<?php
declare( strict_types = 1 );

namespace Automattic\P2\Themes\P2020;

/**
 * Grid view: posts grouped by month, each rendered as a tile.
 *
 * The feed is rendered by o2 (see Views.PostsGrid in the o2 plugin), which
 * buckets the Backbone Posts collection into month sections client-side.
 * This class only:
 *
 *  - exposes the view mode via the body class so CSS can target it,
 *  - tells o2 to use the grid view by setting `viewMode = 'grid'` in o2Config,
 *  - slims the per-post fragments so we don't ship contentFiltered/comments
 *    we won't render in a tile.
 *
 * The initial server-side render of tiles still goes through
 * `partials/post-types/post.php`, which routes to `grid-post` in grid mode
 * (matching how compact view works today).
 */
class Grid_View {

	public static function init(): void {
		add_action( 'wp_enqueue_scripts', [ __CLASS__, 'enqueue_scripts' ] );
		add_filter( 'body_class', [ __CLASS__, 'body_class' ] );
		add_filter( 'o2_options', [ __CLASS__, 'set_view_mode_option' ] );
		add_filter( 'o2_fragment_get_fragment_args', [ __CLASS__, 'slim_fragment_args' ] );
		add_filter( 'o2_post_fragment', [ __CLASS__, 'format_post_preview' ], 11 );
		// Priority 100 — must run after `Feed_Sorter::filter_p2_should_group_pinned_posts`
		// at priority 99, otherwise sort-by-comments would scatter pinned posts
		// across month buckets in grid mode.
		add_filter( 'p2_should_group_pinned_posts', [ __CLASS__, 'force_group_pinned_posts' ], 100 );
	}

	/**
	 * Force the Grouped_Posts system on when grid view is active so pinned
	 * and project-thread posts surface in their own sections at the top,
	 * instead of being scattered across month buckets.
	 *
	 * @param bool $should_group Current value passed through the filter chain.
	 * @return bool
	 */
	public static function force_group_pinned_posts( $should_group ): bool {
		if ( self::should_show_grid_view() ) {
			return true;
		}
		return (bool) $should_group;
	}

	/**
	 * Pull in the small set of shared `o2.Utilities` helpers (currently
	 * `compactViewTimestamp` and `compactViewProjectStatus`) that the tile
	 * underscore template uses. The script lives under Compact_View today
	 * but is just helpers with no side effects, so it's safe to load here.
	 */
	public static function enqueue_scripts(): void {
		if ( ! self::should_show_grid_view() ) {
			return;
		}

		$built_path = get_template_directory() . '/build/inc/compact-view/js/compact-view.js';
		wp_enqueue_script(
			'p2020-compact-view-js',
			get_template_directory_uri() . '/build/inc/compact-view/js/compact-view.js',
			[ 'jquery', 'wp-i18n' ],
			file_exists( $built_path ) ? filemtime( $built_path ) : false,
			true
		);
		wp_set_script_translations( 'p2020-compact-view-js', 'p2020', get_template_directory() . '/languages' );
	}

	/**
	 * @param string[] $classes
	 * @return string[]
	 */
	public static function body_class( array $classes ): array {
		if ( self::should_show_grid_view() ) {
			$classes[] = 'is-p2020-grid-view';
		}

		return $classes;
	}

	public static function is_feature_available(): bool {
		if ( ! is_user_logged_in() ) {
			return false;
		}

		// Default-a8c gate, overridable per blog/user via filter.
		//
		// `is_automattician()` comes from wpcom or the P2 plugin's
		// `compatibility.php` fallback (off-wpcom). The function_exists()
		// guard avoids a fatal during the brief window in a paired deploy
		// where the theme is live but the plugin hasn't loaded yet.
		$default_enabled = function_exists( 'is_automattician' ) && is_automattician();
		/**
		 * Filter whether grid view is available to the current user.
		 *
		 * Defaults to `is_automattician()`, so out of the box only a8c
		 * users see the option. Hook this to widen access (e.g.
		 * `__return_true` for a single test blog, or per-blog/per-role
		 * logic for staged rollouts).
		 *
		 * @param bool $enabled Default availability.
		 */
		if ( ! apply_filters( 'p2020_grid_view_enabled', $default_enabled ) ) {
			return false;
		}

		return ! ( defined( 'REST_API_REQUEST' ) && REST_API_REQUEST ) &&
			! is_admin() && ! is_single() && ! is_page() && ! is_404() &&
			! Compact_View::is_default_mode_only();
	}

	public static function is_grid_view_enabled(): bool {
		return ! empty( $_COOKIE['showGridView'] ) && 'false' !== $_COOKIE['showGridView'];
	}

	public static function should_show_grid_view(): bool {
		return self::is_feature_available() && self::is_grid_view_enabled();
	}

	/**
	 * Tell o2 we're in grid mode so its Router instantiates Views.PostsGrid
	 * instead of the default Views.Posts.
	 *
	 * @param array<string, mixed> $o2_options
	 * @return array<string, mixed>
	 */
	public static function set_view_mode_option( array $o2_options ): array {
		if ( self::should_show_grid_view() ) {
			$o2_options['options']['viewMode'] = 'grid';
		}
		return $o2_options;
	}

	/**
	 * Drop fragment fields we don't render in a tile. Mirrors Compact_View's
	 * slimming — tiles show title + excerpt + author + date only.
	 *
	 * @param array<string, mixed> $args
	 * @return array<string, mixed>
	 */
	public static function slim_fragment_args( array $args ): array {
		if ( self::should_show_grid_view() ) {
			// Tiles only need `commentCount` and `tagsArray` (for project
			// status). Skip everything else expensive — same set compact
			// view skips, including `comments` since tiles never render
			// `.o2-post-comments`.
			$args['skip']['post'] = [
				'contentFiltered' => true,
				'mentions'        => true,
				'shortcodes'      => true,
				'comments'        => true,
			];
		}
		return $args;
	}

	/**
	 * Produce a short tile excerpt:
	 *  - For xposts, "From +blogname" (handled by Compact_View::get_post_content_preview).
	 *  - For regular posts, the first ~28 words of the excerpt.
	 *
	 * Mirrors how Compact_View prepares `contentPreview` so the same field
	 * name is available to the underscore tile template.
	 *
	 * @param array<string, mixed> $fragment
	 * @return array<string, mixed>
	 */
	public static function format_post_preview( array $fragment ): array {
		if ( ! self::should_show_grid_view() ) {
			return $fragment;
		}

		if ( ! empty( $fragment['is_xpost'] ) ) {
			$fragment['contentPreview'] = Compact_View::get_post_content_preview(
				$fragment['contentRaw'] ?? '',
				true
			);
		} else {
			$excerpt                    = wp_strip_all_tags( (string) ( $fragment['contentRaw'] ?? '' ) );
			$fragment['contentPreview'] = wp_trim_words( $excerpt, 28, '…' );
		}

		$fragment['titleFiltered'] = Compact_View::get_post_title_preview(
			$fragment['titleFiltered'] ?? '',
			(bool) ( $fragment['is_xpost'] ?? false )
		);

		if ( '' === trim( (string) $fragment['titleFiltered'] ) ) {
			$fragment['isUntitled'] = true;
		}

		// contentRaw isn't needed once we've derived contentPreview.
		$fragment['contentRaw'] = '';

		return $fragment;
	}
}