<?php
/**
 * Transient cache helpers + invalidation for generated markdown.
 *
 * @package AEL42A
 */

namespace AEL42A;

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

/**
 * Markdown document cache.
 *
 * Documents are stored per post in a transient `ael42a_md_<post_id>`
 * as `array( 'modified' => post_modified_gmt, 'md' => string )` so a stale
 * entry is detected even if invalidation hooks were bypassed (e.g. direct
 * DB edits).
 */
class Cache {

	const MD_PREFIX  = 'ael42a_md_';
	const MD_TTL     = DAY_IN_SECONDS;
	const LLMS_TXT   = 'ael42a_llms_txt';
	const LLMS_FULL  = 'ael42a_llms_full';
	const VITALS     = 'ael42a_vitals';
	const VISIBILITY = 'ael42a_visibility';
	const LOCAL_VITALS = 'ael42a_local_vitals';

	/**
	 * Register invalidation hooks.
	 */
	public static function register_hooks() {
		add_action( 'save_post', array( __CLASS__, 'invalidate_post' ) );
		add_action( 'delete_post', array( __CLASS__, 'invalidate_post' ) );
		add_action( 'trashed_post', array( __CLASS__, 'invalidate_post' ) );
	}

	/**
	 * Get a cached markdown document for a post.
	 *
	 * @param \WP_Post $post Post.
	 * @return string|null Markdown or null on miss/stale.
	 */
	public static function get_markdown( $post ) {
		$entry = get_transient( self::MD_PREFIX . $post->ID );
		if ( ! is_array( $entry ) || ! isset( $entry['modified'], $entry['md'] ) ) {
			return null;
		}
		if ( $entry['modified'] !== $post->post_modified_gmt ) {
			return null;
		}
		return (string) $entry['md'];
	}

	/**
	 * Store a markdown document for a post.
	 *
	 * @param \WP_Post $post     Post.
	 * @param string   $markdown Rendered markdown document.
	 */
	public static function set_markdown( $post, $markdown ) {
		set_transient(
			self::MD_PREFIX . $post->ID,
			array(
				'modified' => $post->post_modified_gmt,
				'md'       => $markdown,
			),
			self::MD_TTL
		);
	}

	/**
	 * Invalidate the cached markdown (and dependent llms.txt caches) for a post.
	 *
	 * @param int $post_id Post ID.
	 */
	public static function invalidate_post( $post_id ) {
		delete_transient( self::MD_PREFIX . (int) $post_id );
		delete_transient( self::LLMS_TXT );
		delete_transient( self::LLMS_FULL );
	}

	/**
	 * Delete every transient this plugin owns. Used on disconnect/uninstall.
	 */
	public static function purge_all() {
		global $wpdb;

		delete_transient( self::LLMS_TXT );
		delete_transient( self::LLMS_FULL );
		delete_transient( self::VITALS );
		delete_transient( self::LOCAL_VITALS );

		// Per-post markdown transients - direct LIKE delete (bounded prefix).
		$wpdb->query( // phpcs:ignore WordPress.DB.DirectDatabaseQuery
			$wpdb->prepare(
				"DELETE FROM {$wpdb->options} WHERE option_name LIKE %s OR option_name LIKE %s",
				$wpdb->esc_like( '_transient_' . self::MD_PREFIX ) . '%',
				$wpdb->esc_like( '_transient_timeout_' . self::MD_PREFIX ) . '%'
			)
		);
	}
}