# ftp.py - handle urls with a ftp scheme
#
# Copyright (C) 1998, 1999 Albert Hopkins (marduk) <marduk@python.net>
# Copyright (C) 2002 Mike Meyer <mwm@mired.org>
# Copyright (C) 2005 Arthur de Jong <arthur@tiefighter.et.tudelft.nl>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA

"""This module defines the functions needed for creating Link objects for urls
using the ftp scheme."""

import urllib
import mimetypes
import ftplib
import urlparse
import myUrlLib
import string
import debugio

Link = myUrlLib.Link

# FIXME: honor ftp proxy settings
# TODO: if browsing an FTP directory, also make it crawlable

def get_info(link):
    link.type = mimetypes.guess_type(link.URL)[0]
    (host, port, user, passwd, path) = _spliturl(link.URL)
    try:
        ftp = ftplib.FTP()
        ftp.connect(host, port)
        ftp.login(user, passwd)
        dirs, filename = _split_dirs(path)
        _cwd(dirs, ftp)
        if filename:
            try:  # FTP.size raises an exception instead of returning None!
                link.size = ftp.size(filename)
            except ftplib.error_perm:
                link.size = 0
                if filename not in ftp.nlst():
                    raise ftplib.error_perm, "No such file or directory"
    except ftplib.all_errors, e:
        link.set_bad_link(link.URL, str(e))
    try:
        ftp.quit()
    except:
        ftp.close()

def _callback(line):
    """Read a line of text and do nothing with it"""
    return

def get_document(link):
    (host, port, user, passwd, path) = _spliturl(link.URL)
    dirs, filename = _split_dirs(path)
    ftp = ftplib.FTP()
    ftp.connect(host, port)
    ftp.login(user, passwd)
    _cwd(dirs, ftp)
    ftp.voidcmd('TYPE I')
    conn, size = ftp.ntransfercmd('RETR ' + filename)
    if size:
       page = conn.makefile().read(size)
    else:
       page = conn.makefile().read()
    try:
       ftp.quit()
    except ftplib.all_errors:
       ftp.close()
    return page

def _split_dirs(path):
    """Given pathname, split it into a tuple consisting of a list of dirs and
    a filename"""
    dirs = map(urllib.unquote, string.split(path, '/'))
    filename = dirs.pop()
    if len(dirs) and not dirs[0]:
        del dirs[0]
    return (dirs, filename)

def _cwd(dirs, ftpobject):
    for dir in dirs:
        ftpobject.cwd(dir)

def _spliturl(url):
    """Split the specified url in host, port, user, password and path
    components, falling back to reasonable defaults for the ftp protocol."""
    (scheme, netloc, path, query, fragment) = urlparse.urlsplit(url)
    (userpass, host) = urllib.splituser(netloc)
    if userpass is not None:
        (user, passwd) = urllib.splitpasswd(userpass)
    else:
        (user, passwd) = ('anonymous', '')
    (host, port) = urllib.splitnport(host,ftplib.FTP_PORT)
    return (host, port, user, passwd, path)