ani-web/server/app.py

"""app.py — ani-web: FastAPI over upstream.py + HLS proxy + static UI.

Browser playback: hls.anidb.app sends no CORS headers, so the player is
pointed at /stream/{token}; the proxy fetches upstream (with the same
Cloudflare workaround) and rewrites playlist URIs to go through itself.
"""
import base64
import json
import os
import time
from pathlib import Path
from base64 import urlsafe_b64encode, urlsafe_b64decode
from collections import OrderedDict
from urllib.parse import quote, urljoin

from fastapi import Body, FastAPI, HTTPException, Query, Request
from fastapi.responses import FileResponse, JSONResponse, RedirectResponse, Response
from fastapi.staticfiles import StaticFiles
from itsdangerous import BadSignature, TimestampSigner

from . import upstream, users

ROOT = Path(__file__).parent.parent
app = FastAPI(title="ani-web")

# ---------- auth: multi-user, signed cookies ----------
users.migrate_legacy()
_SIGNER = TimestampSigner(users.get_secret())
_SESSION = "aniweb_session"
_SESSION_AGE = 30 * 86400
_PUBLIC = {("/login", "GET"), ("/login", "POST")}
_SECURE = os.environ.get("ANIWEB_SECURE") == "1"  # set when served over HTTPS

# ponytail: in-memory lockout per username, single process — 5 fails -> 15 min
_lockout: dict = {}


def _session_user(request) -> str | None:
    try:
        payload = _SIGNER.unsign(request.cookies.get(_SESSION, ""), max_age=_SESSION_AGE)
    except BadSignature:
        return None
    return payload.decode().split(":", 1)[1] if payload.startswith(b"user:") else None


def _lock(user: str, pw: str) -> str:
    lo = _lockout.setdefault(user, {"fails": 0, "until": 0.0})
    if time.time() < lo["until"]:
        return "locked"
    if users.verify(user, pw):
        lo.update(fails=0, until=0.0)
        return "ok"
    lo["fails"] += 1
    if lo["fails"] >= 5:
        lo.update(fails=0, until=time.time() + 900)
    time.sleep(0.5)  # slow down brute force
    return "bad"


@app.middleware("http")
async def require_auth(request, call_next):
    if (request.url.path, request.method) in _PUBLIC:
        return await call_next(request)
    user = _session_user(request)
    # stateless cookie -> re-verify the account still exists, so
    # deleted users' cookies die immediately
    if user is not None and user not in users.load():
        user = None
    if not user:
        if request.url.path.startswith("/api/"):
            return JSONResponse({"detail": "not authenticated"}, status_code=401)
        next_ = request.url.path + (f"?{request.url.query}" if request.url.query else "")
        return RedirectResponse(f"/login?next={quote(next_, safe='')}", status_code=302)
    request.state.user = user
    return await call_next(request)


def _session_cookie(resp, user: str):
    resp.set_cookie(_SESSION, _SIGNER.sign(b"user:" + user.encode()).decode(),
                    max_age=_SESSION_AGE, httponly=True, samesite="lax", secure=_SECURE)


@app.get("/login", include_in_schema=False)
def login_page():
    return FileResponse(ROOT / "static" / "login.html")


@app.post("/login")
async def login(payload: dict = Body(...)):
    u = payload.get("username", "").lower()
    if not u:
        return JSONResponse({"detail": "username required"}, status_code=400)
    state = _lock(u, payload.get("password", ""))
    if state == "ok":
        resp = JSONResponse({"ok": True, "user": u})
        _session_cookie(resp, u)
        return resp
    if state == "locked":
        return JSONResponse({"detail": "too many attempts, try later"}, status_code=429)
    return JSONResponse({"detail": "wrong username or password"}, status_code=401)


@app.get("/api/me", include_in_schema=False)
def api_me(request: Request):
    return {"user": request.state.user}


@app.post("/account/delete")
def delete_account(request: Request):
    users.remove(request.state.user)
    resp = JSONResponse({"ok": True})
    resp.delete_cookie(_SESSION, secure=_SECURE)
    return resp


@app.post("/logout")
def logout():
    resp = JSONResponse({"ok": True})
    resp.delete_cookie(_SESSION, secure=_SECURE)
    return resp


HIST_DIR = Path(os.environ.get("ANIWEB_DATA", Path(__file__).parent / "data")) / "history"


def _load_hist(user: str):
    try:
        return json.loads((HIST_DIR / f"{user}.json").read_text())
    except (FileNotFoundError, json.JSONDecodeError):
        return []


def _save_hist(user: str, entries):
    HIST_DIR.mkdir(exist_ok=True)
    # ponytail: unguarded read-modify-write per file, fine at this scale
    (HIST_DIR / f"{user}.json").write_text(json.dumps(entries, indent=1))


