<?php
namespace App\Http\Controllers\Admin;
use App\Http\Controllers\Controller;
use App\Models\Question;
use App\Models\Subject;
use App\Models\AnswerOption;
use Illuminate\Http\Request;
use Illuminate\Support\Facades\DB;
class QuestionController extends Controller {
    public function index(Request $r) {
        $subjects  = Subject::all();
        $query     = Question::with('subject')->latest();
        if ($r->filled('subject')) $query->where('subject_id', $r->subject);
        $questions = $query->paginate(20)->withQueryString();
        return view('admin.questions.index', compact('questions','subjects'));
    }
    public function create() {
        $subjects = Subject::all();
        return view('admin.questions.create', compact('subjects'));
    }
    public function store(Request $r) {
        $r->validate([
            'subject_id'    => 'required|exists:subjects,id',
            'question_text' => 'required|string',
            'type'          => 'required|in:multiple_choice,number_input',
            'difficulty'    => 'required|in:1,2,3',
            'options'       => 'required_if:type,multiple_choice|array|min:2',
            'options.*'     => 'required|string',
            'correct'       => 'required_if:type,multiple_choice|integer',
            'number_answer' => 'required_if:type,number_input',
        ]);
        $pts = [1=>5, 2=>10, 3=>20][$r->difficulty];
        $q = Question::create([
            'subject_id'    => $r->subject_id,
            'question_text' => $r->question_text,
            'type'          => $r->type,
            'difficulty'    => $r->difficulty,
            'points_value'  => $pts,
            'active'        => true,
        ]);
        if ($r->type === 'multiple_choice') {
            foreach ($r->options as $i => $text) {
                if (trim($text) === '') continue;
                AnswerOption::create([
                    'question_id' => $q->id,
                    'text'        => $text,
                    'is_correct'  => ($i == $r->correct),
                    'sort_order'  => $i,
                ]);
            }
        } else {
            AnswerOption::create([
                'question_id' => $q->id,
                'text'        => $r->number_answer,
                'is_correct'  => true,
                'sort_order'  => 0,
            ]);
        }
        return redirect()->route('admin.questions.index')->with('success','Frage gespeichert.');
    }
    public function edit(Question $question) {
        $subjects = Subject::all();
        $question->load('answerOptions');
        return view('admin.questions.edit', compact('question','subjects'));
    }
    public function update(Request $r, Question $question) {
        $r->validate([
            'subject_id'    => 'required|exists:subjects,id',
            'question_text' => 'required|string',
            'difficulty'    => 'required|in:1,2,3',
            'options'       => 'array',
            'options.*'     => 'string',
            'correct'       => 'integer',
        ]);
        $pts = [1=>5, 2=>10, 3=>20][$r->difficulty];
        $question->update([
            'subject_id'    => $r->subject_id,
            'question_text' => $r->question_text,
            'difficulty'    => $r->difficulty,
            'points_value'  => $pts,
            'active'        => $r->boolean('active', true),
        ]);
        if ($r->filled('options')) {
            $question->answerOptions()->delete();
            foreach ($r->options as $i => $text) {
                if (trim($text) === '') continue;
                AnswerOption::create([
                    'question_id' => $question->id,
                    'text'        => $text,
                    'is_correct'  => ($i == $r->correct),
                    'sort_order'  => $i,
                ]);
            }
        }
        return redirect()->route('admin.questions.index')->with('success','Gespeichert.');
    }
    public function destroy(Question $question) {
        $question->delete();
        return redirect()->route('admin.questions.index')->with('success','Frage gelöscht.');
    }

    public function export(Request $r) {
        $query = Question::with(['subject','answerOptions'])->latest();
        if ($r->filled('subject')) $query->where('subject_id', $r->subject);
        $data = $query->get()->map(fn($q) => [
            'subject'       => $q->subject->slug,
            'question_text' => $q->question_text,
            'type'          => $q->type,
            'difficulty'    => $q->difficulty,
            'points_value'  => $q->points_value,
            'active'        => (bool)$q->active,
            'options'       => $q->answerOptions->map(fn($o) => [
                'text'       => $o->text,
                'is_correct' => (bool)$o->is_correct,
            ])->values(),
        ]);
        $filename = 'fragen-' . now()->format('Y-m-d') . '.json';
        return response()->streamDownload(
            fn() => print(json_encode($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:2048']);
        $raw = json_decode(file_get_contents($r->file('file')->getRealPath()), true);
        if (!is_array($raw)) {
            return back()->with('error', 'Ungültiges JSON-Format.');
        }
        $subjects = Subject::pluck('id','slug');
        $imported = 0;
        $skipped  = 0;
        DB::transaction(function() use ($raw, $subjects, &$imported, &$skipped) {
            foreach ($raw as $item) {
                if (empty($item['subject']) || !isset($subjects[$item['subject']])) { $skipped++; continue; }
                if (empty($item['question_text']))                                  { $skipped++; continue; }
                $q = Question::create([
                    'subject_id'    => $subjects[$item['subject']],
                    'question_text' => $item['question_text'],
                    'type'          => $item['type'] ?? 'multiple_choice',
                    'difficulty'    => $item['difficulty'] ?? 1,
                    'points_value'  => $item['points_value'] ?? 5,
                    'active'        => $item['active'] ?? true,
                ]);
                foreach (($item['options'] ?? []) as $i => $opt) {
                    AnswerOption::create([
                        'question_id' => $q->id,
                        'text'        => $opt['text'],
                        'is_correct'  => $opt['is_correct'] ?? false,
                        'sort_order'  => $i,
                    ]);
                }
                $imported++;
            }
        });
        $msg = "{$imported} Fragen importiert.";
        if ($skipped) $msg .= " {$skipped} übersprungen (unbekanntes Fach oder fehlender Text).";
        return back()->with('success', $msg);
    }
}