#!/usr/bin/python

#    The MIT License (MIT)

#    Copyright (c) 2014 Antonio SJ Musumeci <trapexit@spawn.link>

#    Permission is hereby granted, free of charge, to any person obtaining a copy
#    of this software and associated documentation files (the "Software"), to deal
#    in the Software without restriction, including without limitation the rights
#    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
#    copies of the Software, and to permit persons to whom the Software is
#    furnished to do so, subject to the following conditions:

#    The above copyright notice and this permission notice shall be included in
#    all copies or substantial portions of the Software.

#    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
#    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
#    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
#    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
#    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
#    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
#    THE SOFTWARE.

import sys
import subprocess
import argparse

def git_tags():
    args = ["git", "tag", '-l']
    tags = subprocess.check_output(args)
    tags = tags.split()
    tags.reverse()
    return tags

def git_log(fromtag,totag):
    args = ['git','log','--no-merges','--oneline',fromtag+'...'+totag]
    return subprocess.check_output(args).strip().split('\n')

def git_author_and_time(tag):
    args = ['git','log','-1','--format=-- %an <%ae>  %cD',tag]
    return subprocess.check_output(args).strip()

def git_version():
    args = ['git','describe','--always','--tags','--dirty']
    return subprocess.check_output(args).strip()

def find_distrib_codename(f):
    for line in f:
        (key,value) = line.partition('=')[::2]
        if key == 'DISTRIB_CODENAME':
            return value.strip()

def guess_distribution():
    try:
        with open('/etc/upstream-release/lsb-release') as f:
            return find_distrib_codename(f)
    except:
        try:
            with open('/etc/lsb-release') as f:
                return find_distrib_codename(f)
        except:
            try:
                args = ['lsb_release','-c','-s']
                return subprocess.check_output(args).strip()
            except:
                return 'unknown'

def patch_subprocess():
    if "check_output"  not in dir( subprocess ): # duck punch it in!
        def check_output(*popenargs, **kwargs):
            r"""Run command with arguments and return its output as a byte string.

            Backported from Python 2.7 as it's implemented as pure python on stdlib.

            >>> check_output(['/usr/bin/python', '--version'])
            Python 2.6.2
            """
            process = subprocess.Popen(stdout=subprocess.PIPE, *popenargs, **kwargs)
            output, unused_err = process.communicate()
            retcode = process.poll()
            if retcode:
                cmd = kwargs.get("args")
                if cmd is None:
                    cmd = popenargs[0]
                error = subprocess.CalledProcessError(retcode, cmd)
                error.output = output
                raise error
            return output

        subprocess.check_output = check_output

def main():
    patch_subprocess()

    parser = argparse.ArgumentParser(description='Generated debian/changelog from git log')
    parser.add_argument('--name',type=str,help='Name of package',required=True)
    parser.add_argument('--version',type=str,help='Place in git history to include upto',default='::guess::')
    parser.add_argument('--distro',type=str,help='Distribution name',default='::guess::')
    parser.add_argument('--urgency',type=str,help='Urgency',default='medium')

    args = parser.parse_args()

    if args.distro == '::guess::':
        args.distro = guess_distribution()

    if args.version == '::guess::':
        args.version = git_version()

    tags = git_tags()

    if args.version in tags:
        idx = tags.index(args.version)
        tags = tags[idx:]
        tags = zip(tags,tags)
    else:
        tags = zip(tags,tags)
        tags.insert(0,(args.version,'HEAD'))

    tag = tags[0]
    for prev in tags[1:]:
        print('%s (%s) %s; urgency=%s\n' % (args.name,tag[0],args.distro,args.urgency))

        lines = git_log(tag[1],prev[1])
        for line in lines:
            print "  * " + line

        authorandtime = git_author_and_time(tag[1])
        print(' %s\n' % authorandtime)

        tag = prev

if __name__ == "__main__":
    main()