using CalendarReminder.Api.Data;
using Microsoft.EntityFrameworkCore;

namespace CalendarReminder.Api.Services;

public class ReminderNotificationService : BackgroundService
{
    private readonly IServiceScopeFactory _scopeFactory;
    private readonly ILogger<ReminderNotificationService> _logger;

    public ReminderNotificationService(IServiceScopeFactory scopeFactory,
        ILogger<ReminderNotificationService> logger)
    {
        _scopeFactory = scopeFactory;
        _logger = logger;
    }

    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        _logger.LogInformation("Notification service spustený");

        while (!stoppingToken.IsCancellationRequested)
        {
            await CheckRemindersAsync();
            await Task.Delay(TimeSpan.FromMinutes(1), stoppingToken);
        }
    }

    private async Task CheckRemindersAsync()
    {
        using var scope = _scopeFactory.CreateScope();
        var db = scope.ServiceProvider.GetRequiredService<AppDbContext>();
        var emailService = scope.ServiceProvider.GetRequiredService<EmailService>();

        var now = DateTime.UtcNow;
        var windowEnd = now.AddMinutes(15);

        // Nájdi remindery, ktoré sú do 15 minút a notifikácia ešte nebola odoslaná
        var upcoming = await db.Reminders
            .Include(r => r.User)
            .Where(r => !r.IsCompleted
                     && !r.NotificationSent
                     && r.ReminderDate >= now
                     && r.ReminderDate <= windowEnd)
            .ToListAsync();

        foreach (var reminder in upcoming)
        {
            var minutesLeft = (int)(reminder.ReminderDate - now).TotalMinutes;
            var body = $"""
                <h2>⏰ Pripomienka: {reminder.Title}</h2>
                <p><strong>Čas:</strong> {reminder.ReminderDate:dd.MM.yyyy HH:mm}</p>
                <p><strong>O:</strong> {minutesLeft} minút</p>
                {(reminder.Description != null ? $"<p><strong>Popis:</strong> {reminder.Description}</p>" : "")}
                <hr>
                <small>CalendarReminder</small>
                """;

            await emailService.SendAsync(
                reminder.User!.Email,
                reminder.User.Username,
                $"⏰ Pripomienka: {reminder.Title}",
                body);

            reminder.NotificationSent = true;
        }

        if (upcoming.Count > 0)
            await db.SaveChangesAsync();
    }
}