"""Load configuration from environment (e.g. .env via python-dotenv).

BOT_TOKEN is not validated on import; call require_bot_token() in the entry point
when running the bot.
"""

import os
import re
from dataclasses import dataclass
from pathlib import Path

from dotenv import load_dotenv

from duty_teller.i18n.lang import normalize_lang

load_dotenv()

# Project root (parent of duty_teller package). Used for webapp path, etc.
PROJECT_ROOT = Path(__file__).resolve().parent.parent

# Only digits for phone comparison (same when saving and when checking allowlist).
_PHONE_DIGITS_RE = re.compile(r"\D")


def normalize_phone(phone: str | None) -> str:
    """Return phone as digits only (spaces, +, parentheses, dashes removed).

    Args:
        phone: Raw phone string or None.

    Returns:
        Digits-only string, or empty string if None or empty.
    """
    if not phone or not isinstance(phone, str):
        return ""
    return _PHONE_DIGITS_RE.sub("", phone.strip())


def _parse_phone_list(raw: str) -> set[str]:
    """Parse comma-separated phones into set of normalized (digits-only) strings."""
    result = set()
    for s in (raw or "").strip().split(","):
        normalized = normalize_phone(s)
        if normalized:
            result.add(normalized)
    return result


@dataclass(frozen=True)
class Settings:
    """Injectable settings built from environment. Used in tests or when env is overridden."""

    bot_token: str
    database_url: str
    mini_app_base_url: str
    http_port: int
    allowed_usernames: set[str]
    admin_usernames: set[str]
    allowed_phones: set[str]
    admin_phones: set[str]
    mini_app_skip_auth: bool
    init_data_max_age_seconds: int
    cors_origins: list[str]
    external_calendar_ics_url: str
    duty_display_tz: str
    default_language: str
    duty_pin_notify: bool

    @classmethod
    def from_env(cls) -> "Settings":
        """Build Settings from current environment (same logic as module-level variables).

        Returns:
            Settings instance with all fields populated from env.
        """
        bot_token = os.getenv("BOT_TOKEN") or ""
        raw_allowed = os.getenv("ALLOWED_USERNAMES", "").strip()
        allowed = {
            s.strip().lstrip("@").lower() for s in raw_allowed.split(",") if s.strip()
        }
        raw_admin = os.getenv("ADMIN_USERNAMES", "").strip()
        admin = {
            s.strip().lstrip("@").lower() for s in raw_admin.split(",") if s.strip()
        }
        allowed_phones = _parse_phone_list(os.getenv("ALLOWED_PHONES", ""))
        admin_phones = _parse_phone_list(os.getenv("ADMIN_PHONES", ""))
        raw_cors = os.getenv("CORS_ORIGINS", "").strip()
        cors = (
            [_o.strip() for _o in raw_cors.split(",") if _o.strip()]
            if raw_cors and raw_cors != "*"
            else ["*"]
        )
        return cls(
            bot_token=bot_token,
            database_url=os.getenv("DATABASE_URL", "sqlite:///data/duty_teller.db"),
            mini_app_base_url=os.getenv("MINI_APP_BASE_URL", "").rstrip("/"),
            http_port=int(os.getenv("HTTP_PORT", "8080")),
            allowed_usernames=allowed,
            admin_usernames=admin,
            allowed_phones=allowed_phones,
            admin_phones=admin_phones,
            mini_app_skip_auth=os.getenv("MINI_APP_SKIP_AUTH", "").strip()
            in ("1", "true", "yes"),
            init_data_max_age_seconds=int(os.getenv("INIT_DATA_MAX_AGE_SECONDS", "0")),
            cors_origins=cors,
            external_calendar_ics_url=os.getenv(
                "EXTERNAL_CALENDAR_ICS_URL", ""
            ).strip(),
            duty_display_tz=os.getenv("DUTY_DISPLAY_TZ", "Europe/Moscow").strip()
            or "Europe/Moscow",
            default_language=normalize_lang(os.getenv("DEFAULT_LANGUAGE", "en")),
            duty_pin_notify=os.getenv("DUTY_PIN_NOTIFY", "1").strip().lower()
            not in ("0", "false", "no"),
        )


# Single source of truth: load once at import; entry point must check BOT_TOKEN when needed.
_settings = Settings.from_env()

BOT_TOKEN = _settings.bot_token
DATABASE_URL = _settings.database_url
MINI_APP_BASE_URL = _settings.mini_app_base_url
HTTP_PORT = _settings.http_port
ALLOWED_USERNAMES = _settings.allowed_usernames
ADMIN_USERNAMES = _settings.admin_usernames
ALLOWED_PHONES = _settings.allowed_phones
ADMIN_PHONES = _settings.admin_phones
MINI_APP_SKIP_AUTH = _settings.mini_app_skip_auth
INIT_DATA_MAX_AGE_SECONDS = _settings.init_data_max_age_seconds
CORS_ORIGINS = _settings.cors_origins
EXTERNAL_CALENDAR_ICS_URL = _settings.external_calendar_ics_url
DUTY_DISPLAY_TZ = _settings.duty_display_tz
DEFAULT_LANGUAGE = _settings.default_language
DUTY_PIN_NOTIFY = _settings.duty_pin_notify


def is_admin(username: str) -> bool:
    """Check if Telegram username is in ADMIN_USERNAMES.

    Args:
        username: Telegram username (with or without @; case-insensitive).

    Returns:
        True if in ADMIN_USERNAMES.
    """
    return (username or "").strip().lower() in ADMIN_USERNAMES


def can_access_miniapp(username: str) -> bool:
    """Check if username is allowed to open the calendar Miniapp (env allowlist only).

    Legacy: Miniapp access in production is determined by repository.can_access_miniapp_for_telegram_user
    (DB roles + fallback to ADMIN_*). This function is kept for tests and backward compatibility.

    Args:
        username: Telegram username (with or without @; case-insensitive).

    Returns:
        True if in ALLOWED_USERNAMES or ADMIN_USERNAMES.
    """
    u = (username or "").strip().lower()
    return u in ALLOWED_USERNAMES or u in ADMIN_USERNAMES


def can_access_miniapp_by_phone(phone: str | None) -> bool:
    """Check if phone (set via /set_phone) is allowed to open the Miniapp (env allowlist only).

    Legacy: Miniapp access in production is determined by repository.can_access_miniapp_for_telegram_user
    (DB roles + fallback to ADMIN_*). This function is kept for tests and backward compatibility.

    Args:
        phone: Raw phone string or None.

    Returns:
        True if normalized phone is in ALLOWED_PHONES or ADMIN_PHONES.
    """
    normalized = normalize_phone(phone)
    if not normalized:
        return False
    return normalized in ALLOWED_PHONES or normalized in ADMIN_PHONES


def is_admin_by_phone(phone: str | None) -> bool:
    """Check if phone is in ADMIN_PHONES.

    Args:
        phone: Raw phone string or None.

    Returns:
        True if normalized phone is in ADMIN_PHONES.
    """
    normalized = normalize_phone(phone)
    return bool(normalized and normalized in ADMIN_PHONES)


def require_bot_token() -> None:
    """Raise SystemExit with a clear message if BOT_TOKEN is not set.

    Call from the application entry point (e.g. main.py or duty_teller.run) so the
    process exits with a helpful message instead of failing later.

    Raises:
        SystemExit: If BOT_TOKEN is empty.
    """
    if not BOT_TOKEN:
        raise SystemExit(
            "BOT_TOKEN is not set. Copy .env.example to .env and set your token from @BotFather."
        )