"""Typed application settings. The only place that reads environment variables."""

from functools import lru_cache
from pathlib import Path
from typing import Literal

from pydantic import Field
from pydantic_settings import BaseSettings, SettingsConfigDict

ROOT_DIR = Path(__file__).resolve().parent.parent


class Settings(BaseSettings):
    # Empty values in .env (e.g. `TG_BOT_TOKEN=`) fall back to defaults instead of failing validation.
    model_config = SettingsConfigDict(env_file=".env", extra="ignore", env_ignore_empty=True)

    # Two separate databases (ADR-003): identity holds direct identifiers, clinical holds pseudonymised data.
    identity_db_url: str = "postgresql+asyncpg://identity_app:identity_app@localhost:5432/identity"
    clinical_db_url: str = "postgresql+asyncpg://clinical_app:clinical_app@localhost:5432/clinical"

    # HMAC key linking identity and clinical records (hex, 32+ bytes).
    pseudo_key: str = Field(default="dev-only-insecure-key-change-me-0000000000000000", min_length=32)

    # LLM: GigaChat only (152-FZ: no foreign APIs). `mock` is the offline default (ADR-004).
    llm_provider: Literal["mock", "gigachat"] = "mock"
    gigachat_credentials: str = ""
    gigachat_scope: str = "GIGACHAT_API_PERS"
    gigachat_model: str = "GigaChat"
    gigachat_verify_ssl: bool = False

    # Chat agent (tool-using LLM over RAG + patient record). `auto` = OpenRouter if a key is set, else off
    # (extractive RAG / instruction answers stay). OpenRouter is a TEMPORARY prototype provider on synthetic
    # data only — prod must use GigaChat (152-FZ, foreign services are forbidden for real PII).
    chat_agent: Literal["auto", "off", "mock", "openrouter", "gigachat"] = "auto"
    openrouter_api_key: str = ""
    openrouter_model: str = "anthropic/claude-sonnet-4.5"
    openrouter_base_url: str = "https://openrouter.ai/api/v1"
    chat_agent_timeout_s: float = 25.0
    chat_agent_max_steps: int = 5

    # Telegram is used only for the prototype on synthetic data; prod channel is MAX / Gosuslugi.
    tg_bot_token: str = ""
    doctor_notify_chat_id: int | None = None

    # Virtual clock for the demo (ADR-005).
    demo_clock: bool = True
    tz: str = "Europe/Moscow"

    api_base_url: str = "http://localhost:8000"
    config_dir: Path = ROOT_DIR / "config"
    data_dir: Path = ROOT_DIR / "data"


@lru_cache
def get_settings() -> Settings:
    return Settings()