import sys
import xml.etree.ElementTree as ET
from pathlib import Path

key = 0x26


def extract_web_interface_creds(tree: ET) -> str:
    x_gc_login = tree.find('.//X_GC_LOGIIN')
    result = []
    for account in x_gc_login:
        level = account.find('UserLevel').text
        username = account.find('Username').text
        password = account.find('Passwd').text
        result.append(f'{level}-level account:\nusername: {username}\npassword: {password}')
    return '\n\n'.join(result)


def extract_shell_access_creds(tree: ET) -> str:
    telnet = tree.find('.//RemoteManagement/TELNET')
    ssh = tree.find('.//RemoteManagement/SSH')
    telnet_username = telnet.find('TelnetUserName').text
    telnet_password = telnet.find('TelnetPassword').text
    ssh_username = ssh.find('UserName').text
    ssh_password = ssh.find('Password').text
    if (telnet_username == ssh_username) and (telnet_password == ssh_password):
        return f'Shell credentials (Telnet and SSH):\nusername: {ssh_username}\npassword: {ssh_password}'
    else:
        return f'''Shell credentials:
Telnet:
username: {telnet_username}
password: {telnet_password}

SSH:
username: {ssh_username}
password: {ssh_password}'''


try:
    config_filename = Path(sys.argv[1])
except IndexError:
    print(f'Usage: {sys.argv[0]} <path to config file backup>', file=sys.stderr)
    sys.exit(1)

with open(config_filename, 'rb') as infile:
    test_chunk = infile.read(7)
    infile.seek(0)
    if test_chunk.startswith(b'<?xml'):
        print(f'It looks like file "{config_filename}" has already been decrypted.')
        decrypted_contents = infile.read()
    else:
        decrypted_contents = ''.join(chr(c ^ key) for c in infile.read()).replace(',', '\n')
        decrypted_filename = config_filename.resolve().with_suffix('.xml')
        with open(decrypted_filename, 'wt') as outfile:
            outfile.write(decrypted_contents)
        print(f'File decrypted and saved to "{decrypted_filename}"')

config_tree = ET.fromstring(decrypted_contents)
print(f'\nWeb interface credentials:\n{extract_web_interface_creds(config_tree)}\n\n')
print(extract_shell_access_creds(config_tree))