<?php
/**
 * Reduces the admin menu to a whitelist.
 *
 * @package QuietAdmin
 */

namespace QuietAdmin;

defined( 'ABSPATH' ) || exit;

/**
 * Class Menu_Filter.
 *
 * Instead of individual remove_menu_page() calls, the menu tree is filtered directly via
 * the globals `$menu` / `$submenu` (`admin_menu` with high
 * priority). Advantage: no "screen does not exist" warnings arise
 * and the whitelist stays editable in the settings.
 *
 * In addition, update counters ("Plugins 12"), the admin bar update node
 * and the comment bubble are removed.
 *
 * @since 0.1.0
 */
class Menu_Filter {

	/**
	 * Menu tree saved before filtering (for the settings UI).
	 *
	 * @since 0.1.0
	 * @var array<string,array<int,array>>
	 */
	protected static $captured_tree = array();

	/**
	 * Register hooks.
	 *
	 * @since 0.1.0
	 *
	 * @return void
	 */
	public function register() {
		add_action( 'admin_menu', array( $this, 'capture_tree' ), 90 );
		add_action( 'admin_menu', array( $this, 'apply_whitelist' ), PHP_INT_MAX - 10 );
		add_action( 'admin_bar_menu', array( $this, 'trim_admin_bar' ), PHP_INT_MAX - 10 );
		add_filter( 'admin_body_class', array( $this, 'body_class' ) );
	}

	/**
	 * Saves the complete menu tree before it is reduced.
	 *
	 * @since 0.1.0
	 *
	 * @global array $menu    Top-level menu.
	 * @global array $submenu Submenus.
	 *
	 * @return void
	 */
	public function capture_tree() {
		global $menu, $submenu;

		if ( ! empty( self::$captured_tree ) ) {
			return;
		}

		$tree = array();

		foreach ( (array) $menu as $position => $item ) {
			if ( ! isset( $item[2], $item[0] ) ) {
				continue;
			}

			$slug  = $item[2];
			$label = trim( preg_replace( '/\s*\d+\s*$/', '', wp_strip_all_tags( $item[0] ) ) );

			$tree[ $slug ] = array(
				'label'    => $label,
				'position' => $position,
				'subs'     => array(),
			);

			if ( isset( $submenu[ $slug ] ) && is_array( $submenu[ $slug ] ) ) {
				foreach ( $submenu[ $slug ] as $sub ) {
					if ( ! isset( $sub[0], $sub[2] ) ) {
						continue;
					}

					$tree[ $slug ]['subs'][ $sub[2] ] = trim( preg_replace( '/\s*\d+\s*$/', '', wp_strip_all_tags( $sub[0] ) ) );
				}
			}
		}

		self::$captured_tree = $tree;
	}

	/**
	 * Returns the saved (unfiltered) menu tree.
	 *
	 * @since 0.1.0
	 *
	 * @return array<string,array<int,array>>
	 */
	public static function get_full_tree() {
		if ( empty( self::$captured_tree ) ) {
			// Fallback in case capture_tree() has not run yet (e.g. direct call).
			$filter = new self();
			$filter->capture_tree();
		}

		/**
		 * Filter the menu tree for the whitelist settings.
		 *
		 * @since 0.1.0
		 *
		 * @param array $tree Slug => [ label, position, subs ].
		 */
		return apply_filters( 'quietadmin_menu_tree', self::$captured_tree );
	}

	/**
	 * Applies the whitelist.
	 *
	 * @since 0.1.0
	 *
	 * @global array $menu    Top-level menu.
	 * @global array $submenu Submenus.
	 *
	 * @return void
	 */
	public function apply_whitelist() {
		global $menu, $submenu;

		if ( ! ClientMode::is_active() ) {
			return;
		}

		$whitelist   = $this->resolve_whitelist();
		$strict_subs = (bool) Options::get( 'strict_submenus' );
		$supp_bubble = (bool) Options::get( 'suppress_comment_bubble' );

		foreach ( (array) $menu as $position => $item ) {
			if ( ! isset( $item[2] ) ) {
				continue;
			}

			$slug = $item[2];

			// Keep separators, otherwise the menu layout breaks.
			if ( $this->is_separator( $slug ) ) {
				continue;
			}

			if ( ! in_array( $slug, $whitelist['top'], true ) ) {
				unset( $menu[ $position ] );
				continue;
			}

			// Remove update/comment counters from the label.
			// phpcs:disable WordPress.WP.GlobalVariablesOverride.Prohibited -- The admin menu tree is deliberately rewritten here.
			$menu[ $position ][0] = $this->strip_counts( $item[0], $supp_bubble );
			$menu[ $position ][6] = isset( $item[6] ) ? $this->clean_css_class( $item[6], $supp_bubble ) : '';
			// phpcs:enable

			if ( isset( $submenu[ $slug ] ) && is_array( $submenu[ $slug ] ) ) {
				$allowed_subs = isset( $whitelist['subs'][ $slug ] ) ? $whitelist['subs'][ $slug ] : null;

				if ( null === $allowed_subs && $strict_subs ) {
					// No submenu configured + strict mode => only the first entry stays.
					$allowed_subs = $this->first_sub_slugs( $submenu[ $slug ] );
				}

				foreach ( $submenu[ $slug ] as $sub_pos => $sub ) {
					if ( ! isset( $sub[2] ) ) {
						continue;
					}

					if ( is_array( $allowed_subs ) && ! in_array( $sub[2], $allowed_subs, true ) ) {
						unset( $submenu[ $slug ][ $sub_pos ] );
						continue;
					}

