from __future__ import annotations

from functools import lru_cache
from pathlib import Path

from pydantic import field_validator
from pydantic_settings import BaseSettings, SettingsConfigDict

REPO_ROOT = Path(__file__).resolve().parents[2]
DATA_DIR = REPO_ROOT / "data"


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

    app_name: str = "Crypto Trader"
    env: str = "dev"
    host: str = "0.0.0.0"
    port: int = 8000

    database_url: str = "sqlite:///./data/trader.db"

    mode: str = "paper"
    exchange: str = "binance"
    symbol: str = "BTC/USDT"
    timeframe: str = "5m"
    poll_interval: float = 5.0
    candle_limit: int = 200

    starting_balance: float = 10_000.0
    fee_bps: float = 10.0
    slippage_bps: float = 5.0

    exchange_api_key: str = ""
    exchange_api_secret: str = ""
    exchange_sandbox: bool = False

    # --- Go-live gate ---
    # Live trading only starts when this is exactly "I UNDERSTAND THE RISK".
    # It is deliberately not a boolean: setting MODE=live alone is not enough.
    live_confirmation: str = ""
    # Refuse to start live below this account size (quote currency).
    min_live_balance: float = 100.0

    # --- Risk controls (0 disables a limit) ---
    # Absolute loss in quote currency since the start of the UTC day.
    max_daily_loss: float = 0.0
    # Percentage fall from peak equity.
    max_drawdown_pct: float = 0.0
    # Cap on a single position as a fraction of equity (1.0 = all-in).
    max_position_pct: float = 1.0
    # Maximum number of new entries per UTC day.
    max_trades_per_day: int = 0

    # --- Notifications ---
    telegram_bot_token: str = ""
    telegram_chat_id: str = ""
    notify_webhook_url: str = ""

    # Optional bearer token required on /api requests (defense-in-depth behind
    # the Traefik Basic auth). Empty disables the check.
    api_token: str = ""
    api_token_header: str = "X-API-Token"

    cors_origins: str = "*"

    @field_validator("mode")
    @classmethod
    def _validate_mode(cls, value: str) -> str:
        value = value.lower().strip()
        if value not in {"paper", "live"}:
            raise ValueError("mode must be 'paper' or 'live'")
        return value

    @property
    def cors_origin_list(self) -> list[str]:
        return [origin.strip() for origin in self.cors_origins.split(",") if origin.strip()]

    @property
    def is_live(self) -> bool:
        return self.mode == "live"


@lru_cache
def get_settings() -> Settings:
    settings = Settings()
    DATA_DIR.mkdir(parents=True, exist_ok=True)
    return settings