Bootstrap webmention endpoint

app/webmentions.py

@@ -0,0 +1,62 @@
+from bs4 import BeautifulSoup  # type: ignore
+from fastapi import APIRouter
+from fastapi import HTTPException
+from fastapi import Request
+from fastapi.responses import JSONResponse
+from loguru import logger
+
+from app.utils import microformats
+from app.utils.url import check_url
+from app.utils.url import is_url_valid
+
+router = APIRouter()
+
+
+def is_source_containing_target(source_html: str, target_url: str) -> bool:
+    soup = BeautifulSoup(source_html, "html5lib")
+    for link in soup.find_all("a"):
+        h = link.get("href")
+        if not is_url_valid(h):
+            continue
+
+        if h == target_url:
+            return True
+
+    return False
+
+
+@router.post("/webmentions")
+async def webmention_endpoint(
+    request: Request,
+) -> JSONResponse:
+    form_data = await request.form()
+    try:
+        source = form_data["source"]
+        target = form_data["target"]
+
+        if source == target:
+            raise ValueError("source URL is the same as target")
+
+        check_url(source)
+        check_url(target)
+    except Exception:
+        logger.exception("Invalid webmention request")
+        raise HTTPException(status_code=400, detail="Invalid payload")
+
+    logger.info(f"Received webmention {source=} {target=}")
+
+    # TODO: get outbox via ap_id (URL is the same as ap_id)
+    maybe_data_and_html = await microformats.fetch_and_parse(source)
+    if not maybe_data_and_html:
+        logger.info("failed to fetch source")
+        raise HTTPException(status_code=400, detail="failed to fetch source")
+
+    data, html = maybe_data_and_html
+
+    if not is_source_containing_target(html, target):
+        logger.warning("target not found in source")
+        raise HTTPException(status_code=400, detail="target not found in source")
+
+    logger.info(f"{data=}")
+
+    return JSONResponse(content={}, status_code=200)