<?php

namespace App\Http\Controllers\api;

use App\Http\Controllers\Controller;
use App\Models\Quiz;
use App\Models\QuizCategory;
use App\Models\QuizSubject;
use App\Models\UserQuizAttempt;
use App\Models\UserQuizAnswer;
use App\Models\Question;
use App\Traits\BaseApiResponse;
use Illuminate\Http\Request;
use Illuminate\Support\Facades\DB;

class QuizController extends Controller
{
    use BaseApiResponse;

    /**
     * 1. Get all active Categories
     */
    public function categories()
    {
        $categories = QuizCategory::where('is_active', true)->get();
        return $this->success($categories, 'موفق', 'لیست دسته‌بندی‌ها دریافت شد');
    }

    /**
     * 2. Get all Subjects
     */
    public function subjects()
    {
        $subjects = QuizSubject::all();
        return $this->success($subjects, 'موفق', 'لیست دروس دریافت شد');
    }

    /**
     * 3. List Quizzes (Filterable by Category or Subject)
     */
    public function index(Request $request)
    {
        $query = Quiz::where('is_published', true)->with('category');

        if ($request->filled('category_id')) {
            $query->where('category_id', $request->category_id);
        }

        if ($request->filled('subject_id')) {
            $query->whereHas('questions', function ($q) use ($request) {
                $q->where('subject_id', $request->subject_id);
            });
        }

        $quizzes = $query->latest()->get();

        return $this->success($quizzes, 'موفق', 'لیست آزمون‌ها دریافت شد');
    }

    /**
     * 4. Start a Quiz & Fetch Questions (SECURELY)
     */
    public function start(Quiz $quiz)
    {
        if (!$quiz->is_published) {
            return response()->json(['message' => 'این آزمون در دسترس نیست.'], 403);
        }

        $attempt = UserQuizAttempt::create([
            'user_id' => auth()->id(),
            'quiz_id' => $quiz->id,
            'started_at' => now(),
            'status' => 'in_progress'
        ]);

        $quiz->load(['questions' => function($q) {
            $q->orderBy('order', 'asc');
        }, 'questions.options']);

        // SECURITY: Hide the correct answers and explanations before sending to mobile app
        $quiz->questions->each(function ($question) {
            $question->makeHidden(['solution_explanation']);
            $question->options->each->makeHidden(['is_correct']);
        });

        $data = [
            'attempt_id' => $attempt->id,
            'quiz' => $quiz
        ];

        return $this->success($data, 'موفق', 'آزمون با موفقیت شروع شد');
    }

    /**
     * 5. Submit the Quiz & Calculate Score
     */
    public function submit(Request $request, UserQuizAttempt $attempt)
    {
        if ($attempt->user_id !== auth()->id() || $attempt->status !== 'in_progress') {
            return response()->json(['message' => 'دسترسی غیرمجاز یا آزمون قبلاً پایان یافته است.'], 403);
        }

        $request->validate([
            'answers' => 'required|array',
            'answers.*.question_id' => 'required|exists:questions,id',
            'answers.*.selected_option_id' => 'nullable|exists:question_options,id',
            'answers.*.text_answer' => 'nullable|string',
        ]);

        $quiz = $attempt->quiz;

        $totalScore = 0.00;
        $correctCount = 0;
        $wrongCount = 0;
        $unansweredCount = 0;
        $needsGrading = false;

        DB::beginTransaction();
        try {
            foreach ($request->answers as $ans) {
                $question = Question::with('options')->find($ans['question_id']);

                $isCorrect = false;
                $earnedScore = 0.00;

                // Handle Multiple Choice
                if ($question->type === 'multiple_choice') {
                    if (empty($ans['selected_option_id'])) {
                        $unansweredCount++;
                        $isCorrect = null;
                    } else {
                        $correctOption = $question->options->where('is_correct', true)->first();

                        if ($correctOption && $correctOption->id == $ans['selected_option_id']) {
                            $isCorrect = true;
                            $earnedScore = $question->score;
                            $totalScore += $earnedScore;
                            $correctCount++;
                        } else {
                            $isCorrect = false;
                            if ($quiz->has_negative_score) {
                                $earnedScore = -($question->score / 3);
                                $totalScore += $earnedScore;
                            }
                            $wrongCount++;
                        }
                    }
                }
                // Handle Descriptive
                else if ($question->type === 'descriptive') {
                    $needsGrading = true;
                    $isCorrect = null;
                }

                UserQuizAnswer::create([
                    'attempt_id' => $attempt->id,
                    'question_id' => $question->id,
                    'selected_option_id' => $ans['selected_option_id'] ?? null,
                    'text_answer' => $ans['text_answer'] ?? null,
                    'is_correct' => $isCorrect,
                    'earned_score' => $earnedScore,
                ]);
            }

            $attempt->update([
                'completed_at' => now(),
                'total_score' => $totalScore,
                'correct_answers' => $correctCount,
                'wrong_answers' => $wrongCount,
                'unanswered' => $unansweredCount,
                'status' => $needsGrading ? 'pending_grading' : 'completed',
            ]);

            DB::commit();

            $data = [
                'attempt_id' => $attempt->id,
                'status' => $attempt->status
            ];

            return $this->success($data, 'موفق', 'آزمون با موفقیت ثبت شد.');

        } catch (\Exception $e) {
            DB::rollBack();
            return response()->json(['message' => 'خطا در ثبت اطلاعات آزمون.'], 500);
        }
    }

    /**
     * 6. Fetch Results
     */
    public function result(UserQuizAttempt $attempt)
    {
        if ($attempt->user_id !== auth()->id()) {
            return response()->json(['message' => 'غیرمجاز'], 403);
        }

        $attempt->load([
            'quiz.category',
            'answers.question.options',
            'answers.question.subject',
            'answers.selectedOption'
        ]);

        return $this->success($attempt, 'موفق', 'نتیجه آزمون با موفقیت دریافت شد');
    }
}