<?php

namespace FluentCommunity\Modules\Course\Services;

use FluentCommunity\App\Models\Activity;
use FluentCommunity\App\Models\Meta;
use FluentCommunity\App\Models\Reaction;
use FluentCommunity\App\Models\SpaceUserPivot;
use FluentCommunity\App\Models\Term;
use FluentCommunity\App\Services\CustomSanitizer;
use FluentCommunity\App\Services\Helper;
use FluentCommunity\Framework\Support\Arr;
use FluentCommunity\Modules\Course\Model\Course;
use FluentCommunity\Modules\Course\Model\CourseLesson;

class CourseHelper
{
    public static function getCourseProgressTrack($courseId, $userId = null)
    {
        $isEnrolled = self::isEnrolled($courseId, $userId);

        return [
            'completed_lessons' => $isEnrolled ? self::getCompletedLessonIds($courseId, $userId) : [],
            'isEnrolled'        => $isEnrolled,
            'progress'          => $isEnrolled ? self::getCourseProgress($courseId, $userId) : 0,
        ];
    }

    public static function isEnrolled($courseId, $userId = null)
    {
        if (!$userId) {
            $userId = get_current_user_id();
        }

        if (!$userId) {
            return false;
        }

        return SpaceUserPivot::where('space_id', $courseId)
            ->where('user_id', $userId)
            ->exists();
    }

    public static function getCourseEnrollment($courseId, $userId = null)
    {
        if (!$userId) {
            $userId = get_current_user_id();
        }

        if (!$userId) {
            return null;
        }

        return SpaceUserPivot::where('space_id', $courseId)
            ->where('user_id', $userId)
            ->first();

    }

    public static function getCoursePublishedLessonIds($courseId)
    {
        static $counts = [];

        if (isset($counts[$courseId])) {
            return $counts[$courseId];
        }

        $counts[$courseId] = CourseLesson::where('space_id', $courseId)
            ->where('status', 'published')
            ->pluck('id')
            ->toArray();

        return $counts[$courseId];
    }

    public static function getCourseProgress($courseId, $userId = null)
    {
        if (!$userId) {
            $userId = get_current_user_id();
        }

        if (!$userId) {
            return 0;
        }

        $lessonIds = self::getCoursePublishedLessonIds($courseId);

        if (!$lessonIds) {
            return 0;
        }

        $completedLessons = Reaction::where('user_id', $userId)
            ->whereIn('object_id', $lessonIds)
            ->where('object_type', 'lesson_completed')
            ->where('type', 'completed')
            ->count();

        if (!$completedLessons) {
            return 0;
        }

        $result = floor(($completedLessons / count($lessonIds)) * 100);

        if (!$result) {
            return 0;
        }

        if ($result > 100) {
            return 100;
        }

        return $result;

    }

    public static function getCompletedLessonIds($courseId, $userId = null)
    {
        if (!$userId) {
            $userId = get_current_user_id();
        }

        if (!$userId) {
            return [];
        }

        return Reaction::where('user_id', $userId)
            ->where('parent_id', $courseId)
            ->where('object_type', 'lesson_completed')
            ->where('type', 'completed')
            ->pluck('object_id')
            ->toArray();
    }

    public static function overallCourseProgressAverage($course)
    {
        $lessonsCount = CourseLesson::where('space_id', $course->id)
            ->where('status', 'published')
            ->count();

        if (!$lessonsCount) {
            return 0;
        }

        $allCompletedCount = Reaction::where('object_type', 'lesson_completed')
            ->where('type', 'completed')
            ->where('parent_id', $course->id)
            ->count();

        $studentsCount = $course->students_count ? $course->students_count : $course->students()->count();

        if (!$studentsCount) {
            return 0;
        }

        // calculate the average of all students
        return ceil(($allCompletedCount / ($studentsCount * $lessonsCount)) * 100);
    }

    public static function updateLessonCompletion($lesson, $userId, $state = 'completed')
    {
        $reaction = Reaction::where('user_id', $userId)
            ->where('object_id', $lesson->id)
            ->where('object_type', 'lesson_completed')
            ->first();

        if ($reaction) {
            if ($state != 'completed') {
                $reaction->type = 'incomplete';
                $reaction->save();
            } else {
                $reaction->type = 'completed';
                $reaction->save();
            }
            return true;
        }

