#!/usr/bin/python

import gzip, urllib, sys, tempfile, os.path, apt_pkg, shutil
import subprocess

blacklist = ['language-pack', 'language-support']

def any(iterable):
    for element in iterable:
	if element:
	    return True
    return False

def package_list_map(url, merge_to = None):
    '''Read a package list and parse it into a map package->key->value.

    E. g. package_list_map('Sources.gz')['dpkg']['Version'] would deliver the
    Version of the dpkg source package.
    '''
    # write the uncompressed downloaded list into a temporary file
    downloadfile = urllib.urlretrieve(url, tempfile.mkstemp()[1])[0]
    list = tempfile.TemporaryFile()
    try:
        print >> list, gzip.open(downloadfile).read()
    except IOError:
        print >> list, open(downloadfile).read()
    os.unlink(downloadfile)
    list.seek(0)

    if merge_to is None:
        map = {}
    else:
        map = merge_to
    parser = apt_pkg.ParseTagFile(list)
    while parser.Step() == True:
        pkg = {}
        for key in parser.Section.keys():
            if key != 'Package':
                pkg[key] = parser.Section.get(key)
        map[parser.Section.get('Package')] = pkg
    return map

def process_dsc(dscpath, command):
    '''Unpack a .dsc and run command in it.'''

    print '==== %s ====' % os.path.basename(dscpath)
    d = tempfile.mkdtemp()
    os.chdir(d)
    try:
        subprocess.call(['dpkg-source', '-x', dscpath], stdout=subprocess.PIPE,
	    stderr=subprocess.PIPE)
        subprocess.call(command, shell=True)
    finally:
        shutil.rmtree(d)

#
# main
#

if len(sys.argv) != 4:
    print >> sys.stderr, 'Usage: %s <archive root> <Sources path> <command to run in source package>' % sys.argv[0]
    sys.exit(1)

(archive_root, sources_path, command) = sys.argv[1:]

map = package_list_map(archive_root + '/' + sources_path)
for pkg, i in map.iteritems():
    if any([b in pkg for b in blacklist]):
	continue
    for fline in i['Files'].splitlines():
        if fline.endswith('.dsc'):
            process_dsc(os.path.join(archive_root, i['Directory'], fline.split()[-1]), command)
            break