<?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;
use OpenAI;

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'
        ];
    }
   /**
     * @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
     *                 }
     *             )
     *         )
     *     )
     * )
     */
    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")
     *     )
     * )
     */
    public function show(Question $question)
    {
        $question->load(['author', 'category']);
        return new QuestionResource($question);
    }

    /**
     * @OA\Post(
     *     path="/api/questions",
     *     summary="Create a new question (only admin or creator)",
     *     description="Store a new question in the system.",
     *     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\Response(
     *         response=200,
     *         description="Question created successfully",
     *         @OA\JsonContent(ref="#/components/schemas/QuestionResource")
     *     )
     * )
     */
    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 (only admin or creator)",
     *     description="Update an existing question by ID.",
     *     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\Response(
     *         response=200,
     *         description="Question updated successfully",
     *         @OA\JsonContent(ref="#/components/schemas/QuestionResource")
     *     )
     * )
     */
    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 (only admin or creator)",
     *     description="Delete a question by ID .",
     *     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")
     *         )
     *     )
     * )
     */
    public function destroy(Request $request, Question $question)
    {
        $this->authorize('delete', $question);
        $question->delete();
        Log::writeLog("Question '" . $question->title . "' is deleted by " . $request->user()->username);

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

    /**
     * @OA\Post(
     *     path="/api/questions/openai-generate",
     *     summary="Generate a question using OpenAI (Creator or Admin)",
     *     description="Generates a new question via OpenAI API. Only authorized users (creator or admin) can call this endpoint.",
     *     tags={"Questions"},
     *     security={{"bearerAuth":{}}},
     *     @OA\RequestBody(
     *         required=true,
     *         @OA\JsonContent(
     *             required={"type","category_id","language","difficulty","promt"},
     *             @OA\Property(property="type", type="string", description="Type of the question", enum={"single","multiple","text"}, example="single"),
     *             @OA\Property(property="category_id", type="integer", description="ID of the category", example=3),
     *             @OA\Property(property="language", type="string", description="Language for AI prompt", example="en"),
     *             @OA\Property(property="difficulty", type="integer", description="Difficulty level (0-10)", example=5),
     *             @OA\Property(property="promt", type="string", description="The prompt for AI to generate the question", example="Explain HTTP methods")
     *         )
     *     ),
     *     @OA\Response(
     *         response=200,
     *         description="AI-generated question",
     *         @OA\JsonContent(
     *             @OA\Property(property="question", type="object",
     *                 @OA\Property(property="title", type="string", example="Sample question"),
     *                 @OA\Property(property="description", type="string", example="Optional description"),
     *                 @OA\Property(property="type", type="string", enum={"single","multiple","text"}),
     *                 @OA\Property(property="difficulty", type="integer", example=5),
     *                 @OA\Property(property="variants", type="array",
     *                     @OA\Items(
     *                         @OA\Property(property="id", type="integer"),
     *                         @OA\Property(property="text", type="string")
     *                     )
     *                 ),
     *                 @OA\Property(property="correct_answers", type="array",
     *                     @OA\Items(oneOf={@OA\Schema(type="integer"), @OA\Schema(type="string")})
     *                 ),
     *                 @OA\Property(property="category_id", type="integer", example=3)
     *             )
     *         )
     *     ),
     *     @OA\Response(
     *         response=422,
     *         description="Validation error",
     *         @OA\JsonContent(
     *             @OA\Property(property="message", type="string"),
     *             @OA\Property(property="errors", type="object")
     *         )
     *     ),
     *     @OA\Response(
     *         response=500,
     *         description="AI returned invalid JSON",
     *         @OA\JsonContent(
     *             @OA\Property(property="error", type="string"),
     *             @OA\Property(property="raw", type="string")
     *         )
     *     )
     * )
     */
    public function openai_generate(Request $request)
    {
        $this->authorize('create', Question::class);

        $fields = $request->validate([
            'type' => 'required|string|in:single,multiple,text',
            'category_id' => 'required|exists:categories,id',
            'language' => 'required|string',
            'difficulty' => 'required|integer',
            'promt' => 'required|string'
        ]);
        $type = $fields['type'];
        $lang = $fields['language'];
        $difficulty = $fields['difficulty'];
        $cat_id = $fields['category_id'];
        $promt_json = json_encode($fields['promt']);

        $question_type_promt = "";
        $answer = "";
        $variations = <<< EOT
[
    {
        "id": 1,
        "text": "Option 1"
    },
    {
        "id": 2,
        "text": "Option 2"
    },
    {
        "id": 3,
        "text": "Option 3"
    },
    {
        "id": 4,
        "text": "Option 4"
    }
]
EOT;
        switch ($type) {
            case 'single':
                $question_type_promt = "Create 4 answer options, with one of them being correct (the \"correct_answers\" field is an array containing the ID of the correct option).";
                $answer = json_encode([2]); ;
                break;
            case 'multiple':
                $question_type_promt = "Create between 4 and 6 answer options, with several of them being correct (the \"correct_answers\" field is an array containing the IDs of the correct options).";
                $answer = json_encode([1,2]); ;
                break;
            case 'text':
                $question_type_promt = "Generate a question where there can only be a single, precise answer that can be written without an extended explanation. The \"correct_answers\" field should be an array containing only ONE answer as a string. The \"variations\" must be empty array";
                $answer = json_encode(["Answer"]);
                $variations = '[]';
                break;
        }

        $openai_promt = <<< EOT
Generate 1 question using the following template (this is example):

{
  "title": "Sample question",
  "description": "Optional description",
  "type": "$type",
  "difficulty": $difficulty,
  "variants": $variations,
  "correct_answers": $answer,
  "category_id": $cat_id
}

You can change only variants, correct_answers, description and title.
Your response should be only JSON with no explanations, exactly following the template.

$question_type_promt

Question difficulty: $difficulty/10
The question should be based on the following prompt with language $lang: 
$promt_json

EOT;
        $client = OpenAI::client(env("OPENAI_KEY"));

        $response = $client->responses()->create([
            'model' => env('OPENAI_MODEL', 'gpt-4.1-mini'),
            'input' => $openai_promt,
            'temperature' => 0,
        ]);
        $ai_answer = $response->outputText;

        $question_json = json_decode($ai_answer, true);

        if (json_last_error() !== JSON_ERROR_NONE) {
            return response()->json([
                'error' => 'AI returned invalid JSON',
                'raw' => $ai_answer,
            ], 500);
        }

        return response()->json([
            'question' => $question_json,
        ]);
    }
}