add proxy app to repo

Signed-off-by: disqualifier <dev@disqualifier.me>

app.py

@@ -0,0 +1,111 @@
+"""
+discord webhook reformat proxy
+
+drop-in for discord.com: swap the hostname on a gitea (discord-type) webhook
+so it points here, e.g.
+    https://discord.com/api/webhooks/<id>/<token>
+becomes
+    https://proxy.example.com/api/webhooks/<id>/<token>
+
+the proxy receives gitea's native discord embed, rewrites only the embed
+`description` into github's `[`hash`](url)` backtick style (hash backticked,
+commit message collapsed to its first line, author kept), and forwards the
+otherwise-untouched payload to the real discord webhook. everything gitea
+already handled (title, branches, multiple commits, tags, colors) passes
+through as-is.
+
+run:
+    pip install fastapi httpx uvicorn
+    uvicorn discord_reformat_proxy:app --host 127.0.0.1 --port 8000
+
+then set a gitea webhook (type: discord) to:
+    http://127.0.0.1:8000/api/webhooks/<id>/<token>
+"""
+
+import re
+import logging
+
+import httpx
+from fastapi import FastAPI, Request, Response
+
+log = logging.getLogger(__name__)
+
+app = FastAPI()
+
+DISCORD_BASE = "https://discord.com"
+TIMEOUT = 10
+
+# gitea commit line:  [hash](url) <message possibly spanning lines> - author
+# github commit line: [`hash`](url) <first line of message> - author
+# match a hash-link, then the message up to an optional trailing " - author",
+# stopping at the next commit line or end of string.
+_COMMIT = re.compile(
+    r"\[`?([0-9a-f]{6,40})`?\]\((https?://[^)]+)\)"
+    r"\s+(.*?)"
+    r"(\s-\s[^\n]+?)?"
+    r"(?=\n\[|\Z)",
+    re.DOTALL,
+)
+
+
+def _commit_sub(m: "re.Match") -> str:
+    """rebuild one commit line github-style: backtick hash, first message line only"""
+    short, url, message, author = m.group(1), m.group(2), m.group(3), m.group(4) or ""
+    first_line = message.strip().split("\n", 1)[0].strip()
+    return f"[`{short}`]({url}) {first_line}{author}"
+
+
+def _reformat(description: str) -> str:
+    """rewrite gitea commit lines into github-style (backtick hash, one line each)"""
+    return _COMMIT.sub(_commit_sub, description)
+
+
+@app.get("/healthz")
+async def healthz():
+    """liveness probe"""
+    return {"ok": True}
+
+
+@app.post("/api/webhooks/{webhook_id}/{token}")
+async def proxy(webhook_id: str, token: str, request: Request):
+    """reformat embed descriptions and forward to the real discord webhook"""
+    try:
+        payload = await request.json()
+    except Exception:
+        body = await request.body()
+        async with httpx.AsyncClient(timeout=TIMEOUT) as client:
+            resp = await client.post(
+                f"{DISCORD_BASE}/api/webhooks/{webhook_id}/{token}",
+                content=body,
+                params=dict(request.query_params),
+                headers={"content-type": request.headers.get("content-type", "application/json")},
+            )
+        return _passthrough(resp)
+
+    if isinstance(payload, dict):
+        for embed in payload.get("embeds") or []:
+            if isinstance(embed, dict) and embed.get("description"):
+                embed["description"] = _reformat(embed["description"])
+
+    async with httpx.AsyncClient(timeout=TIMEOUT) as client:
+        resp = await client.post(
+            f"{DISCORD_BASE}/api/webhooks/{webhook_id}/{token}",
+            json=payload,
+            params=dict(request.query_params),
+        )
+
+    return _passthrough(resp)
+
+
+def _passthrough(resp: httpx.Response) -> Response:
+    """return discord's response verbatim, preserving rate-limit headers"""
+    forward = {
+        k: v for k, v in resp.headers.items()
+        if k.lower().startswith("x-ratelimit") or k.lower() == "retry-after"
+    }
+    return Response(
+        content=resp.content,
+        status_code=resp.status_code,
+        media_type=resp.headers.get("content-type"),
+        headers=forward,
+    )