 by default; without this
		//    German umlauts and all non-ASCII chars render incorrectly.
		LLMSTXT_Htaccess::insert();

		if ( $ok ) {
			update_option(
				'llmstxt_file_info',
				array(
					'updated' => current_time( 'mysql' ),
					'size'    => strlen( $content ),
					'lines'   => substr_count( $content, "\n" ) + 1,
				)
			);
		}

		return (bool) $ok;
	}

	/**
	 * Reads the stored llms.txt content (from uploads storage).
	 *
	 * @param string $type 'standard' or 'full'.
	 * @return string File contents or empty string.
	 */
	public static function read( string $type = 'standard' ): string {
		$fs   = self::get_fs();
		$file = self::get_dir() . self::get_filename( $type );

		if ( ! $fs || ! $fs->exists( $file ) ) {
			return '';
		}

		$contents = $fs->get_contents( $file );
		return is_string( $contents ) ? $contents : '';
	}

	/**
	 * Checks whether the llms.txt file exists (uploads storage).
	 *
	 * @param string $type 'standard' or 'full'.
	 */
	public static function exists( string $type = 'standard' ): bool {
		$fs   = self::get_fs();
		$file = self::get_dir() . self::get_filename( $type );
		return $fs && $fs->exists( $file );
	}

	/**
	 * Returns the public URL for the llms.txt file.
	 *
	 * @param string $type 'standard' or 'full'.
	 */
	public static function get_url( string $type = 'standard' ): string {
		return home_url( '/' . self::get_filename( $type ) );
	}

	/**
	 * Deletes the stored llms.txt file(s) from both locations.
	 *
	 * @param string $type 'standard' or 'full'.
	 */
	public static function delete( string $type = 'standard' ): void {
		$fs       = self::get_fs();
		$filename = self::get_filename( $type );

		if ( ! $fs ) {
			return;
		}

		// Remove from uploads storage.
		$upload_file = self::get_dir() . $filename;
		if ( $fs->exists( $upload_file ) ) {
			$fs->delete( $upload_file );
		}

		// Remove physical root copy.
		$root_file = rtrim( ABSPATH, '/' ) . '/' . $filename;
		if ( $fs->exists( $root_file ) ) {
			$fs->delete( $root_file );
		}
	}
}


/**
 * Manages the .htaccess charset rule for llms.txt files.
 */
class LLMSTXT_Htaccess {

	const MARKER = 'LLMs.txt Generator';

	/**
	 * Insert charset rule into the root .htaccess via WordPress markers.
	 * Called on plugin activation and after every write.
	 */
	public static function insert(): void {
		$htaccess = rtrim( ABSPATH, '/' ) . '/.htaccess';

		if ( ! function_exists( 'insert_with_markers' ) ) {
			require_once ABSPATH . 'wp-admin/includes/misc.php';
		}

		$rules = array(
			'<FilesMatch "^llms(-full)?\.txt$">',
			'  AddDefaultCharset UTF-8',
			'</FilesMatch>',
		);

		insert_with_markers( $htaccess, self::MARKER, $rules );
	}

	/**
	 * Remove the charset rule from .htaccess on deactivation/uninstall.
	 */
	public static function remove(): void {
		$htaccess = rtrim( ABSPATH, '/' ) . '/.htaccess';

		if ( ! function_exists( 'insert_with_markers' ) ) {
			require_once ABSPATH . 'wp-admin/includes/misc.php';
		}

		insert_with_markers( $htaccess, self::MARKER, array() );
	}
}