<?php

namespace App\Http\Controllers;

use App\Http\Resources\QuestionResource;
use App\Models\Log;
use App\Models\Question;
use App\Rules\ValidVariants;
use Illuminate\Http\Request;

class QuestionController extends Controller
{
    const PAGINATION_COUNT = 20;

    private static function get_field_rules(): array
    {
        return [
            'title' => 'required|string|max:255',
            'description' => 'nullable|string',
            'type' => 'required|in:single,multiple,text',
            'difficulty' => 'required|integer',
            'category_id' => 'nullable|exists:categories,id',
            'variants' => ['array', 'nullable'],
            'variants.*.id' => ['required', 'integer'],
            'variants.*.text' => ['required', 'string'],
            'correct_answers' => 'required|array',
            'is_pending_question' => 'integer'
        ];
    }
   /**
     * @OA\Get(
     *     path="/api/questions",
     *     summary="Get a paginated list of questions (paginated)",
     *     description="Retrieve questions. Optional filter by category_id.",
     *     tags={"Questions"},
     *     @OA\Parameter(
     *         name="category_id",
     *         in="query",
     *         description="Filter questions by category ID",
     *         required=false,
     *         @OA\Schema(type="integer")
     *     ),
     *     @OA\Parameter(
     *         name="page",
     *         in="query",
     *         description="Page number for pagination",
     *         required=false,
     *         @OA\Schema(type="integer", default=1)
     *     ),
     *     @OA\Response(
     *         response=200,
     *         description="Paginated list of questions",
     *         @OA\JsonContent(
     *             @OA\Property(
     *                 property="data",
     *                 type="array",
     *                 @OA\Items(ref="#/components/schemas/QuestionResource")
     *             ),
     *             @OA\Property(
     *                 property="links",
     *                 type="object",
     *                 example={
     *                     "first": "http://localhost/api/questions?page=1",
     *                     "last": "http://localhost/api/questions?page=10",
     *                     "prev": null,
     *                     "next": "http://localhost/api/questions?page=2"
     *                 }
     *             ),
     *             @OA\Property(
     *                 property="meta",
     *                 type="object",
     *                 example={
     *                     "current_page": 1,
     *                     "from": 1,
     *                     "last_page": 10,
     *                     "path": "http://localhost/api/questions",
     *                     "per_page": 15,
     *                     "to": 15,
     *                     "total": 150
     *                 }
     *             )
     *         )
     *     ),
     *     @OA\Response(
     *         response=401,
     *         description="Unauthorized"
     *     )
     * )
     */
    public function index(Request $request)
    {
        $query = Question::with(['author', 'category']);

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

        $questions = $query->paginate(self::PAGINATION_COUNT);

        return QuestionResource::collection($questions);
    }

    /**
     * @OA\Get(
     *     path="/api/questions/{id}",
     *     summary="Get a single question",
     *     description="Retrieve a single question by its ID, including author and category",
     *     tags={"Questions"},
     *     @OA\Parameter(
     *         name="id",
     *         in="path",
     *         description="ID of the question to retrieve",
     *         required=true,
     *         @OA\Schema(type="integer")
     *     ),
     *     @OA\Response(
     *         response=200,
     *         description="Question retrieved successfully",
     *         @OA\JsonContent(ref="#/components/schemas/QuestionResource")
     *     ),
     *     @OA\Response(
     *         response=401,
     *         description="Unauthorized"
     *     ),
     *     @OA\Response(
     *         response=404,
     *         description="Question not found"
     *     )
     * )
     */
    public function show(Question $question)
    {
        $question->load(['author', 'category']);
        return new QuestionResource($question);
    }

    /**
     * @OA\Post(
     *     path="/api/questions",
     *     summary="Create a new question",
     *     description="Store a new question in the system (only admin or creator).",
     *     tags={"Questions"},
     *     security={{"bearerAuth":{}}},
     *     @OA\RequestBody(
     *         required=true,
     *         @OA\JsonContent(
     *             required={"title","type","difficulty","variants","correct_answers"},
     *             @OA\Property(property="title", type="string", maxLength=255, example="Sample question"),
     *             @OA\Property(property="description", type="string", nullable=true, example="Optional description"),
     *             @OA\Property(property="type", type="string", enum={"single","multiply","text"}, example="single"),
     *             @OA\Property(property="difficulty", type="integer", example=2),
     *             @OA\Property(
     *                  property="variants",
     *                  type="array",
     *                  @OA\Items(
     *                      type="object",
     *                      @OA\Property(property="id", type="integer", example=1),
     *                      @OA\Property(property="text", type="string", example="Option 1")
     *                  )
     *             ),
     *             @OA\Property(
     *                  property="correct_answers", 
     *                  type="array", 
     *                  @OA\Items(
     *                      type="integer",
     *                      example=1
     *                  )
     *              ),
     *             @OA\Property(property="category_id", type="integer", nullable=true, example=3),
     *             @OA\Property(property="is_pending_question", type="integer", example=0)
     *         )
     *     ),
     *     @OA\Response(
     *         response=200,
     *         description="Question created successfully",
     *         @OA\JsonContent(ref="#/components/schemas/QuestionResource")
     *     ),
     *     @OA\Response(
     *         response=401,
     *         description="Unauthorized"
     *     ),
     *     @OA\Response(
     *         response=422,
     *         description="Validation error"
     *     )
     * )
     */
    public function store(Request $request)
    {
        $this->authorize('create', Question::class);
        $fields = $request->validate(self::get_field_rules());
        $fields['author_id'] = $request->user()->id;

