using Microsoft.EntityFrameworkCore;
using NetCord.Services;
using StreakBot.Data;
using StreakBot.Data.Entities;

namespace StreakBot.Services;

public class StreakService
{
    private readonly StreakDbContext _context;
    private readonly ChannelService _channelService;

    public StreakService(StreakDbContext context, ChannelService channelService)
    {
        _context = context;
        _channelService = channelService;
    }

    public async Task ProcessMessageAsync(ulong userId, ulong serverId)
    {
        //Streaks are per server
        var streak = await _context.Streaks
            .Where(s => s.ServerId == serverId &&
                       (s.User1Id == userId || s.User2Id == userId))
            .FirstOrDefaultAsync();

        if (streak == null)
        {
            return;
        }

        ProcessStreakMessage(streak, userId);

        if (_context.ChangeTracker.HasChanges())
        {
            await _context.SaveChangesAsync();

            if (streak.User1MessageSent && streak.User2MessageSent)
            {
                await _channelService.UpdateStreakChannelAsync(serverId, streak.StreakNumber);
            }
        }
    }

    public async Task ProcessDmMessageAsync(ulong userId, ulong channelId)
    {
        var streaks = await _context.Streaks
            .Where(s => s.ServerId == 0 &&
                       s.ChannelId == channelId &&
                       (s.User1Id == userId || s.User2Id == userId))
            .ToListAsync();

        foreach (var streak in streaks)
        {
            ProcessStreakMessage(streak, userId);
        }

        if (_context.ChangeTracker.HasChanges())
        {
            await _context.SaveChangesAsync();

            // Update DM message for each affected streak
            foreach (var streak in streaks)
            {
                var channel = await _context.Channels
                    .FirstOrDefaultAsync(c => c.ChannelId == channelId && c.ChannelType == Data.Entities.ChannelType.DmChannel);

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

    private static void ProcessStreakMessage(Streak streak, ulong userId)
    {
        bool wasUser1 = streak.User1Id == userId;
        bool wasUser2 = streak.User2Id == userId;

        bool previousUser1Sent = streak.User1MessageSent;
        bool previousUser2Sent = streak.User2MessageSent;

        if (wasUser1 && !streak.User1MessageSent)
        {
            streak.User1MessageSent = true;
        }
        else if (wasUser2 && !streak.User2MessageSent)
        {
            streak.User2MessageSent = true;
        }

        if (streak.User1MessageSent && streak.User2MessageSent &&
            !(previousUser1Sent && previousUser2Sent))
        {
            streak.StreakNumber++;
        }
    }
    
    public async Task<Streak?> CreateStreakAsync(ulong user1Id, ulong user2Id, ulong serverId, ulong channelId = 0)
    {
        var streaks = serverId == 0
            ? await _context.Streaks
                .Where(s => s.ChannelId == channelId &&
                            (s.User1Id == user1Id || s.User2Id == user1Id))
                .ToListAsync()
            : await _context.Streaks
                .Where(s => s.ServerId == serverId &&
                            (s.User1Id == user1Id || s.User2Id == user1Id))
                .ToListAsync();

        if (streaks.Any(c =>
                (c.User1Id == user1Id && c.User2Id == user2Id) || (c.User1Id == user2Id && c.User2Id == user1Id)))
        {
            return null;
        }

        var now = DateTime.UtcNow;
        var streak = new Streak
        {
            CreatedDate = now,
            User1Id = user1Id,
            User2Id = user2Id,
            ServerId = serverId,
            ChannelId = channelId,
            User1MessageSent = false,
            User2MessageSent = false,
            StreakNumber = 0,
            LastResetCheck = now.AddDays(1)
        };

        _context.Streaks.Add(streak);
        await _context.SaveChangesAsync();

        if (serverId == 0)
        {
            await _channelService.CreateDmStreakMessageAsync(channelId, streak.StreakNumber, streak.CreatedDate.TimeOfDay);
        }
        else
        {
            await _channelService.UpdateStreakChannelAsync(serverId, streak.StreakNumber);
            await _channelService.UpdateTimeChannelAsync(serverId, streak.CreatedDate.TimeOfDay);
        }

        return streak;
    }

    public async Task<List<Streak>> CheckStreaksAsync(ulong user1Id)
    {
        var streaks = await _context.Streaks
            .Where(s => s.User1Id == user1Id || s.User2Id == user1Id)
            .ToListAsync();

        return streaks;
    }

    public async Task<Streak?> GetStreakAsync(ulong user1Id, ulong user2Id)
    {
        return await _context.Streaks
            .Where(s => (s.User1Id == user1Id && s.User2Id == user2Id) || (s.User1Id == user2Id && s.User2Id == user1Id))
            .FirstOrDefaultAsync();
    }

    public async Task<string> RestoreStreakAsync(ulong user1Id, ulong user2Id)
    {
        var streak = await GetStreakAsync(user1Id, user2Id);

        if (streak == null)
        {
            return $"No streak found between <@{user1Id}> and <@{user2Id}>.";
        }

        if (streak.MonthlyRestores <= 0)
        {
            return "No restores available this month. Restores reset at the start of each month.";
        }

        if (streak.StreakNumberToRestore == null || streak.StreakNumber >= streak.StreakNumberToRestore)
        {
            return "No broken streak to restore.";
        }

        var restoredNumber = streak.StreakNumberToRestore.Value;
        if (streak.User1MessageSent && streak.User2MessageSent)
        {
            restoredNumber++;
        }
        streak.StreakNumber = restoredNumber;
        streak.StreakNumberToRestore = null;
        streak.MonthlyRestores--;

        await _context.SaveChangesAsync();

        if (streak.ServerId != 0)
        {
            await _channelService.UpdateStreakChannelAsync(streak.ServerId, streak.StreakNumber, !(streak.User1MessageSent && streak.User2MessageSent));
        }
        else
        {
            var channel = await _context.Channels
                .FirstOrDefaultAsync(c => c.ChannelId == streak.ChannelId && c.ChannelType == ChannelType.DmChannel);

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

        return $"Streak restored to {restoredNumber}! You have {streak.MonthlyRestores} restore(s) remaining this month.";
    }

    public async Task<bool?> DeleteStreakAsync(ulong user1Id, ulong user2Id)
    {
        var streak = await GetStreakAsync(user1Id, user2Id);

        if (streak == null)
        {
            return null;
        }

        var channels = await _context.Channels
            .Where(c => c.ServerId == streak.ServerId)
            .ToListAsync();

        foreach (var channel in channels)
        {
            await _channelService.DeleteChannelAsync(channel.ChannelId);
        }

        return true;
    }
}