#!/usr/bin/env python3

from os import (stat, utime, fdopen, supports_fd, O_CREAT, O_APPEND, 
    open as osopen)
from os.path import exists, isfile
from argparse import ArgumentParser
from sys import exit, stderr
from email.mime.text import MIMEText
from subprocess import Popen, PIPE
from getpass import getuser
from pwd import getpwuid
from socket import gethostname
from shlex import split as shell_split

def eprint(*args, **kwargs):
    print(*args, file=stderr, **kwargs)

def touch(fname, mode=0o666, dir_fd=None, **kwargs):
    flags = O_CREAT | O_APPEND
    with fdopen(osopen(fname, flags=flags, mode=mode, dir_fd=dir_fd)) as f:
        utime(f.fileno() if utime in supports_fd else fname,
            dir_fd=None if supports_fd else dir_fd, **kwargs)

def ownership(filename):
    return getpwuid(stat(filename).st_uid).pw_name

def mail(user, subject, body):
    domain = gethostname()
    message = MIMEText(body)
    message["From"] = "{}@{}".format(user, domain)
    message["To"] = "root@{}".format(domain)
    message["Subject"] = subject
    command = shell_split("/usr/sbin/sendmail -t -oi")
    proc = Popen(command, stdin=PIPE, universal_newlines=True)
    proc.communicate(message.as_string())

def share_list(config_file, splitter):
    scripts = None
    with open(config_file, "r") as cfgfile:
        scripts = cfgfile.read().split("\n")
    if len(scripts) == 1 and len(scripts[0]) == 0:
        print("There are currently no shared user scripts")
        exit(0)
    for script in scripts:
        name, path, desc, author = script.split(splitter)
        print("{}\t{} (made by {})".format(name, desc, author).expandtabs())

def share_submit(queue_file, splitter):
    script_path = input("Absolute path to script: ")
    if not isfile(script_path):
        eprint("ERROR: That script does not exist")
        exit(1)
    user = getuser()
    owner = ownership(script_path)
    if user != owner:
        eprint("ERROR: You do not own this script")
        exit(1)
    script_name = script_path.split("/")[-1]
    script_desc = input("Description of script: ")
    with open(queue_file, "a") as queue:
        queue.write("{0}{4}{1}{4}{2}{4}{3}".format(script_name, script_path, 
            script_desc, user, splitter))
    subject = "Submission of '{}' script".format(script_name)
    body = "\n".join([
        "Path to script: {}".format(script_path),
        "Description: {}".format(script_desc),
        "Author: {}".format(user)
    ])
    mail(user, subject, body)
    print("SUCCESS: Your script has been submitted for approval")

config_file = "/center/etc/shared"
splitter = "%%"
if not exists(config_file):
    touch(config_file)

queue_file = "{}.queue".format(config_file)
if not exists(queue_file):
    touch(queue_file)

description = "Allows users to share their scripts with the server"
parser = ArgumentParser(prog="share", description=description)
subparsers = parser.add_subparsers(title="commands", dest="commands")
subparsers.required = False
list_parser = subparsers.add_parser("list", help="list all shared scripts")
submit_parser = subparsers.add_parser("submit", 
    help="starts interactive prompt to share your script")
arguments = parser.parse_args()

if arguments.commands == "list":
    share_list(config_file, splitter)
elif arguments.commands == "submit":
    share_submit(queue_file, splitter)
else:
    parser.print_help()