task 002: centralize Gemini voice fallbacks

6 files changed, 112 insertions, 60 deletions

diff --git a/internal/audio/fallbacks.go b/internal/audio/fallbacks.go
new file mode 100644
index 0000000..bd0c86e
--- /dev/null
+++ b/internal/audio/fallbacks.go
@@ -0,0 +1,29 @@
+package audio
+
+import (
+	"fmt"
+	"strings"
+)
+
+// RunWithVoiceFallbacks tries the selected Gemini voice first, then the remaining known voices.
+func RunWithVoiceFallbacks(initialVoice string, generate func(voice string) error) (usedVoice string, err error) {
+	attempted := make([]string, 0, len(GeminiVoices))
+	var lastErr error
+
+	for _, voice := range GeminiVoiceFallbacks(initialVoice) {
+		attempted = append(attempted, voice)
+
+		err := generate(voice)
+		if err == nil {
+			return voice, nil
+		}
+		if !IsGeminiNoAudioDataError(err) {
+			return "", err
+		}
+
+		lastErr = err
+		fmt.Printf("Warning: Gemini returned no audio for voice %s\n", voice)
+	}
+
+	return "", fmt.Errorf("Gemini returned no audio for voices %s: %w", strings.Join(attempted, ", "), lastErr)
+}
diff --git a/internal/audio/voices_test.go b/internal/audio/voices_test.go
index ea0f797..5e940d0 100644
--- a/internal/audio/voices_test.go
+++ b/internal/audio/voices_test.go
@@ -1,10 +1,13 @@
 package audio
 
 import (
+	"errors"
 	"reflect"
 	"testing"
 )
 
+var errTestSentinel = errors.New("test sentinel error")
+
 func TestVoiceLists(t *testing.T) {
 	t.Parallel()
 
@@ -57,3 +60,49 @@ func TestGeminiVoiceFallbacks(t *testing.T) {
 		}
 	})
 }
+
+func TestRunWithVoiceFallbacks(t *testing.T) {
+	originalVoices := append([]string(nil), GeminiVoices...)
+	t.Cleanup(func() {
+		GeminiVoices = originalVoices
+	})
+	GeminiVoices = []string{"Charon", "Kore", "Leda"}
+
+	t.Run("retries no-audio errors until success", func(t *testing.T) {
+		var attempted []string
+		usedVoice, err := RunWithVoiceFallbacks("Charon", func(voice string) error {
+			attempted = append(attempted, voice)
+			if voice == "Charon" {
+				return ErrGeminiNoAudioData
+			}
+			return nil
+		})
+		if err != nil {
+			t.Fatalf("RunWithVoiceFallbacks() unexpected error: %v", err)
+		}
+		if usedVoice != "Kore" {
+			t.Fatalf("used voice = %q, want %q", usedVoice, "Kore")
+		}
+		if got, want := attempted, []string{"Charon", "Kore"}; !reflect.DeepEqual(got, want) {
+			t.Fatalf("attempted voices = %#v, want %#v", got, want)
+		}
+	})
+
+	t.Run("returns non-retryable errors immediately", func(t *testing.T) {
+		sentinel := errTestSentinel
+		var attempted []string
+		usedVoice, err := RunWithVoiceFallbacks("Charon", func(voice string) error {
+			attempted = append(attempted, voice)
+			return sentinel
+		})
+		if !errors.Is(err, sentinel) {
+			t.Fatalf("error = %v, want %v", err, sentinel)
+		}
+		if usedVoice != "" {
+			t.Fatalf("used voice = %q, want empty", usedVoice)
+		}
+		if got, want := attempted, []string{"Charon"}; !reflect.DeepEqual(got, want) {
+			t.Fatalf("attempted voices = %#v, want %#v", got, want)
+		}
+	})
+}
diff --git a/internal/gui/generator.go b/internal/gui/generator.go
index a1ab22c..f3fe9b5 100644
--- a/internal/gui/generator.go
+++ b/internal/gui/generator.go
@@ -133,31 +133,6 @@ func (a *Application) generateAudioFile(ctx context.Context, text, outputFile, v
 	return provider.GenerateAudio(ctx, text, outputFile)
 }
 
