Add Whisper client (#2)

* Add Whisper client

* Fix merge conflicts + abstract request sending

openai.go

@@ -6,8 +6,10 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
-	"io/ioutil"
+	"io"
+	"mime/multipart"
 	"net/http"
+	"net/url"
 	"time"
 )
 
@@ -39,25 +41,45 @@ func NewSession(apiKey string) *Session {
 // MakeRequest make HTTP requests and authenticates them with
 // session's API key. MakeRequest marshals input as the request body,
 // and unmarshals the response as output.
-func (s *Session) MakeRequest(ctx context.Context, endpoint string, input, output interface{}) error {
+func (s *Session) MakeRequest(ctx context.Context, endpoint string, input, output any) error {
 	buf, err := json.Marshal(input)
 	if err != nil {
 		return err
 	}
 
-	req, err := http.NewRequest("POST", endpoint, bytes.NewReader(buf))
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, endpoint, bytes.NewReader(buf))
 	if err != nil {
 		return err
 	}
-	req = req.WithContext(ctx)
 
+	return s.sendRequest(req, "application/json", output)
+}
+
+// Upload makes a multi-part form data upload them with
+// session's API key. Upload combines the file with the given params
+// and unmarshals the response as output.
+func (s *Session) Upload(ctx context.Context, endpoint string, file io.Reader, fileExt string, params url.Values, output any) error {
+	pr, pw := io.Pipe()
+	mw := multipart.NewWriter(pw)
+	go func() {
+		err := upload(mw, file, fileExt, params)
+		pw.CloseWithError(err)
+	}()
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, endpoint, pr)
+	if err != nil {
+		return err
+	}
+	return s.sendRequest(req, mw.FormDataContentType(), output)
+}
+
+func (s *Session) sendRequest(req *http.Request, contentType string, output any) error {
 	if s.apiKey != "" {
 		req.Header.Set("Authorization", "Bearer "+s.apiKey)
 	}
 	if s.OrganizationID != "" {
 		req.Header.Set("OpenAI-Organization", s.OrganizationID)
 	}
-	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("Content-Type", contentType)
 
 	resp, err := s.HTTPClient.Do(req)
 	if err != nil {
@@ -66,7 +88,7 @@ func (s *Session) MakeRequest(ctx context.Context, endpoint string, input, outpu
 	defer resp.Body.Close()
 
 	if resp.StatusCode < 200 || resp.StatusCode >= 400 {
-		respBody, err := ioutil.ReadAll(resp.Body)
+		respBody, err := io.ReadAll(resp.Body)
 		if err != nil {
 			return err
 		}
@@ -78,6 +100,32 @@ func (s *Session) MakeRequest(ctx context.Context, endpoint string, input, outpu
 	return json.NewDecoder(resp.Body).Decode(output)
 }
 
+func upload(mw *multipart.Writer, file io.Reader, fileExt string, params url.Values) error {
+	for key := range params {
+		w, err := mw.CreateFormField(key)
+		if err != nil {
+			return fmt.Errorf("error creating %q field: %w", key, err)
+		}
+		_, err = fmt.Fprint(w, params.Get(key))
+		if err != nil {
+			return fmt.Errorf("error writing %q field: %w", key, err)
+		}
+	}
+	w, err := mw.CreateFormFile("file", "audio."+fileExt)
+	if err != nil {
+		return fmt.Errorf("error creating file: %w", err)
+	}
+	_, err = io.Copy(w, file)
+	if err != nil {
+		return fmt.Errorf("error copying file: %w", err)
+	}
+	err = mw.Close()
+	if err != nil {
+		return fmt.Errorf("error closing multipart writer: %w", err)
+	}
+	return nil
+}
+
 // APIError is returned from API requests if the API
 // responds with an error.
 type APIError struct {

whisper/whisper.go

@@ -0,0 +1,64 @@
+// Package whisper implements a client for OpenAI's Whisper
+// audio transcriber.
+package whisper
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net/url"
+
+	"github.com/rakyll/openai-go"
+)
+
+const defaultCreateCompletionsEndpoint = "https://api.openai.com/v1/audio/transcriptions"
+
+// Client is a client to communicate with Open AI's ChatGPT APIs.
+type Client struct {
+	s     *openai.Session
+	model string
+
+	// CreateCompletionsEndpoint allows overriding the default API endpoint.
+	// Set this field before using the client.
+	CreateCompletionEndpoint string
+}
+
+// NewClient creates a new default client that uses the given session
+// and defaults to the given model.
+func NewClient(session *openai.Session, model string) *Client {
+	if model == "" {
+		model = "whisper-1"
+	}
+	return &Client{
+		s:                        session,
+		model:                    model,
+		CreateCompletionEndpoint: defaultCreateCompletionsEndpoint,
+	}
+}
+
+type CreateCompletionParams struct {
+	Model       string
+	Language    string
+	Audio       io.Reader
+	AudioFormat string // such as "mp3" or "wav", etc.
+}
+
+type CreateCompletionResponse struct {
+	Text string `json:"text,omitempty"`
+}
+
+func (c *Client) Transcribe(ctx context.Context, p *CreateCompletionParams) (*CreateCompletionResponse, error) {
+	if p.AudioFormat == "" {
+		return nil, fmt.Errorf("audio format is required")
+	}
+	if p.Model == "" {
+		p.Model = c.model
+	}
+	params := url.Values{}
+	params.Set("model", p.Model)
+	if p.Language != "" {
+		params.Set("language", p.Language)
+	}
+	var r CreateCompletionResponse
+	return &r, c.s.Upload(ctx, c.CreateCompletionEndpoint, p.Audio, p.AudioFormat, params, &r)
+}