using av_motion_api.Data; 
using av_motion_api.Models;
using Microsoft.AspNetCore.Identity;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Options;

namespace av_motion_api.Services
{
    public class UserDeletionService : IHostedService, IDisposable
    {
        private readonly IServiceProvider _serviceProvider;
        private readonly IOptionsMonitor<DeletionSettings> _settings;
        private Timer _timer;

        public UserDeletionService(IServiceProvider serviceProvider, IOptionsMonitor<DeletionSettings> settings)
        {
            _serviceProvider = serviceProvider;
            _settings = settings;
        }

        public Task StartAsync(CancellationToken cancellationToken)
        {
            ScheduleDeletionTask();
            _settings.OnChange(settings => ScheduleDeletionTask());
            return Task.CompletedTask;
        }

        private void ScheduleDeletionTask()
        {
            var interval = GetTimeSpan(_settings.CurrentValue.DeletionTimeValue, _settings.CurrentValue.DeletionTimeUnit);
            _timer = new Timer(DeleteDeactivatedUsers, null, TimeSpan.Zero, interval);
        }

        private void DeleteDeactivatedUsers(object state)
        {
            using (var scope = _serviceProvider.CreateScope())
            {
                var context = scope.ServiceProvider.GetRequiredService<AppDbContext>();
                var userManager = scope.ServiceProvider.GetRequiredService<UserManager<User>>();

                var deletionThreshold = DateTime.UtcNow.Subtract(GetTimeSpan(_settings.CurrentValue.DeletionTimeValue, _settings.CurrentValue.DeletionTimeUnit));

                var usersToDelete = context.Users
                    .Where(u => u.User_Status_ID == 2 && u.DeactivatedAt < deletionThreshold)
                    .ToList();

                foreach (var user in usersToDelete)
                {
                    userManager.DeleteAsync(user).Wait();
                }

                context.SaveChanges();
            }
        }

        private TimeSpan GetTimeSpan(int value, string unit)
        {
            return unit.ToLower() switch
            {
                "minutes" => TimeSpan.FromMinutes(value),
                "hours" => TimeSpan.FromHours(value),
                "days" => TimeSpan.FromDays(value),
                "weeks" => TimeSpan.FromDays(value * 7),
                "months" => TimeSpan.FromDays(value * 30), // Approximation
                "years" => TimeSpan.FromDays(value * 365), // Approximation
                _ => TimeSpan.FromMinutes(value),
            };
        }

        public Task StopAsync(CancellationToken cancellationToken)
        {
            _timer?.Change(Timeout.Infinite, 0);
            return Task.CompletedTask;
        }

        public void Dispose()
        {
            _timer?.Dispose();
        }
    }
}