"""
Operating system utilities for the Edison application.
"""
import os
import platform
import subprocess
import distro

def get_os_friendly_name():
    """
    Returns a friendly name of the user's operating system.

    The function retrieves the current system platform name using the `platform.system()` function.
    For Linux, it appends the distribution name retrieved from `distro.name(pretty=True)` to give a
    more descriptive representation. For Darwin (Apple's macOS), it appends "macOS" to "Darwin" to
    make the output clearer to the user.

    Returns:
        str: A friendly name for the user's operating system. It will be one of the following:
            - "Linux/<distribution name>"
            - "Darwin/macOS"
            - The system string returned by `platform.system()` if it's not Linux or Darwin.
    """
    os_name = platform.system()

    if os_name == "Linux":
        os_name = "Linux/" + distro.name(pretty=True)
    elif os_name == "Darwin":
        os_name = "Darwin/macOS"

    return os_name

def missing_posix_display():
    """
    Checks if the DISPLAY environment variable is set in a POSIX-compliant shell.

    This function runs a shell subprocess that outputs the value of the DISPLAY environment
    variable. It then checks if this value is unset (i.e., equals a newline 'b'\\n'') in the
    current shell environment. If the DISPLAY variable is unset, the function returns `True`
    indicating a "missing" display; otherwise, it returns `False`.

    Returns:
        bool: `True` if the DISPLAY environment variable is unset or empty, `False` otherwise.
    """
    if os.name != "posix":
        return False
        
    display = subprocess.check_output("echo $DISPLAY", shell=True)
    return display == b'\n'

def get_default_shell():
    """
    Get the default shell for the current operating system.
    
    Returns:
        str: The default shell.
    """
    # Unix based SHELL (/bin/bash, /bin/zsh), otherwise assuming it's Windows
    return os.environ.get("SHELL", "powershell.exe")