-func (a *Application) generateGeminiAudioWithFallbacks(initialVoice string, generate func(voice string) error) (string, error) {
-	attempted := make([]string, 0, len(audio.GeminiVoices))
-	var lastErr error
-
-	for i, voice := range audio.GeminiVoiceFallbacks(initialVoice) {
-		if i > 0 {
-			fmt.Printf("Retrying Gemini audio with voice: %s\n", voice)
-		}
-
-		attempted = append(attempted, voice)
-		err := generate(voice)
-		if err == nil {
-			return voice, nil
-		}
-		if !audio.IsGeminiNoAudioDataError(err) {
-			return "", err
-		}
-
-		lastErr = err
-		fmt.Printf("Warning: Gemini returned no audio for voice %s\n", voice)
-	}
-
-	return "", fmt.Errorf("Gemini returned no audio for voices %s: %w", strings.Join(attempted, ", "), lastErr)
-}
-
 // translateWord translates a Bulgarian word to English
 func (a *Application) translateWord(word string) (string, error) {
 	if a.translator == nil {
@@ -207,7 +182,10 @@ func (a *Application) generateAudio(ctx context.Context, word string, cardDir st
 	finalVoice := voice
 	var err error
 	if a.audioProviderName() == "gemini" && !a.geminiVoicePinned() {
-		finalVoice, err = a.generateGeminiAudioWithFallbacks(voice, func(candidate string) error {
+		finalVoice, err = audio.RunWithVoiceFallbacks(voice, func(candidate string) error {
+			if candidate != voice {
+				fmt.Printf("Retrying Gemini audio with voice: %s\n", candidate)
+			}
 			return a.generateAudioFile(ctx, word, outputFile, candidate, speed)
 		})
 	} else {
@@ -246,7 +224,10 @@ func (a *Application) generateAudioFront(ctx context.Context, word string, cardD
 	finalVoice := voice
 	var err error
 	if a.audioProviderName() == "gemini" && !a.geminiVoicePinned() {
-		finalVoice, err = a.generateGeminiAudioWithFallbacks(voice, func(candidate string) error {
+		finalVoice, err = audio.RunWithVoiceFallbacks(voice, func(candidate string) error {
+			if candidate != voice {
+				fmt.Printf("Retrying Gemini audio with voice: %s\n", candidate)
+			}
 			return a.generateAudioFile(ctx, word, frontFile, candidate, speed)
 		})
 	} else {
@@ -283,7 +264,10 @@ func (a *Application) generateAudioBack(ctx context.Context, text string, cardDi
 	finalVoice := voice
 	var err error
 	if a.audioProviderName() == "gemini" && !a.geminiVoicePinned() {
-		finalVoice, err = a.generateGeminiAudioWithFallbacks(voice, func(candidate string) error {
+		finalVoice, err = audio.RunWithVoiceFallbacks(voice, func(candidate string) error {
+			if candidate != voice {
+				fmt.Printf("Retrying Gemini audio with voice: %s\n", candidate)
+			}
 			return a.generateAudioFile(ctx, text, backFile, candidate, speed)
 		})
 	} else {
@@ -336,7 +320,12 @@ func (a *Application) generateAudioBgBg(ctx context.Context, front, back, cardDi
 	finalVoice := voice
 	var err error
 	if a.audioProviderName() == "gemini" && !a.geminiVoicePinned() {
-		finalVoice, err = a.generateGeminiAudioWithFallbacks(voice, runPair)
+		finalVoice, err = audio.RunWithVoiceFallbacks(voice, func(candidate string) error {
+			if candidate != voice {
+				fmt.Printf("Retrying Gemini audio with voice: %s\n", candidate)
+			}
+			return runPair(candidate)
+		})
 	} else {
 		err = runPair(voice)
 	}
diff --git a/internal/gui/generator_test.go b/internal/gui/generator_test.go
index 2828337..fcb8f51 100644
--- a/internal/gui/generator_test.go
+++ b/internal/gui/generator_test.go
@@ -398,11 +398,11 @@ func TestGenerateGeminiAudioWithFallbacksRetriesAlternateVoice(t *testing.T) {
 		},
 	}
 
