from pydantic_settings import BaseSettings
from functools import lru_cache
import os

import yaml


class Settings(BaseSettings):
    APP_NAME: str = "TianpuEMS"
    DEBUG: bool = True
    API_V1_PREFIX: str = "/api/v1"

    # Customer configuration
    CUSTOMER: str = "tianpu"  # tianpu, zpark, etc.
    CUSTOMER_DISPLAY_NAME: str = ""  # Loaded from customer config

    # Database: set DATABASE_URL in .env to override.
    # Default: SQLite for local dev. Docker sets PostgreSQL via env var.
    # Examples:
    #   SQLite:      sqlite+aiosqlite:///./tianpu_ems.db
    #   PostgreSQL:  postgresql+asyncpg://tianpu:tianpu2026@localhost:5432/tianpu_ems
    DATABASE_URL: str = "sqlite+aiosqlite:///./tianpu_ems.db"
    REDIS_URL: str = "redis://localhost:6379/0"

    SECRET_KEY: str = "tianpu-ems-secret-key-change-in-production-2026"
    ALGORITHM: str = "HS256"
    ACCESS_TOKEN_EXPIRE_MINUTES: int = 480

    CELERY_ENABLED: bool = False  # Set True when Celery worker is running
    USE_SIMULATOR: bool = True  # True=simulator mode, False=real IoT collectors

    # Infrastructure flags
    TIMESCALE_ENABLED: bool = False
    REDIS_ENABLED: bool = True
    INGESTION_QUEUE_ENABLED: bool = False
    AGGREGATION_ENABLED: bool = True

    # SMTP Email settings
    SMTP_HOST: str = ""
    SMTP_PORT: int = 587
    SMTP_USER: str = ""
    SMTP_PASSWORD: str = ""
    SMTP_FROM: str = "noreply@tianpu-ems.com"
    SMTP_ENABLED: bool = False

    # Platform URL for links in emails
    PLATFORM_URL: str = "http://localhost:3000"

    @property
    def DATABASE_URL_SYNC(self) -> str:
        """Derive synchronous URL from async DATABASE_URL for Alembic."""
        url = self.DATABASE_URL
        return url.replace("+aiosqlite", "").replace("+asyncpg", "+psycopg2")

    @property
    def is_sqlite(self) -> bool:
        return "sqlite" in self.DATABASE_URL

    @property
    def customer_config_path(self) -> str:
        return os.path.join(os.path.dirname(os.path.dirname(os.path.dirname(__file__))),
                            "..", "customers", self.CUSTOMER)

    def load_customer_config(self) -> dict:
        """Load customer-specific config from customers/{CUSTOMER}/config.yaml"""
        config_file = os.path.join(self.customer_config_path, "config.yaml")
        if os.path.exists(config_file):
            with open(config_file, 'r', encoding='utf-8') as f:
                return yaml.safe_load(f) or {}
        return {}

    class Config:
        env_file = ".env"
        extra = "ignore"


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