#!/usr/bin/python3

########################################################
##################  kremount v0.1.2  ###################
###  This script is a part of KozConfigurator v0.4.0 ###
########################################################
#########  Leonid Kozarin <kozalo@nekochan.ru  #########
#########  License: MIT                        #########
#########  (c) Copyright Kozalo.Ru, 2017-2018  #########
########################################################

import sys
import os
import re
import subprocess

DEFAULT_CONFIG_FILE = '/etc/kremount/.remotehosts'
MOUNT_POINT = '/mnt'


def read_config(config_file):
    """Reads a configuration file and returns its values as a dict."""

    hosts = {}

    with open(config_file, 'r') as config:
        current_host = None

        for line in config:
            line = line.strip()
            matches = re.match("(.*)\s*=\s*(.*)", line)
            if line[0] == "[" and line[-1] == "]":
                current_host = {}
                hosts[line[1:-1]] = current_host
            elif matches and current_host is not None:
                current_host[matches.group(1)] = matches.group(2)

    return hosts


def create_temporary_credentials_file(host, credentials):
    """Writes credentials to a temporary file and returns its path to pass it to the smbclient."""

    dir_path = "/tmp/kremount"
    file_path = "%s/.%s" % (dir_path, host)

    if not os.path.isdir(dir_path):
        os.mkdir(dir_path, 0o700)

    with open(file_path, 'w') as credentials_file:
        credentials_file.write("username=%s\n" % credentials['username'])
        credentials_file.write("password=%s\n" % credentials['password'])

    os.chmod(file_path, 0o600)
    return file_path


def get_remote_folders(host, credentials_file):
    """Uses smbclient to get the list of accessible folders of the host using a given file with credentials."""

    with open(os.devnull, 'w') as fnull:
        smbclient_result = subprocess.Popen(('smbclient', '-L', host, '-A', credentials_file), stdout=subprocess.PIPE, stderr=fnull)
    grep_result = subprocess.check_output(('grep', 'Disk'), stdin=smbclient_result.stdout)

    remote_resources = grep_result.decode("utf-8")
    folders = []

    for line in remote_resources.splitlines():
        if "$" in line or line[:2] == "OS" or line == "":
            continue
    
        name = re.match("(.+)Disk", line.lstrip()).group(1)
        folders.append(name.rstrip())

    return folders


def mount_folders(folders, credentials):
    """Mounts the 'folders' using your 'credentials' to a local disk."""

    username = credentials['username']
    password = credentials['password']

    for folder in folders:
        remote_path = "%s/%s" % (host, folder)
        local_path = "%s/%s" % (MOUNT_POINT, remote_path)

        if not os.access(MOUNT_POINT, os.W_OK):
            subprocess.call("sudo setfacl -m 'u:%s:rwx' '%s'" % (username, MOUNT_POINT), shell=True)

        os.makedirs(local_path, 0o700, exist_ok=True)
        subprocess.call("sudo mount.cifs '//%s' '%s' -o 'user=%s,pass=%s'" % (remote_path, local_path, username, password), shell=True)


def print_help_message():
    """Prints a help message."""

    print("\nThis script is supposed to help you mount remote folders on other computers within a local network.")
    print("It works automatically, but you must tell it a list of required hosts and credentials for htem.")
    print("By default, the script uses the %s file, but you can pass another path as a parameter." % DEFAULT_CONFIG_FILE)
    print("All remote folders will be mounted to %s." % MOUNT_POINT)
    print("And don't run the script as root! It won't be able read your credentials and set permissions to you.", end='\n\n')
    print("Your %s file must adhere to the following syntax:" % DEFAULT_CONFIG_FILE)
    print("\t[HOSTNAME]")
    print("\tusername=USERNAME")
    print("\tpassword=PASSWORD", end='\n\n')
    print("Note, the script makes assumption that your username in the network is equal to your login in the system.")
    print("If it's wrong, you shouldn't use the script.", end='\n\n')
    print("(c) Leonid Kozarin <kozalo@nekochan.ru> (Kozalo.Ru, 2017)", end='\n\n')



if __name__ == "__main__":
    if len(sys.argv) > 1 and ("help" in sys.argv[1] or sys.argv[1] == "-h"):
        print_help_message()
        exit()
    elif len(sys.argv) > 1 and os.path.isfile(sys.argv[1]):
        hosts = read_config(sys.argv[1])
    elif os.path.isfile(DEFAULT_CONFIG_FILE):
        hosts = read_config(DEFAULT_CONFIG_FILE)
    else:
        print("Couldn't find your credentials!")
        exit(1)

    for host, credentials in hosts.items():
        credentials_file = create_temporary_credentials_file(host, credentials)
        folders = get_remote_folders(host, credentials_file)
        mount_folders(folders, credentials)

        os.remove(credentials_file)
        subprocess.call("sudo setfacl -x '%s' '%s'" % (credentials['username'], MOUNT_POINT), shell=True)

    print("\nYour remote folders have been successfully mounted to %s!" % MOUNT_POINT)