backend/utils.py

"""
Shared utilities: logging, IDs, safe paths.
"""
import hashlib
import json
import logging
import os
from pathlib import Path
from typing import Any, Dict, List, Optional
from uuid import uuid4

from backend.config import DATA_ROOT, LOGS_DIR, MOCK_USER

# Logging: write to file and console
_log_file = LOGS_DIR / "app.log"
logging.basicConfig(
    level=logging.INFO,
    format="%(asctime)s [%(levelname)s] %(name)s: %(message)s",
    handlers=[
        logging.FileHandler(_log_file, encoding="utf-8"),
        logging.StreamHandler(),
    ],
)
logger = logging.getLogger("notebooklm")


def get_username_from_request(request: Any) -> str:
    """
    Derive username from Gradio request (HF OAuth) or MOCK_USER.
    request may be None in local dev or when Gradio doesn't pass it.
    """
    if MOCK_USER:
        return MOCK_USER
    if request is not None:
        # Gradio 4.x: request can have .username from HF OAuth
        if hasattr(request, "username") and request.username:
            return str(request.username).strip()
        if hasattr(request, "user") and request.user:
            u = request.user
            if isinstance(u, dict) and u.get("username"):
                return str(u["username"]).strip()
            if hasattr(u, "username"):
                return str(u.username).strip()
        # Some setups pass username in headers
        if hasattr(request, "headers"):
            h = getattr(request, "headers", {}) or {}
            if isinstance(h, dict) and h.get("x-username"):
                return str(h["x-username"]).strip()
    return "anonymous"


def user_data_dir(username: str) -> Path:
    """Path to /data/users/<username>. Validates no path escape."""
    username = (username or "").strip() or "anonymous"
    if ".." in username or "/" in username or "\\" in username:
        username = "anonymous"
    root = DATA_ROOT.resolve()
    path = (root / "users" / username).resolve()
    if not str(path).startswith(str(root)):
        path = root / "users" / "anonymous"
    return path


def ensure_dir(path: Path) -> Path:
    path.mkdir(parents=True, exist_ok=True)
    return path


def new_uuid() -> str:
    return str(uuid4())


def file_hash(path: Path) -> str:
    """SHA256 hash of file for dedupe."""
    h = hashlib.sha256()
    with open(path, "rb") as f:
        for chunk in iter(lambda: f.read(8192), b""):
            h.update(chunk)
    return h.hexdigest()


def read_json(path: Path, default: Any = None) -> Any:
    if default is None:
        default = {}
    if not path.exists():
        return default
    try:
        with open(path, "r", encoding="utf-8") as f:
            return json.load(f)
    except (json.JSONDecodeError, OSError) as e:
        logger.warning("read_json %s: %s", path, e)
        return default


def write_json(path: Path, data: Any) -> None:
    ensure_dir(path.parent)
    with open(path, "w", encoding="utf-8") as f:
        json.dump(data, f, indent=2, ensure_ascii=False)


def read_jsonl(path: Path) -> List[Dict[str, Any]]:
    if not path.exists():
        return []
    out: List[Dict[str, Any]] = []
    with open(path, "r", encoding="utf-8") as f:
        for line in f:
            line = line.strip()
            if not line:
                continue
            try:
                out.append(json.loads(line))
            except json.JSONDecodeError:
                continue
    return out


def append_jsonl(path: Path, record: Dict[str, Any]) -> None:
    ensure_dir(path.parent)
    with open(path, "a", encoding="utf-8") as f:
        f.write(json.dumps(record, ensure_ascii=False) + "\n")


def normalize_text(text: str) -> str:
    """Normalize whitespace and strip."""
    if not text:
        return ""
    return " ".join(text.split()).strip()