#!/usr/bin/env python

from ftplib import FTP
import ftplib
import sys
from optparse import OptionParser

parser = OptionParser()

parser.add_option("-a", "--remote_host_address", dest="remote_host_address",
    help="REMOTE FTP HOST.", 
    metavar="REMOTE FTP HOST")

parser.add_option("-r", "--remote_file", dest="remote_file",
    help="REMOTE FILE NAME to download.", 
    metavar="REMOTE FILE NAME")

parser.add_option("-l", "--local_file", dest="local_file",
    help="LOCAL FILE NAME to save remote file to", metavar="LOCAL FILE NAME")

parser.add_option("-u", "--username", dest="username",
    help="USERNAME for ftp server", metavar="USERNAME")

parser.add_option("-p", "--password", dest="password",
    help="PASSWORD for ftp server", metavar="PASSWORD")

(options, args) = parser.parse_args()

if not (options.remote_file and 
        options.local_file and 
        options.remote_host_address):
    parser.error('REMOTE HOST, LOCAL FILE NAME, ' \
            'and REMOTE FILE NAME are mandatory')

if options.username and not options.password:
    parser.error('PASSWORD is mandatory if USERNAME is present')

ftp = FTP(options.remote_host_address)
if options.username:
    try:
        ftp.login(options.username, options.password)
    except ftplib.error_perm, e:
        print "Login failed: %s" % e
        sys.exit(1)
else:
    try:
        ftp.login()
    except ftplib.error_perm, e:
        print "Anonymous login failed: %s" % e
        sys.exit(1)
try:
    local_file = open(options.local_file, 'wb')
    ftp.retrbinary('RETR %s' % options.remote_file, local_file.write)
finally:
    local_file.close()
    ftp.close()