feat: initial TTS support (#528)

* feat: initial TTS support

* chore: lint, omitempty

* chore: dont use pointer in struct

* fix: add mocked server tests to speech_test.go

Co-authored-by: Lachlan Laycock <supagroova@gmail.com>

* chore: update imports

* chore: fix lint

* chore: add an error check

* chore: ignore lint

* chore: add error checks in package

* chore: add test

* chore: fix test

---------

Co-authored-by: Lachlan Laycock <supagroova@gmail.com>

client_test.go

@@ -358,6 +358,9 @@ func TestClientReturnsRequestBuilderErrors(t *testing.T) {
 		{"ListRunSteps", func() (any, error) {
 			return client.ListRunSteps(ctx, "", "", Pagination{})
 		}},
+		{"CreateSpeech", func() (any, error) {
+			return client.CreateSpeech(ctx, CreateSpeechRequest{Model: TTSModel1, Voice: VoiceAlloy})
+		}},
 	}
 
 	for _, testCase := range testCases {

speech.go

@@ -0,0 +1,87 @@
+package openai
+
+import (
+	"context"
+	"errors"
+	"io"
+	"net/http"
+)
+
+type SpeechModel string
+
+const (
+	TTSModel1   SpeechModel = "tts-1"
+	TTsModel1HD SpeechModel = "tts-1-hd"
+)
+
+type SpeechVoice string
+
+const (
+	VoiceAlloy   SpeechVoice = "alloy"
+	VoiceEcho    SpeechVoice = "echo"
+	VoiceFable   SpeechVoice = "fable"
+	VoiceOnyx    SpeechVoice = "onyx"
+	VoiceNova    SpeechVoice = "nova"
+	VoiceShimmer SpeechVoice = "shimmer"
+)
+
+type SpeechResponseFormat string
+
+const (
+	SpeechResponseFormatMp3  SpeechResponseFormat = "mp3"
+	SpeechResponseFormatOpus SpeechResponseFormat = "opus"
+	SpeechResponseFormatAac  SpeechResponseFormat = "aac"
+	SpeechResponseFormatFlac SpeechResponseFormat = "flac"
+)
+
+var (
+	ErrInvalidSpeechModel = errors.New("invalid speech model")
+	ErrInvalidVoice       = errors.New("invalid voice")
+)
+
+type CreateSpeechRequest struct {
+	Model          SpeechModel          `json:"model"`
+	Input          string               `json:"input"`
+	Voice          SpeechVoice          `json:"voice"`
+	ResponseFormat SpeechResponseFormat `json:"response_format,omitempty"` // Optional, default to mp3
+	Speed          float64              `json:"speed,omitempty"`           // Optional, default to 1.0
+}
+
+func contains[T comparable](s []T, e T) bool {
+	for _, v := range s {
+		if v == e {
+			return true
+		}
+	}
+	return false
+}
+
+func isValidSpeechModel(model SpeechModel) bool {
+	return contains([]SpeechModel{TTSModel1, TTsModel1HD}, model)
+}
+
+func isValidVoice(voice SpeechVoice) bool {
+	return contains([]SpeechVoice{VoiceAlloy, VoiceEcho, VoiceFable, VoiceOnyx, VoiceNova, VoiceShimmer}, voice)
+}
+
+func (c *Client) CreateSpeech(ctx context.Context, request CreateSpeechRequest) (response io.ReadCloser, err error) {
+	if !isValidSpeechModel(request.Model) {
+		err = ErrInvalidSpeechModel
+		return
+	}
+	if !isValidVoice(request.Voice) {
+		err = ErrInvalidVoice
+		return
+	}
+	req, err := c.newRequest(ctx, http.MethodPost, c.fullURL("/audio/speech", request.Model),
+		withBody(request),
+		withContentType("application/json; charset=utf-8"),
+	)
+	if err != nil {
+		return
+	}
+
+	response, err = c.sendRequestRaw(req)
+
+	return
+}

speech_test.go

@@ -0,0 +1,115 @@
+package openai_test
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"mime"
+	"net/http"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/sashabaranov/go-openai"
+	"github.com/sashabaranov/go-openai/internal/test"
+	"github.com/sashabaranov/go-openai/internal/test/checks"
+)
+
+func TestSpeechIntegration(t *testing.T) {
+	client, server, teardown := setupOpenAITestServer()
+	defer teardown()
+
+	server.RegisterHandler("/v1/audio/speech", func(w http.ResponseWriter, r *http.Request) {
+		dir, cleanup := test.CreateTestDirectory(t)
+		path := filepath.Join(dir, "fake.mp3")
+		test.CreateTestFile(t, path)
+		defer cleanup()
+
+		// audio endpoints only accept POST requests
+		if r.Method != "POST" {
+			http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
+			return
+		}
+
+		mediaType, _, err := mime.ParseMediaType(r.Header.Get("Content-Type"))
+		if err != nil {
+			http.Error(w, "failed to parse media type", http.StatusBadRequest)
+			return
+		}
+
+		if mediaType != "application/json" {
+			http.Error(w, "request is not json", http.StatusBadRequest)
+			return
+		}
+
+		// Parse the JSON body of the request
+		var params map[string]interface{}
+		err = json.NewDecoder(r.Body).Decode(&params)
+		if err != nil {
+			http.Error(w, "failed to parse request body", http.StatusBadRequest)
+			return
+		}
+
+		// Check if each required field is present in the parsed JSON object
+		reqParams := []string{"model", "input", "voice"}
+		for _, param := range reqParams {
+			_, ok := params[param]
+			if !ok {
+				http.Error(w, fmt.Sprintf("no %s in params", param), http.StatusBadRequest)
+				return
+			}
+		}
+
+		// read audio file content
+		audioFile, err := os.ReadFile(path)
+		if err != nil {
+			http.Error(w, "failed to read audio file", http.StatusInternalServerError)
+			return
+		}
+
+		// write audio file content to response
+		w.Header().Set("Content-Type", "audio/mpeg")
+		w.Header().Set("Transfer-Encoding", "chunked")
+		w.Header().Set("Connection", "keep-alive")
+		_, err = w.Write(audioFile)
+		if err != nil {
+			http.Error(w, "failed to write body", http.StatusInternalServerError)
+			return
+		}
+	})
+
+	t.Run("happy path", func(t *testing.T) {
+		res, err := client.CreateSpeech(context.Background(), openai.CreateSpeechRequest{
+			Model: openai.TTSModel1,
+			Input: "Hello!",
+			Voice: openai.VoiceAlloy,
+		})
+		checks.NoError(t, err, "CreateSpeech error")
+		defer res.Close()
+
+		buf, err := io.ReadAll(res)
+		checks.NoError(t, err, "ReadAll error")
+
+		// save buf to file as mp3
+		err = os.WriteFile("test.mp3", buf, 0644)
+		checks.NoError(t, err, "Create error")
+	})
+	t.Run("invalid model", func(t *testing.T) {
+		_, err := client.CreateSpeech(context.Background(), openai.CreateSpeechRequest{
+			Model: "invalid_model",
+			Input: "Hello!",
+			Voice: openai.VoiceAlloy,
+		})
+		checks.ErrorIs(t, err, openai.ErrInvalidSpeechModel, "CreateSpeech error")
+	})
+
+	t.Run("invalid voice", func(t *testing.T) {
+		_, err := client.CreateSpeech(context.Background(), openai.CreateSpeechRequest{
+			Model: openai.TTSModel1,
+			Input: "Hello!",
+			Voice: "invalid_voice",
+		})
+		checks.ErrorIs(t, err, openai.ErrInvalidVoice, "CreateSpeech error")
+	})
+}