import httpx
from fastapi import FastAPI, Request
from starlette.responses import HTMLResponse, StreamingResponse

app = FastAPI()
TARGET = "https://ewt360.com"          # 目标站

# -------- 工具函数 ---------------------------------------------------------
INJECT_JS = """
<script>
function clickZa() {
  document.querySelectorAll('button').forEach(btn => {
    if (btn.textContent.trim() === '在') btn.click();
  });
}
document.addEventListener('DOMContentLoaded', clickZa);

// 处理 SPA / 懒加载：DOM 变化时再检测一次
new MutationObserver(clickZa).observe(document.documentElement, {
  childList: true,
  subtree: true
});
</script>
"""

def _inject(html: str) -> str:
    """把注入脚本塞到 </body> 前；若无 </body> 则直接追加"""
    return html.replace("</body>", INJECT_JS + "</body>") if "</body>" in html else html + INJECT_JS

async def _fetch_upstream(req: Request, path: str) -> httpx.Response:
    """把客户端请求转发到目标站"""
    async with httpx.AsyncClient(follow_redirects=True, timeout=30) as client:
        upstream_url = f"{TARGET}/{path}"
        headers = {k: v for k, v in req.headers.items()
                   if k.lower() not in {"host", "content-length", "accept-encoding", "connection"}}
        return await client.request(
            req.method,
            upstream_url,
            params=req.query_params,
            content=await req.body(),
            headers=headers
        )

# -------- 统一代理入口 ------------------------------------------------------
@app.api_route("/{path:path}", methods=["GET", "POST", "PUT", "PATCH", "DELETE"])
async def proxy(path: str, request: Request):
    upstream = await _fetch_upstream(request, path)
    ct = upstream.headers.get("content-type", "")
    
    # 对 HTML 页面做脚本注入
    if "text/html" in ct:
        html = _inject(upstream.text)
        # 过滤掉与内容长度 / 压缩相关的头，避免浏览器警告
        safe_headers = {k: v for k, v in upstream.headers.items()
                        if k.lower() not in {"content-length", "content-encoding"}}
        return HTMLResponse(html, status_code=upstream.status_code, headers=safe_headers)
    
    # 其他资源直接流式返回（JS / CSS / 图片等）
    return StreamingResponse(
        upstream.aiter_bytes(),
        status_code=upstream.status_code,
        media_type=ct or None,
        headers={k: v for k, v in upstream.headers.items()
                 if k.lower() not in {"content-length", "content-encoding"}}
    )