using BotPages.Core;
using BotPages.Core.Abstractions;
using BotPages.Core.Logging;
using System.Collections.Generic;
using System.IO;
using System.Threading;
using System.Threading.Tasks;
using Telegram.Bot;
using Telegram.Bot.Types;

namespace BotPages.Telegram;


/// <summary>
/// Внутренний билдер альбомов (медиагрупп) для Telegram.
/// </summary>
public sealed class TelegramAlbumBuilder : IAlbumBuilder
{
    private readonly TelegramAdapter _adapter;
    private readonly PageContext _ctx;
    private readonly ILogger _logger;
    private readonly TelegramBotClient? _client;
    private readonly List<(FileDescriptor file, string? caption, MessageFormat? captionFormat)> _items = new();

    /// <summary>Создать билдер альбома.</summary>
    public TelegramAlbumBuilder(TelegramAdapter adapter, PageContext ctx, ILogger logger, TelegramBotClient? client)
    {
        _adapter = adapter;
        _ctx = ctx;
        _logger = logger;
        _client = client;
    }

    /// <inheritdoc />
    public IAlbumBuilder Add(FileDescriptor file, string? caption = null, MessageFormat? captionFormat = null)
    {
        _items.Add((file, caption, captionFormat));
        return this;
    }

    /// <inheritdoc />
    public async Task SendAsync(CancellationToken ct = default)
    {
        if (_client is null)
        {
            _logger.Log(LogLevel.Critical, "Telegram client is not initialized.");
            return;
        }

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

        if (!_adapter.Capabilities.SupportsAlbums)
        {
            _logger.Log(LogLevel.Warn, "Albums not supported. Degraded to sequential sends.");
            foreach (var (file, caption, captionFormat) in _items)
                await _adapter.SendFileAsync(_ctx.Update.Chat.Id, file, caption, captionFormat, ct: ct);
            return;
        }

        var media = new List<IAlbumInputMedia>();
        foreach (var (file, caption, captionFormat) in _items)
        {
            Stream? stream = null;
            if (file.GetStreamAsync is not null)
            {
                stream = await file.GetStreamAsync(ct);
            }

            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);
            }

            IAlbumInputMedia? m = file.Kind switch
            {
                FileKind.Audio => new InputMediaAudio(inputFile) { Caption = caption ?? "" },
                FileKind.Document => new InputMediaDocument(inputFile) { Caption = caption ?? "" },
                FileKind.Photo => new InputMediaPhoto(inputFile) { Caption = caption ?? "" },
                FileKind.Video => new InputMediaVideo(inputFile) { Caption = caption ?? "" },
                _ => null
            };

            if (m is not null) media.Add(m);
            else
            {
                // Telegram не поддерживает document в альбомах — деградация
                _logger.Log(LogLevel.Warn, $"Document '{file.Kind}' in album not supported. Sending document separately.");
                await _adapter.SendFileAsync(_ctx.Update.Chat.Id, file, caption, captionFormat, ct: ct);
            }
        }

        if (media.Count > 0)
            await _client.SendMediaGroup(chatId, media, cancellationToken: ct);
    }
}