<?php
/**
 * Tells Aivastark that this site's content changed, so the knowledge base can
 * show a "Site changed — Refresh now" badge instead of quietly going stale.
 *
 * WHY A PING AND NOT A CRAWL: Aivastark's only previous way of noticing an edit
 * was to re-crawl the whole site on a schedule and compare hashes — expensive,
 * and on the slower schedules a page edited today could stay stale for a week.
 * A publish here is the cheapest and most certain possible signal, so we send
 * it and let the site owner decide whether to spend a re-crawl on it. This
 * class never triggers indexing; it only raises a flag in the dashboard.
 *
 * WHAT IS DELIBERATELY NOT SENT: no post content, no title, no URL, no user.
 * The endpoint derives the project from the pairing token and needs nothing
 * else, so a publish leaks nothing about what was published.
 *
 * @package Aivastark_Widget
 */

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

class Aivastark_Widget_Change_Ping {

	/** Single-event hook name. Also cleared on deactivate/uninstall. */
	const EVENT = 'aivastark_send_change_ping';

	/**
	 * Debounce window. Bulk-editing 200 posts, or a Gutenberg save that fires
	 * several transitions, must cost one HTTP call — not two hundred.
	 */
	const DEBOUNCE_SECONDS = 300;

	public static function init() {
		add_action( 'transition_post_status', array( __CLASS__, 'on_transition' ), 10, 3 );
		add_action( 'before_delete_post', array( __CLASS__, 'on_before_delete' ), 10, 2 );
		add_action( self::EVENT, array( __CLASS__, 'send' ) );
	}

	/**
	 * Published, updated, unpublished or trashed — all four change what a
	 * visitor (and therefore the crawler) sees.
	 *
	 * @param string  $new_status New post status.
	 * @param string  $old_status Previous post status.
	 * @param WP_Post $post       The post.
	 */
	public static function on_transition( $new_status, $old_status, $post ) {
		// A draft being edited, or an auto-draft being created, changes nothing
		// on the public site. Only transitions that touch 'publish' matter.
		if ( 'publish' !== $new_status && 'publish' !== $old_status ) {
			return;
		}
		if ( self::is_ignorable( $post ) ) {
			return;
		}
		self::schedule();
	}

	/**
	 * A published post deleted outright (wp_delete_post with force), skipping
	 * the trash transition above.
	 *
	 * @param int          $post_id Post ID.
	 * @param WP_Post|null $post    The post, on WP 5.5+.
	 */
	public static function on_before_delete( $post_id, $post = null ) {
		if ( ! $post instanceof WP_Post ) {
			$post = get_post( $post_id );
		}
		if ( ! $post || 'publish' !== $post->post_status ) {
			return;
		}
		if ( self::is_ignorable( $post ) ) {
			return;
		}
		self::schedule();
	}

	/**
	 * Revisions, autosaves, attachments and private post types are not the
	 * public pages the crawler reads.
	 *
	 * @param WP_Post|null $post The post.
	 */
	private static function is_ignorable( $post ) {
		if ( ! $post instanceof WP_Post ) {
			return true;
		}
		if ( wp_is_post_revision( $post ) || wp_is_post_autosave( $post ) ) {
			return true;
		}
		if ( 'attachment' === $post->post_type ) {
			return true;
		}
		$type = get_post_type_object( $post->post_type );
		return ! $type || empty( $type->public );
	}

	/**
	 * Queue one ping, unless one is already queued.
	 *
	 * Deferring rather than calling inline also keeps a slow or unreachable
	 * backend from ever showing up as a slow "Publish" button.
	 */
	private static function schedule() {
		if ( ! self::enabled() ) {
			return;
		}
		if ( wp_next_scheduled( self::EVENT ) ) {
			return;
		}
		wp_schedule_single_event( time() + self::DEBOUNCE_SECONDS, self::EVENT );
	}

	/**
	 * Fire the ping. Runs on WP-Cron, where the admin-only includes are not
	 * loaded — hence the explicit require.
	 */
	public static function send() {
		if ( ! self::enabled() ) {
			return;
		}
		require_once AIVASTARK_WIDGET_PATH . 'includes/class-aivastark-api.php';

		$access = Aivastark_Widget_Api::ensure_fresh_token();
		if ( is_wp_error( $access ) ) {
			return;
		}
		// Failure is silently ignored on purpose: this is a nice-to-have badge,
		// and a backend hiccup must never surface as an error on a site owner's
		// publish screen. The daily HTTP probe on our side is the backstop.
		Aivastark_Widget_Api::post(
			'kb-change-signal',
			array( 'reason' => 'content_update' ),
			$access
		);
	}

	/**
	 * Connected, and the owner hasn't switched "Knowledge sync" off on
	 * Aivastark → Settings.
	 */
	private static function enabled() {
		$opts = aivastark_widget_get_options();
		return ! empty( $opts['change_ping'] ) && Aivastark_Widget_Options::is_connected();
	}

	/** Drop any queued ping (deactivation / uninstall). */
	public static function clear_scheduled() {
		$timestamp = wp_next_scheduled( self::EVENT );
		while ( $timestamp ) {
			wp_unschedule_event( $timestamp, self::EVENT );
			$timestamp = wp_next_scheduled( self::EVENT );
		}
	}
}