import os
from pathlib import Path
from typing import Optional


def read_env(env_name: str) -> Optional[str]:
    if env_name in os.environ:
        return os.environ[env_name]

    file_path_key = f"{env_name}_FILE"
    if file_path_key in os.environ:
        file_path = os.environ[file_path_key]
        try:
            return Path(file_path).read_text(encoding="utf-8").strip()
        except (OSError, IOError) as e:
            raise ValueError(
                f"Failed to read {env_name}_FILE from file {file_path}: {e}"
            )

    return None


def read_str_env(env_name: str, default: str) -> str:
    value = read_env(env_name)
    if value is None:
        return default
    return value


def read_int_env(env_name: str, default: int) -> int:
    value = read_env(env_name)
    if value is None:
        return default
    try:
        return int(value)
    except ValueError:
        raise ValueError(
            f"Environment variable {env_name} must be an integer, got '{value}'"
        )


def read_bool_env(env_name: str, default: bool) -> bool:
    value = read_env(env_name)
    if value is None:
        return default
    return value.strip().lower() == "true"