Convert-it/Services/AudioTranscriptionService.cs

using System;
using System.IO;
using System.Net.Http;
using System.Threading.Tasks;
using Whisper.net;
using Whisper.net.Ggml;
using Xabe.FFmpeg;
using Microsoft.Extensions.Logging;

namespace Convert_It_Online.Services
{
    public class AudioTranscriptionService : IAudioTranscriptionService
    {
        private readonly string _modelPath;
        private readonly ILogger<AudioTranscriptionService> _logger;
        private readonly HttpClient _httpClient;

        public AudioTranscriptionService(ILogger<AudioTranscriptionService> logger)
        {
            _logger = logger;
            _httpClient = new HttpClient();
            _modelPath = Path.Combine(AppContext.BaseDirectory, "Models", "ggml-base.bin");
            
            // Garantir que a pasta Models existe
            var modelsDir = Path.GetDirectoryName(_modelPath);
            if (!Directory.Exists(modelsDir))
            {
                Directory.CreateDirectory(modelsDir!);
            }
        }

        private async Task EnsureModelExistsAsync()
        {
            if (!System.IO.File.Exists(_modelPath))
            {
                _logger.LogInformation("Baixando modelo Whisper Base...");
                var downloader = new WhisperGgmlDownloader(_httpClient);
                using var modelStream = await downloader.GetGgmlModelAsync(GgmlType.Base);
                using var fileStream = System.IO.File.Create(_modelPath);
                await modelStream.CopyToAsync(fileStream);
                _logger.LogInformation("Modelo Whisper baixado com sucesso.");
            }
        }

        public async Task<string> TranscribeAsync(string inputPath, string culture = "pt-BR")
        {
            await EnsureModelExistsAsync();

            string tempWavPath = Path.Combine(Path.GetTempPath(), $"{Guid.NewGuid()}.wav");

            try
            {
                _logger.LogInformation("Convertendo áudio para WAV 16kHz Mono...");
                
                // Configurar FFmpeg (assume que está no PATH em Linux)
                // Se estiver no Windows, pode precisar de FFmpeg.SetExecutablesPath
                
                var conversion = await FFmpeg.Conversions.New()
                    .AddParameter($"-i \"{inputPath}\"")
                    .AddParameter("-ar 16000")
                    .AddParameter("-ac 1")
                    .AddParameter("-c:a pcm_s16le")
                    .SetOutput(tempWavPath)
                    .Start();

                _logger.LogInformation("Iniciando transcrição com Whisper...");

                using var factory = WhisperFactory.FromPath(_modelPath);
                using var processor = factory.CreateBuilder()
                    .WithLanguage(culture.Split('-')[0]) // Usa "pt", "es", etc
                    .Build();

                using var wavStream = System.IO.File.OpenRead(tempWavPath);
                
                var result = "";
                await foreach (var segment in processor.ProcessAsync(wavStream))
                {
                    result += segment.Text + " ";
                }

                return result.Trim();
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Erro durante a transcrição de áudio.");
                throw;
            }
            finally
            {
                if (System.IO.File.Exists(tempWavPath))
                {
                    System.IO.File.Delete(tempWavPath);
                }
            }
        }
    }
}