<?php

namespace App\Services;

use App\Http\Resources\ExerciseResource;
use App\Models\Exercise;
use App\Models\ExerciseSkill;
use App\Models\Question;
use App\Models\QuestionBlank;
use App\Models\QuestionChoice;
use App\Models\QuestionGroup;
use Illuminate\Database\Eloquent\ModelNotFoundException;
use Illuminate\Support\Facades\DB;

class ExerciseService
{

    public function getExercises($params)
    {
        $limit = isset($params['limit']) ? min((int)$params['limit'], 100) : 10;
        $offset = isset($params['offset']) ? max((int)$params['offset'], 0) : 0;
        $lessonName = $params['search'] ?? null;

        $query = Exercise::select('id', 'lesson_name', 'description', 'status', 'level', 'year', 'created_at');

        if (!empty($lessonName)) {
            $query->where('lesson_name', 'like', '%' . $lessonName . '%');
        }

        // Lấy dữ liệu chính
        $data = $query->orderByDesc('created_at')
            ->skip($offset)
            ->take($limit)
            ->get()
            ->map(function ($item) {
                $item->level = match ((int)$item->level) {
                    0 => 'easy',
                    1 => 'normal',
                    2 => 'hard',
                    default => 'unknown',
                };
                return $item;
            });

        return $data;
    }
    public function createExercise($dataExercise)
    {
        $dataCreateExercise = [
            'lesson_name' => $dataExercise['name'] ?? null,
            'description' => $dataExercise['description'] ?? null,
            'subject_id' => $dataExercise['subject_id'] ?? null,
            'level' => $dataExercise['level'] ?? null,
            'status' => $dataExercise['status'] ?? null,
            'category_id' => $dataExercise['category_id'] ?? null,
            'year' => $dataExercise['year'] ?? null,
        ];

        $exercise = Exercise::create($dataCreateExercise);

        return $exercise->id;
    }

    public function detail($id)
    {
        $exercise = Exercise::with([
            'skills:id,name',
            'questionGroups' => function ($q) {
                $q->select('id', 'exercise_id', 'content');
            },
            'questionGroups.questions' => function ($q) {
                $q->select('id', 'content', 'group_id', 'question_type_id', 'description', 'score', 'explanation', 'hint');
            },
            'questionGroups.questions.type:id,code,name',
            'questionGroups.questions.choices',
            'questionGroups.questions.blanks',
        ])->findOrFail($id);

        return new ExerciseResource($exercise);
    }

    public function destroy($id)
    {
        try {
            $exercise = Exercise::findOrFail($id);

            DB::transaction(function () use ($exercise) {

                $groupIds = $exercise->questionGroups()->pluck('id');
                $questionIds = DB::table('se_questions')
                    ->whereIn('group_id', $groupIds)
                    ->pluck('id');

                QuestionChoice::whereIn('question_id', $questionIds)->delete();
                QuestionBlank::whereIn('question_id', $questionIds)->delete();
                Question::whereIn('id', $questionIds)->delete();
                QuestionGroup::whereIn('id', $groupIds)->delete();
                ExerciseSkill::where('exercise_id', $exercise->id)->delete();

                $exercise->delete();
            });

            return [
                'status' => true,
                'message' => 'Xoá đề thi thành công.'
            ];
        } catch (ModelNotFoundException $e) {
            return [
                'status' => false,
                'message' => 'Không tìm thấy đề thi.'
            ];
        } catch (\Exception $e) {
            return [
                'status' => false,
                'message' => 'Lỗi hệ thống: ' . $e->getMessage()
            ];
        }
    }
}