using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.Json;
using System.Threading.Tasks;
using Kurs.Platform.Entities;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc;
using Volo.Abp.Application.Dtos;
using Volo.Abp.Domain.Repositories;

namespace Kurs.Platform.Classrooms;

[Authorize]
public class ClassroomAppService : PlatformAppService, IClassroomAppService
{
    private readonly IRepository<Classroom, Guid> _classSessionRepository;
    private readonly IRepository<ClassParticipant, Guid> _participantRepository;
    private readonly IRepository<ClassAttandance, Guid> _attendanceRepository;

    public ClassroomAppService(
        IRepository<Classroom, Guid> classSessionRepository,
        IRepository<ClassParticipant, Guid> participantRepository,
        IRepository<ClassAttandance, Guid> attendanceRepository)
    {
        _classSessionRepository = classSessionRepository;
        _participantRepository = participantRepository;
        _attendanceRepository = attendanceRepository;
    }

    public async Task<ClassroomDto> GetAsync(Guid id)
    {
        var classSession = await _classSessionRepository.GetAsync(id);
        return ObjectMapper.Map<Classroom, ClassroomDto>(classSession);
    }

    public async Task<PagedResultDto<ClassroomDto>> GetListAsync(PagedAndSortedResultRequestDto input)
    {
        var query = await _classSessionRepository.GetQueryableAsync();
        var totalCount = query.Count();
        var items = query
            .OrderBy(x => x.ScheduledStartTime)
            .Skip(input.SkipCount)
            .Take(input.MaxResultCount)
            .ToList();

        return new PagedResultDto<ClassroomDto>(
            totalCount,
            ObjectMapper.Map<List<Classroom>, List<ClassroomDto>>(items)
        );
    }

    public async Task<ClassroomDto> CreateAsync(ClassroomDto input)
    {
        var classSession = new Classroom(
            GuidGenerator.Create(),
            input.Name,
            input.Description,
            input.Subject,
            CurrentUser.Id,
            CurrentUser.Name,
            input.ScheduledStartTime,
            input.ScheduledStartTime.AddMinutes(input.Duration),
            input.Duration,
            input.MaxParticipants,
            input.SettingsJson = JsonSerializer.Serialize(input.SettingsDto)
        );

        await _classSessionRepository.InsertAsync(classSession);

        return ObjectMapper.Map<Classroom, ClassroomDto>(classSession);
    }

    public async Task<ClassroomDto> UpdateAsync(Guid id, ClassroomDto input)
    {
        var classSession = await _classSessionRepository.GetAsync(id);

        if (classSession.TeacherId != CurrentUser.Id)
        {
            throw new UnauthorizedAccessException("Only the teacher can update this class");
        }

        classSession.Name = input.Name;
        classSession.Description = input.Description;
        classSession.Subject = input.Subject;
        classSession.TeacherId = input.TeacherId;
        classSession.TeacherName = input.TeacherName;
        classSession.ScheduledStartTime = input.ScheduledStartTime;
        classSession.ScheduledEndTime = input.ScheduledStartTime.AddMinutes(input.Duration);
        classSession.Duration = input.Duration;
        classSession.MaxParticipants = input.MaxParticipants;
        classSession.SettingsJson = JsonSerializer.Serialize(input.SettingsDto);

        await _classSessionRepository.UpdateAsync(classSession);
        return ObjectMapper.Map<Classroom, ClassroomDto>(classSession);
    }

    public async Task DeleteAsync(Guid id)
    {
        var classSession = await _classSessionRepository.GetAsync(id);

        if (classSession.TeacherId != CurrentUser.Id)
        {
            throw new UnauthorizedAccessException("Only the teacher can delete this class");
        }

        await _classSessionRepository.DeleteAsync(id);
    }

    [HttpPut]
    public async Task<ClassroomDto> StartClassAsync(Guid id)
    {
        var classSession = await _classSessionRepository.GetAsync(id);

