using GymLogAI.Application.Handlers;
using GymLogAI.Core.Enums;
using Microsoft.Extensions.Logging;
using Telegram.Bot;
using Telegram.Bot.Types;
using Telegram.Bot.Types.Enums;

namespace GymLogAI.TelegramBot;

public sealed class UpdateHandler(
    ImportTelegramMessageHandler importTelegramMessageHandler,
    RecommendWorkoutHandler recommendWorkoutHandler,
    ILogger<UpdateHandler> logger)
{
    public async Task HandleUpdateAsync(ITelegramBotClient botClient, Update update, CancellationToken cancellationToken)
    {
        if (update.Type != UpdateType.Message || update.Message?.Text is null)
        {
            return;
        }

        var message = update.Message;
        var text = message.Text.Trim();

        if (text.Equals("/start", StringComparison.OrdinalIgnoreCase))
        {
            await botClient.SendMessage(
                message.Chat.Id,
                "GymLogAI bot is ready. Send workout text or use /today for a recommendation.",
                cancellationToken: cancellationToken);
            return;
        }

        if (text.Equals("/today", StringComparison.OrdinalIgnoreCase))
        {
            var userId = CreateUserId(message.From?.Id ?? message.Chat.Id);
            var recommendation = await recommendWorkoutHandler.HandleAsync(
                new RecommendWorkoutCommand(userId, GoalType.Maintain, "Requested from Telegram command /today"),
                cancellationToken);

            await botClient.SendMessage(
                message.Chat.Id,
                $"{recommendation.Title}\n{recommendation.Summary}\nExercises: {string.Join(", ", recommendation.Exercises)}",
                cancellationToken: cancellationToken);
            return;
        }

        var importedMessageId = await importTelegramMessageHandler.HandleAsync(
            new ImportTelegramMessageCommand(
                CreateUserId(message.From?.Id ?? message.Chat.Id),
                message.From?.Id ?? message.Chat.Id,
                message.Chat.Id,
                message.MessageId,
                text,
                message.Date.ToUniversalTime(),
                message.From?.Username,
                message.From?.FirstName,
                message.From?.LastName),
            cancellationToken);

        logger.LogInformation("Imported telegram message {MessageId} from chat {ChatId}", importedMessageId, message.Chat.Id);

        await botClient.SendMessage(
            message.Chat.Id,
            "Message imported. It will be parsed by the worker shortly.",
            cancellationToken: cancellationToken);
    }

    public Task HandleErrorAsync(ITelegramBotClient botClient, Exception exception, CancellationToken cancellationToken)
    {
        logger.LogError(exception, "Telegram bot polling error");
        return Task.CompletedTask;
    }

    private static Guid CreateUserId(long telegramUserId)
    {
        Span<byte> buffer = stackalloc byte[16];
        BitConverter.TryWriteBytes(buffer[..8], telegramUserId);
        BitConverter.TryWriteBytes(buffer[8..], telegramUserId);
        return new Guid(buffer);
    }
}