<?php

namespace AcademicCrew\Roles;

use AcademicCrew\Core\Loader;

/**
 * Grants `edit_post` capability to all instructors linked to a course page.
 *
 * Instructor WP user IDs are stored in `_academiccrew_instructor_user_ids` on the
 * page post and refreshed each time the course CPT post is saved.
 */
class CoursePageCapabilities {

    public function register( Loader $loader ): void {
        $loader->add_filter( 'user_has_cap', $this, 'grant_course_page_edit', 10, 4 );
    }

    public function grant_course_page_edit(
        array $allcaps,
        array $caps,
        array $args,
        \WP_User $user
    ): array {
        // $caps holds the primitive caps the meta cap was mapped to, so the
        // requested meta cap itself is in $args[0].
        if ( ! in_array( $args[0] ?? '', [ 'edit_post', 'edit_page' ], true ) ) {
            return $allcaps;
        }

        $post_id = $args[2] ?? null;
        if ( ! $post_id || 'page' !== get_post_type( $post_id ) ) {
            return $allcaps;
        }

        // Is this a academiccrew course page?
        $course_id = get_post_meta( $post_id, '_academiccrew_course_id', true );
        if ( ! $course_id ) {
            return $allcaps;
        }

        // Is the current user among the course instructors?
        $instructor_ids = get_post_meta( $post_id, '_academiccrew_instructor_user_ids', true );
        if ( is_array( $instructor_ids ) && in_array( $user->ID, $instructor_ids, true ) ) {
            // Grant the primitive caps this meta cap maps to (edit_pages,
            // edit_published_pages, …), for this one page only.
            foreach ( $caps as $cap ) {
                $allcaps[ $cap ] = true;
            }
        }

        return $allcaps;
    }
}