1 files changed, 166 insertions, 0 deletions
diff --git a/extra/stt.go b/extra/stt.go
new file mode 100644
index 0000000..ce107b4
--- /dev/null
+++ b/extra/stt.go
@@ -0,0 +1,166 @@
+package extra
+
+import (
+	"bytes"
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"io"
+	"log/slog"
+	"mime/multipart"
+	"net/http"
+	"regexp"
+	"strings"
+
+	"github.com/gordonklaus/portaudio"
+)
+
+var specialRE = regexp.MustCompile(`\[.*?\]`)
+
+type STT interface {
+	StartRecording() error
+	StopRecording() (string, error)
+	IsRecording() bool
+}
+
+type StreamCloser interface {
+	Close() error
+}
+
+type WhisperSTT struct {
+	logger      *slog.Logger
+	ServerURL   string
+	SampleRate  int
+	AudioBuffer *bytes.Buffer
+	recording   bool
+}
+
+func NewWhisperSTT(logger *slog.Logger, serverURL string, sampleRate int) *WhisperSTT {
+	return &WhisperSTT{
+		logger:      logger,
+		ServerURL:   serverURL,
+		SampleRate:  sampleRate,
+		AudioBuffer: new(bytes.Buffer),
+	}
+}
+
+func (stt *WhisperSTT) StartRecording() error {
+	if err := stt.microphoneStream(stt.SampleRate); err != nil {
+		return fmt.Errorf("failed to init microphone: %w", err)
+	}
+	stt.recording = true
+	return nil
+}
+
+func (stt *WhisperSTT) StopRecording() (string, error) {
+	stt.recording = false
+	// wait loop to finish?
+	if stt.AudioBuffer == nil {
+		err := errors.New("unexpected nil AudioBuffer")
+		stt.logger.Error(err.Error())
+		return "", err
+	}
+	// Create WAV header first
+	body := &bytes.Buffer{}
+	writer := multipart.NewWriter(body)
+	// Add audio file part
+	part, err := writer.CreateFormFile("file", "recording.wav")
+	if err != nil {
+		stt.logger.Error("fn: StopRecording", "error", err)
+		return "", err
+	}
+	// Stream directly to multipart writer: header + raw data
+	dataSize := stt.AudioBuffer.Len()
+	stt.writeWavHeader(part, dataSize)
+	if _, err := io.Copy(part, stt.AudioBuffer); err != nil {
+		stt.logger.Error("fn: StopRecording", "error", err)
+		return "", err
+	}
+	// Reset buffer for next recording
+	stt.AudioBuffer.Reset()
+	// Add response format field
+	err = writer.WriteField("response_format", "text")
+	if err != nil {
+		stt.logger.Error("fn: StopRecording", "error", err)
+		return "", err
+	}
+	if writer.Close() != nil {
+		stt.logger.Error("fn: StopRecording", "error", err)
+		return "", err
+	}
+	// Send request
+	resp, err := http.Post(stt.ServerURL, writer.FormDataContentType(), body) //nolint:noctx
+	if err != nil {
+		stt.logger.Error("fn: StopRecording", "error", err)
+		return "", err
+	}
+	defer resp.Body.Close()
+	// Read and print response
+	responseTextBytes, err := io.ReadAll(resp.Body)
+	if err != nil {
+		stt.logger.Error("fn: StopRecording", "error", err)
+		return "", err
+	}
+	resptext := strings.TrimRight(string(responseTextBytes), "\n")
+	// in case there are special tokens like [_BEG_]
+	resptext = specialRE.ReplaceAllString(resptext, "")
+	return strings.TrimSpace(strings.ReplaceAll(resptext, "\n ", "\n")), nil
+}
+
+func (stt *WhisperSTT) writeWavHeader(w io.Writer, dataSize int) {
+	header := make([]byte, 44)
+	copy(header[0:4], "RIFF")
+	binary.LittleEndian.PutUint32(header[4:8], uint32(36+dataSize))
+	copy(header[8:12], "WAVE")
+	copy(header[12:16], "fmt ")
+	binary.LittleEndian.PutUint32(header[16:20], 16)
+	binary.LittleEndian.PutUint16(header[20:22], 1)
+	binary.LittleEndian.PutUint16(header[22:24], 1)
+	binary.LittleEndian.PutUint32(header[24:28], uint32(stt.SampleRate))
+	binary.LittleEndian.PutUint32(header[28:32], uint32(stt.SampleRate)*1*(16/8))
+	binary.LittleEndian.PutUint16(header[32:34], 1*(16/8))
+	binary.LittleEndian.PutUint16(header[34:36], 16)
+	copy(header[36:40], "data")
+	binary.LittleEndian.PutUint32(header[40:44], uint32(dataSize))
+	if _, err := w.Write(header); err != nil {
+		stt.logger.Error("writeWavHeader", "error", err)
+	}
+}
+
+func (stt *WhisperSTT) IsRecording() bool {
+	return stt.recording
+}
+
+func (stt *WhisperSTT) microphoneStream(sampleRate int) error {
+	if err := portaudio.Initialize(); err != nil {
+		return fmt.Errorf("portaudio init failed: %w", err)
+	}
+	in := make([]int16, 64)
+	stream, err := portaudio.OpenDefaultStream(1, 0, float64(sampleRate), len(in), in)
+	if err != nil {
+		if paErr := portaudio.Terminate(); paErr != nil {
+			return fmt.Errorf("failed to open microphone: %w; terminate error: %w", err, paErr)
+		}
+		return fmt.Errorf("failed to open microphone: %w", err)
+	}
+	go func(stream *portaudio.Stream) {
+		if err := stream.Start(); err != nil {
+			stt.logger.Error("microphoneStream", "error", err)
+			return
+		}
+		for {
+			if !stt.IsRecording() {
+				return
+			}
+			if err := stream.Read(); err != nil {
+				stt.logger.Error("reading stream", "error", err)
+				return
+			}
+			if err := binary.Write(stt.AudioBuffer, binary.LittleEndian, in); err != nil {
+				stt.logger.Error("writing to buffer", "error", err)
+				return
+			}
+		}
+	}(stream)
+	return nil
+}