fix file preview url

routes/side/main.py

@@ -24,6 +24,12 @@ def find_file(files: list[dict], file_id: str):
       return file_data
   return None
 
+def build_share_url(file_id: str) -> str:
+  scheme = (request.headers.get("X-Forwarded-Proto") or request.scheme or "http").split(",")[0].strip()
+  host = (request.headers.get("X-Forwarded-Host") or request.host).split(",")[0].strip()
+  root_path = request.root_path.rstrip("/")
+  return f"{scheme}://{host}{root_path}/-{file_id}"
+
 @side_main_bp.route('/')
 @LIMITER.limit("10 per minute;50 per hour")
 async def index():
@@ -54,7 +60,7 @@ async def file_info(file_id, user):
     abort(404)
 
   access_data = await current_app.convex.get_file_access(file_id=file_id, user_id=user["sub"]) or []
-  share_url = request.url_root.rstrip("/") + f"/-{file_id}"
+  share_url = build_share_url(file_id)
   return await render_template(
     "views/webpage/files/info.htm",
     file=file_data,
@@ -69,7 +75,7 @@ async def file_edit(file_id, user):
   if not file_data:
     abort(404)
 
-  share_url = request.url_root.rstrip("/") + f"/-{file_id}"
+  share_url = build_share_url(file_id)
   return await render_template(
     "views/webpage/files/edit.htm", file=file_data, share_url=share_url, file_id=file_id
   )