using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Options;
using backend.Data;
using backend.DTOs;
using backend.Models;

namespace backend.Controllers;

[ApiController]
[Route("api/[controller]")]
public class QuizController : ControllerBase
{
    private readonly AppDbContext _db;
    private readonly AppConfig _appConfig;

    public QuizController(AppDbContext db, IOptions<AppConfig> appConfig)
    {
        _db = db;
        _appConfig = appConfig.Value;
    }

    [HttpGet("questions")]
    public async Task<IActionResult> GetQuestions()
    {
        var questions = await _db.QuizQuestions
            .OrderBy(q => q.Id)
            .Select(q => new QuestionDto
            {
                Id = q.Id,
                QuestionText = q.QuestionText,
                Options = new List<string> { q.Option1, q.Option2, q.Option3, q.Option4 }
            })
            .ToListAsync();

        return Ok(questions);
    }

    [HttpPost("submit")]
    public async Task<IActionResult> SubmitQuiz([FromBody] QuizSubmitRequest request)
    {
        // Check if user already attempted
        var existingAttempt = await _db.UserQuizAttempts
            .AnyAsync(qa => qa.UserId == request.UserId);

        if (existingAttempt)
        {
            return BadRequest(new { message = "شما قبلاً در مسابقه شرکت کرده‌اید." });
        }

        var user = await _db.Users.FindAsync(request.UserId);
        if (user == null)
        {
            return NotFound(new { message = "کاربر یافت نشد." });
        }

        var questions = await _db.QuizQuestions.ToListAsync();
        var participationPoints = _appConfig.Quiz.ParticipationPoints;
        var correctAnswerPoints = _appConfig.Quiz.CorrectAnswerPoints;

        int correctCount = 0;
        var answers = new List<UserQuizAnswer>();

        foreach (var answer in request.Answers)
        {
            var question = questions.FirstOrDefault(q => q.Id == answer.QuestionId);
            if (question == null) continue;

            bool isCorrect = question.CorrectOption == answer.SelectedOption;
            if (isCorrect) correctCount++;

            answers.Add(new UserQuizAnswer
            {
                QuestionId = answer.QuestionId,
                SelectedOption = answer.SelectedOption,
                IsCorrect = isCorrect
            });
        }

        int totalQuizPoints = participationPoints + (correctCount * correctAnswerPoints);

        var attempt = new UserQuizAttempt
        {
            UserId = request.UserId,
            ParticipationPoints = participationPoints,
            CorrectAnswersCount = correctCount,
            TotalQuizPoints = totalQuizPoints,
            CompletedAt = DateTime.UtcNow,
            Answers = answers
        };

        _db.UserQuizAttempts.Add(attempt);

        // Update total score
        await RecalculateTotalScore(request.UserId);

        await _db.SaveChangesAsync();

        var totalScore = await _db.UserTotalScores
            .Where(ts => ts.UserId == request.UserId)
            .Select(ts => ts.TotalPoints)
            .FirstOrDefaultAsync();

        return Ok(new QuizSubmitResponse
        {
            ParticipationPoints = participationPoints,
            CorrectCount = correctCount,
            TotalQuizPoints = totalQuizPoints,
            TotalScore = totalScore
        });
    }

    [HttpGet("user/{userId}")]
    public async Task<IActionResult> GetUserQuiz(int userId)
    {
        var attempt = await _db.UserQuizAttempts
            .Include(qa => qa.Answers)
            .ThenInclude(a => a.Question)
            .FirstOrDefaultAsync(qa => qa.UserId == userId);

        if (attempt == null)
        {
            return NotFound(new { message = "کاربر هنوز در مسابقه شرکت نکرده است." });
        }

        var questions = attempt.Answers.Select(a => new UserQuestionDto
        {
            Id = a.Question.Id,
            QuestionText = a.Question.QuestionText,
            Options = new List<string> { a.Question.Option1, a.Question.Option2, a.Question.Option3, a.Question.Option4 },
            SelectedOption = a.SelectedOption,
            IsCorrect = a.IsCorrect
        }).ToList();

        return Ok(new UserQuizResponse
        {
            Questions = questions,
            ParticipationPoints = attempt.ParticipationPoints,
            CorrectCount = attempt.CorrectAnswersCount,
            TotalQuizPoints = attempt.TotalQuizPoints
        });
    }

    private async Task RecalculateTotalScore(int userId)
    {
        var quizPoints = await _db.UserQuizAttempts
            .Where(qa => qa.UserId == userId)
            .Select(qa => (int?)qa.TotalQuizPoints)
            .FirstOrDefaultAsync() ?? 0;

        var khatmPoints = await _db.UserKhatmSelections
            .Where(ks => ks.UserId == userId && ks.IsSelected)
            .SumAsync(ks => ks.KhatmItem.Points);

        int total = quizPoints + khatmPoints;

        var totalScore = await _db.UserTotalScores
            .FirstOrDefaultAsync(ts => ts.UserId == userId);

        if (totalScore != null)
        {
            totalScore.TotalPoints = total;
        }
    }
}