#!/usr/bin/env python3
#
# Copyright (C) 2019 VyOS maintainers and contributors
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2 or later as
# published by the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#
# Description:
# Check if a given file exists on the system. Used for files that
# are referenced from the CLI and need to be preserved during an image upgrade.
# Warn the user if these aren't under /config

import os
import sys
import argparse


def exit(strict, message):
    if strict:
        sys.exit(f'ERROR: {message}')
    print(f'WARNING: {message}', file=sys.stderr)
    sys.exit()


if __name__ == '__main__':
    parser = argparse.ArgumentParser()
    parser.add_argument("-d", "--directory", type=str, help="File must be present in this directory.")
    parser.add_argument("-e", "--error", action="store_true", help="Tread warnings as errors - change exit code to '1'")
    parser.add_argument("file", type=str, help="Path of file to validate")

    args = parser.parse_args()

    #
    # Always check if the given file exists
    #
    if not os.path.exists(args.file):
        exit(args.error, f"File '{args.file}' not found")

    #
    # Optional check if the file is under a certain directory path
    #
    if args.directory:
        # remove directory path from path to verify
        rel_filename = args.file.replace(args.directory, '').lstrip('/')

        if not os.path.exists(args.directory + '/' + rel_filename):
            exit(args.error,
                f"'{args.file}' lies outside of '{args.directory}' directory.\n"
                  "It will not get preserved during image upgrade!"
            )

    sys.exit()