using System.Collections.Concurrent;
using Catalogger.Backend.Cache;
using Catalogger.Backend.Cache.InMemoryCache;
using Catalogger.Backend.Extensions;
using Remora.Discord.API;
using Remora.Discord.API.Abstractions.Objects;
using Remora.Discord.API.Abstractions.Rest;
using Remora.Discord.API.Objects;
using Remora.Rest.Core;
using Guild = Catalogger.Backend.Database.Models.Guild;

namespace Catalogger.Backend.Services;

// TODO: this entire class is a mess, clean it up
public class WebhookExecutorService(
    Config config,
    ILogger logger,
    IWebhookCache webhookCache,
    ChannelCache channelCache,
    IDiscordRestWebhookAPI webhookApi)
{
    private readonly ILogger _logger = logger.ForContext<WebhookExecutorService>();
    private readonly Snowflake _applicationId = DiscordSnowflake.New(config.Discord.ApplicationId);
    private readonly ConcurrentDictionary<ulong, ConcurrentQueue<IEmbed>> _cache = new();
    private readonly ConcurrentDictionary<ulong, object> _locks = new();
    private readonly ConcurrentDictionary<ulong, Timer> _timers = new();
    private IUser? _selfUser;

    public void SetSelfUser(IUser user) => _selfUser = user;

    public async Task QueueLogAsync(Guild guild, LogChannelType logChannelType, IEmbed embed)
    {
        var logChannel = GetLogChannel(guild, logChannelType, channelId: null, userId: null);
        if (logChannel == null) return;

        await QueueLogAsync(logChannel.Value, embed);
    }

    private List<IEmbed> TakeFromQueue(ulong channelId)
    {
        var queue = _cache.GetOrAdd(channelId, []);
        var channelLock = _locks.GetOrAdd(channelId, channelId);
        lock (channelLock)
        {
            var embeds = new List<IEmbed>();
            for (var i = 0; i < 5; i++)
            {
                if (!queue.TryDequeue(out var embed)) break;
                embeds.Add(embed);
            }

            return embeds;
        }
    }

    public async Task QueueLogAsync(ulong channelId, IEmbed embed)
    {
        if (channelId == 0) return;
        
        var queue = _cache.GetOrAdd(channelId, []);
        queue.Enqueue(embed);
        _cache[channelId] = queue;

        await SetTimer(channelId, queue);
    }

    private async Task SetTimer(ulong channelId, ConcurrentQueue<IEmbed> queue)
    {
        if (_timers.TryGetValue(channelId, out var existingTimer)) await existingTimer.DisposeAsync();
        _timers[channelId] = new Timer(_ =>
        {
            _logger.Debug("Sending 5 queued embeds");

            var __ = SendLogsAsync(channelId, TakeFromQueue(channelId));
            if (!queue.IsEmpty)
            {
                if (_timers.TryGetValue(channelId, out var timer)) timer.Dispose();
                var ___ = SetTimer(channelId, queue);
            }
        }, null, 3000, Timeout.Infinite);
    }

    private async Task SendLogsAsync(ulong channelId, List<IEmbed> embeds)
    {
        _logger.Debug("Sending {Count} embeds to channel {ChannelId}", embeds.Count, channelId);
        if (embeds.Count == 0) return;

        var webhook = await webhookCache.GetOrFetchWebhookAsync(channelId, id => FetchWebhookAsync(id));

        await webhookApi.ExecuteWebhookAsync(DiscordSnowflake.New(webhook.Id), webhook.Token, shouldWait: false,
            embeds: embeds, username: _selfUser!.Username, avatarUrl: _selfUser.AvatarUrl());
    }

    public async Task SendLogWithAttachmentsAsync(ulong channelId, List<Embed> embeds, IEnumerable<FileData> files)
    {
        if (channelId == 0) return;

        var attachments = files
            .Select<FileData, OneOf.OneOf<FileData, IPartialAttachment>>(f => f)
            .ToList();

        var webhook = await webhookCache.GetOrFetchWebhookAsync(channelId, id => FetchWebhookAsync(id));
        await webhookApi.ExecuteWebhookAsync(DiscordSnowflake.New(webhook.Id), webhook.Token, shouldWait: false,
            embeds: embeds, attachments: attachments, username: _selfUser!.Username,
            avatarUrl: _selfUser.AvatarUrl());
    }

    private async Task<IWebhook> FetchWebhookAsync(Snowflake channelId, CancellationToken ct = default)
    {
        var channelWebhooks =
            await webhookApi.GetChannelWebhooksAsync(channelId, ct).GetOrThrow();
        var webhook = channelWebhooks.FirstOrDefault(w => w.ApplicationID == _applicationId && w.Token.IsDefined());
        if (webhook != null) return webhook;

        return await webhookApi.CreateWebhookAsync(channelId, "Catalogger", default, reason: "Creating logging webhook",
            ct: ct).GetOrThrow();
    }

    public ulong? GetLogChannel(Guild guild, LogChannelType logChannelType, Snowflake? channelId = null,
        ulong? userId = null)
    {
        if (channelId == null) return GetDefaultLogChannel(guild, logChannelType);
        if (!channelCache.TryGet(channelId.Value, out var channel)) return null;

