#!/usr/bin/python
# -*- coding: UTF-8 -*-
# Copyright (C) 2008 Terence Simpson <tsimpson@ubuntu.com>
# License:
#  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 Street, Fifth Floor, Boston, MA 02110-1301 USA.
#
# This script simulates «dget»'s behaviour for files hosted at
# launchpadlibrarian.net.
#
# Detailed description:
# This script attempts to download the source package in the same
# way as dget does, but from launchpadlibrarian.net, which doesn't
# store all the files in the same directory. It (the script) assumes
# that the files are stored in sequential directories on Launchpad
# Librarian and attempts to download and then unpack them.
# This is a Python rewrite of the original bash script

import cStringIO
import email.feedparser
import hashlib
import optparse
import os
import sys
import urllib2

try:
    import GnuPGInterface
except ImportError:
    print >> sys.stderr, ("Please install 'python-gnupginterface' in order to "
                          "use this utility.")
    sys.exit(1)

from ubuntutools import subprocess
import ubuntutools.misc

USAGE = u"""Usage: %prog [-d|(-v|-q)] <Launchpad URL>

This scripts simulates «dget»'s behaviour for files hosted at
launchpadlibrarian.net.

If you specify the -d option then it won't do anything, except download the
.dsc file, but just print the commands it would run otherwise.

Example:
    %prog http://launchpadlibrarian.net/10348157/coreutils_5.97-5.4ubuntu1.dsc
"""

BASE_URL = "http://launchpadlibrarian.net/"

Debug = Verbose = Quiet = False

def unsign(data):
    if data.splitlines()[0] != "-----BEGIN PGP SIGNED MESSAGE-----":
        return data
    oldstdout = sys.stdout
    oldstderr = sys.stderr
    sys.stdout = sys.__stdout__
    sys.stderr = sys.__stderr__
    gpg = GnuPGInterface.GnuPG()
    proc = gpg.run(["--decrypt"], create_fhs=['stdin', 'stdout'])
    proc.handles['stdin'].write(data)
    proc.handles['stdin'].close()
    plain = proc.handles['stdout'].read()
    proc.handles['stdout'].close()
    try:
        proc.wait()
    except:
        pass
    sys.stdout = oldstdout
    sys.stderr = oldstderr
    return plain

def get_entries(data):
    parser = email.feedparser.FeedParser()
    parser.feed(data)
    return parser.close()

class DscParse(object):
    """Attempt to get the file list from the .dsc file"""
    def __init__(self, data):
        """
        __init__(data)
        Given the contents of a .dsc, parse it and extract it's content
        """
        self.entries = get_entries(unsign(data))
        self.files = [x.strip().split() for x in
                      self.entries['Files'].splitlines()]

    def verify_all(self):
        """
        verify_all()
        Verifies all the files, first checking the size, then the md5 sum.
        Currently not used in this utility.
        """
        assert self.files, "I have no files"
        ret = []
        for f in self.files:
            ret.append(self.verify(f))
        return ret

    def verify(self, name):
        """
        verify(name)
        Verify the file 'name', first checking the size, then the md5 sum.
        """
        assert self.files, "I have no files"
        f = None
        if isinstance(name, list):
            f = name
        else:
            for i in self.files:
                if i[2] == name:
                    f = i
        if not f:
            raise ValueError, "%s is not in the .dsc" % name
        (md5sum, size, name) = tuple(f)
        stat = os.stat(name)
        if str(stat.st_size) != size:
            return (False, name, "Expected a size of %s, got %s" % \
                (size, stat.st_size))
        return self.getsum(name, md5sum)

    def getsum(self, name, md5sum=None):
        """
        getsum(name[, md5sum])
        Read the file 'name' (in 1MB chunks) and generate an md5 sum,
        then compares that to the md5 sum in the .dsc file.
        """
        chunk_size = 1073741824
        fd = open(name, 'rb')
        res = hashlib.md5()
        if not md5sum:
            assert self.files, "I have no files"
            md5sum = [x[0] for x in self.files if x[2] == name][0]
        data = fd.read(chunk_size)
        while data:
            res.update(data)
            data = fd.read(chunk_size)
        if res.hexdigest() != md5sum:
            return (False, name, "Expected md5sum of %r, got %r" % \
                                 (md5sum, res.hexdigest()))
        return (True, name, None)

    def is_native(self):
        """
        is_native()
        Returns True if this .dsc describes a native debian package;
        else false.
        """
        return len(self.files) == 1

