<?php
/**
 * Main Plugin Class
 *
 * Orchestrates plugin initialization and component integration.
 *
 * @package ROBOTSTXT_OG
 * @since 1.0.0
 */

if ( ! defined( 'ABSPATH' ) ) {
	exit; // Exit if accessed directly.
}

/**
 * Class Robotstxt_OG_Image_Fallback
 *
 * Main plugin class using singleton pattern.
 *
 * @since 1.0.0
 */
class Robotstxt_OG_Image_Fallback {

	/**
	 * Single instance of the class.
	 *
	 * @since 1.0.0
	 * @var Robotstxt_OG_Image_Fallback|null
	 */
	private static ?Robotstxt_OG_Image_Fallback $instance = null;

	/**
	 * Image resolver instance.
	 *
	 * @since 1.0.0
	 * @var Robotstxt_OG_Image_Resolver
	 */
	private Robotstxt_OG_Image_Resolver $resolver;

	/**
	 * OG tags generator instance.
	 *
	 * @since 1.0.0
	 * @var Robotstxt_OG_Tags
	 */
	private Robotstxt_OG_Tags $tags;

	/**
	 * Admin settings instance.
	 *
	 * @since 1.0.0
	 * @var Robotstxt_OG_Admin_Settings|null
	 */
	private ?Robotstxt_OG_Admin_Settings $admin_settings = null;

	/**
	 * REST API instance.
	 *
	 * @since 1.0.0
	 * @var Robotstxt_OG_REST_API
	 */
	private Robotstxt_OG_REST_API $rest_api;

	/**
	 * Meta box instance.
	 *
	 * @since 1.2.0
	 * @var Robotstxt_OG_Meta_Box
	 */
	private Robotstxt_OG_Meta_Box $meta_box;

	/**
	 * Get singleton instance.
	 *
	 * @since 1.0.0
	 *
	 * @return Robotstxt_OG_Image_Fallback
	 */
	public static function get_instance(): Robotstxt_OG_Image_Fallback {
		if ( null === self::$instance ) {
			self::$instance = new self();
		}

		return self::$instance;
	}

	/**
	 * Constructor.
	 *
	 * Private to enforce singleton pattern.
	 *
	 * @since 1.0.0
	 */
	private function __construct() {
		// Constructor is private.
	}

	/**
	 * Initialize the plugin.
	 *
	 * @since 1.0.0
	 *
	 * @return void
	 */
	public function init(): void {
		// Load dependencies.
		$this->load_dependencies();

		// Initialize components.
		$this->resolver = new Robotstxt_OG_Image_Resolver();
		$this->tags     = new Robotstxt_OG_Tags( $this->resolver );

		// Initialize OG tags generator.
		$this->tags->init();

		// Initialize REST API.
		$this->rest_api = new Robotstxt_OG_REST_API( $this->resolver );
		$this->rest_api->init();

		// Initialize meta box (registers post meta for REST + editor UI).
		$this->meta_box = new Robotstxt_OG_Meta_Box();
		$this->meta_box->init();

		// Initialize admin settings if in admin context.
		if ( is_admin() ) {
			$this->admin_settings = new Robotstxt_OG_Admin_Settings( $this->resolver );
			$this->admin_settings->init();
		}

		// Register WP-CLI commands.
		if ( defined( 'WP_CLI' ) && WP_CLI ) {
			WP_CLI::add_command( 'og-fallback', new Robotstxt_OG_CLI( $this->resolver ) );
		}

		// Auto-regenerate cache when featured image changes.
		add_action( 'updated_post_meta', array( $this, 'handle_thumbnail_change' ), 10, 4 );
		add_action( 'deleted_post_meta', array( $this, 'handle_thumbnail_change' ), 10, 4 );

		// Register activation and deactivation hooks.
		register_activation_hook( ROBOTSTXT_OG_PATH . 'robotstxt-og.php', array( $this, 'activate' ) );
		register_deactivation_hook( ROBOTSTXT_OG_PATH . 'robotstxt-og.php', array( $this, 'deactivate' ) );
	}

	/**
	 * Load plugin dependencies.
	 *
	 * @since 1.0.0
	 *
	 * @return void
	 */
	private function load_dependencies(): void {
		require_once ROBOTSTXT_OG_PATH . 'includes/class-robotstxt-og-image-resolver.php';
		require_once ROBOTSTXT_OG_PATH . 'includes/class-robotstxt-og-tags.php';
		require_once ROBOTSTXT_OG_PATH . 'includes/class-robotstxt-og-rest-api.php';
		require_once ROBOTSTXT_OG_PATH . 'includes/class-robotstxt-og-meta-box.php';

		// Load admin class if in admin context.
		if ( is_admin() ) {
			require_once ROBOTSTXT_OG_PATH . 'admin/class-robotstxt-og-admin-settings.php';
		}

		// Load WP-CLI class if running in CLI context.
		if ( defined( 'WP_CLI' ) && WP_CLI ) {
			require_once ROBOTSTXT_OG_PATH . 'includes/class-robotstxt-og-cli.php';
		}
	}

	/**
	 * Activation hook callback.
	 *
	 * Runs when the plugin is activated.
	 *
	 * @since 1.0.0
	 *
	 * @return void
	 */
	public function activate(): void {
		// Set default options if they don't exist.
		if ( false === get_option( 'robotstxt_og_fallback_image' ) ) {
			add_option( 'robotstxt_og_fallback_image', '' );
		}

		if ( false === get_option( 'robotstxt_og_delete_data_on_uninstall' ) ) {
			add_option( 'robotstxt_og_delete_data_on_uninstall', false );
		}

		// Flush rewrite rules (if needed in future).
		flush_rewrite_rules();
	}

	/**
	 * Deactivation hook callback.
	 *
	 * Runs when the plugin is deactivated.
	 *
	 * @since 1.0.0
	 *
	 * @return void
	 */
	public function deactivate(): void {
		// Flush rewrite rules (if needed in future).
		flush_rewrite_rules();
	}

	/**
	 * Clear fallback cache when a post's featured image is changed or removed.
	 *
	 * Hooked to `updated_post_meta` and `deleted_post_meta` for `_thumbnail_id`.
	 *
	 * @since 1.0.0
	 *
	 * @param int    $meta_id    ID of the meta data entry.
	 * @param int    $post_id    Post ID.
	 * @param string $meta_key   Meta key being updated.
	 * @param mixed  $meta_value New meta value (unused).
	 * @return void
	 */
	public function handle_thumbnail_change( int $meta_id, int $post_id, string $meta_key, $meta_value = null ): void { // phpcs:ignore Generic.CodeAnalysis.UnusedFunctionParameter.FoundAfterLastUsed
		if ( '_thumbnail_id' !== $meta_key ) {
			return;
		}

		$this->resolver->clear_cache( $post_id );
	}

	/**
	 * Get image resolver instance.
	 *
	 * @since 1.0.0
	 *
	 * @return Robotstxt_OG_Image_Resolver
	 */
	public function get_resolver(): Robotstxt_OG_Image_Resolver {
		return $this->resolver;
	}

	/**
	 * Get OG tags generator instance.
	 *
	 * @since 1.0.0
	 *
	 * @return Robotstxt_OG_Tags
	 */
	public function get_tags(): Robotstxt_OG_Tags {
		return $this->tags;
	}
}