refactor: 重构Gemini和OpenAI聊天服务以支持工具和安全设置

- 将 `_build_payload`、`_build_tools`、`_get_safety_settings` 和 `_has_image_parts` 函数从 `OpenAIChatService` 和 `GeminiChatService` 类中提取为独立的函数。
- 将 `_handle_stream_response` 和 `_handle_normal_response` 函数从 `GeminiResponseHandler` 和 `OpenAIResponseHandler` 类中提取为独立的函数。
- 将 `_extract_text` 函数从 `OpenAIResponseHandler` 类中提取为独立的函数, 并在 `GeminiResponseHandler` 中复用。
- 将 `_convert_image` 函数从 `OpenAIMessageConverter` 类中提取为独立的函数。
- 优化 `OpenAIChatService` 和 `GeminiChatService` 中的代码结构, 使其更清晰。
- 优化 `app/api/openai_routes.py` 和 `app/api/gemini_routes.py` 中的路由函数, 移除不必要的参数。

app/services/openai_chat_service.py

@@ -13,6 +13,76 @@ from app.services.key_manager import KeyManager
 logger = get_openai_logger()
 
 
+def _has_image_parts(contents: List[Dict[str, Any]]) -> bool:
+    """判断消息是否包含图片部分"""
+    for content in contents:
+        if "parts" in content:
+            for part in content["parts"]:
+                if "image_url" in part or "inline_data" in part:
+                    return True
+    return False
+
+
+def _build_tools(
+        request: ChatRequest, messages: List[Dict[str, Any]]
+) -> List[Dict[str, Any]]:
+    """构建工具"""
+    tools = []
+    model = request.model
+
+    if (
+        settings.TOOLS_CODE_EXECUTION_ENABLED
+        and not (model.endswith("-search") or "-thinking" in model)
+        and not _has_image_parts(messages)
+    ):
+        tools.append({"code_execution": {}})
+    if model.endswith("-search"):
+        tools.append({"googleSearch": {}})
+    return tools
+
+
+def _get_safety_settings(model: str) -> List[Dict[str, str]]:
+    """获取安全设置"""
+    # if (
+    #     "2.0" in model
+    #     and "gemini-2.0-flash-thinking-exp" not in model
+    #     and "gemini-2.0-pro-exp" not in model
+    # ):
+    if model == "gemini-2.0-flash-exp":
+        return [
+            {"category": "HARM_CATEGORY_HARASSMENT", "threshold": "OFF"},
+            {"category": "HARM_CATEGORY_HATE_SPEECH", "threshold": "OFF"},
+            {"category": "HARM_CATEGORY_SEXUALLY_EXPLICIT", "threshold": "OFF"},
+            {"category": "HARM_CATEGORY_DANGEROUS_CONTENT", "threshold": "OFF"},
+            {"category": "HARM_CATEGORY_CIVIC_INTEGRITY", "threshold": "OFF"},
+        ]
+    return [
+        {"category": "HARM_CATEGORY_HARASSMENT", "threshold": "BLOCK_NONE"},
+        {"category": "HARM_CATEGORY_HATE_SPEECH", "threshold": "BLOCK_NONE"},
+        {"category": "HARM_CATEGORY_SEXUALLY_EXPLICIT", "threshold": "BLOCK_NONE"},
+        {"category": "HARM_CATEGORY_DANGEROUS_CONTENT", "threshold": "BLOCK_NONE"},
+        {"category": "HARM_CATEGORY_CIVIC_INTEGRITY", "threshold": "BLOCK_NONE"},
+    ]
+
+
+def _build_payload(
+        request: ChatRequest, messages: List[Dict[str, Any]]
+) -> Dict[str, Any]:
+    """构建请求payload"""
+    return {
+        "contents": messages,
+        "generationConfig": {
+            "temperature": request.temperature,
+            "maxOutputTokens": request.max_tokens,
+            "stopSequences": request.stop,
+            "topP": request.top_p,
+            "topK": request.top_k,
+        },
+        "tools": _build_tools(request, messages),
+        "safetySettings": _get_safety_settings(request.model),
+    }
+
+
 class OpenAIChatService:
     """聊天服务"""
 
@@ -32,7 +102,7 @@ class OpenAIChatService:
         messages = self.message_converter.convert(request.messages)
 
         # 构建请求payload
-        payload = self._build_payload(request, messages)
+        payload = _build_payload(request, messages)
 
         if request.stream:
             return self._handle_stream_completion(request.model, payload, api_key)
@@ -84,69 +154,3 @@ class OpenAIChatService:
                     yield f"data: {json.dumps({'error': 'Streaming failed after retries'})}\n\n"
                     yield "data: [DONE]\n\n"
                     break
-
-    def _build_payload(
-        self, request: ChatRequest, messages: List[Dict[str, Any]]
-    ) -> Dict[str, Any]:
-        """构建请求payload"""
-        return {
-            "contents": messages,
-            "generationConfig": {
-                "temperature": request.temperature,
-                "maxOutputTokens": request.max_tokens,
-                "stopSequences": request.stop,
-                "topP": request.top_p,
-                "topK": request.top_k,
-            },
-            "tools": self._build_tools(request, messages),
-            "safetySettings": self._get_safety_settings(request.model),
-        }
-
-    def _build_tools(
-        self, request: ChatRequest, messages: List[Dict[str, Any]]
-    ) -> List[Dict[str, Any]]:
-        """构建工具"""
-        tools = []
-        model = request.model
-
-        if (
-            settings.TOOLS_CODE_EXECUTION_ENABLED
-            and not (model.endswith("-search") or "-thinking" in model)
-            and not self._has_image_parts(messages)
-        ):
-            tools.append({"code_execution": {}})
-        if model.endswith("-search"):
-            tools.append({"googleSearch": {}})
-        return tools
-
-    def _has_image_parts(self, contents: List[Dict[str, Any]]) -> bool:
-        """判断消息是否包含图片部分"""
-        for content in contents:
-            if "parts" in content:
-                for part in content["parts"]:
-                    if "image_url" in part or "inline_data" in part:
-                        return True
-        return False
-
-    def _get_safety_settings(self, model: str) -> List[Dict[str, str]]:
-        """获取安全设置"""
-        # if (
-        #     "2.0" in model
-        #     and "gemini-2.0-flash-thinking-exp" not in model
-        #     and "gemini-2.0-pro-exp" not in model
-        # ):
-        if model == "gemini-2.0-flash-exp":
-            return [
-                {"category": "HARM_CATEGORY_HARASSMENT", "threshold": "OFF"},
-                {"category": "HARM_CATEGORY_HATE_SPEECH", "threshold": "OFF"},
-                {"category": "HARM_CATEGORY_SEXUALLY_EXPLICIT", "threshold": "OFF"},
-                {"category": "HARM_CATEGORY_DANGEROUS_CONTENT", "threshold": "OFF"},
-                {"category": "HARM_CATEGORY_CIVIC_INTEGRITY", "threshold": "OFF"},
-            ]
-        return [
-            {"category": "HARM_CATEGORY_HARASSMENT", "threshold": "BLOCK_NONE"},
-            {"category": "HARM_CATEGORY_HATE_SPEECH", "threshold": "BLOCK_NONE"},
-            {"category": "HARM_CATEGORY_SEXUALLY_EXPLICIT", "threshold": "BLOCK_NONE"},
-            {"category": "HARM_CATEGORY_DANGEROUS_CONTENT", "threshold": "BLOCK_NONE"},
-            {"category": "HARM_CATEGORY_CIVIC_INTEGRITY", "threshold": "BLOCK_NONE"},
-        ]