using BotPages.Core;
using BotPages.Core.Abstractions;
using BotPages.Core.Context;
using BotPages.Core.Logging;
using BotPages.Core.Messaging;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using Telegram.Bot;
using Telegram.Bot.Types;
using Telegram.Bot.Types.Enums;
using Telegram.Bot.Types.ReplyMarkups;

namespace BotPages.Telegram;


/// <summary>
/// Адаптер для Telegram на базе Telegram.Bot.
/// Реализует отправку текста, кнопок, файлов, альбомов и прогресса.
/// </summary>
public sealed class TelegramAdapter : IMessengerAdapter
{
    private readonly ILogger _logger;
    private TelegramBotClient? _client;

    /// <summary>Создать адаптер Telegram.</summary>
    public TelegramAdapter(ILogger logger) => _logger = logger;

    /// <summary>
    /// Запустить polling для приема обновлений от Telegram.
    /// </summary>
    public async Task StartPollingAsync(string token, Func<UpdateContext, Task> onUpdate, CancellationToken ct)
    {
        _client = new TelegramBotClient(token);

        _client.StartReceiving(
            updateHandler: async (_, update, ct2) =>
            {
                var mapped = TelegramUpdateMapper.Map(update, _client);
                if (mapped is not null)
                    await onUpdate(mapped);
            },

            errorHandler: async (_, ex, ct2) =>
            {
                _logger.Log(LogLevel.Warn, "Telegram error.", ex);
                await Task.CompletedTask;
            },

            cancellationToken: ct
        );


        var me = await _client.GetMe();
        _logger.Log(LogLevel.Info, $"Telegram started: @{me.Username}");

        return;
    }

    /// <inheritdoc />
    public async Task SendTextAsync(PageContext ctx, string text, MessageFormat format,
        IEnumerable<IEnumerable<InlineButton>>? inline,
        IEnumerable<IEnumerable<ReplyButton>>? reply, CancellationToken ct)
    {
        if (_client is null)
        {
            _logger.Log(LogLevel.Critical, "Telegram client is not initialized.");
            return;
        }

        ReplyMarkup? markup = null;

        if (inline is not null && inline.Any())
        {
            markup = new InlineKeyboardMarkup(
                inline.Select(row => row.Select(b => new InlineKeyboardButton(b.Label, b.Value)).ToArray())
                      .ToArray()
            );
        }
        else if (reply is not null && reply.Any())
        {
            markup = new ReplyKeyboardMarkup(
                reply.Select(row => row.Select(b => new KeyboardButton(b.Label)).ToArray()).ToArray()
            )
            {
                ResizeKeyboard = true
            };
        }

        var parseMode = ParseMode.None;

        switch (format)
        {
            case MessageFormat.Html:
                {
                    parseMode = ParseMode.Html;
                    break;
                }
            case MessageFormat.Plain:
                {
                    parseMode = ParseMode.None;
                    break;
                }
            case MessageFormat.Markdown:
                {
                    parseMode = ParseMode.MarkdownV2;
                    break;
                }
            default:
                {
                    _logger.Log(LogLevel.Warn, $"MessageFormat '{format}' not supported. Degraded to plain text.");
                    break;
                }
        }

        // Длина сообщения
        if (text.Length > ctx.Update.Chat.Capabilities.MaxMessageLength)
        {
            _logger.Log(LogLevel.Warn, $"Message too long ({text.Length}). Truncated to {ctx.Update.Chat.Capabilities.MaxMessageLength}.");
            text = text.Substring(0, ctx.Update.Chat.Capabilities.MaxMessageLength);
        }

        await _client.SendMessage(
            chatId: long.Parse(ctx.Update.Chat.Id),
            text: text,
            parseMode: parseMode,
            replyMarkup: markup,
            cancellationToken: ct
        );
    }

    /// <inheritdoc />
    public async Task SendFileAsync(PageContext ctx, FileDescriptor file, string? caption, CancellationToken ct)
    {
        if (_client is null)
        {
            _logger.Log(LogLevel.Critical, "Telegram client is not initialized.");
            return;
        }

        var chatId = long.Parse(ctx.Update.Chat.Id);

        // Получаем поток, если он задан
        Stream? stream = null;
        if (file.GetStreamAsync is not null)
        {
            stream = await file.GetStreamAsync(ct);
            stream.Position = 0;
        }

        InputFile inputFile;

        if (stream is not null && stream != Stream.Null)
        {
            inputFile = new InputFileStream(stream, file.Name);
        }
        else if (file.Id.StartsWith("http://") || file.Id.StartsWith("https://"))
        {
            inputFile = new InputFileUrl(file.Id);
        }
        else
        {
            inputFile = new InputFileId(file.Id);
        }

        // В зависимости от FileKind выбираем подходящий метод
        switch (file.Kind)
        {
            case FileKind.Photo:
                await _client.SendPhoto(chatId, inputFile, caption ?? "", cancellationToken: ct);
                break;
            case FileKind.Video:
                await _client.SendVideo(chatId, inputFile, caption: caption ?? "", cancellationToken: ct);
                break;
            case FileKind.Audio:
                await _client.SendAudio(chatId, inputFile, caption ?? "", cancellationToken: ct);
                break;
            default:
                await _client.SendDocument(chatId, inputFile, caption ?? "", cancellationToken: ct);
                break;
        }
    }

    /// <inheritdoc />
    public IAlbumBuilder CreateAlbumBuilder(PageContext ctx) => new TelegramAlbumBuilder(this, ctx, _logger, _client);

    /// <inheritdoc />
    public async Task<string?> StartProgressAsync(PageContext ctx, string title, CancellationToken ct)
    {
        if (_client is null)
        {
            _logger.Log(LogLevel.Critical, "Telegram client is not initialized.");
            return null;
        }

        string text = "0%";
        if (!string.IsNullOrEmpty(title))
        {
            text = title + Environment.NewLine + text;
        }

        var message = await _client.SendMessage(
            chatId: long.Parse(ctx.Update.Chat.Id),
            text: text,
            cancellationToken: ct
        );

        return message.Id.ToString();
    }

    /// <inheritdoc />
    public async Task UpdateProgressAsync(PageContext ctx, string messageId, string title, int percent, CancellationToken ct)
    {
        if (_client is null)
        {
            _logger.Log(LogLevel.Critical, "Telegram client is not initialized.");
            return;
        }

        percent = Math.Clamp(percent, 0, 100);

        string text = $"{percent}%";
        if (!string.IsNullOrEmpty(title))
        {
            text = title + Environment.NewLine + text;
        }

        try
        {
            await _client.EditMessageText(
                messageId: int.Parse(messageId),
                chatId: long.Parse(ctx.Update.Chat.Id),
                text: text,
                cancellationToken: ct
            );
        }
        catch (Exception ex)
        {
            _logger.Log(LogLevel.Critical, ex.Message, ex);
        }
    }

    /// <inheritdoc />
    public Task OnLeaveAsync(PageContext ctx, CancellationToken ct) => Task.CompletedTask;
}