@app.get("/api/history")
def api_history(request: Request):
    # no-store: this JSON mutates while a tab is open (position saves);
    # a stale copy has caused "poster gone" confusion before
    return JSONResponse(
        sorted(_load_hist(request.state.user), key=lambda e: e.get("t", 0), reverse=True)[:5],
        headers={"Cache-Control": "no-store"})


@app.post("/api/history")
def api_history_post(entry: dict = Body(...), request: Request = None):
    if "ep_id" not in entry:
        raise HTTPException(422, "ep_id required")
    entry["t"] = time.time()
    u = request.state.user
    entries = _load_hist(u)
    for i, e in enumerate(entries):
        if e.get("slug_id") == entry.get("slug_id") and e.get("ep_id") == entry.get("ep_id"):
            entries[i] = {**e, **entry}
            break
    else:
        entries.append(entry)
    _save_hist(u, sorted(entries, key=lambda e: e.get("t", 0), reverse=True)[:50])
    return entry


def _b64(url: str) -> str:
    return base64.urlsafe_b64encode(url.encode()).decode()


def _url(token: str) -> str:
    return base64.urlsafe_b64decode(token.encode()).decode()


def _upstream(fn, *a, **kw):
    try:
        return fn(*a, **kw)
    except HTTPException:
        raise
    except Exception as e:
        raise HTTPException(502, f"upstream error: {e}")


@app.middleware("http")
async def no_cache(request, call_next):
    # ponytail: no-store on everything except /stream (immutable HLS
    # data) and the vendored hls.min.js (immutable, 500KB — re-downloading
    # it on every page load hurt on mobile)
    r = await call_next(request)
    if request.url.path == "/hls.min.js":
        r.headers["Cache-Control"] = "public, max-age=2592000"
    elif not request.url.path.startswith("/stream"):
        r.headers["Cache-Control"] = "no-store"
    return r


@app.get("/api/search")
def api_search(q: str = Query(min_length=1)):
    return _upstream(upstream.search, q)


@app.get("/api/anime/{slug_id}")
def api_anime(slug_id: str):
    return _upstream(upstream.details, slug_id)


@app.get("/api/anime/{anime_id}/episodes")
def api_episodes(anime_id: int):
    return _upstream(upstream.episodes, anime_id)


@app.get("/api/episode/{ep_id}/stream")
def api_stream(ep_id: int, lang: str = "eng"):
    def go():
        master = _upstream(upstream.master_m3u8, ep_id, lang)
        if not master:
            raise HTTPException(404, f"no {lang} stream for episode {ep_id}")
        return {"token": _b64(master),
                "qualities": _upstream(upstream.master_variants, master)}
    try:
        return go()
    except HTTPException as e:
        # one-shot retry with a cold cache: recovers rotated/expired
        # playlist URLs from the TTL cache
        if e.status_code == 502:
            upstream.clear_cache()
            return go()
        raise


def _rewrite_m3u8(text: str, base: str) -> str:
    # ponytail: rewrites plain URIs only; URI-list attributes in
    # #EXT-X-* tags (e.g. SUBTITLES) are ignored — fine for video-only playlists
    return "\n".join(
        line if line.startswith("#") or not line
        else "/stream/" + _b64(urljoin(base, line))
        for line in text.splitlines()) + "\n"


_STREAM_CACHE = OrderedDict()  # ponytail: LRU of proxied HLS data (immutable);
_STREAM_MAX = 24                # segments ~1-2MB -> <= ~48MB


@app.get("/stream/{token}")
def stream(token: str):
    # ponytail: buffers whole response in memory; .ts segments are small
    url = _url(token)
    hit = _STREAM_CACHE.get(url)
    if hit:
        _STREAM_CACHE.move_to_end(url)
        return Response(hit[1], media_type=hit[0])
    r = _upstream(upstream._get, url)
    body = r.content
    if url.endswith(".m3u8") or "mpegurl" in r.headers.get("content-type", ""):
        body = _rewrite_m3u8(body.decode(), url).encode()
    _STREAM_CACHE[url] = (r.headers.get("content-type", "application/octet-stream"), body)
    while len(_STREAM_CACHE) > _STREAM_MAX:
        _STREAM_CACHE.popitem(last=False)
    return Response(body, media_type=r.headers.get("content-type", "application/octet-stream"))


app.mount("/", StaticFiles(directory=ROOT / "static", html=True), name="static")