        $question = Question::create($fields);

        Log::writeLog("Question '" . $question->title . "' is created by " . $request->user()->username);

        return new QuestionResource($question);
    }

    /**
     * @OA\Put(
     *     path="/api/questions/{id}",
     *     summary="Update a question",
     *     description="Update an existing question by ID (only admin or creator).",
     *     tags={"Questions"},
     *     security={{"bearerAuth":{}}},
     *     @OA\Parameter(
     *         name="id",
     *         in="path",
     *         required=true,
     *         description="ID of the question to update",
     *         @OA\Schema(type="integer")
     *     ),
     *     @OA\RequestBody(
     *         required=true,
     *         @OA\JsonContent(
     *             required={"title","type","difficulty","variants","correct_answers"},
     *             @OA\Property(property="title", type="string", maxLength=255, example="Updated question"),
     *             @OA\Property(property="description", type="string", nullable=true, example="Updated description"),
     *             @OA\Property(property="type", type="string", enum={"single","multiply","text"}, example="multiply"),
     *             @OA\Property(property="difficulty", type="integer", example=3),
     *             @OA\Property(
     *                  property="variants",
     *                  type="array",
     *                  @OA\Items(
     *                      type="object",
     *                      @OA\Property(property="id", type="integer", example=1),
     *                      @OA\Property(property="text", type="string", example="Option 1")
     *                  )
     *             ),
     *             @OA\Property(
     *                  property="correct_answers", 
     *                  type="array", 
     *                  @OA\Items(
     *                      type="integer",
     *                      example=1
     *                  )
     *              ),
     *             @OA\Property(property="category_id", type="integer", nullable=true, example=2),
     *             @OA\Property(property="is_pending_question", type="integer", example=0)
     *         )
     *     ),
     *     @OA\Response(
     *         response=200,
     *         description="Question updated successfully",
     *         @OA\JsonContent(ref="#/components/schemas/QuestionResource")
     *     ),
     *     @OA\Response(
     *         response=401,
     *         description="Unauthorized"
     *     ),
     *     @OA\Response(
     *         response=422,
     *         description="Validation error"
     *     )
     * )
     */
    public function update(Request $request, Question $question)
    {
        $this->authorize('update', $question);
        $fields = $request->validate(self::get_field_rules());
        $fields['variants'] = json_encode($fields['variants']);

        $question->update($fields);

        Log::writeLog("Question '" . $question->title . "' is updated by " . $request->user()->username);

        return new QuestionResource($question);
    }

    /**
     * @OA\Delete(
     *     path="/api/questions/{id}",
     *     summary="Delete a question",
     *     description="Delete a question by ID (only admin or creator).",
     *     tags={"Questions"},
     *     security={{"bearerAuth":{}}},
     *     @OA\Parameter(
     *         name="id",
     *         in="path",
     *         required=true,
     *         description="ID of the question to delete",
     *         @OA\Schema(type="integer")
     *     ),
     *     @OA\Response(
     *         response=200,
     *         description="Question deleted successfully",
     *         @OA\JsonContent(
     *             @OA\Property(property="message", type="string", example="The hitcount was deleted")
     *         )
     *     ),
     *     @OA\Response(
     *         response=401,
     *         description="Unauthorized"
     *     ),
     *     @OA\Response(
     *         response=403,
     *         description="Forbidden"
     *     ),
     *     @OA\Response(
     *         response=404,
     *         description="Question not found"
     *     )
     * )
     */
    public function destroy(Request $request, Question $question)
    {
        $this->authorize('delete', $question);
        $question->delete();
        Log::writeLog("Question '" . $question->id . "' is deleted by " . $request->user()->username);

        return ['message' => 'The hitcount was deleted'];
    }
}