        if (classSession.TeacherId != CurrentUser.Id)
        {
            throw new UnauthorizedAccessException("Only the teacher can start this class");
        }

        classSession.ActualStartTime = DateTime.Now;

        await _classSessionRepository.UpdateAsync(classSession);

        return ObjectMapper.Map<Classroom, ClassroomDto>(classSession);
    }

    [HttpPut]
    public async Task EndClassAsync(Guid id)
    {
        var classSession = await _classSessionRepository.GetAsync(id);

        if (classSession.TeacherId != CurrentUser.Id)
        {
            throw new UnauthorizedAccessException("Only the teacher can end this class");
        }

        classSession.ActualEndTime = DateTime.Now;

        await _classSessionRepository.UpdateAsync(classSession);

        // Update attendance records
        var activeAttendances = await _attendanceRepository.GetListAsync(
            x => x.SessionId == id && x.LeaveTime == null
        );

        foreach (var attendance in activeAttendances)
        {
            attendance.LeaveTime = DateTime.Now;
            attendance.CalculateDuration();
            await _attendanceRepository.UpdateAsync(attendance);
        }
    }

    public async Task<ClassroomDto> JoinClassAsync(Guid id)
    {
        var classSession = await _classSessionRepository.GetAsync(id);

        if (classSession.ParticipantCount >= classSession.MaxParticipants)
        {
            throw new InvalidOperationException("Class is full");
        }

        // Check if user is already in the class
        var existingParticipant = await _participantRepository.FirstOrDefaultAsync(
            x => x.SessionId == id && x.UserId == CurrentUser.Id
        );

        if (existingParticipant == null)
        {
            // Add participant
            var participant = new ClassParticipant(
                GuidGenerator.Create(),
                id,
                CurrentUser.Id,
                CurrentUser.Name,
                CurrentUser.Email,
                false // isTeacher
            );

            await _participantRepository.InsertAsync(participant);

            // Create attendance record
            var attendance = new ClassAttandance(
                GuidGenerator.Create(),
                id,
                CurrentUser.Id,
                CurrentUser.Name,
                DateTime.Now
            );

            await _attendanceRepository.InsertAsync(attendance);

            // Update participant count
            classSession.ParticipantCount++;
            await _classSessionRepository.UpdateAsync(classSession);
        }

        return ObjectMapper.Map<Classroom, ClassroomDto>(classSession);
    }

    public async Task LeaveClassAsync(Guid id)
    {
        var participant = await _participantRepository.FirstOrDefaultAsync(
            x => x.SessionId == id && x.UserId == CurrentUser.Id
        );

        if (participant != null)
        {
            await _participantRepository.DeleteAsync(participant);

            // Update attendance record
            var attendance = await _attendanceRepository.FirstOrDefaultAsync(
                x => x.SessionId == id && x.StudentId == CurrentUser.Id && x.LeaveTime == null
            );

            if (attendance != null)
            {
                attendance.LeaveTime = DateTime.UtcNow;
                attendance.CalculateDuration();
                await _attendanceRepository.UpdateAsync(attendance);
            }

            // Update participant count
            var classSession = await _classSessionRepository.GetAsync(id);
            classSession.ParticipantCount = Math.Max(0, classSession.ParticipantCount - 1);
            await _classSessionRepository.UpdateAsync(classSession);
        }
    }

    public async Task<List<ClassAttendanceDto>> GetAttendanceAsync(Guid sessionId)
    {
        var classSession = await _classSessionRepository.GetAsync(sessionId);

        if (classSession.TeacherId != CurrentUser.Id)
        {
            throw new UnauthorizedAccessException("Only the teacher can view attendance");
        }

        var attendanceRecords = await _attendanceRepository.GetListAsync(
            x => x.SessionId == sessionId
        );

        return ObjectMapper.Map<List<ClassAttandance>, List<ClassAttendanceDto>>(attendanceRecords);
    }
}