#!/usr/bin/python
#
# Usage : Download latest .jpa file from FTP Server.

import ftplib                                                           ## IMPORT MODULES
import string                                                           ## IMPORT MODULES
import os                                                               ## IMPORT MODULES
import re                                                               ## IMPORT MODULES

ftpserver = "ftp.server"                                                ## ASSIGN VARIABLE
username = "username"                                                   ## ASSIGN VARIABLE
password = "password"                                                   ## ASSIGN VARIABLE
localdir = "/path/example"                                              ## ASSIGN VARIABLE

data = []                                                               ## SET EMPTY LIST
list2 = []                                                              ## SET EMPTY LIST

os.chdir(localdir)                                                      ## CHANGE LOCAL DIRECTORY

ftp = ftplib.FTP(ftpserver)                                             ## SET FTPLIB MODULE TO FTPSERVER + ASSIGN TO FTP

try:
        ftp.login(username, password)                                   ## LOG INTO FTP SERVER

        ftp.dir(data.append)                                            ## GET DIRECTORY LISTING + ASSIGN TO LIST

                                                                        ## CONVERT DIR LISTING LINES TO WORDS FOR EACH ELEMENT
        data = " ".join(data)                                           ## CONVERT DATA LIST INTO STR
        data = data.split()                                             ## CONVERT DATA STR INTO LIST

        y = re.compile('.*\.jpa$')                                      ## SET REGEX MATCH CRITERIA

        for x in data:                                                  ## LOOP THROUGH DATA LIST + APPEND ...
                if y.match(x):                                          ## ... ANY ELEMENT MATCHING REGEX TO LIST2.
                        list2.append(x)

        dstfile = (' '.join(sorted(list2, key = lambda x:x[-19:-4])))   ## SORT LIST2 BY NUMERIC DIGITS WITHIN ELEMENTS + ASSIGN TO STR
        dstfile = dstfile.split()                                       ## SPLIT STR TO LIST
        dstfile = dstfile[-1]                                           ## ASSIGN LAST ELEMENT OF LIST TO STR

        ftp.retrbinary('RETR '+dstfile, open(dstfile, 'wb').write)      ## GET FILE

        ftp.close()                                                     ## CLOSE FTP CONNECTION GRACEFULLY

except Exception, e:
    print e