-	voice, err := app.generateGeminiAudioWithFallbacks("Charon", func(candidate string) error {
+	voice, err := audio.RunWithVoiceFallbacks("Charon", func(candidate string) error {
 		return app.generateAudioFile(context.Background(), "ябълка", outputPath, candidate, 1.0)
 	})
 	if err != nil {
-		t.Fatalf("generateGeminiAudioWithFallbacks() unexpected error: %v", err)
+		t.Fatalf("RunWithVoiceFallbacks() unexpected error: %v", err)
 	}
 
 	if voice != "Kore" {
diff --git a/internal/processor/processor.go b/internal/processor/processor.go
index 38c2413..f6eb706 100644
--- a/internal/processor/processor.go
+++ b/internal/processor/processor.go
@@ -344,31 +344,6 @@ func (p *Processor) logSelectedAudioVoice(provider, voice string) {
 	}
 }
 
-func (p *Processor) generateGeminiAudioWithFallbacks(initialVoice string, generate func(voice string) error) error {
-	attempted := make([]string, 0, len(audio.GeminiVoices))
-	var lastErr error
-
-	for i, voice := range audio.GeminiVoiceFallbacks(initialVoice) {
-		if i > 0 {
-			fmt.Printf("  Retrying Gemini audio with voice: %s\n", voice)
-		}
-
-		attempted = append(attempted, voice)
-		err := generate(voice)
-		if err == nil {
-			return nil
-		}
-		if !audio.IsGeminiNoAudioDataError(err) {
-			return err
-		}
-
-		lastErr = err
-		fmt.Printf("  Warning: Gemini returned no audio for voice %s\n", voice)
-	}
-
-	return fmt.Errorf("Gemini returned no audio for voices %s: %w", strings.Join(attempted, ", "), lastErr)
-}
-
 // generateAudio generates audio files for a word
 func (p *Processor) generateAudio(word string) error {
 	provider := p.audioProviderName()
@@ -381,9 +356,13 @@ func (p *Processor) generateAudio(word string) error {
 		voice := p.audioVoiceForProvider()
 		p.logSelectedAudioVoice(provider, voice)
 		if provider == "gemini" && p.geminiVoice() == "" {
-			return p.generateGeminiAudioWithFallbacks(voice, func(candidate string) error {
+			_, err := audio.RunWithVoiceFallbacks(voice, func(candidate string) error {
+				if candidate != voice {
+					fmt.Printf("  Retrying Gemini audio with voice: %s\n", candidate)
+				}
 				return p.generateAudioWithVoice(word, candidate)
 			})
+			return err
 		}
 		voices = []string{voice}
 	}
@@ -427,7 +406,13 @@ func (p *Processor) generateAudioBgBg(front, back string) error {
 	}
 
 	if provider == "gemini" && p.geminiVoice() == "" {
-		return p.generateGeminiAudioWithFallbacks(voice, generatePair)
+		_, err := audio.RunWithVoiceFallbacks(voice, func(candidate string) error {
+			if candidate != voice {
+				fmt.Printf("  Retrying Gemini audio with voice: %s\n", candidate)
+			}
+			return generatePair(candidate)
+		})
+		return err
 	}
 
 	if err := generatePair(voice); err != nil {
diff --git a/internal/processor/processor_test.go b/internal/processor/processor_test.go
index a0c6ae1..cd6e2eb 100644
--- a/internal/processor/processor_test.go
+++ b/internal/processor/processor_test.go
@@ -712,10 +712,10 @@ func TestGenerateGeminiAudioWithFallbacksRetriesAlternateVoice(t *testing.T) {
 	flags.AudioProvider = "gemini"
 
 	p := NewProcessor(flags)
-	if err := p.generateGeminiAudioWithFallbacks("Charon", func(voice string) error {
+	if _, err := audio.RunWithVoiceFallbacks("Charon", func(voice string) error {
 		return p.generateAudioWithVoice("ябълка", voice)
 	}); err != nil {
-		t.Fatalf("generateGeminiAudioWithFallbacks() unexpected error: %v", err)
+		t.Fatalf("RunWithVoiceFallbacks() unexpected error: %v", err)
 	}
 
 	if got, want := strings.Join(attemptedVoices, ","), "Charon,Kore"; got != want {