backend/internal/ai/tts/openai.go

@@ -0,0 +1,149 @@
+package tts
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"time"
+
+	"go.uber.org/zap"
+)
+
+// OpenAIService 基于 OpenAI TTS API 的语音合成实现。
+type OpenAIService struct {
+	apiKey   string
+	voice    string
+	speed    float64
+	endpoint string
+	timeout  time.Duration
+	logger   *zap.SugaredLogger
+	client   *http.Client
+}
+
+// NewOpenAIService 创建 OpenAI TTS 服务。
+func NewOpenAIService(apiKey, voice, endpoint string, speed float64, timeoutSec int, logger *zap.SugaredLogger) *OpenAIService {
+	if voice == "" {
+		voice = "alloy"
+	}
+	if speed <= 0 {
+		speed = 1.0
+	}
+	if endpoint == "" {
+		endpoint = "https://api.openai.com/v1"
+	}
+	timeout := time.Duration(timeoutSec) * time.Second
+	if timeout <= 0 {
+		timeout = 5 * time.Second
+	}
+	return &OpenAIService{
+		apiKey:   apiKey,
+		voice:    voice,
+		speed:    speed,
+		endpoint: endpoint,
+		timeout:  timeout,
+		logger:   logger,
+		client:   &http.Client{Timeout: 30 * time.Second},
+	}
+}
+
+// ttsRequest OpenAI TTS API 请求。
+type ttsRequest struct {
+	Model          string  `json:"model"`
+	Input          string  `json:"input"`
+	Voice          string  `json:"voice"`
+	ResponseFormat string  `json:"response_format"`
+	Speed          float64 `json:"speed"`
+}
+
+// SynthesizeStream 实现 tts.Service。从 textStream 读取句子，逐句调用 OpenAI TTS API。
+func (o *OpenAIService) SynthesizeStream(ctx context.Context, textStream <-chan string, opts Options) (<-chan Chunk, error) {
+	voice := opts.Voice
+	if voice == "" {
+		voice = o.voice
+	}
+	speed := opts.Speed
+	if speed <= 0 {
+		speed = o.speed
+	}
+
+	ch := make(chan Chunk, 4)
+	go func() {
+		defer close(ch)
+
+		for text := range textStream {
+			if text == "" {
+				continue
+			}
+
+			audio, err := o.synthesize(ctx, text, voice, speed)
+			if err != nil {
+				o.logger.Warnw("tts: synthesize failed", "error", err, "text", text)
+				// 静默跳过，不中断整个流
+				continue
+			}
+
+			select {
+			case ch <- Chunk{Audio: audio, IsLast: false}:
+			case <-ctx.Done():
+				return
+			}
+		}
+
+		// textStream 关闭，发送 IsLast 标记
+		select {
+		case ch <- Chunk{Audio: nil, IsLast: true}:
+		case <-ctx.Done():
+		}
+	}()
+
+	return ch, nil
+}
+
+// synthesize 调用 OpenAI TTS API 合成单个句子。
+func (o *OpenAIService) synthesize(ctx context.Context, text, voice string, speed float64) ([]byte, error) {
+	// 单句超时
+	ctx, cancel := context.WithTimeout(ctx, o.timeout)
+	defer cancel()
+
+	body := ttsRequest{
+		Model:          "tts-1",
+		Input:          text,
+		Voice:          voice,
+		ResponseFormat: "mp3",
+		Speed:          speed,
+	}
+
+	payload, err := json.Marshal(body)
+	if err != nil {
+		return nil, fmt.Errorf("tts: marshal request: %w", err)
+	}
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, o.endpoint+"/audio/speech", bytes.NewReader(payload))
+	if err != nil {
+		return nil, fmt.Errorf("tts: create request: %w", err)
+	}
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("Authorization", "Bearer "+o.apiKey)
+
+	resp, err := o.client.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("tts: send request: %w", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		errBody, _ := io.ReadAll(resp.Body)
+		return nil, fmt.Errorf("tts: api error (status %d): %s", resp.StatusCode, string(errBody))
+	}
+
+	// 读取整个 MP3 响应
+	audio, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, fmt.Errorf("tts: read response: %w", err)
+	}
+
+	return audio, nil
+}