<?php
namespace AccessNow\SimpleLMS;

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

class Access_Control {

	public static function init() {
		add_action( 'template_redirect', array( __CLASS__, 'check_access' ) );

		// The block editor needs lessons in the REST API; don't let it bypass enrolment.
		add_filter( 'rest_prepare_slms_lesson', array( __CLASS__, 'protect_rest_lesson' ), 10, 2 );
	}

	/**
	 * Hide lesson content in REST responses from people who could not view the lesson page.
	 *
	 * @param WP_REST_Response $response Response object.
	 * @param WP_Post          $post     Lesson post.
	 * @return WP_REST_Response
	 */
	public static function protect_rest_lesson( $response, $post ) {
		if ( current_user_can( 'edit_post', $post->ID ) || current_user_can( 'manage_slms' ) ) {
			return $response;
		}

		$user_id   = get_current_user_id();
		$course_id = (int) self::get_course_id_from_content( $post->ID, 'slms_lesson' );
		if ( $user_id && $course_id && Enrollment::has_access( $user_id, $course_id ) ) {
			return $response;
		}

		$data = $response->get_data();
		foreach ( array( 'content', 'excerpt' ) as $field ) {
			if ( isset( $data[ $field ] ) && is_array( $data[ $field ] ) ) {
				$data[ $field ]['rendered']  = '';
				$data[ $field ]['protected'] = true;
				unset( $data[ $field ]['raw'] );
			}
		}
		$response->set_data( $data );

		return $response;
	}

	public static function check_access() {
		if ( is_admin() ) {
			return;
		}

		$post_type = get_post_type();
		if ( ! in_array( $post_type, array( 'slms_lesson', 'slms_quiz' ), true ) ) {
			return;
		}

		if ( ! is_user_logged_in() ) {
			wp_safe_redirect( wp_login_url( get_permalink() ) );
			exit;
		}

		$post_id = get_the_ID();
		$user_id = get_current_user_id();

		// Get the course ID from the content hierarchy
		$course_id = self::get_course_id_from_content( $post_id, $post_type );
		if ( ! $course_id ) {
			return;
		}

		// Enrolled, and access hasn't ended (the course page says when it ended).
		if ( ! Enrollment::has_access( $user_id, $course_id ) && ! Capabilities::can_preview( $post_id ) ) {
			wp_safe_redirect( get_permalink( $course_id ) );
			exit;
		}

		// Check sequential access for lessons
		if ( 'slms_lesson' === $post_type ) {
			if ( ! Progress::can_access_lesson( $user_id, $post_id, $course_id ) && ! Capabilities::can_preview( $post_id ) ) {
				wp_safe_redirect( get_permalink( $course_id ) );
				exit;
			}
		}
	}

	public static function get_course_id_from_content( $post_id, $post_type = '' ) {
		if ( ! $post_type ) {
			$post_type = get_post_type( $post_id );
		}

		if ( 'slms_course' === $post_type ) {
			return $post_id;
		}

		if ( 'slms_lesson' === $post_type ) {
			$unit_id = get_post_meta( $post_id, '_slms_parent_unit', true );
			if ( $unit_id ) {
				return get_post_meta( $unit_id, '_slms_parent_course', true );
			}
		}

		if ( 'slms_quiz' === $post_type ) {
			$lesson_id = get_post_meta( $post_id, '_slms_parent_lesson', true );
			if ( $lesson_id ) {
				return self::get_course_id_from_content( $lesson_id, 'slms_lesson' );
			}
		}

		return 0;
	}
}