<?php
namespace AccessNow\SimpleLMS;

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

class Rewrites {

	public static function init() {
		add_action( 'init', array( __CLASS__, 'register_rules' ), 20 );
		add_filter( 'query_vars', array( __CLASS__, 'register_query_vars' ) );
		add_action( 'parse_request', array( __CLASS__, 'resolve_request' ) );
		add_filter( 'post_type_link', array( __CLASS__, 'lesson_permalink' ), 10, 2 );
		add_filter( 'post_type_link', array( __CLASS__, 'quiz_permalink' ), 10, 2 );
		add_action( 'template_redirect', array( __CLASS__, 'legacy_redirects' ) );

		// One-time rewrite flush on upgrade
		add_action( 'init', array( __CLASS__, 'maybe_flush_rules' ), 99 );
	}

	/** Option recording the plugin version whose rewrite rules are in place. */
	const REWRITE_VERSION_OPTION = 'accessnow_slms_rewrite_version';

	public static function maybe_flush_rules() {
		if ( get_option( self::REWRITE_VERSION_OPTION ) !== ACCESSNOW_SLMS_VERSION ) {
			flush_rewrite_rules();
			update_option( self::REWRITE_VERSION_OPTION, ACCESSNOW_SLMS_VERSION );
		}
	}

	public static function register_rules() {
		// Quiz: /courses/{course}/{unit}/{lesson}/{quiz}/
		add_rewrite_rule(
			'^courses/([^/]+)/([^/]+)/([^/]+)/([^/]+)/?$',
			'index.php?accessnow_slms_resolve=quiz&accessnow_slms_course_slug=$matches[1]&accessnow_slms_unit_slug=$matches[2]&accessnow_slms_lesson_slug=$matches[3]&accessnow_slms_quiz_slug=$matches[4]',
			'top'
		);

		// Lesson: /courses/{course}/{unit}/{lesson}/
		add_rewrite_rule(
			'^courses/([^/]+)/([^/]+)/([^/]+)/?$',
			'index.php?accessnow_slms_resolve=lesson&accessnow_slms_course_slug=$matches[1]&accessnow_slms_unit_slug=$matches[2]&accessnow_slms_lesson_slug=$matches[3]',
			'top'
		);
	}

	public static function register_query_vars( $vars ) {
		$vars[] = 'accessnow_slms_resolve';
		$vars[] = 'accessnow_slms_course_slug';
		$vars[] = 'accessnow_slms_unit_slug';
		$vars[] = 'accessnow_slms_lesson_slug';
		$vars[] = 'accessnow_slms_quiz_slug';
		return $vars;
	}

	public static function resolve_request( $wp ) {
		$resolve = $wp->query_vars['accessnow_slms_resolve'] ?? '';
		if ( ! $resolve ) {
			return;
		}

		$course_slug = $wp->query_vars['accessnow_slms_course_slug'] ?? '';
		$unit_slug   = $wp->query_vars['accessnow_slms_unit_slug'] ?? '';

		if ( ! $course_slug || ! $unit_slug ) {
			return;
		}

		// Find course
		$course = self::get_post_by_slug( $course_slug, 'slms_course' );
		if ( ! $course ) {
			return;
		}

		// Find unit by slug + parent course
		$unit = self::get_child_by_slug( $unit_slug, 'slms_unit', '_slms_parent_course', $course->ID );
		if ( ! $unit ) {
			return;
		}

		if ( 'lesson' === $resolve ) {
			$lesson_slug = $wp->query_vars['accessnow_slms_lesson_slug'] ?? '';
			if ( ! $lesson_slug ) {
				return;
			}

			$lesson = self::get_child_by_slug( $lesson_slug, 'slms_lesson', '_slms_parent_unit', $unit->ID );
			if ( ! $lesson ) {
				return;
			}

			$wp->query_vars = array(
				'p'         => $lesson->ID,
				'post_type' => 'slms_lesson',
			);
		} elseif ( 'quiz' === $resolve ) {
			$lesson_slug = $wp->query_vars['accessnow_slms_lesson_slug'] ?? '';
			$quiz_slug   = $wp->query_vars['accessnow_slms_quiz_slug'] ?? '';
			if ( ! $lesson_slug || ! $quiz_slug ) {
				return;
			}

			$lesson = self::get_child_by_slug( $lesson_slug, 'slms_lesson', '_slms_parent_unit', $unit->ID );
			if ( ! $lesson ) {
				return;
			}

			$quiz = self::get_child_by_slug( $quiz_slug, 'slms_quiz', '_slms_parent_lesson', $lesson->ID );
			if ( ! $quiz ) {
				return;
			}