					// phpcs:ignore WordPress.WP.GlobalVariablesOverride.Prohibited -- Remove counters from submenu labels.
					$submenu[ $slug ][ $sub_pos ][0] = $this->strip_counts( $sub[0], $supp_bubble );
				}

				if ( empty( $submenu[ $slug ] ) ) {
					unset( $submenu[ $slug ] );
				}
			}
		}

		/**
		 * After the menu has been reduced.
		 *
		 * @since 0.1.0
		 *
		 * @param array $whitelist Resolved whitelist.
		 */
		do_action( 'quietadmin_menu_filtered', $whitelist );
	}

	/**
	 * Cleans up the admin bar.
	 *
	 * @since 0.1.0
	 *
	 * @param \WP_Admin_Bar $wp_admin_bar Admin bar instance.
	 * @return void
	 */
	public function trim_admin_bar( $wp_admin_bar ) {
		if ( ! ClientMode::is_active() || ! is_admin_bar_showing() ) {
			return;
		}

		if ( Options::get( 'hide_wp_logo' ) ) {
			$wp_admin_bar->remove_node( 'wp-logo' );
		}

		if ( Options::get( 'suppress_update_nags' ) ) {
			$wp_admin_bar->remove_node( 'updates' );
		}

		if ( Options::get( 'suppress_comment_bubble' ) ) {
			$wp_admin_bar->remove_node( 'comments' );
		}

		$wp_admin_bar->remove_node( 'about' );
		$wp_admin_bar->remove_node( 'contribute' );
		$wp_admin_bar->remove_node( 'wordpress-org' );
		$wp_admin_bar->remove_node( 'documentation' );
		$wp_admin_bar->remove_node( 'support-forums' );
		$wp_admin_bar->remove_node( 'feedback' );

		// Reduce the "New" menu to the allowed content types.
		$whitelist = $this->resolve_whitelist();
		$new_nodes = array(
			'new-post'  => 'edit.php',
			'new-media' => 'upload.php',
			'new-page'  => 'edit.php?post_type=page',
			'new-user'  => 'users.php',
		);

		foreach ( $new_nodes as $node => $required_slug ) {
			if ( ! in_array( $required_slug, $whitelist['top'], true ) ) {
				$wp_admin_bar->remove_node( $node );
			}
		}

		if ( ! current_user_can( 'edit_posts' ) ) {
			$wp_admin_bar->remove_node( 'new-content' );
		}
	}

	/**
	 * Body classes for targeted CSS hiding.
	 *
	 * @since 0.1.0
	 *
	 * @param string $classes Previous classes.
	 * @return string
	 */
	public function body_class( $classes ) {
		if ( ! ClientMode::is_active() ) {
			return $classes;
		}

		$extra = array( 'qa-client-mode' );

		if ( Options::get( 'suppress_notices' ) ) {
			$extra[] = 'qa-hide-notices';
		}

		if ( Options::get( 'suppress_update_nags' ) ) {
			$extra[] = 'qa-hide-updates';
		}

		if ( Options::get( 'suppress_comment_bubble' ) ) {
			$extra[] = 'qa-hide-comment-bubble';
		}

		if ( Options::get( 'suppress_site_health' ) ) {
			$extra[] = 'qa-hide-site-health';
		}

		if ( Options::get( 'remove_default_widgets' ) ) {
			$extra[] = 'qa-minimal-dashboard';
		}

		if ( ClientMode::is_ghost_mode() && ! Roles::is_client() ) {
			$extra[] = 'qa-ghost-mode';
		}

		return trim( $classes . ' ' . implode( ' ', $extra ) );
	}

	/**
	 * Builds the effective whitelist from the settings.
	 *
	 * @since 0.1.0
	 *
	 * @return array{top:string[],subs:array<string,string[]>}
	 */
	protected function resolve_whitelist() {
		$top  = (array) Options::get( 'menu_whitelist' );
		$subs = array();

		foreach ( (array) Options::get( 'submenu_whitelist' ) as $token ) {
			if ( false === strpos( (string) $token, '||' ) ) {
				continue;
			}

			list( $parent, $sub ) = explode( '||', (string) $token, 2 );

			if ( '' === $parent || '' === $sub ) {
				continue;
			}

			$subs[ $parent ][] = $sub;
		}

		$whitelist = array(
			'top'  => array_values( array_filter( array_map( 'strval', $top ) ) ),
			'subs' => $subs,
		);

		/**
		 * Filter the effective menu whitelist.
		 *
		 * Example: `add_filter( 'quietadmin_menu_whitelist', fn( $w ) => array_merge( $w['top'], [ 'woocommerce' ] ) );`
		 *
		 * @since 0.1.0
		 *
		 * @param array $whitelist Whitelist with the keys 'top' and 'subs'.
		 */
		$whitelist = apply_filters( 'quietadmin_menu_whitelist', $whitelist );

