#!/usr/bin/python
# vim: set fileencoding=utf-8 :
#
# (C) 2007 Guido Guenther <agx@sigxcpu.org>
#    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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
#
"""Generate Debian changelog entries from git changelogs"""

import sys
import re
import os.path
import shutil
import subprocess
import gbp.command_wrappers as gbpc
from gbp.git_utils import (GitRepositoryError, GitRepository, build_tag)
from gbp.config import GbpOptionParser
from gbp.errors import GbpError
from gbp.deb_utils import parse_changelog
from gbp.command_wrappers import (Command, CommandExecFailed)

snapshot_re = "\s*\*\* SNAPSHOT build @(?P<commit>[a-z0-9]+)\s+\*\*"

def get_log(start, end, options, paths):
    """Get the shortlog from commit 'start' to commit 'end'"""
    try:
        p1 = subprocess.Popen("git-log %s %s...%s -- %s" % (options, start, end, paths), shell=True,
                              stdout=subprocess.PIPE)
        p2 = subprocess.Popen(["git-shortlog"], stdin=p1.stdout, stdout=subprocess.PIPE)
        changes = p2.communicate()[0].split('\n')
    except OSError, err:
        raise GbpError, "Cannot get changes: %s" % err
    except ValueError, err:
        raise GbpError, "Cannot get changes: %s" % err
    if p1.wait() or p2.wait():
        raise GbpError, "Cannot get changes, use --since."
    return changes


def system(cmd):
    try:
        Command(cmd, shell=True)()
    except CommandExecFailed:
        raise GbpError


def add_changelog_entry(msg, author):
    "add aa single changelog entry"
    cmd = """DEBFULLNAME="%s" dch --append -- "%s" """ % (author, msg.replace('"','\\\"'))
    system(cmd)


def add_changelog_section(msg, distribution):
    "add a new changelog section"
    cmd = "dch --distribution=%s -i %s" % (distribution, msg)
    system(cmd)

def fixup_trailer():
    """fixup the changelog trailer's comitter and email address - it might
    otherwise point to the last git committer instead of the person creating
    the changelog"""
    cmd = "dch \"\""
    system(cmd)

def head_commit():
    """get the full sha1 of the last commit on HEAD"""
    commit = subprocess.Popen([ 'git-log', 'HEAD^..' ], stdout=subprocess.PIPE).stdout
    sha = commit.readline().split()[-1]
    return sha


def snapshot_version(version):
    """
    get the current release and snapshot version
    Format is <debian-version>~<release>.gbp<short-commit-id>
    """
    try:
        (release, suffix) = version.rsplit('~', 1)
        (snapshot, commit)  = suffix.split('.', 1)
        if not commit.startswith('gbp'):
            raise ValueError
        else:
            snapshot = int(snapshot)
    except ValueError: # not a snapshot release
        release = version
        snapshot = 0
    return release, snapshot


def mangle_changelog(changelog, cp, snapshot, sha='unknown'):
    """Mangle changelog to either add or remove snapshot markers"""
    try:
        tmp = '%s.%s' % (changelog, str(snapshot))
        cw = file(tmp, 'w')
        cr = file(changelog, 'r')
        cr.readline() # skip version and empty line
        cr.readline()
        print >>cw, "%(Source)s (%(MangledVersion)s) %(Distribution)s; urgency=%(urgency)s\n" % cp

        line = cr.readline()
        if re.match(snapshot_re, line):
            cr.readline() # consume the empty line
            line = ''

        if snapshot:
            print >>cw, "  ** SNAPSHOT build @%s **\n" % sha

        if line:
            print >>cw, line.rstrip()
        shutil.copyfileobj(cr, cw)
        cw.close()
        cr.close()
        os.unlink(changelog)
        os.rename(tmp, changelog)
    except OSError, e:
        raise GbpError, "Error mangling changelog %s" % e


def do_release(changelog, cp):
    "remove the snapshot header and set the distribution"
    (release, snapshot) = snapshot_version(cp['Version'])
    if snapshot:
        cp['MangledVersion'] = release
        mangle_changelog(changelog, cp, 0)
    cmd = "dch --release"
    system(cmd)


def do_snapshot(changelog, next_snapshot):
    """
    Add new snapshot banner to most recent changelog section. The next snapshot
    number is calculated by eval()'ing next_snapshot
    """
    commit = head_commit()