    # Access to fields in the .dsc via a dict-like interface
    def __getitem__(self, item):
        """
        x.__getitem(item) -> x[item]
        """
        return self.entries.__getitem__(item)

    def __contains__(self, item):
        """
        x.__contains__(item) -> item in x
        """
        return self.entries.__contains__(item)

    def __getattr__(self, attr):
        """
        x.__getattr__(attr) -> item.attr
        """
        return getattr(self.entries, attr)

def error(ret, msg, *args):
    """Prints an error message, unless quiet is set, and exits with ret"""
    if not Quiet:
        print >> sys.stderr, msg % args
    sys.exit(ret)

def debug(msg, *args):
    """If debugging is enabled, print a message"""
    if Debug:
        print >> sys.stderr, msg % args

def info(msg, *args):
    """If verbose is enabled, print a message"""
    if Verbose:
        print msg % tuple(args)

def status(msg, *args):
    """Prints a message, unless quiet is enabled"""
    if not Quiet:
        print msg % tuple(args)

def download(dscinfo, number, filename, verify=True):
    """download filename"""
    ftype = filename.endswith(".diff.gz") and "diff.gz" or \
        filename.endswith(".orig.tar.gz") and "orig.tar.gz" or \
        filename.endswith(".dsc") and "dsc" or "tar.gz"
    if verify and os.path.exists(filename):
        info('Verifying "%s"', filename)
        res = dscinfo.verify(filename)
        if not res[0]:
            error(104, "Verification of %s failed: %s", filename, res[2])
    status("Getting %s", filename)
    debug("%s%s/%s", BASE_URL, number, filename)
    try:
        fd = urllib2.urlopen("%s%s/%s" % (BASE_URL, number, filename))
        outfd = open(filename, 'wb')
        outfd.write(fd.read())
        fd.close()
        outfd.close()
    except urllib2.HTTPError, err:
        status(u"Failed to fetch «%s» file, aborting.", ftype)
        error(106, "Error: (%d %s)", err.code, err.msg)
    except urllib2.URLError, err:
        status(u"Failed to fetch «%s» file, aborting.", ftype)
        error(105, "Error: %s", err)
    except IOError, err:
        status('Could not create "%s"', filename)
        error(107, "Error: %s", err)

def unpack(filename):
    out = open('/dev/null', 'w')
    err = open('/dev/null', 'w')
    cmd = ["dpkg-source", "-x", filename]
    ret = subprocess.call(cmd, stdout=out, stderr=err)
    out.close()
    err.close()
    if ret:
        status("Failed to unpack source, aborting.")
        sys.exit(108)

def get_host(url):
    return urllib2.splithost(urllib2.splittype(url)[1])[0]

def main():
    global Debug, Verbose, Quiet
    parser = optparse.OptionParser(usage=USAGE)
    parser.add_option("-d", "--debug", action="store_true", dest="debug",
                      default=False, help="Enable debugging")
    parser.add_option("-v", "--verbose", action="store_true", dest="verbose",
                      default=False, help="Enable verbose output")
    parser.add_option("-q", "--quiet", action="store_true", dest="quiet",
                      default=False, help="Never print any output")

    (options, args) = parser.parse_args()
    ubuntutools.misc.require_utf8()

    if len(args) != 1:
        parser.error("Missing URL")
    Debug = options.debug
    Verbose = options.verbose
    Quiet = options.quiet
    if Verbose and Quiet:
        error(4, "Specifying both --verbose and --quiet does not make sense")
    if Quiet:
        sys.stderr = cStringIO.StringIO()
        sys.stdout = cStringIO.StringIO()

    url = args[0]

    if url.startswith("https://"):
        url = url.replace("https://", "http://", 1)

    if not url.startswith("http://"):
        url = "http://" + url

    if get_host(url).startswith("www."):
        url = url.replace("www.", "", 1)

    if get_host(url) != get_host(BASE_URL):
        error(1, "Error: This utility only works for files on %s.\n"
                 "Maybe you want to try dget?", BASE_URL)

    (number, filename) = url.split('/')[3:]

    if not filename.endswith('.dsc'):
        error(2, "You have to provide the URL for the .dsc file.")

    try:
        number = int(number)
    except:
        error(3, "Bad URL format")

    if os.path.exists(filename):
        os.remove(filename)

    download(None, number, filename, False)
    try:
        fd = open(filename)
        dsc_data = fd.read()
        fd.close()
    except Exception:
        status("Error: Please report this bug, providing the URL and attach"
               " the following backtrace")
        raise

    dscinfo = DscParse(dsc_data)

# launchpadlibrarian.net seems to store in this order:
# For native packages:
# <number>/.changes
# <number>+1/.tar.gz
# <number>+2/.dsc
# For non-native packages:
# <number>/.changes
# <number>+1/.orig.tar.gz
# <number>+2/.diff.gz
# <number>+3/.dsc
##
# *Assuming* this does not change, we can figure out where the files are on
# launchpadlibrarian.net relative to the .dsc file we're given.

# Only one file listed in the .dsc means it's native package
    if len(dscinfo.files) == 1:
        download(dscinfo, number-1, dscinfo.files[0][-1]) # .tar.gz
    else:
        download(dscinfo, number-1, dscinfo.files[1][-1]) # .diff.gz
        download(dscinfo, number-2, dscinfo.files[0][-1]) # .orig.tar.gz

    status("Unpacking")
    unpack(filename)

if __name__ == "__main__":
    main()