Add prompt-based picture command

internal/telegram/api.go

@@ -14,6 +14,12 @@ import (
 	"time"
 )
 
+type PhotoUpload struct {
+	Filename string
+	Data     []byte
+	Caption  string
+}
+
 type Client struct {
 	token       string
 	baseURL     string
@@ -205,6 +211,80 @@ func (c *Client) SendPhotoBytes(ctx context.Context, chatID int64, filename stri
 	return decoded.Result, nil
 }
 
+func (c *Client) SendPhotoGroupBytes(ctx context.Context, chatID int64, photos []PhotoUpload) ([]Message, error) {
+	if len(photos) == 0 {
+		return nil, nil
+	}
+	if len(photos) == 1 {
+		message, err := c.SendPhotoBytes(ctx, chatID, photos[0].Filename, photos[0].Data, photos[0].Caption)
+		if err != nil {
+			return nil, err
+		}
+		return []Message{message}, nil
+	}
+
+	var body bytes.Buffer
+	writer := multipart.NewWriter(&body)
+	if err := writer.WriteField("chat_id", fmt.Sprint(chatID)); err != nil {
+		return nil, err
+	}
+	media := make([]map[string]string, 0, len(photos))
+	for i, photo := range photos {
+		name := fmt.Sprintf("photo%d", i)
+		entry := map[string]string{
+			"type":  "photo",
+			"media": "attach://" + name,
+		}
+		if photo.Caption != "" {
+			entry["caption"] = photo.Caption
+		}
+		media = append(media, entry)
+	}
+	mediaJSON, err := json.Marshal(media)
+	if err != nil {
+		return nil, err
+	}
+	if err := writer.WriteField("media", string(mediaJSON)); err != nil {
+		return nil, err
+	}
+	for i, photo := range photos {
+		name := fmt.Sprintf("photo%d", i)
+		part, err := writer.CreateFormFile(name, filepath.Base(photo.Filename))
+		if err != nil {
+			return nil, err
+		}
+		if _, err := part.Write(photo.Data); err != nil {
+			return nil, err
+		}
+	}
+	if err := writer.Close(); err != nil {
+		return nil, err
+	}
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, c.baseURL+"/sendMediaGroup", &body)
+	if err != nil {
+		return nil, err
+	}
+	req.Header.Set("Content-Type", writer.FormDataContentType())
+	resp, err := c.httpClient.Do(req)
+	if err != nil {
+		return nil, c.redactError(err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
+		payload, _ := io.ReadAll(io.LimitReader(resp.Body, 4096))
+		return nil, fmt.Errorf("sendMediaGroup: telegram returned %s: %s", resp.Status, string(payload))
+	}
+	var decoded apiResponse[[]Message]
+	if err := json.NewDecoder(resp.Body).Decode(&decoded); err != nil {
+		return nil, err
+	}
+	if !decoded.OK {
+		return nil, fmt.Errorf("sendMediaGroup: telegram error %d: %s", decoded.ErrorCode, decoded.Description)
+	}
+	return decoded.Result, nil
+}
+
 func (c *Client) SendDocumentBytes(ctx context.Context, chatID int64, filename string, data []byte, caption string) (Message, error) {
 	var body bytes.Buffer
 	writer := multipart.NewWriter(&body)