"""HF Dataset repo storage for user notebook data."""

import json
import os
import tempfile

from huggingface_hub import HfApi, hf_hub_download

from state import UserData


class StorageService:
    REPO_ID = "Group-1-5010/notebooklm-data"
    REPO_TYPE = "dataset"
    _repo_ensured = False

    @staticmethod
    def _get_token():
        token = os.environ.get("HF_TOKEN")
        if not token:
            raise RuntimeError("HF_TOKEN not found in environment. Add it as a Secret in your HF Space settings.")
        return token

    @staticmethod
    def _ensure_repo(api: HfApi):
        """Create the dataset repo if it doesn't already exist (once per process)."""
        if StorageService._repo_ensured:
            return
        api.create_repo(
            repo_id=StorageService.REPO_ID,
            repo_type=StorageService.REPO_TYPE,
            private=True,
            exist_ok=True,
        )
        StorageService._repo_ensured = True
        print(f"[StorageService] Ensured dataset repo exists: {StorageService.REPO_ID}", flush=True)

    @staticmethod
    def save_user_data(user_data: UserData) -> None:
        """Serialize UserData to JSON and upload to HF Dataset repo.

        Raises on failure so the caller can show the error to the user.
        """
        token = StorageService._get_token()

        data_json = json.dumps(user_data.to_dict(), ensure_ascii=False, indent=2)

        tmp_path = None
        try:
            with tempfile.NamedTemporaryFile(
                mode="w", suffix=".json", delete=False
            ) as tmp:
                tmp.write(data_json)
                tmp_path = tmp.name

            api = HfApi(token=token)
            StorageService._ensure_repo(api)
            api.upload_file(
                path_or_fileobj=tmp_path,
                path_in_repo=f"data/{user_data.user_id}.json",
                repo_id=StorageService.REPO_ID,
                repo_type=StorageService.REPO_TYPE,
            )
            print(f"[StorageService] Saved user data for '{user_data.user_id}'", flush=True)
        finally:
            if tmp_path:
                try:
                    os.unlink(tmp_path)
                except Exception:
                    pass

    @staticmethod
    def load_user_data(user_id: str, user_name: str) -> UserData | None:
        """Download and deserialize UserData from HF Dataset repo.

        Returns None if the file doesn't exist (new user).
        """
        try:
            token = StorageService._get_token()
        except RuntimeError:
            print("[StorageService] HF_TOKEN not set — skipping load", flush=True)
            return None

        try:
            path = hf_hub_download(
                repo_id=StorageService.REPO_ID,
                filename=f"data/{user_id}.json",
                repo_type=StorageService.REPO_TYPE,
                token=token,
            )
            with open(path, "r") as f:
                data = json.load(f)
            print(f"[StorageService] Loaded user data for '{user_id}'", flush=True)
            return UserData.from_dict(data)
        except Exception as e:
            # EntryNotFoundError or network errors — treat as new user
            print(f"[StorageService] No existing data for '{user_id}': {e}", flush=True)
            return None