using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using StreakBot.Data;
using StreakBot.Data.Entities;

namespace StreakBot.Services;

public class StreakResetBackgroundService : BackgroundService
{
    private readonly IServiceScopeFactory _scopeFactory;
    private readonly ILogger<StreakResetBackgroundService> _logger;
    private readonly TimeSpan _checkInterval = TimeSpan.FromMinutes(1);

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

    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        while (!stoppingToken.IsCancellationRequested)
        {
            try
            {
                await CheckAllStreaksAsync();
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error checking streaks for reset");
            }

            await Task.Delay(_checkInterval, stoppingToken);
        }
    }

    private async Task CheckAllStreaksAsync()
    {
        using var scope = _scopeFactory.CreateScope();
        var context = scope.ServiceProvider.GetRequiredService<StreakDbContext>();
        var channelService = scope.ServiceProvider.GetRequiredService<ChannelService>();

        var streaks = await context.Streaks.ToListAsync();
        var affectedStreaks = new List<Streak>();

        foreach (var streak in streaks)
        {
            var result = await CheckAndResetIfNeededAsync(streak, channelService);

            if (result != null)
            {
                affectedStreaks.Add(result);
            }
        }

        if (context.ChangeTracker.HasChanges())
        {
            var count = await context.SaveChangesAsync();
            _logger.LogInformation("Reset {Count} streak(s)", count);
        }

        foreach (var streak in affectedStreaks.Where(s => s.ServerId != 0))
        {
            await channelService.UpdateStreakChannelAsync(streak.ServerId, streak.StreakNumber, true);
        }

        await UpdateAllTimeChannelsAsync(streaks, channelService);
        await UpdateAllDmMessagesAsync(streaks, channelService, context);
    }

    private async Task<Streak?> CheckAndResetIfNeededAsync(Streak streak, ChannelService channelService)
    {
        var now = DateTime.UtcNow;
        var timeUntilReset = streak.LastResetCheck - now;

        // Check if we need to send a reminder (less than 1 hour until reset and not both have sent)
        if (timeUntilReset > TimeSpan.Zero && timeUntilReset <= TimeSpan.FromHours(1))
        {
            if ((!streak.User1MessageSent || !streak.User2MessageSent) && !streak.ReminderSent)
            {
                await channelService.SendStreakReminderAsync(
                    streak.User1Id,
                    streak.User2Id,
                    !streak.User1MessageSent,
                    !streak.User2MessageSent, 
                    streak.ServerId);

                streak.ReminderSent = true;
            }
        }

        if (now <= streak.LastResetCheck)
        {
            return null;
        }

        if (!streak.User1MessageSent || !streak.User2MessageSent)
        {
            streak.StreakNumberToRestore = streak.StreakNumber;
            streak.StreakNumber = 0;
            _logger.LogInformation("Resetting streak between {0} and {1}", streak.User1Id, streak.User2Id);
        }

        streak.User1MessageSent = false;
        streak.User2MessageSent = false;
        streak.ReminderSent = false;
        
        var daysToAdd = (int)Math.Ceiling((now - streak.LastResetCheck).TotalDays);
        streak.LastResetCheck = streak.LastResetCheck.AddDays(daysToAdd);

        return streak;
    }

    private async Task UpdateAllTimeChannelsAsync(List<Streak> streaks, ChannelService channelService)
    {
        var serverStreaks = streaks
            .Where(s => s.ServerId != 0)
            .DistinctBy(s => s.ServerId)
            .ToList();

        foreach (var streak in serverStreaks)
        {
            await channelService.UpdateTimeChannelAsync(streak.ServerId, streak.CreatedDate.TimeOfDay);
        }
    }

    private async Task UpdateAllDmMessagesAsync(List<Streak> streaks, ChannelService channelService, StreakDbContext context)
    {
        var dmStreaks = streaks.Where(s => s.ServerId == 0).ToList();

        foreach (var streak in dmStreaks)
        {
            var channel = await context.Channels
                .FirstOrDefaultAsync(c => c.ChannelId == streak.ChannelId && c.ChannelType == ChannelType.DmChannel);

            if (channel?.MessageId != null)
            {
                await channelService.UpdateDmStreakMessageAsync(channel.ChannelId, channel.MessageId.Value, streak.StreakNumber, streak.CreatedDate.TimeOfDay);
            }
        }
    }
}