from __future__ import annotations

import os
from pathlib import Path


class Config:
    """Bootstrap configuration.

    For a basic install, ``THOUGHTSYNC_DATABASE_URL`` is the ONLY required env var —
    every other tunable lives in the DB-backed Settings UI (rule 25). The only other
    env var is an optional "break-glass" item:

    - ``THOUGHTSYNC_SECRET_KEY`` — optional override for the cookie-signing secret.
      If unset, a key is generated and persisted in the DB (see
      ``thoughtsync.settings.load_or_create_secret_key``), so sessions survive
      restarts with no volume required.

    Uploaded media lives under ``DATA_DIR`` — a fixed, authoritative path
    (``/var/thoughtsync``), intentionally NOT configurable (a mutable data path only
    invites breakage). Mount a volume there if you want uploads to persist across
    container recreation; a text-notes-only install never writes to it.
    """

    DATA_DIR = "/var/thoughtsync"

    DATABASE_URL = os.environ.get(
        "THOUGHTSYNC_DATABASE_URL",
        "postgresql+asyncpg://thoughtsync:thoughtsync@localhost:5432/thoughtsync",
    )

    @classmethod
    def media_root(cls) -> Path:
        return Path(cls.DATA_DIR) / "media"

    @classmethod
    def client_root(cls) -> Path:
        """Where the Android APK this server hands out lives.

        Under DATA_DIR rather than baked into the image: the APK is ~55 MiB and an
        install that never touches Android should not carry it. Being on the same
        mounted volume as uploads also means an operator drops a build there once
        and container recreation does not lose it. See client_dist.py.
        """
        return Path(cls.DATA_DIR) / "client"

    @classmethod
    def secret_key_env(cls) -> str | None:
        """Optional break-glass override for the cookie-signing secret."""
        return os.environ.get("THOUGHTSYNC_SECRET_KEY") or None