<?php
namespace App\Http\Controllers\Admin;
use App\Http\Controllers\Controller;
use App\Models\{Quiz, QuizQuestion, QuizAnswerOption, Subject};
use Illuminate\Http\Request;
use Illuminate\Support\Facades\DB;

class QuizController extends Controller {

    public function index() {
        $quizzes = Quiz::with('subject')->withCount('questions')->latest()->get();
        return view('admin.quizzes.index', compact('quizzes'));
    }

    public function create() {
        $subjects = Subject::all();
        return view('admin.quizzes.create', compact('subjects'));
    }

    public function store(Request $r) {
        $r->validate(['title'=>'required|string|max:120','subject_id'=>'required|exists:subjects,id','description'=>'nullable|string|max:500']);
        $quiz = Quiz::create($r->only('title','subject_id','description') + ['active'=>true]);
        return redirect()->route('admin.quizzes.edit', $quiz)->with('success','Quiz erstellt – jetzt Fragen hinzufügen.');
    }

    public function edit(Quiz $quiz) {
        $subjects  = Subject::all();
        $questions = $quiz->questions()->with('answerOptions')->get();
        return view('admin.quizzes.edit', compact('quiz','subjects','questions'));
    }

    public function update(Request $r, Quiz $quiz) {
        $r->validate(['title'=>'required|string|max:120','subject_id'=>'required|exists:subjects,id','description'=>'nullable|string|max:500']);
        $quiz->update($r->only('title','subject_id','description') + ['active'=>$r->boolean('active')]);
        return back()->with('success','Quiz gespeichert.');
    }

    public function destroy(Quiz $quiz) {
        $quiz->delete();
        return redirect()->route('admin.quizzes.index')->with('success','Quiz gelöscht.');
    }

    public function export(Quiz $quiz) {
        $quiz->load('subject','questions.answerOptions');
        $data = [
            'subject'     => $quiz->subject->slug,
            'title'       => $quiz->title,
            'description' => $quiz->description,
            'questions'   => $quiz->questions->map(fn($q) => [
                'type'           => $q->type,
                'question_text'  => $q->question_text,
                'time_limit'     => $q->time_limit,
                'correct_answer' => $q->correct_answer,
                'options'        => $q->answerOptions->map(fn($o) => [
                    'text'       => $o->text,
                    'is_correct' => (bool)$o->is_correct,
                ])->values(),
            ])->values(),
        ];
        $filename = 'quiz-'.now()->format('Y-m-d').'-'.str($quiz->title)->slug().'.json';
        return response()->streamDownload(
            fn() => print(json_encode($data, JSON_PRETTY_PRINT|JSON_UNESCAPED_UNICODE)),
            $filename, ['Content-Type'=>'application/json']
        );
    }

    public function import(Request $r) {
        $r->validate(['file'=>'required|file|mimes:json|max:4096']);
        $raw = json_decode(file_get_contents($r->file('file')->getRealPath()), true);
        if (!is_array($raw) || !isset($raw['title'],$raw['subject'],$raw['questions'])) {
            return back()->with('error','Ungültiges JSON-Format. Felder: title, subject, questions erwartet.');
        }
        $subject = Subject::where('slug',$raw['subject'])->first();
        if (!$subject) return back()->with('error','Unbekanntes Fach: '.$raw['subject']);

        DB::transaction(function() use ($raw,$subject) {
            $quiz = Quiz::create([
                'subject_id'  => $subject->id,
                'title'       => $raw['title'],
                'description' => $raw['description'] ?? null,
                'active'      => true,
            ]);
            foreach (array_slice($raw['questions'],0,10) as $i => $item) {
                $q = QuizQuestion::create([
                    'quiz_id'        => $quiz->id,
                    'sort_order'     => $i,
                    'type'           => $item['type'] ?? 'multiple_choice',
                    'question_text'  => $item['question_text'],
                    'time_limit'     => $item['time_limit'] ?? null,
                    'correct_answer' => $item['correct_answer'] ?? null,
                ]);
                foreach (($item['options'] ?? []) as $j => $opt) {
                    QuizAnswerOption::create([
                        'quiz_question_id' => $q->id,
                        'text'       => $opt['text'],
                        'is_correct' => $opt['is_correct'] ?? false,
                        'sort_order' => $j,
                    ]);
                }
            }
        });
        return redirect()->route('admin.quizzes.index')->with('success','Quiz "'.$raw['title'].'" importiert.');
    }
}