		$whitelist['top']  = array_values( array_unique( (array) $whitelist['top'] ) );
		$whitelist['subs'] = (array) $whitelist['subs'];

		// Always allow the dashboard, otherwise the client ends up nowhere.
		if ( ! in_array( 'index.php', $whitelist['top'], true ) ) {
			array_unshift( $whitelist['top'], 'index.php' );
		}

		return $whitelist;
	}

	/**
	 * Removes counter suffixes such as " <span class="update-plugins count-3">3</span>".
	 *
	 * The core bubbles contain nested spans; a simple regex
	 * would leave remnants, so balanced parsing is used here.
	 *
	 * @since 0.1.0
	 *
	 * @param string $label          Raw label.
	 * @param bool   $strip_comments Also remove comment counters.
	 * @return string
	 */
	protected function strip_counts( $label, $strip_comments = true ) {
		$label = (string) $label;

		$patterns = array(
			'/class="[^"]*\bupdate-plugins\b/i',
			'/id="ab-awaiting-mod"/i',
		);

		if ( $strip_comments ) {
			$patterns[] = '/class="[^"]*\b(?:awaiting-mod|pending-mod)\b/i';
			$patterns[] = '/class="[^"]*\bcount-\d+/i';
		}

		$label = $this->remove_matching_spans( $label, $patterns );

		// Simple counters without markup, e.g. "Plugins 3".
		$label = preg_replace( '/\s+\d+\s*$/u', '', $label );

		return trim( (string) $label );
	}

	/**
	 * Removes <span> elements including nested children.
	 *
	 * @since 0.1.0
	 *
	 * @param string   $html     Markup.
	 * @param string[] $patterns Regexes that must match the opening tag.
	 * @return string
	 */
	protected function remove_matching_spans( $html, $patterns ) {
		$offset = 0;
		$length = strlen( $html );

		while ( $offset < $length && '' !== $html ) {
			$start = stripos( $html, '<span', $offset );

			if ( false === $start ) {
				break;
			}

			$tag_end = strpos( $html, '>', $start );

			if ( false === $tag_end ) {
				break;
			}

			$tag   = substr( $html, $start, $tag_end - $start + 1 );
			$match = false;

			foreach ( $patterns as $pattern ) {
				if ( preg_match( $pattern, $tag ) ) {
					$match = true;
					break;
				}
			}

			if ( ! $match ) {
				$offset = $tag_end + 1;
				continue;
			}

			// Find the balanced end (count nested spans).
			$depth = 1;
			$pos   = $tag_end + 1;
			$found = false;

			$html_length = strlen( $html );

			while ( $pos < $html_length ) {
				$next_open  = stripos( $html, '<span', $pos );
				$next_close = stripos( $html, '</span>', $pos );

				if ( false === $next_close ) {
					break;
				}

				if ( false !== $next_open && $next_open < $next_close ) {
					++$depth;
					$pos = $next_open + 5;
					continue;
				}

				--$depth;
				$pos = $next_close + 7;

				if ( 0 === $depth ) {
					$found = true;
					break;
				}
			}

			if ( ! $found ) {
				$offset = $tag_end + 1;
				continue;
			}

			$html   = substr( $html, 0, $start ) . substr( $html, $pos );
			$length = strlen( $html );
			$offset = $start;
		}

		return $html;
	}

	/**
	 * Removes CSS classes that draw counter bubbles.
	 *
	 * @since 0.1.0
	 *
	 * @param string $css_class      Class string.
	 * @param bool   $strip_comments Remove comment classes.
	 * @return string
	 */
	protected function clean_css_class( $css_class, $strip_comments = true ) {
		$parts = preg_split( '/\s+/', (string) $css_class );
		$keep  = array();

		foreach ( (array) $parts as $part ) {
			if ( '' === $part ) {
				continue;
			}

			if ( preg_match( '/^(update-plugins|count-\d+)$/', $part ) ) {
				continue;
			}

			if ( $strip_comments && preg_match( '/^(awaiting-mod|pending-mod|count-\d+)$/', $part ) ) {
				continue;
			}

			$keep[] = $part;
		}

		return implode( ' ', $keep );
	}

	/**
	 * First submenu slugs of a parent menu (typically the overview page).
	 *
	 * @since 0.1.0
	 *
	 * @param array $subs Submenu entries.
	 * @return string[]
	 */
	protected function first_sub_slugs( $subs ) {
		$slugs = array();

		foreach ( (array) $subs as $sub ) {
			if ( isset( $sub[2] ) ) {
				$slugs[] = $sub[2];
			}

			if ( count( $slugs ) >= 1 ) {
				break;
			}
		}

		return $slugs;
	}

	/**
	 * Whether the slug is a menu separator.
	 *
	 * @since 0.1.0
	 *
	 * @param string $slug Menu slug.
	 * @return bool
	 */
	protected function is_separator( $slug ) {
		return (bool) preg_match( '/^separator\d*$/', (string) $slug );
	}
}