"""
Configuration for ctxd — context daemon.

Environment variables take precedence over ctxd.yaml, which takes precedence
over built-in defaults. This allows fully env-driven deployments (Docker,
Compose, Kubernetes) while preserving file-based config for local dev.
"""
import os
from pathlib import Path


def _env_bool(key: str, fallback: bool = False) -> bool:
    val = os.environ.get(key, "")
    if not val:
        return fallback
    return val.lower() in ("1", "true", "yes", "on")


def _env_int(key: str, fallback: int) -> int:
    val = os.environ.get(key, "")
    if not val:
        return fallback
    try:
        return int(val)
    except ValueError:
        return fallback


def _env_str(key: str, fallback: str = "") -> str:
    return os.environ.get(key, fallback)


# Default home directory (~/.ctx) — overridable via CTXD_HOME env var
DEFAULT_HOME = Path(os.environ.get("CTXD_HOME", Path.home() / ".ctx"))

# Built-in defaults (lowest precedence)
DEFAULT_CONFIG = {
    "server": {
        "host": "0.0.0.0",
        "port": 9091,
    },
    "snapshots": {
        "min_keep": 5,
        "max_keep": 25,
    },
    "auth": {
        "enabled": False,
        "api_key": "",
        "external_readonly_key": "",
    },
    "oauth": {
        "enabled": False,
        "issuer": "",
        "approval_key": "",
        "approval_user_id": "admin",
        "access_token_ttl_seconds": 3600,
        "refresh_token_ttl_seconds": 2592000,
    },
    "web_sessions": {
        "ttl_seconds": 604800,
    },
    "seed": {
        "admin_user": "admin",
        "admin_display": "Administrator",
        "service_user": "hermes-gateway",
        "service_display": "Hermes Agent",
    },
}


class CtxConfig:
    """Holds resolved paths and config for a ctxd runtime.

    Precedence: env var > ctxd.yaml value > built-in default.
    """

    def __init__(self, home: Path | str | None = None, config: dict | None = None):
        resolved = Path(home) if home else DEFAULT_HOME
        self.home = resolved.resolve()
        self._cfg = config or dict(DEFAULT_CONFIG)

    # ── Directory layout ──────────────────────────────────────────
    @property
    def db_path(self) -> Path:
        return self.home / "ctxd.db"

    @property
    def snapshots_dir(self) -> Path:
        return self.home / "snapshots"

    @property
    def projects_dir(self) -> Path:
        return self.home / "projects"

    @property
    def user_dir(self) -> Path:
        return self.home / "users"

    @property
    def config_path(self) -> Path:
        return self.home / "ctxd.yaml"

    @property
    def oauth_state_path(self) -> Path:
        return self.home / "oauth_state.json"

    @property
    def web_sessions_path(self) -> Path:
        return self.home / "web_sessions.json"

    # ── Database ──────────────────────────────────────────────────
    @property
    def database_url(self) -> str:
        return _env_str("DATABASE_URL")

    @property
    def use_postgres(self) -> bool:
        return bool(self.database_url)

    # ── Server ────────────────────────────────────────────────────
    @property
    def host(self) -> str:
        return _env_str("CTXD_HOST", self._cfg.get("server", {}).get("host", "0.0.0.0"))

    @property
    def port(self) -> int:
        return _env_int("CTXD_PORT", self._cfg.get("server", {}).get("port", 9091))

    @property
    def log_level(self) -> str:
        return _env_str("LOG_LEVEL", "info")

    @property
    def demo_mode(self) -> bool:
        return _env_bool("CTXD_DEMO_MODE", False)

    # ── Snapshots ─────────────────────────────────────────────────
    @property
    def min_snapshots(self) -> int:
        return _env_int("SNAPSHOT_MIN_KEEP", self._cfg.get("snapshots", {}).get("min_keep", 5))

    @property
    def max_snapshots(self) -> int:
        return _env_int("SNAPSHOT_MAX_KEEP", self._cfg.get("snapshots", {}).get("max_keep", 25))

    # ── Auth ──────────────────────────────────────────────────────
    @property
    def auth_enabled(self) -> bool:
        return _env_bool("CTXD_AUTH_ENABLED", self._cfg.get("auth", {}).get("enabled", False))

    @property
    def api_key(self) -> str:
        return _env_str("CTXD_API_KEY", self._cfg.get("auth", {}).get("api_key", ""))

    @property
    def external_readonly_key(self) -> str:
        return _env_str("CTXD_EXTERNAL_READONLY_KEY", self._cfg.get("auth", {}).get("external_readonly_key", ""))

    # ── OAuth ─────────────────────────────────────────────────────
    @property
    def oauth_enabled(self) -> bool:
        return _env_bool("OAUTH_ENABLED", self._cfg.get("oauth", {}).get("enabled", False))

    @property
    def oauth_issuer(self) -> str:
        return _env_str("OAUTH_ISSUER", self._cfg.get("oauth", {}).get("issuer", ""))

    @property
    def oauth_approval_key(self) -> str:
        return _env_str("OAUTH_APPROVAL_KEY", self._cfg.get("oauth", {}).get("approval_key", ""))

    @property
    def oauth_approval_user_id(self) -> str:
        return _env_str("OAUTH_APPROVAL_USER_ID", self._cfg.get("oauth", {}).get("approval_user_id", "admin"))

    @property
    def oauth_access_token_ttl_seconds(self) -> int:
        return _env_int("OAUTH_ACCESS_TOKEN_TTL", self._cfg.get("oauth", {}).get("access_token_ttl_seconds", 3600))

    @property
    def oauth_refresh_token_ttl_seconds(self) -> int:
        return _env_int("OAUTH_REFRESH_TOKEN_TTL", self._cfg.get("oauth", {}).get("refresh_token_ttl_seconds", 2592000))

    # ── Web Sessions ───────────────────────────────────────────────
    @property
    def web_session_ttl_seconds(self) -> int:
        return _env_int("WEB_SESSION_TTL", self._cfg.get("web_sessions", {}).get("ttl_seconds", 604800))

    # ── Bootstrap ─────────────────────────────────────────────────
    def ensure_dirs(self):
        """Create all required directories if they don't exist."""
        for d in [self.home, self.snapshots_dir, self.projects_dir, self.user_dir]:
            d.mkdir(parents=True, exist_ok=True)

    @classmethod
    def from_home(cls, home: Path | str | None = None) -> "CtxConfig":
        """Load from ctxd.yaml if it exists, otherwise use defaults.
        Env vars always take precedence over yaml values at read time.
        """
        home = Path(home).resolve() if home else DEFAULT_HOME
        cfg_path = home / "ctxd.yaml"
        if cfg_path.exists():
            import yaml
            with open(cfg_path) as f:
                data = yaml.safe_load(f) or {}
            return cls(home=str(home), config=data)
        return cls(home=str(home))

    def save(self):
        """Write config to ctxd.yaml. Rarely needed in env-driven deployments."""
        import yaml
        self.ensure_dirs()
        with open(self.config_path, "w") as f:
            yaml.dump(self._cfg, f, default_flow_style=False, sort_keys=False)