        Snowflake? categoryId;
        if (channel.Type is ChannelType.AnnouncementThread or ChannelType.PrivateThread or ChannelType.PublicThread)
        {
            // parent_id should always have a value for threads
            channelId = channel.ParentID.Value!.Value;
            if (!channelCache.TryGet(channelId.Value, out var parentChannel))
                return GetDefaultLogChannel(guild, logChannelType);
            categoryId = parentChannel.ParentID.Value;
        }
        else
        {
            channelId = channel.ID;
            categoryId = channel.ParentID.Value;
        }

        // Check if the channel, or its category, or the user is ignored
        if (guild.Channels.IgnoredChannels.Contains(channelId.Value.Value) ||
            categoryId != null && guild.Channels.IgnoredChannels.Contains(categoryId.Value.Value)) return null;
        if (userId != null)
        {
            if (guild.Channels.IgnoredUsers.Contains(userId.Value)) return null;

            // Check the channel-local and category-local ignored users
            var channelIgnoredUsers =
                guild.Channels.IgnoredUsersPerChannel.GetValueOrDefault(channelId.Value.Value) ?? [];
            var categoryIgnoredUsers = (categoryId != null
                ? guild.Channels.IgnoredUsersPerChannel.GetValueOrDefault(categoryId.Value.Value)
                : []) ?? [];
            if (channelIgnoredUsers.Concat(categoryIgnoredUsers).Contains(userId.Value)) return null;
        }

        // These three events can be redirected to other channels. Redirects can be on a channel or category level.
        // Obviously, the events are only redirected if they're supposed to be logged in the first place.
        if (logChannelType is LogChannelType.MessageUpdate or LogChannelType.MessageDelete
            or LogChannelType.MessageDeleteBulk)
        {
            if (GetDefaultLogChannel(guild, logChannelType) == 0) return null;

            var categoryRedirect = categoryId != null
                ? guild.Channels.Redirects.GetValueOrDefault(categoryId.Value.Value)
                : 0;

            if (guild.Channels.Redirects.TryGetValue(channelId.Value.Value, out var channelRedirect))
                return channelRedirect;
            if (categoryRedirect != 0) return categoryRedirect;
            return GetDefaultLogChannel(guild, logChannelType);
        }

        return GetDefaultLogChannel(guild, logChannelType);
    }

    public static ulong GetDefaultLogChannel(Guild guild, LogChannelType channelType) => channelType switch
    {
        LogChannelType.GuildUpdate => guild.Channels.GuildUpdate,
        LogChannelType.GuildEmojisUpdate => guild.Channels.GuildEmojisUpdate,
        LogChannelType.GuildRoleCreate => guild.Channels.GuildRoleCreate,
        LogChannelType.GuildRoleUpdate => guild.Channels.GuildRoleUpdate,
        LogChannelType.GuildRoleDelete => guild.Channels.GuildRoleDelete,
        LogChannelType.ChannelCreate => guild.Channels.ChannelCreate,
        LogChannelType.ChannelUpdate => guild.Channels.ChannelUpdate,
        LogChannelType.ChannelDelete => guild.Channels.ChannelDelete,
        LogChannelType.GuildMemberAdd => guild.Channels.GuildMemberAdd,
        LogChannelType.GuildMemberUpdate => guild.Channels.GuildMemberUpdate,
        LogChannelType.GuildKeyRoleUpdate => guild.Channels.GuildKeyRoleUpdate,
        LogChannelType.GuildMemberNickUpdate => guild.Channels.GuildMemberNickUpdate,
        LogChannelType.GuildMemberAvatarUpdate => guild.Channels.GuildMemberAvatarUpdate,
        LogChannelType.GuildMemberRemove => guild.Channels.GuildMemberRemove,
        LogChannelType.GuildMemberKick => guild.Channels.GuildMemberKick,
        LogChannelType.GuildBanAdd => guild.Channels.GuildBanAdd,
        LogChannelType.GuildBanRemove => guild.Channels.GuildBanRemove,
        LogChannelType.InviteCreate => guild.Channels.InviteCreate,
        LogChannelType.InviteDelete => guild.Channels.InviteDelete,
        LogChannelType.MessageUpdate => guild.Channels.MessageUpdate,
        LogChannelType.MessageDelete => guild.Channels.MessageDelete,
        LogChannelType.MessageDeleteBulk => guild.Channels.MessageDeleteBulk,
        _ => throw new ArgumentOutOfRangeException(nameof(channelType))
    };
}

public enum LogChannelType
{
    GuildUpdate,
    GuildEmojisUpdate,
    GuildRoleCreate,
    GuildRoleUpdate,
    GuildRoleDelete,
    ChannelCreate,
    ChannelUpdate,
    ChannelDelete,
    GuildMemberAdd,
    GuildMemberUpdate,
    GuildKeyRoleUpdate,
    GuildMemberNickUpdate,
    GuildMemberAvatarUpdate,
    GuildMemberRemove,
    GuildMemberKick,
    GuildBanAdd,
    GuildBanRemove,
    InviteCreate,
    InviteDelete,
    MessageUpdate,
    MessageDelete,
    MessageDeleteBulk
}