import os
from dataclasses import dataclass

@dataclass
class Config:
    bot_token: str
    database_url: str
    metrics_port: int = 8000
    log_level: str = os.getenv("LOG_LEVEL", "INFO")

def load_config() -> "Config":
    bot_token = os.getenv("BOT_TOKEN", "").strip()
    if not bot_token:
        raise RuntimeError("BOT_TOKEN is not set")
    # DATABASE_URL takes precedence; else compose from parts
    db_url = os.getenv("DATABASE_URL", "").strip()
    if not db_url:
        host = os.getenv("DB_HOST", "db")
        port = os.getenv("DB_PORT", "5432")
        name = os.getenv("DB_NAME", "tg_poster")
        user = os.getenv("DB_USER", "postgres")
        pwd  = os.getenv("DB_PASSWORD", "postgres")
        db_url = f"postgresql+psycopg://{user}:{pwd}@{host}:{port}/{name}"
    metric_port = int(os.getenv("METRICS_PORT", 9010))
    return Config(bot_token=bot_token, database_url=db_url, metrics_port=metric_port)