Add STT and TTS clients

internal/tts/tts.go

@@ -0,0 +1,208 @@
+// Package tts provides a client for kokoro-fastapi text-to-speech.
+package tts
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"log/slog"
+	"net/http"
+	"time"
+)
+
+// Config holds the configuration for a TTS client.
+type Config struct {
+	// URL is the base URL of kokoro-fastapi.
+	// For example, "http://localhost:8880".
+	URL string `yaml:"url"`
+	// Voice is the default voice ID to use (e.g., "af_heart").
+	Voice string `yaml:"voice"`
+	// Timeout is the maximum duration for a synthesis request.
+	// Defaults to 60s if empty.
+	Timeout string `yaml:"timeout"`
+	// VoiceMap maps whisper language names to voice IDs.
+	// Used by SelectVoice to auto-select voices based on detected
+	// language.
+	// If empty, defaultVoices is used.
+	VoiceMap map[string]string `yaml:"voice_map"`
+}
+
+// Validate checks that required configuration values are present and valid.
+func (cfg Config) Validate() error {
+	if cfg.URL == "" {
+		return fmt.Errorf("missing URL")
+	}
+	if cfg.Voice == "" {
+		return fmt.Errorf("missing voice")
+	}
+	if cfg.Timeout != "" {
+		if _, err := time.ParseDuration(cfg.Timeout); err != nil {
+			return fmt.Errorf("invalid timeout: %w", err)
+		}
+	}
+	return nil
+}
+
+// Client wraps an HTTP client for kokoro-fastapi requests.
+type Client struct {
+	client   *http.Client
+	log      *slog.Logger
+	timeout  time.Duration
+	url      string
+	voice    string
+	voiceMap map[string]string
+}
+
+// NewClient creates a new TTS client with the provided configuration.
+func NewClient(cfg Config, log *slog.Logger) (*Client, error) {
+	if err := cfg.Validate(); err != nil {
+		return nil, fmt.Errorf("invalid config: %v", err)
+	}
+
+	timeout := 60 * time.Second
+	if cfg.Timeout != "" {
+		d, err := time.ParseDuration(cfg.Timeout)
+		if err != nil {
+			return nil, fmt.Errorf("parse timeout: %v", err)
+		}
+		timeout = d
+	}
+
+	voiceMap := cfg.VoiceMap
+	if len(voiceMap) == 0 {
+		voiceMap = defaultVoices
+	}
+
+	return &Client{
+		client:   &http.Client{Timeout: timeout},
+		log:      log,
+		timeout:  timeout,
+		url:      cfg.URL,
+		voice:    cfg.Voice,
+		voiceMap: voiceMap,
+	}, nil
+}
+
+// defaultVoices maps whisper language names to default Kokoro voices.
+// Used when Config.VoiceMap is empty.
+var defaultVoices = map[string]string{
+	"chinese":    "zf_xiaobei",
+	"english":    "af_heart",
+	"french":     "ff_siwis",
+	"hindi":      "hf_alpha",
+	"italian":    "if_sara",
+	"japanese":   "jf_alpha",
+	"korean":     "kf_sarah",
+	"portuguese": "pf_dora",
+	"spanish":    "ef_dora",
+}
+
+// SelectVoice returns the voice ID for the given whisper language name.
+// Returns an empty string if no mapping exists for the language.
+func (c *Client) SelectVoice(lang string) string {
+	if voice, ok := c.voiceMap[lang]; ok {
+		return voice
+	}
+	return ""
+}
+
+// Synthesize converts text to speech and returns WAV audio.
+// If voice is empty, the default configured voice is used.
+func (c *Client) Synthesize(ctx context.Context, text, voice string) (
+	[]byte, error,
+) {
+	ctx, cancel := context.WithTimeout(ctx, c.timeout)
+	defer cancel()
+	if voice == "" {
+		voice = c.voice
+	}
+
+	body, err := json.Marshal(struct {
+		Input string `json:"input"`
+		Voice string `json:"voice"`
+	}{
+		Input: text,
+		Voice: voice,
+	})
+	if err != nil {
+		return nil, fmt.Errorf("marshal request: %w", err)
+	}
+
+	req, err := http.NewRequestWithContext(
+		ctx,
+		http.MethodPost,
+		c.url+"/v1/audio/speech",
+		bytes.NewReader(body),
+	)
+	if err != nil {
+		return nil, fmt.Errorf("create request: %w", err)
+	}
+	req.Header.Set("Content-Type", "application/json")
+
+	res, err := c.client.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("send request: %w", err)
+	}
+	defer res.Body.Close()
+
+	if res.StatusCode != http.StatusOK {
+		body, err := io.ReadAll(res.Body)
+		if err != nil {
+			c.log.ErrorContext(
+				ctx,
+				"failed to read response body",
+				slog.Any("error", err),
+			)
+		}
+		return nil, fmt.Errorf(
+			"tts error %d: %s", res.StatusCode, body,
+		)
+	}
+
+	audio, err := io.ReadAll(res.Body)
+	if err != nil {
+		return nil, fmt.Errorf("read response: %w", err)
+	}
+
+	return audio, nil
+}
+
+// ListVoices returns the available voices from kokoro-fastapi.
+func (c *Client) ListVoices(ctx context.Context) ([]string, error) {
+	ctx, cancel := context.WithTimeout(ctx, c.timeout)
+	defer cancel()
+
+	req, err := http.NewRequestWithContext(
+		ctx,
+		http.MethodGet,
+		c.url+"/v1/audio/voices",
+		nil,
+	)
+	if err != nil {
+		return nil, fmt.Errorf("create request: %w", err)
+	}
+
+	res, err := c.client.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("send request: %w", err)
+	}
+	defer res.Body.Close()
+
+	if res.StatusCode != http.StatusOK {
+		body, _ := io.ReadAll(res.Body)
+		return nil, fmt.Errorf(
+			"voices error %d: %s", res.StatusCode, body,
+		)
+	}
+
+	var voices = struct {
+		Voices []string `json:"voices"`
+	}{}
+	if err := json.NewDecoder(res.Body).Decode(&voices); err != nil {
+		return nil, fmt.Errorf("decode response: %w", err)
+	}
+
+	return voices.Voices, nil
+}