using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using Telegram.Bot.Exceptions;
using Telegram.Bot.Types;
using TelegramBotBase.Args;
using TelegramBotBase.Attributes;
using TelegramBotBase.Base;
using TelegramBotBase.Enums;

namespace TelegramBotBase.Form;

/// <summary>
///     A form which cleans up old messages sent within
/// </summary>
public class AutoCleanForm : FormBase
{
    public AutoCleanForm()
    {
        OldMessages = new List<int>();
        DeleteMode = EDeleteMode.OnEveryCall;
        DeleteSide = EDeleteSide.BotOnly;

        Opened += AutoCleanForm_Init;

        Closed += AutoCleanForm_Closed;
    }

    [SaveState] public List<int> OldMessages { get; set; }

    [SaveState] public EDeleteMode DeleteMode { get; set; }

    [SaveState] public EDeleteSide DeleteSide { get; set; }

    private Task AutoCleanForm_Init(object sender, EventArgs e)
    {
        if (Device == null)
        {
            return Task.CompletedTask;
        }

        Device.MessageSent += Device_MessageSent;

        Device.MessageReceived += Device_MessageReceived;

        Device.MessageDeleted += Device_MessageDeleted;
        return Task.CompletedTask;
    }

    private void Device_MessageDeleted(object sender, MessageDeletedEventArgs e)
    {
        if (OldMessages.Contains(e.MessageId))
        {
            OldMessages.Remove(e.MessageId);
        }
    }

    private void Device_MessageReceived(object sender, MessageReceivedEventArgs e)
    {
        if (DeleteSide == EDeleteSide.BotOnly)
        {
            return;
        }

        OldMessages.Add(e.Message.MessageId);
    }

    private Task Device_MessageSent(object sender, MessageSentEventArgs e)
    {
        if (DeleteSide == EDeleteSide.UserOnly
         || Device.ActiveForm != this)
        {
            return Task.CompletedTask;
        }

        OldMessages.Add(e.Message.MessageId);
        return Task.CompletedTask;
    }

    public override async Task PreLoad(MessageResult message)
    {
        if (DeleteMode != EDeleteMode.OnEveryCall)
        {
            return;
        }

        await MessageCleanup();
    }

    /// <summary>
    ///     Adds a message to this of removable ones
    /// </summary>
    /// <param name="Id"></param>
    public void AddMessage(Message m)
    {
        OldMessages.Add(m.MessageId);
    }


    /// <summary>
    ///     Adds a message to this of removable ones
    /// </summary>
    /// <param name="Id"></param>
    public void AddMessage(int messageId)
    {
        OldMessages.Add(messageId);
    }

    /// <summary>
    ///     Keeps the message by removing it from the list
    /// </summary>
    /// <param name="id"></param>
    public void LeaveMessage(int id)
    {
        OldMessages.Remove(id);
    }

    /// <summary>
    ///     Keeps the last sent message
    /// </summary>
    public void LeaveLastMessage()
    {
        if (OldMessages.Count == 0)
        {
            return;
        }

        OldMessages.RemoveAt(OldMessages.Count - 1);
    }

    private Task AutoCleanForm_Closed(object sender, EventArgs e)
    {
        if (DeleteMode != EDeleteMode.OnLeavingForm)
        {
            return Task.CompletedTask;
        }

        Device.MessageSent -= Device_MessageSent;

        Device.MessageReceived -= Device_MessageReceived;

        Device.MessageDeleted -= Device_MessageDeleted;

        MessageCleanup().Wait();
        return Task.CompletedTask;
    }

    /// <summary>
    ///     Cleans up all remembered messages.
    /// </summary>
    /// <returns></returns>
    public async Task MessageCleanup()
    {
        var oldMessages = OldMessages.AsEnumerable();

#if !NETSTANDARD2_0
            while (oldMessages.Any())
            {
                using var cts = new CancellationTokenSource();
                var deletedMessages = new ConcurrentBag<int>();
                var parallelQuery = OldMessages.AsParallel()
                                                .WithCancellation(cts.Token);
                Task retryAfterTask = null;
                try
                {
                    parallelQuery.ForAll(i =>
                    {
                        try
                        {
                            Device.DeleteMessage(i).GetAwaiter().GetResult();
                            deletedMessages.Add(i);
                        }
                        catch (ApiRequestException req) when (req.ErrorCode == 400)
                        {
                            deletedMessages.Add(i);
                        }
                    });
                }
                catch (AggregateException ex)
                {
                    cts.Cancel();

                    var retryAfterSeconds = ex.InnerExceptions
                        .Where(e => e is ApiRequestException apiEx && apiEx.ErrorCode == 429)
                        .Max(e => ((ApiRequestException)e).Parameters.RetryAfter) ?? 0;
                    retryAfterTask = Task.Delay(retryAfterSeconds * 1000);
                }

                //deletedMessages.AsParallel().ForAll(i => Device.OnMessageDeleted(new MessageDeletedEventArgs(i)));

                oldMessages = oldMessages.Where(x => !deletedMessages.Contains(x));
                if (retryAfterTask != null)
                    await retryAfterTask;
            }
#else
        while (oldMessages.Any())
        {
            using (var cts = new CancellationTokenSource())
            {
                var deletedMessages = new ConcurrentBag<int>();
                var parallelQuery = OldMessages.AsParallel()
                                               .WithCancellation(cts.Token);
                Task retryAfterTask = null;
                try
                {
                    parallelQuery.ForAll(i =>
                    {
                        try
                        {
                            Device.DeleteMessage(i).GetAwaiter().GetResult();
                            deletedMessages.Add(i);
                        }
                        catch (ApiRequestException req) when (req.ErrorCode == 400)
                        {
                            deletedMessages.Add(i);
                        }
                    });
                }
                catch (AggregateException ex)
                {
                    cts.Cancel();

                    var retryAfterSeconds = ex.InnerExceptions
                                              .Where(e => e is ApiRequestException apiEx && apiEx.ErrorCode == 429)
                                              .Max(e => ((ApiRequestException)e).Parameters.RetryAfter) ?? 0;
                    retryAfterTask = Task.Delay(retryAfterSeconds * 1000, cts.Token);
                }

                //deletedMessages.AsParallel().ForAll(i => Device.OnMessageDeleted(new MessageDeletedEventArgs(i)));
                oldMessages = oldMessages.Where(x => !deletedMessages.Contains(x));
                if (retryAfterTask != null)
                {
                    await retryAfterTask;
                }
            }
        }


#endif

        OldMessages.Clear();
    }
}