			$wp->query_vars = array(
				'p'         => $quiz->ID,
				'post_type' => 'slms_quiz',
			);
		}
	}

	/* ─── Permalink Filters ──────────────────────────────────── */

	public static function lesson_permalink( $post_link, $post ) {
		if ( 'slms_lesson' !== $post->post_type ) {
			return $post_link;
		}

		$ancestors = self::get_lesson_ancestors( $post->ID );
		if ( ! $ancestors ) {
			return $post_link;
		}

		return home_url(
			sprintf(
				'/courses/%s/%s/%s/',
				$ancestors['course_slug'],
				$ancestors['unit_slug'],
				$post->post_name
			)
		);
	}

	public static function quiz_permalink( $post_link, $post ) {
		if ( 'slms_quiz' !== $post->post_type ) {
			return $post_link;
		}

		$ancestors = self::get_quiz_ancestors( $post->ID );
		if ( ! $ancestors ) {
			return $post_link;
		}

		return home_url(
			sprintf(
				'/courses/%s/%s/%s/%s/',
				$ancestors['course_slug'],
				$ancestors['unit_slug'],
				$ancestors['lesson_slug'],
				$post->post_name
			)
		);
	}

	/* ─── Legacy URL Redirects ───────────────────────────────── */

	public static function legacy_redirects() {
		if ( ! is_singular( array( 'slms_lesson', 'slms_quiz' ) ) ) {
			return;
		}

		// Path relative to the site root, so subdirectory installs match too.
		$uri  = isset( $_SERVER['REQUEST_URI'] ) ? esc_url_raw( wp_unslash( $_SERVER['REQUEST_URI'] ) ) : '';
		$path = (string) wp_parse_url( $uri, PHP_URL_PATH );
		$home = (string) wp_parse_url( home_url( '/' ), PHP_URL_PATH );
		if ( '' !== $home && '/' !== $home && 0 === strpos( $path, $home ) ) {
			$path = '/' . substr( $path, strlen( $home ) );
		}

		if ( ( is_singular( 'slms_lesson' ) && preg_match( '#^/lessons/#', $path ) )
			|| ( is_singular( 'slms_quiz' ) && preg_match( '#^/quizzes/#', $path ) ) ) {
			wp_safe_redirect( get_permalink(), 301 );
			exit;
		}
	}

	/* ─── Helper Methods ─────────────────────────────────────── */

	private static function get_post_by_slug( $slug, $post_type ) {
		$posts = get_posts(
			array(
				'post_type'      => $post_type,
				'name'           => $slug,
				'post_status'    => array( 'publish', 'draft', 'private' ),
				'posts_per_page' => 1,
			)
		);

		return ! empty( $posts ) ? $posts[0] : null;
	}

	private static function get_child_by_slug( $slug, $post_type, $parent_meta_key, $parent_id ) {
		$posts = get_posts(
			array(
				'post_type'      => $post_type,
				'name'           => $slug,
				'post_status'    => array( 'publish', 'draft', 'private' ),
				'posts_per_page' => 1,
				'meta_key'       => $parent_meta_key, // phpcs:ignore WordPress.DB.SlowDBQuery.slow_db_query_meta_key -- course structure is stored as post meta.
				'meta_value'     => $parent_id, // phpcs:ignore WordPress.DB.SlowDBQuery.slow_db_query_meta_value -- course structure is stored as post meta.
			)
		);

		return ! empty( $posts ) ? $posts[0] : null;
	}

	private static function get_lesson_ancestors( $lesson_id ) {
		$unit_id = get_post_meta( $lesson_id, '_slms_parent_unit', true );
		if ( ! $unit_id ) {
			return null;
		}

		$unit = get_post( $unit_id );
		if ( ! $unit ) {
			return null;
		}

		$course_id = get_post_meta( $unit_id, '_slms_parent_course', true );
		if ( ! $course_id ) {
			return null;
		}

		$course = get_post( $course_id );
		if ( ! $course ) {
			return null;
		}

		return array(
			'course_slug' => $course->post_name,
			'unit_slug'   => $unit->post_name,
		);
	}

	private static function get_quiz_ancestors( $quiz_id ) {
		$lesson_id = get_post_meta( $quiz_id, '_slms_parent_lesson', true );
		if ( ! $lesson_id ) {
			return null;
		}

		$lesson = get_post( $lesson_id );
		if ( ! $lesson ) {
			return null;
		}

		$ancestors = self::get_lesson_ancestors( $lesson_id );
		if ( ! $ancestors ) {
			return null;
		}

		$ancestors['lesson_slug'] = $lesson->post_name;
		return $ancestors;
	}
}