# Copyright (C) 2007 Giampaolo Rodola' <g.rodola@gmail.com>.
# Use of this source code is governed by MIT license that can be
# found in the LICENSE file.

"""
Start a stand alone anonymous FTP server from the command line as in:

$ python3 -m pyftpdlib
"""

import argparse
import logging
import os
import sys

from . import __ver__
from .authorizers import DummyAuthorizer
from .handlers import FTPHandler
from .log import config_logging
from .servers import FTPServer


def main(args=None):
    """Start a stand alone anonymous FTP server."""
    usage = "python3 -m pyftpdlib [options]"
    parser = argparse.ArgumentParser(
        usage=usage,
        description=main.__doc__,
    )
    parser.add_argument(
        '-i',
        '--interface',
        default=None,
        metavar="ADDRESS",
        help="specify the interface to run on (default all interfaces)",
    )
    parser.add_argument(
        '-p',
        '--port',
        type=int,
        default=2121,
        metavar="PORT",
        help="specify port number to run on (default 2121)",
    )
    parser.add_argument(
        '-w',
        '--write',
        action="store_true",
        default=False,
        help="grants write access for logged in user (default read-only)",
    )
    parser.add_argument(
        '-d',
        '--directory',
        default=os.getcwd(),
        metavar="FOLDER",
        help="specify the directory to share (default current directory)",
    )
    parser.add_argument(
        '-n',
        '--nat-address',
        default=None,
        metavar="ADDRESS",
        help="the NAT address to use for passive connections",
    )
    parser.add_argument(
        '-r',
        '--range',
        default=None,
        metavar="FROM-TO",
        help=(
            "the range of TCP ports to use for passive "
            "connections (e.g. -r 8000-9000)"
        ),
    )
    parser.add_argument(
        '-D', '--debug', action='store_true', help="enable DEBUG logging level"
    )
    parser.add_argument(
        '-v',
        '--version',
        action='store_true',
        help="print pyftpdlib version and exit",
    )
    parser.add_argument(
        '-V',
        '--verbose',
        action='store_true',
        help="activate a more verbose logging",
    )
    parser.add_argument(
        '-u',
        '--username',
        type=str,
        default=None,
        help=(
            "specify username to login with (anonymous login "
            "will be disabled and password required "
            "if supplied)"
        ),
    )
    parser.add_argument(
        '-P',
        '--password',
        type=str,
        default=None,
        help=(
            "specify a password to login with (username required to be useful)"
        ),
    )

    options = parser.parse_args(args=args)
    if options.version:
        sys.exit(f"pyftpdlib {__ver__}")
    if options.debug:
        config_logging(level=logging.DEBUG)

    passive_ports = None
    if options.range:
        try:
            start, stop = options.range.split('-')
            start = int(start)
            stop = int(stop)
        except ValueError:
            parser.error('invalid argument passed to -r option')
        else:
            passive_ports = list(range(start, stop + 1))
    # On recent Windows versions, if address is not specified and IPv6
    # is installed the socket will listen on IPv6 by default; in this
    # case we force IPv4 instead.
    if os.name in ('nt', 'ce') and not options.interface:
        options.interface = '0.0.0.0'

    authorizer = DummyAuthorizer()
    perm = "elradfmwMT" if options.write else "elr"
    if options.username:
        if not options.password:
            parser.error(
                "if username (-u) is supplied, password ('-P') is required"
            )
        authorizer.add_user(
            options.username, options.password, options.directory, perm=perm
        )
    else:
        authorizer.add_anonymous(options.directory, perm=perm)

    handler = FTPHandler
    handler.authorizer = authorizer
    handler.masquerade_address = options.nat_address
    handler.passive_ports = passive_ports

    ftpd = FTPServer((options.interface, options.port), FTPHandler)
    # On Windows specify a timeout for the underlying select() so
    # that the server can be interrupted with CTRL + C.
    try:
        ftpd.serve_forever(timeout=2 if os.name == 'nt' else None)
    finally:
        ftpd.close_all()
    if args:  # only used in unit tests
        return ftpd


if __name__ == '__main__':
    main()