app.py

# app.py
import os
import io
import base64
from typing import List, Dict, Any, Optional

import httpx
import gradio as gr
from PIL import Image

# ====== 配置（可用环境变量覆写）======
STEPFUN_ENDPOINT = os.getenv("STEPFUN_ENDPOINT", "https://api.stepfun.com/v1")
MODEL_NAME = os.getenv("STEPFUN_MODEL", "step-3")  # 也可填 step-r1-v-mini
REQUEST_TIMEOUT = float(os.getenv("REQUEST_TIMEOUT", "60"))
# ===================================


def _get_api_key() -> Optional[str]:
    """
    优先读 OPENAI_API_KEY（与 OpenAI 兼容），否则读 STEPFUN_KEY。
    在 HF Space: Settings → Variables and secrets 添加其中一个即可。
    """
    return os.getenv("OPENAI_API_KEY") or os.getenv("STEPFUN_KEY")


def _pil_to_data_url(img: Image.Image, fmt: str = "PNG") -> str:
    """
    PIL -> data:image/...;base64,... 字符串（适配 OpenAI 兼容的 image_url 输入）
    """
    buf = io.BytesIO()
    img.save(buf, format=fmt)
    b64 = base64.b64encode(buf.getvalue()).decode("utf-8")
    mime = "image/png" if fmt.upper() == "PNG" else "image/jpeg"
    return f"data:{mime};base64,{b64}"


def _post_chat(messages: List[Dict[str, Any]], temperature: float = 0.7, max_tokens: Optional[int] = None) -> str:
    """
    直接请求 StepFun 的 /v1/chat/completions（OpenAI 兼容）。
    返回纯字符串，避免 Gradio schema 问题。
    """
    api_key = _get_api_key()
    if not api_key:
        raise RuntimeError(
            "未检测到 API Key。请到 Space 的 Settings → Variables and secrets 添加：\n"
            "  OPENAI_API_KEY=你的 StepFun API Key   （或使用 STEPFUN_KEY）"
        )

    url = f"{STEPFUN_ENDPOINT.rstrip('/')}/chat/completions"
    headers = {
        "Authorization": f"Bearer {api_key}",
        "Content-Type": "application/json",
    }
    payload: Dict[str, Any] = {
        "model": MODEL_NAME,
        "messages": messages,
        "temperature": temperature,
        # StepFun 多数情况下无需强制 max_tokens；需要时再放开
    }
    if max_tokens is not None:
        payload["max_tokens"] = max_tokens

    with httpx.Client(timeout=REQUEST_TIMEOUT) as client:
        resp = client.post(url, headers=headers, json=payload)
        # 让 httpx 抛出更清晰的错误
        resp.raise_for_status()
        data = resp.json()

    # 标准 OpenAI 兼容返回
    try:
        return str(data["choices"][0]["message"]["content"])
    except Exception:
        # 返回原始数据便于诊断
        return f"[WARN] 无法解析返回格式：{data}"


def chat_with_step3(image: Optional[Image.Image], question: str, temperature: float) -> str:
    """
    Gradio 的回调函数：接收 PIL 图片与文本，返回字符串。
    """
    if image is None and not question.strip():
        return "请上传一张图片，或至少输入一个问题。"

    # 构造 messages（支持纯文本、纯图像，或图文混合）
    content: List[Dict[str, Any]] = []
    if image is not None:
        data_url = _pil_to_data_url(image, fmt="PNG")
        content.append({"type": "image_url", "image_url": {"url": data_url}})

    if question.strip():
        content.append({"type": "text", "text": question.strip()})
    else:
        content.append({"type": "text", "text": "请描述这张图片。"})  # 默认问题

    messages = [{"role": "user", "content": content}]

    try:
        return _post_chat(messages, temperature=temperature)
    except httpx.HTTPStatusError as e:
        # 返回服务端 HTTP 错误 + 文本体，便于排查
        try:
            detail = e.response.text
        except Exception:
            detail = repr(e)
        return f"[HTTP {e.response.status_code}] 接口错误：{detail}"
    except Exception as e:
        return f"调用失败：{e!r}"


# ================ Gradio UI ================
with gr.Blocks(title="Step3 (StepFun API Demo)") as demo:
    gr.Markdown(
        """
        # Step3 · 图文对话演示（StepFun OpenAI 兼容接口）
        - 在 **Settings → Variables and secrets** 添加 `OPENAI_API_KEY`（或 `STEPFUN_KEY`）后即可使用  
        - 后端直连 `https://api.stepfun.com/v1/chat/completions`，不依赖 `openai` SDK
        """
    )

    with gr.Row():
        image = gr.Image(type="pil", label="上传图片（可选）")
    question = gr.Textbox(label="问题", placeholder="例如：帮我看看这是什么菜，怎么做？")
    temperature = gr.Slider(0.0, 1.5, value=0.7, step=0.1, label="Temperature")
    submit = gr.Button("提交", variant="primary")
    output = gr.Textbox(label="模型回答", lines=8)

    submit.click(fn=chat_with_step3, inputs=[image, question, temperature], outputs=[output])

    gr.Markdown(
        """
        **提示：**
        - 如果看到 `调用失败：RuntimeError('未检测到 API Key')`，请检查 Space 的 Secrets
        - 如需改模型：设置环境变量 `STEPFUN_MODEL`，或在代码顶部修改默认值
        """
    )

if __name__ == "__main__":
    # HF Space 环境会自动执行；本地运行也 OK
    demo.launch()