#!/usr/bin/python

import os, os.path, sys, urllib, subprocess, shutil

def retrieve_file(url):
    '''Download file (by URL)  to the current directory.

    If the file is already present, this function does nothing.'''

    fname = os.path.basename(url)
    if not os.path.exists(fname):
	print 'downloading', url
	urllib.urlretrieve(url, fname)

def cur_version(sourcepkg, release):
    madison = subprocess.Popen(['apt-cache', 'madison', sourcepkg], stdout=subprocess.PIPE)
    out = madison.communicate()[0]
    assert (madison.returncode == 0)

    for l in out.splitlines():
	(pkg, version, aptsrc) = l.split('|')
	if aptsrc.endswith('Sources') and aptsrc.find(release) > 0:
	    return version.strip()

    raise Exception('apt-cache madison does not contain %s/%s' % (sourcepkg, release))

def dsc_getfiles(dsc):
    '''Return list of files in a .dsc file (excluding the .dsc file itself).'''

    f = open(dsc)
    files = []

    # skip until 'Files:'
    for l in f:
	if l.strip() == 'Files:':
	    break

    for l in f:
	if l.strip() == '':
	    break
        if not l.startswith(' '):
            break
	fname = l.split()[2]
	if not fname.endswith('.dsc'):
	    files.append(fname)

    f.close()
    return files

#
# entry point
#

if len(sys.argv) != 3:
    print 'Usage: syncpackage <.dsc URL or path> <target release>'
    sys.exit (1)

(dscurl, release) = sys.argv[1:]
dscname = os.path.basename(dscurl)
basepath = os.path.dirname(dscurl)
(srcpkg, new_ver) = dscname.split('_')
new_ver = new_ver[:-4] # strip off '.dsc'

cur_ver = cur_version(srcpkg, release)

retrieve_file(dscurl)
files = dsc_getfiles(dscname)

# do we need the orig.tar.gz?
need_orig = True
if cur_ver.find('-') > 0 and new_ver.find('-') > 0 and \
    cur_ver.split('-')[0] == new_ver.split('-')[0]:
    need_orig = False
    #files = [f for f in files if not f.endswith('orig.tar.gz')]

print 'Source %s: current version %s, new version %s' % (srcpkg, cur_ver, new_ver)
print 'needs orig.tar.gz', need_orig
print 'Files:', files
for f in files:
    retrieve_file(os.path.join(basepath, f))

uidx = cur_ver.find('ubuntu')
if uidx > 0:
    cur_ver = cur_ver[:uidx]
    print 'WARNING! Overwriting modified Ubuntu version, setting current version to', cur_ver

uidx = cur_ver.find('build')
if uidx > 0:
    cur_ver = cur_ver[:uidx]

orig_arg = ''
if need_orig:
    orig_arg = '-sa'

# extract package, build Source
assert subprocess.call(['dpkg-source', '-x', dscname]) == 0
os.chdir(srcpkg + '-' + new_ver.split('-')[0])
assert subprocess.call("dpkg-genchanges -q -S %s -v%s -e\"$(getent passwd $(id -u)|cut -f5 -d:|cut -f1 -d,) <$DEBEMAIL>\" | \
    	sed 's/^Distribution:.*$/Distribution: %s/; 1 i\Origin: debian/unstable' > ../%s_%s_source.changes" % 
	(orig_arg, cur_ver, release, srcpkg, new_ver), shell=True) == 0
os.chdir('..')
shutil.rmtree(srcpkg + '-' + new_ver.split('-')[0], True)
assert subprocess.call("debsign %s_%s_source.changes" % (srcpkg, new_ver), shell=True) == 0