# 舊架構（ADK）
runner = Runner(agent=root_agent, ...)
async for event in runner.run_async(...):
    ...  # ADK 幫你處理所有 function call，但你無法控制回應內容

# 新架構（直接用 google.genai）
response = await client.aio.models.generate_content(
    model=model,
    contents=contents,
    config=types.GenerateContentConfig(tools=ECOMMERCE_TOOLS),
)
# 自己處理 function call，自己夾帶圖片

def generate_product_image(product: dict) -> bytes:
    """讀取商品圖片並返回 JPEG bytes。"""
    with open(product["image_path"], "rb") as f:
        return f.read()

from google.genai import types

ECOMMERCE_TOOLS = [
    types.Tool(function_declarations=[
        types.FunctionDeclaration(
            name="get_order_history",
            description="查詢當前用戶的訂單歷史記錄",
            parameters=types.Schema(
                type=types.Type.OBJECT,
                properties={
                    "time_range": types.Schema(
                        type=types.Type.STRING,
                        description="時間範圍：all / last_month / last_3_months",
                        enum=["all", "last_month", "last_3_months"],
                    ),
                },
                required=[],
            ),
        ),
        # ... search_products, get_product_details
    ])
]

async def process_message(self, text: str, line_user_id: str):
    contents = self._get_history(line_user_id) + [
        types.Content(role="user", parts=[types.Part(text=text)])
    ]

    for _iteration in range(5):  # 最多 5 次，防止無限循環
        response = await self._client.aio.models.generate_content(
            model=self._model,
            contents=contents,
            config=types.GenerateContentConfig(
                system_instruction=_SYSTEM_INSTRUCTION,
                tools=ECOMMERCE_TOOLS,
            ),
        )

        model_content = response.candidates[0].content
        contents.append(model_content)

        # 找出所有 function_call parts
        fc_parts = [p for p in model_content.parts if p.function_call and p.function_call.name]

        if not fc_parts:
            # 沒有 function call → 最終文字回應
            final_text = "".join(p.text for p in model_content.parts if p.text)
            break

        # 有 function call → 執行工具、夾帶圖片
        tool_parts = []
        for fc_part in fc_parts:
            result_dict, image_bytes = _execute_tool(
                fc_part.function_call.name,
                dict(fc_part.function_call.args),
                line_user_id,
            )
            tool_parts.append(
                self._build_multimodal_response(fc_part.function_call.name, result_dict, image_bytes)
            )

        contents.append(types.Content(role="tool", parts=tool_parts))

def _build_multimodal_response(self, func_name, result_dict, image_bytes):
    multimodal_parts = []

    if image_bytes:
        # ⚠️ 注意：這裡要用 FunctionResponseBlob，不是 types.Blob！
        multimodal_parts.append(
            types.FunctionResponsePart(
                inline_data=types.FunctionResponseBlob(
                    mime_type="image/jpeg",
                    data=image_bytes,  # raw bytes，SDK 內部自動處理 base64
                )
            )
        )

    return types.Part.from_function_response(
        name=func_name,
        response=result_dict,          # 結構化 JSON 資料
        parts=multimodal_parts or None, # ← 圖片在這裡！Gemini 收到後能「看見」
    )

# main.py

ai_text, image_bytes = await ecommerce_agent.process_message(msg_text, line_user_id)

reply_messages = [TextSendMessage(text=ai_text)]

if image_bytes:
    image_id = str(uuid.uuid4())
    image_cache[image_id] = image_bytes              # 暫存
    image_url = f"{BOT_HOST_URL}/images/{image_id}"  # FastAPI 提供服務
    reply_messages.append(
        ImageSendMessage(
            original_content_url=image_url,
            preview_image_url=image_url,
        )
    )

await get_line_bot_api().reply_message(event.reply_token, reply_messages)

# ❌ 錯誤（會 TypeError）
types.FunctionResponsePart(
    inline_data=types.Blob(mime_type="image/jpeg", data=image_bytes)
)

# ✅ 正確
types.FunctionResponsePart(
    inline_data=types.FunctionResponseBlob(mime_type="image/jpeg", data=image_bytes)
)

# ❌ 舊寫法：module level
session = aiohttp.ClientSession()  # 如果沒有 running event loop 就會警告或出錯
async_http_client = AiohttpAsyncHttpClient(session)

# ✅ 新寫法：lazy init
_line_bot_api = None

def get_line_bot_api():
    global _line_bot_api
    if _line_bot_api is None:
        session = aiohttp.ClientSession()  # 在 async route handler 內呼叫，保證有 event loop
        _line_bot_api = AsyncLineBotApi(channel_access_token, AiohttpAsyncHttpClient(session))
    return _line_bot_api

@app.get("/images/{image_id}")
async def serve_image(image_id: str):
    image_bytes = image_cache.get(image_id)
    if image_bytes is None:
        raise HTTPException(status_code=404, detail="Image not found")
    return Response(content=image_bytes, media_type="image/jpeg")

# Gemini 看到函式回傳圖片的完整寫法
types.Part.from_function_response(
    name="get_order_history",
    response={"orders": [...]},
    parts=[
        types.FunctionResponsePart(
            inline_data=types.FunctionResponseBlob(  # ← 不是 types.Blob！
                mime_type="image/jpeg",
                data=image_bytes,
            )
        )
    ],
)