feat: add sub2api compatibility

handler/ai.go

@@ -9,8 +9,10 @@ import (
 	"mime"
 	"mime/multipart"
 	"net/http"
+	"net/textproto"
 	"strings"
 
+	"github.com/basketikun/infinite-canvas/model"
 	"github.com/basketikun/infinite-canvas/service"
 )
 
@@ -84,6 +86,12 @@ func proxyAIRequest(w http.ResponseWriter, r *http.Request, path string) {
 		Fail(w, "AI 接口请求失败")
 		return
 	}
+	body, contentType, err = adaptAIRequestForChannel(body, contentType, path, channel)
+	if err != nil {
+		log.Printf("AI proxy adapt request failed: model=%s path=%s err=%v", modelName, path, err)
+		Fail(w, "AI 接口请求失败")
+		return
+	}
 	path = resolveAIProxyPath(channel.BaseURL, modelName, path)
 	request, err := http.NewRequest(http.MethodPost, service.BuildModelChannelURL(channel, path), bytes.NewReader(body))
 	if err != nil {
@@ -140,6 +148,90 @@ func copyAIResponse(w http.ResponseWriter, request *http.Request, onFailure func
 	_, _ = io.Copy(w, response.Body)
 }
 
+func adaptAIRequestForChannel(body []byte, contentType string, path string, channel model.ModelChannel) ([]byte, string, error) {
+	if path != "/images/generations" && path != "/images/edits" {
+		return body, contentType, nil
+	}
+	format := strings.ToLower(strings.TrimSpace(channel.RequestOptions.ImageResponseFormat))
+	if format == "" {
+		if strings.EqualFold(strings.TrimSpace(channel.Compatibility), "sub2api") {
+			format = "url"
+		} else {
+			format = "b64_json"
+		}
+	}
+	if format != "url" && format != "b64_json" {
+		return body, contentType, nil
+	}
+	if strings.HasPrefix(contentType, "multipart/form-data") {
+		return setMultipartField(body, contentType, "response_format", format)
+	}
+	var payload map[string]any
+	if err := json.Unmarshal(body, &payload); err != nil {
+		return nil, "", err
+	}
+	payload["response_format"] = format
+	nextBody, err := json.Marshal(payload)
+	if err != nil {
+		return nil, "", err
+	}
+	return nextBody, contentType, nil
+}
+
+func setMultipartField(body []byte, contentType string, fieldName string, value string) ([]byte, string, error) {
+	_, params, err := mime.ParseMediaType(contentType)
+	if err != nil {
+		return nil, "", err
+	}
+	reader := multipart.NewReader(bytes.NewReader(body), params["boundary"])
+	var buffer bytes.Buffer
+	writer := multipart.NewWriter(&buffer)
+	written := false
+	for {
+		part, err := reader.NextPart()
+		if err == io.EOF {
+			break
+		}
+		if err != nil {
+			return nil, "", err
+		}
+		if part.FormName() == fieldName && part.FileName() == "" {
+			if err := writer.WriteField(fieldName, value); err != nil {
+				_ = part.Close()
+				return nil, "", err
+			}
+			written = true
+			_ = part.Close()
+			continue
+		}
+		header := make(textproto.MIMEHeader, len(part.Header))
+		for key, values := range part.Header {
+			copied := make([]string, len(values))
+			copy(copied, values)
+			header[key] = copied
+		}
+		target, err := writer.CreatePart(header)
+		if err != nil {
+			_ = part.Close()
+			return nil, "", err
+		}
+		if _, err := io.Copy(target, part); err != nil {
+			_ = part.Close()
+			return nil, "", err
+		}
+		_ = part.Close()
+	}
+	if !written {
+		if err := writer.WriteField(fieldName, value); err != nil {
+			return nil, "", err
+		}
+	}
+	if err := writer.Close(); err != nil {
+		return nil, "", err
+	}
+	return buffer.Bytes(), writer.FormDataContentType(), nil
+}
+
 func readAIRequest(r *http.Request) ([]byte, string, string, error) {
 	contentType := r.Header.Get("Content-Type")
 	body, err := io.ReadAll(r.Body)