<?php

namespace Automattic\P2\Themes\P2020\Pages_Index;

class Pages_Index {
	public static function init() {
		// Do not load if we're not inside the pages index.
		if ( ! self::is_pages_index_active() ) {
			return;
		}

		add_filter( 'wp_enqueue_scripts', array( __CLASS__, 'enqueue_scripts' ) );
		add_filter( 'index_template', array( __CLASS__, 'load_custom_template' ) );
		add_filter( 'home_template', array( __CLASS__, 'load_custom_template' ) );
		add_filter( 'frontpage_template', array( __CLASS__, 'load_custom_template' ) );
		add_filter( 'template_redirect', array( __CLASS__, 'prevent_404s' ) );
		add_filter( 'body_class', array( __CLASS__, 'custom_body_class' ) );
		add_filter( 'o2_options', array( __CLASS__, 'customize_o2_options' ) );
		add_action( 'after_setup_theme', array( __CLASS__, 'remove_infinite_scroll' ), 11 );

		// For performance, turn off what we can.
		add_filter( 'p2_inline_terms_disabled', '__return_true' );
		add_filter( 'jetpack_mentions_should_load_ui', '__return_false', 99 );
		add_filter( 'o2_should_process_terms', '__return_false', 99 );
		/**
		 * To prevent result of `posts_pre_query` from being cached, `posts_fields` or
		 * another post-related query needs to be filtered.
		 *
		 * See `$id_query_is_cacheable` in `class-wp-query.php` for details.
		 *
		 * Fix for https://github.com/Automattic/p2/issues/6185
		 */
		add_filter( 'posts_pre_query', array( __CLASS__, 'skip_post_query' ), 10, 2 );
		add_filter( 'posts_fields', array( __CLASS__, 'empty_posts_fields' ), 10, 2 );
		add_filter( 'p2_glossary_enabled', '__return_false' );
	}

	public static function enqueue_scripts() {
		wp_enqueue_script(
			'p2020-pages-index-tree-js',
			get_template_directory_uri() . '/inc/pages-index/js/tree-collapser.js',
			[ 'jquery' ],
			(string) filemtime( get_template_directory() . '/inc/pages-index/js/tree-collapser.js' ),
			false
		);

		wp_enqueue_script(
			'p2020-pages-index-post-actions-js',
			get_template_directory_uri() . '/inc/pages-index/js/post-actions.js',
			[ 'jquery' ],
			(string) filemtime( get_template_directory() . '/inc/pages-index/js/post-actions.js' ),
			true
		);
		wp_set_script_translations( 'p2020-pages-index-post-actions-js', 'p2020', get_template_directory() . '/languages' );

		wp_enqueue_script(
			'p2020-pages-index-dragndrop-js',
			get_template_directory_uri() . '/inc/pages-index/js/drag-n-drop.js',
			[ 'jquery' ],
			(string) filemtime( get_template_directory() . '/inc/pages-index/js/drag-n-drop.js' ),
			true
		);
	}

	/**
	 * Filter: posts_pre_query
	 */
	public static function skip_post_query( ?array $posts, \WP_Query $wp_query ) {
		if ( $wp_query->is_main_query() ) {
			$wp_query->set( 'cache_results', false );
			return [];
		}

		return $posts;
	}

	/**
	 * Filter: posts_fields
	 */
	public static function empty_posts_fields( string $fields, \WP_Query $wp_query ) {
		if ( $wp_query->is_main_query() ) {
			return '1';
		}

		return $fields;
	}

	/**
	 * Filter: home_template, frontpage_template and index_template
	 */
	public static function load_custom_template() {
		return get_template_directory() . '/inc/pages-index/templates/tpl-pages-index.php';
	}

	/**
	 * When the front page is set to a static page, Pages Index
	 * is wrongly tagged as '404'. This is to handle P2s
	 * that need their front page to be static, e.g. document-heavy P2s.
	 */
	public static function prevent_404s() {
		// Extra check: this should only apply to the Pages Index.
		if ( ! self::is_pages_index_active() ) {
			return;
		}

		global $wp_query;
		status_header( 200 );
		$wp_query->is_404 = false;
	}

	public static function custom_body_class( $classes ) {
		// Add special pages index class.
		$classes[] = 'is-pages-index';

		// Remove 'home' class.
		return array_diff( $classes, [ 'home' ] );
	}

	public static function remove_infinite_scroll() {
		remove_theme_support( 'infinite-scroll' );
	}

	public static function customize_o2_options( array $o2_options ) {
		$o2_options['options']['infiniteScroll']       = false;
		$o2_options['options']['hideAppControls']      = true;
		$o2_options['options']['showFrontSidePostBox'] = false;
		$o2_options['options']['viewType']             = 'archive';

		return $o2_options;
	}

	public static function print_pages_tree() {
		$options = array(
			'title_li'    => '',
			'sort_column' => 'menu_order, post_title',
			'echo'        => 0,
			'walker'      => new Custom_Walker_Page(),
		);

		// Exclude page set as Posts page, to keep this list only for
		// actual pages, in the context of P2.
		$page_for_posts = get_option( 'page_for_posts' );
		if ( ! empty( $page_for_posts ) ) {
			$options['exclude'] = $page_for_posts;
		}

		// phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
		echo \wp_list_pages( $options );
	}

	public static function is_pages_index_active(): bool {
		return isset( $_GET['pages'] );
	}

	public static function get_pages_index_url(): string {
		return add_query_arg( [ 'pages' => true ], get_home_url() );
	}
}