<?php
/**
 * Plugin bootstrap and wiring.
 *
 * @package FeedWeaver
 */

namespace FeedWeaver;

use FeedWeaver\Access\Access_Policy;
use FeedWeaver\Admin\Admin;
use FeedWeaver\Config\Feed_Repository;
use FeedWeaver\Feed\Feed_Builder;
use FeedWeaver\Http\Endpoint;
use FeedWeaver\Http\Feed_Controller;

defined( 'ABSPATH' ) || exit;

/**
 * Composition root.
 */
class Plugin {

	/** @var Plugin|null */
	private static $instance = null;

	/** @var Feed_Repository */
	public $repository;

	/** @var Feed_Builder */
	public $builder;

	/** @var Access_Policy */
	public $access;

	/** @var Feed_Controller */
	public $controller;

	/**
	 * Shared instance.
	 *
	 * @return Plugin
	 */
	public static function instance(): Plugin {
		if ( null === self::$instance ) {
			self::$instance = new self();
		}
		return self::$instance;
	}

	/**
	 * Wires the object graph.
	 */
	private function __construct() {
		$this->repository = new Feed_Repository();
		$this->builder    = new Feed_Builder();
		$this->access     = new Access_Policy( $this->repository );
		$this->controller = new Feed_Controller( $this->repository, $this->builder, $this->access );
	}

	/**
	 * Registers hooks.
	 */
	public function boot(): void {
		add_action( 'init', array( $this->repository, 'register_post_type' ) );
		add_action( 'init', array( Endpoint::class, 'add_rewrite_rule' ) );
		( new Endpoint( $this->controller ) )->register();

		// Cache invalidation: one cheap option write bumps a generation number.
		add_action( 'wp_after_insert_post', array( $this, 'on_after_insert_post' ), 10, 2 );
		add_action( 'transition_post_status', array( $this, 'on_status_transition' ), 10, 3 );
		add_action( 'deleted_post', array( $this, 'on_deleted_post' ), 10, 2 );
		add_action( 'added_post_meta', array( $this, 'on_meta_change' ), 10, 4 );
		add_action( 'updated_post_meta', array( $this, 'on_meta_change' ), 10, 4 );
		add_action( 'deleted_post_meta', array( $this, 'on_meta_change' ), 10, 4 );
		add_action( 'set_object_terms', array( $this, 'on_terms_set' ), 10, 1 );
		add_action( 'deleted_term_relationships', array( $this, 'on_terms_set' ), 10, 1 );
		add_action( 'edited_term', array( Feed_Builder::class, 'bump_generation' ) );
		add_action( 'delete_term', array( Feed_Builder::class, 'bump_generation' ) );
		add_action( 'profile_update', array( Feed_Builder::class, 'bump_generation' ) );

		if ( is_admin() ) {
			( new Admin( $this->repository, $this->builder ) )->register();
		}
	}

	/**
	 * Whether a post could appear in a public feed (revisions, autosaves,
	 * FeedWeaver's own records and non-viewable types never do).
	 *
	 * @param \WP_Post|null $post Post.
	 * @return bool
	 */
	private function is_feed_relevant( $post ): bool {
		return $post instanceof \WP_Post
			&& Feed_Repository::POST_TYPE !== $post->post_type
			&& 'revision' !== $post->post_type
			&& is_post_type_viewable( $post->post_type );
	}

	/**
	 * After a post (with its terms and meta) has been saved: refresh when it is published.
	 *
	 * @param int      $post_id Post ID.
	 * @param \WP_Post $post    Post.
	 */
	public function on_after_insert_post( $post_id, $post ): void {
		if ( $this->is_feed_relevant( $post ) && 'publish' === $post->post_status && ! wp_is_post_autosave( $post_id ) ) {
			Feed_Builder::bump_generation();
		}
	}

	/**
	 * Publishing, unpublishing, trashing: any change to or from "publish".
	 *
	 * @param string   $new_status New status.
	 * @param string   $old_status Old status.
	 * @param \WP_Post $post       Post.
	 */
	public function on_status_transition( $new_status, $old_status, $post ): void {
		if ( $new_status !== $old_status && ( 'publish' === $new_status || 'publish' === $old_status ) && $this->is_feed_relevant( $post ) ) {
			Feed_Builder::bump_generation();
		}
	}

	/**
	 * Permanent deletion of a published post.
	 *
	 * @param int           $post_id Post ID.
	 * @param \WP_Post|null $post    Post (WordPress 5.5+).
	 */
	public function on_deleted_post( $post_id, $post = null ): void {
		if ( $this->is_feed_relevant( $post ) && 'publish' === $post->post_status ) {
			Feed_Builder::bump_generation();
		}
	}

	/**
	 * Term assignments changed (REST, bulk edit, code): refresh when the post is published.
	 *
	 * @param int $object_id Post ID.
	 */
	public function on_terms_set( $object_id ): void {
		$post = get_post( (int) $object_id );
		if ( $this->is_feed_relevant( $post ) && 'publish' === $post->post_status ) {
			Feed_Builder::bump_generation();
		}
	}

	/**
	 * Public custom field changes on published posts (protected "_" keys never appear in feeds).
	 *
	 * @param int|int[] $meta_id  Meta ID(s).
	 * @param int       $post_id  Post ID.
	 * @param string    $meta_key Meta key.
	 */
	public function on_meta_change( $meta_id, $post_id, $meta_key ): void {
		if ( is_string( $meta_key ) && '' !== $meta_key && '_' !== $meta_key[0] && 'publish' === get_post_status( $post_id ) ) {
			Feed_Builder::bump_generation();
		}
	}

	/**
	 * Activation: register the rules, then flush once.
	 */
	public static function activate(): void {
		( new Feed_Repository() )->register_post_type();
		Endpoint::add_rewrite_rule();
		flush_rewrite_rules( false );
		update_option( Endpoint::VERSION_OPTION, Endpoint::REWRITE_VERSION, true );
	}

	/**
	 * Deactivation: remove the rules.
	 */
	public static function deactivate(): void {
		flush_rewrite_rules( false );
	}
}