using System;
using System.Collections.Concurrent;
using System.Text;
using System.Threading.Tasks;
using BotFramework.Abstractions;
using Kruzya.TelegramBot.Core.Service;
using Microsoft.Extensions.Logging;
using Telegram.Bot;
using Telegram.Bot.Exceptions;
using Telegram.Bot.Types;

namespace Kruzya.TelegramBot.RichSiteSummary.Service;

public class MessageSender : AbstractTimedHostedService
{
    protected override TimeSpan TimerPeriod => TimeSpan.FromSeconds(1);
        
    protected readonly ConcurrentQueue<UserMessage> Queue;
    protected readonly ConcurrentQueue<UserUnsubscribe> UnsubscribeQueue;
        
    public MessageSender(ILogger<MessageSender> logger, IBotInstance bot, ConcurrentQueue<UserMessage> userMessageQueue, ConcurrentQueue<UserUnsubscribe> userUnsubscribeQueue) : base(logger, bot)
    {
        UnsubscribeQueue = userUnsubscribeQueue;
        Queue = userMessageQueue;
    }

    protected override async Task OnRun()
    {
        if (Queue.IsEmpty || !Queue.TryDequeue(out var message))
        {
            return;
        }

        _logger.LogDebug("Message for {ChatId} dequeued.", message.ChatId.Identifier);
        try
        {
            if (string.IsNullOrWhiteSpace(message.ImageUrl))
            {
                await _bot.BotClient.SendMessage(message.ChatId, message.Text, message.ParseMode, linkPreviewOptions: message.DisableWebPagePreview);
            }

            else
            {
                await _bot.BotClient.SendPhoto(message.ChatId, new InputFileUrl(message.ImageUrl), message.Text, message.ParseMode);
            }
        }
        catch (ApiRequestException e)
        {
            _logger.LogDebug("Message for {ChatId} is failed: {error}.", message.ChatId.Identifier, e.Message);
            if (!e.Message.Contains("bot was blocked by user"))
            {
                ReEnqueue(message, e, message.ChatId); // looks like a network issue
                return;
            }

            // User added bot to blacklist.
            // Unsubscribe him.
            UnsubscribeQueue.Enqueue(new UserUnsubscribe
            {
                ChatId = message.ChatId
            });
        }
        catch (Exception e)
        {
            _logger.LogDebug("Message for {ChatId} is failed: {error}.", message.ChatId.Identifier, e.Message);
            ReEnqueue(message, e);
        }
    }
        
    private void ReEnqueue(UserMessage message, Exception e = null, ChatId chatId = null)
    {
        if (e != null)
        {
            var eMessage = new StringBuilder();
            eMessage.Append(e.Message);
            if (chatId != null)
            {
                eMessage.Append($" ({chatId.Identifier})");
            }

            _logger.LogError(eMessage.ToString());
        }

        Queue.Enqueue(message);
    }
}