add WhisperCppAdapter for local whisper-cpp transcription

internal/transcriber/adapter_whisper_cpp.go

@@ -0,0 +1,107 @@
+package transcriber
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"log"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"github.com/leonardotrapani/hyprvoice/internal/language"
+)
+
+// WhisperCppAdapter implements BatchAdapter for local whisper-cpp transcription
+type WhisperCppAdapter struct {
+	modelPath string
+	language  string
+	threads   int
+}
+
+// NewWhisperCppAdapter creates a new whisper-cpp adapter
+// modelPath: full path to the model file (e.g., ~/.local/share/hyprvoice/models/whisper/ggml-base.en.bin)
+// lang: canonical language code (will be converted to whisper-cpp format)
+// threads: number of CPU threads (0 for auto)
+func NewWhisperCppAdapter(modelPath, lang string, threads int) *WhisperCppAdapter {
+	return &WhisperCppAdapter{
+		modelPath: modelPath,
+		language:  lang,
+		threads:   threads,
+	}
+}
+
+func (a *WhisperCppAdapter) Transcribe(ctx context.Context, audioData []byte) (string, error) {
+	if len(audioData) == 0 {
+		return "", nil
+	}
+
+	// check whisper-cli exists
+	whisperPath, err := exec.LookPath("whisper-cli")
+	if err != nil {
+		return "", fmt.Errorf("whisper-cli not found: install whisper.cpp first")
+	}
+
+	// check model file exists
+	if _, err := os.Stat(a.modelPath); os.IsNotExist(err) {
+		return "", fmt.Errorf("model file not found: %s", a.modelPath)
+	}
+
+	// convert raw PCM to WAV
+	wavData, err := convertToWAV(audioData)
+	if err != nil {
+		return "", fmt.Errorf("convert to WAV: %w", err)
+	}
+
+	// write to temp file
+	tmpDir := os.TempDir()
+	tmpFile := filepath.Join(tmpDir, fmt.Sprintf("hyprvoice-%d.wav", time.Now().UnixNano()))
+	if err := os.WriteFile(tmpFile, wavData, 0600); err != nil {
+		return "", fmt.Errorf("write temp file: %w", err)
+	}
+	defer os.Remove(tmpFile)
+
+	// convert language to whisper-cpp format
+	lang := language.ToProviderFormat(a.language, "whisper-cpp")
+
+	// build command args
+	args := []string{
+		"-m", a.modelPath,
+		"-l", lang,
+		"-nt", // no timestamps
+		"-np", // no progress
+		"-f", tmpFile,
+	}
+
+	// add threads if specified
+	if a.threads > 0 {
+		args = append(args, "-t", fmt.Sprintf("%d", a.threads))
+	}
+
+	// execute whisper-cli
+	cmd := exec.CommandContext(ctx, whisperPath, args...)
+	var stdout, stderr bytes.Buffer
+	cmd.Stdout = &stdout
+	cmd.Stderr = &stderr
+
+	start := time.Now()
+	err = cmd.Run()
+	duration := time.Since(start)
+
+	if err != nil {
+		// check if context was cancelled
+		if ctx.Err() != nil {
+			return "", ctx.Err()
+		}
+		log.Printf("whisper-cpp: command failed after %v: %v\nstderr: %s", duration, err, stderr.String())
+		return "", fmt.Errorf("whisper-cli failed: %w", err)
+	}
+
+	// parse output - whisper-cli outputs transcription text directly (with -nt flag)
+	text := strings.TrimSpace(stdout.String())
+
+	log.Printf("whisper-cpp: transcribed %d bytes in %v: %q", len(audioData), duration, text)
+	return text, nil
+}