<?php

namespace App\Http\Controllers;

use App\Models\Course;
use App\Models\Lesson;
use App\Models\Enrollment;
use App\Models\UserProgress;
use Illuminate\Http\Request;
use Inertia\Inertia;
use Inertia\Response;

class CoursePlayerController extends Controller
{
    /**
     * Display the course player.
     */
    public function show(Request $request, string $courseSlug, string $lessonSlug = null): Response
    {
        $user = $request->user();
        
        $course = Course::where('slug', $courseSlug)
            ->with(['modules.lessons'])
            ->firstOrFail();

        // Check enrollment
        $isEnrolled = Enrollment::where('user_id', $user->id)
            ->where('course_id', $course->id)
            ->exists();

        if (!$isEnrolled) {
            return Inertia::render('Errors/Unauthorized', [
                'message' => 'Anda belum terdaftar di kursus ini.'
            ]);
        }

        // Get all lessons for navigation and progress check
        $allLessons = $course->modules->flatMap->lessons;
        
        // Find current lesson with vocabularies
        $currentLesson = $lessonSlug 
            ? Lesson::where('slug', $lessonSlug)->with('vocabularies')->firstOrFail()
            : $allLessons->first()->load('vocabularies');

        // Navigation Logic (Next/Prev)
        $currentIndex = $allLessons->search(function ($item) use ($currentLesson) {
            return $item->id === $currentLesson->id;
        });
        
        $prevLesson = $currentIndex > 0 ? $allLessons[$currentIndex - 1] : null;
        $nextLesson = $currentIndex < $allLessons->count() - 1 ? $allLessons[$currentIndex + 1] : null;

        // Get user progress for this course
        $completedLessonsIds = UserProgress::where('user_id', $user->id)
            ->whereIn('lesson_id', $allLessons->pluck('id'))
            ->whereNotNull('completed_at')
            ->pluck('lesson_id')
            ->toArray();

        // Initialize started_at if first time viewing
        UserProgress::firstOrCreate(
            ['user_id' => $user->id, 'lesson_id' => $currentLesson->id],
            ['started_at' => now(), 'last_heartbeat_at' => now()]
        );

        return Inertia::render('Courses/Learn', [
            'course' => [
                'id' => $course->id,
                'title' => $course->title,
                'slug' => $course->slug,
                'progress_percentage' => count($allLessons) > 0 ? round((count($completedLessonsIds) / count($allLessons)) * 100) : 0,
            ],
            'modules' => $course->modules->map(function ($module) use ($completedLessonsIds) {
                return [
                    'id' => $module->id,
                    'title' => $module->title,
                    'lessons' => $module->lessons->map(function ($lesson) use ($completedLessonsIds) {
                        return [
                            'id' => $lesson->id,
                            'title' => $lesson->title,
                            'slug' => $lesson->slug,
                            'type' => $lesson->type,
                            'duration_seconds' => $lesson->duration_seconds,
                            'is_completed' => in_array($lesson->id, $completedLessonsIds),
                        ];
                    })
                ];
            }),
            'lesson' => [
                'id' => $currentLesson->id,
                'title' => $currentLesson->title,
                'slug' => $currentLesson->slug,
                'type' => $currentLesson->type,
                'content' => $currentLesson->content,
                'video_url' => $currentLesson->video_url,
                // Prefer Spatie Media Library URL (R2), fallback to legacy column
                'content_pdf' => $currentLesson->getFirstMediaUrl('content_pdf') ?: $currentLesson->content_pdf, 
                'duration_seconds' => $currentLesson->duration_seconds,
                'is_completed' => in_array($currentLesson->id, $completedLessonsIds),
                'vocabularies' => $currentLesson->vocabularies,
                'next_lesson_slug' => $nextLesson?->slug,
                'prev_lesson_slug' => $prevLesson?->slug,
                'attachments' => $currentLesson->getMedia('attachments')->map(function ($media) {
                    return [
                        'id' => $media->uuid,
                        'name' => $media->file_name,
                        'url' => $media->getUrl(),
                        'size' => $media->human_readable_size,
                    ];
                }),
            ],
        ]);
    }

    /**
     * Mark a lesson as completed.
     */
    public function complete(Request $request, Lesson $lesson)
    {
        $user = $request->user();

        $alreadyCompleted = UserProgress::where('user_id', $user->id)
            ->where('lesson_id', $lesson->id)
            ->exists();

        UserProgress::updateOrCreate(
            ['user_id' => $user->id, 'lesson_id' => $lesson->id],
            ['completed_at' => now()]
        );

        if (!$alreadyCompleted) {
            $user->increment('xp_points', 50);
        }

        return back()->with('success', 'Materi selesai! +50 XP');
    }

    /**
     * Update learning duration via heartbeat.
     */
    public function heartbeat(Request $request, Lesson $lesson)
    {
        $user = $request->user();
        $now = now();

        $progress = UserProgress::firstOrCreate(
            ['user_id' => $user->id, 'lesson_id' => $lesson->id],
            ['started_at' => $now, 'last_heartbeat_at' => $now]
        );

        $lastHeartbeat = $progress->last_heartbeat_at ?? $progress->created_at;
        $diffSeconds = $now->diffInSeconds($lastHeartbeat);

        // Limit diff to prevent massive jumps (e.g. if user leaves tab open and comes back hours later)
        // Max 90 seconds per heartbeat (assuming heartbeat is every 60s)
        $increment = min($diffSeconds, 90);

        $progress->increment('time_spent_seconds', $increment);
        $progress->update(['last_heartbeat_at' => $now]);

        return response()->json([
            'status' => 'success',
            'time_spent' => $progress->time_spent_seconds,
        ]);
    }
}