    cp = parse_changelog(changelog)
    (release, snapshot) = snapshot_version(cp['Version'])
    snapshot = int(eval(next_snapshot))

    suffix = "%d.gbp%s" % (snapshot, "".join(commit[0:6]))
    cp['MangledVersion'] = "%s~%s" % (release, suffix)

    mangle_changelog(changelog, cp, snapshot, commit)
    return snapshot, commit


def shortlog_to_dch(changes):
    """convert the changes in git shortlog format to debian changelog format"""    
    commit_re = re.compile('\s+(?P<msg>.*)')
    author_re = re.compile('(?P<author>.*) \([0-9]+\)')
    author = 'Unknown'

    for line in changes:
        r = commit_re.match(line)
        msg = ''
        if r:
            msg = r.group('msg')
        else:
            r = author_re.match(line)
            if r:
                author = r.group('author')
            elif line:
                print >>sys.stderr, "Unknown changelog line: %s" % line
        if msg:
            add_changelog_entry(msg, author)


def guess_snapshot_commit(cp):
    """guess the last commit documented in the changelog from the snapshot banner"""
    sr = re.search(snapshot_re, cp['Changes'])
    if sr:
        return sr.group('commit')


def main(argv):
    ret = 0
    changelog = 'debian/changelog'
    until = 'HEAD'

    parser = GbpOptionParser(command=os.path.basename(argv[0]), prefix='',
                             usage='%prog [options] paths')

    parser.add_config_file_option(option_name="debian-branch", dest='debian_branch',
                      help="branch the debian patch is being developed on, default is '%(debian-branch)s'")
    parser.add_config_file_option(option_name="debian-tag", dest="debian_tag",
                      help="Format string for debian tags, default is '%(debian-tag)s'")
    parser.add_config_file_option(option_name="snapshot-number", dest="snapshot_number",
                      help="Expression to determine the next snapshot number, default is '%(snapshot-number)s'")
    parser.add_config_file_option(option_name="git-log", dest="git_log",
                      help="options to pass to git-log, default is '%(git-log)s'")
    parser.add_option("-v", "--verbose", action="store_true", dest="verbose", default=False,
                      help="verbose command execution")
    parser.add_option("-s", "--since", dest="since", help="commit to start from")
    parser.add_option("-R", "--release", action="store_true", dest="release", default=False,
                      help="mark as release")
    parser.add_option("-S", "--snapshot", action="store_true", dest="snapshot", default=False,
                      help="mark as snapshot build")
    parser.add_option("-a", "--auto", action="store_true", dest="auto", default=False,
                      help="autocomplete changelog from last snapshot or tag")
    (options, args) = parser.parse_args(argv[1:])

    if options.snapshot and options.release:
        parser.error("--snapshot and --release are incompatible options")

    try:
        if options.verbose:
            gbpc.Command.verbose = True

        try:
            repo = GitRepository('.')
        except GitRepositoryError:
            raise GbpError, "%s is not a git repository" % (os.path.abspath('.'))

        branch = repo.get_branch()
        if options.debian_branch != branch:
            print >>sys.stderr, "You are not on branch '%s' but on '%s'" % (options.debian_branch, branch)
            raise GbpError, "Use --debian-branch to set the branch to pick changes from"

        cp = parse_changelog(changelog)

        if options.since:
            since = options.since
        else:
            since = ''
            if options.auto:
                since = guess_snapshot_commit(cp)
                if since:
                    print "Continuing from commit '%s'" % since
                else:
                    print "Couldn't get snapshot header, using version info"
            if not since:
                since = build_tag(options.debian_tag, cp['Version'])

        if args:
            print "Only looking for changes on '%s'" % " ".join(args)
        changes = get_log(since, until, options.git_log, " ".join(args))
        if changes:
            if cp['Distribution'] != "UNRELEASED":
                add_changelog_section(distribution="UNRELEASED", msg="UNRELEASED")
            shortlog_to_dch(changes)
            fixup_trailer()
            if options.snapshot:
                (snap, version) = do_snapshot(changelog, options.snapshot_number)
                print "Changelog has been prepared for snapshot #%d at %s" % (snap, version)
        else:
            print "No changes detected from %s to %s." % (since, until)
        if options.release:
            do_release(changelog, cp)

    except GbpError, err:
        if len(err.__str__()):
            print >>sys.stderr, err
        ret = 1
    return ret

if __name__ == "__main__":
    sys.exit(main(sys.argv))

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