#!/usr/bin/env python3

import os

from .print_input_args import print_input_args
from .print_msg import print_err_msg_exit
from .filesys_cmds_vrfy import ln_vrfy


def create_symlink_to_file(target, symlink, relative=True):
    """Create a symbolic link to the specified target file.

    Args:
        target: target file
        symlink: symbolic link to target file
        relative: optional argument to specify relative symoblic link creation
    Returns:
        None
    """

    print_input_args(locals())

    if target is None:
        print_err_msg_exit(
            f"""
            The argument 'target' specifying the target of the symbolic link that
            this function will create was not specified in the call to this function:
              target = '{target}'"""
        )

    if symlink is None:
        print_err_msg_exit(
            f"""
            The argument 'symlink' specifying the target of the symbolic link that
            this function will create was not specified in the call to this function:
              symlink = '{symlink}'"""
        )

    if not os.path.exists(target):
        print_err_msg_exit(
            f"""
            Cannot create symlink to specified target file because the latter does
            not exist or is not a file:
                target = '{target}'"""
        )

    relative_flag = ""
    if relative:
        RELATIVE_LINK_FLAG = os.getenv("RELATIVE_LINK_FLAG")
        if RELATIVE_LINK_FLAG is not None:
            relative_flag = f"{RELATIVE_LINK_FLAG}"

    ln_vrfy(f"-sf {relative_flag} {target} {symlink}")