"""Centralized application configuration via pydantic-settings."""

from __future__ import annotations

from typing import Literal

from pydantic import model_validator
from pydantic_settings import BaseSettings, SettingsConfigDict


class Settings(BaseSettings):
    model_config = SettingsConfigDict(
        env_file=".env",
        env_file_encoding="utf-8",
        extra="ignore",
    )

    database_url: str

    llm_provider: Literal["anthropic", "openai", "google"] = "anthropic"
    llm_model: str = "claude-sonnet-4-6"

    session_ttl_minutes: int = 30
    interrupt_ttl_minutes: int = 30

    ws_host: str = "0.0.0.0"
    ws_port: int = 8000

    anthropic_api_key: str = ""
    openai_api_key: str = ""
    google_api_key: str = ""

    @model_validator(mode="after")
    def validate_provider_key(self) -> Settings:
        key_map = {
            "anthropic": self.anthropic_api_key,
            "openai": self.openai_api_key,
            "google": self.google_api_key,
        }
        key = key_map.get(self.llm_provider, "")
        if not key:
            raise ValueError(
                f"API key for provider '{self.llm_provider}' is required. "
                f"Set the corresponding environment variable."
            )
        return self