        Reaction::create([
            'user_id'     => $userId,
            'object_id'   => $lesson->id,
            'object_type' => 'lesson_completed',
            'parent_id'   => $lesson->space_id,
            'type'        => 'completed'
        ]);

        do_action('fluent_community/lesson_completed', $lesson, $userId);

        return true;
    }

    public static function getCourseMeta($key, $default = false, $withModel = false)
    {
        $meta = Meta::where('meta_key', $key)
            ->where('object_type', 'course')
            ->first();

        if ($withModel) {
            return $meta;
        }

        return $meta ? $meta->value : $default;
    }

    public static function updateCourseMeta($key, $value)
    {
        $meta = Meta::where('meta_key', $key)
            ->where('object_type', 'course')
            ->first();

        if ($meta) {
            $meta->update([
                'value' => $value
            ]);
            return $meta;
        }

        return Meta::create([
            'meta_key'    => $key,
            'value'       => $value,
            'object_type' => 'course'
        ]);
    }

    public static function completeCourse($course, $userId)
    {
        $exists = Activity::where('feed_id', $course->id) // we are using feed_id as it's indexed in the DB
        ->where('user_id', $userId)
            ->where('action_name', 'course_completed')
            ->exists();

        if ($exists) {
            return false;
        }

        Activity::create([
            'feed_id'     => $course->id,
            'user_id'     => $userId,
            'action_name' => 'course_completed'
        ]);

        do_action('fluent_community/course/completed', $course, $userId);

        return true;
    }

    public static function enrollCourse($course, $userId = null, $by = 'self')
    {
        return Helper::addToSpace($course, $userId, 'student', $by);
    }

    public static function enrollCourses($courseIds, $userId = null, $by = 'self')
    {
        if (!$userId) {
            $userId = get_current_user_id();
        }

        $enrolledCourseIds = [];

        foreach ($courseIds as $courseId) {
            $course = Course::find($courseId);
            if ($course) {
                if (self::enrollCourse($course, $userId, $by)) {
                    $enrolledCourseIds[] = $courseId;
                }
            }
        }

        return $enrolledCourseIds;
    }

    public static function leaveCourse($course, $userId = null, $by = 'self')
    {
        if (!$userId) {
            $userId = get_current_user_id();
        }

        if (!self::isEnrolled($course->id, $userId)) {
            return false;
        }

        SpaceUserPivot::where('user_id', $userId)->where('space_id', $course->id)->delete();

        do_action('fluent_community/course/left', $course, $userId, $by);

        return true;
    }

    public static function leaveCourses($courseIds, $userId = null, $by = 'self')
    {
        if (!$userId) {
            $userId = get_current_user_id();
        }

        $processedCourseIds = [];

        foreach ($courseIds as $courseId) {
            $course = Course::find($courseId);
            if ($course) {
                if (self::leaveCourse($course, $userId, $by)) {
                    $processedCourseIds[] = $courseId;
                }
            }

        }

        return $processedCourseIds;
    }

    public static function getEnrolledCourseIds($userId = null)
    {
        if (!$userId) {
            $userId = get_current_user_id();
        }

        if (!$userId) {
            return [];
        }

        return SpaceUserPivot::where('user_id', $userId)
            ->where('role', 'student')
            ->pluck('space_id')
            ->toArray();

    }

    public static function getSectionAccessDate($section, $courseType, $enrollment = null)
    {
        if ($courseType == 'slef_paced') {
            return null;
        }

        if ($courseType == 'scheduled') {
            return $section->scheduled_at;
        }

        // This is for structured course
        if (!$enrollment) {
            return null;
        }

        $accessAfterEnrollment = $section->reactions_count;

        return gmdate('Y-m-d H:i:s', strtotime($enrollment->created_at) + $accessAfterEnrollment * 86400);
    }

    public static function sanitizeLessonMeta($meta)
    {
        $validFields = [
            'enable_comments',
            'enable_media',
            'media',
            'video_length',
        ];

        $meta = Arr::only($meta, $validFields);

        $yesNoFields = ['enable_comments', 'enable_media'];

        foreach ($yesNoFields as $field) {
            $meta[$field] = Arr::get($meta, $field, 'no') == 'yes' ? 'yes' : 'no';
        }

        if (Arr::get($meta, 'enable_media') == 'yes') {
            if ($media = Arr::get($meta, 'media', [])) {
                $media = array_filter([
                    'type'         => sanitize_text_field(Arr::get($media, 'type', '')),
                    'url'          => sanitize_url(Arr::get($media, 'url', '')),
                    'content_type' => sanitize_text_field(Arr::get($media, 'content_type', '')),
                    'provider'     => sanitize_url(Arr::get($media, 'provider', '')),
                    'title'        => sanitize_text_field(Arr::get($media, 'title', '')),
                    'author_name'  => sanitize_text_field(Arr::get($media, 'author_name', '')),
                    'html'         => CustomSanitizer::sanitizeRichText(Arr::get($media, 'html', '')),
                ]);
                $meta['media'] = $media;
            }
        } else {
            $meta['media'] = [
                'provider' => ''
            ];
        }

        $numericFields = ['video_length'];

        foreach ($numericFields as $field) {
            $meta[$field] = absint(Arr::get($meta, $field, 0));
        }

        return $meta;
    }

    public static function getCourseCategories()
    {
        $terms = Term::whereHas('base_spaces', function ($q) {
            $q->where('type', 'course');
        })->get();

        $formattedTerms = [];

        foreach ($terms as $term) {
            $formattedTerms[] = [
                'id'          => $term->id,
                'title'       => $term->title,
                'slug'        => $term->slug
            ];
        }

        return $formattedTerms;
    }
}