#! /usr/bin/env python

# This script expects one line for each new revision on the form
#   <oldrev> <newrev> <refname>
#
# For example:
#   aa453216d1b3e49e7f6f98441fa56946ddcd6a20
#   68f7abf4e6f922807889f52bc043ecd31b79f814 refs/heads/master
#
# Each of these changes will be passed to the buildbot server along
# with any other change information we manage to extract from the
# repository.
#
# This script is meant to be run from hooks/post-receive in the git
# repository. It can also be run at client side with hooks/post-merge
# after using this wrapper:

#!/bin/sh
# PRE=$(git rev-parse 'HEAD@{1}')
# POST=$(git rev-parse HEAD)
# SYMNAME=$(git rev-parse --symbolic-full-name HEAD)
# echo "$PRE $POST $SYMNAME" | git_buildbot.py
#
# Largely based on contrib/hooks/post-receive-email from git.

import commands
import logging
import os
import re
import sys

from twisted.spread import pb
from twisted.cred import credentials
from twisted.internet import reactor, defer

from optparse import OptionParser

# Modify this to fit your setup, or pass in --master server:host on the
# command line

master = "localhost:9989"

# When sending the notification, send this category iff
# it's set (via --category)

category = None

# When sending the notification, send this repository iff
# it's set (via --repository)

repository = None

# When converting strings to unicode, assume this encoding. 
# (set with --encoding)

encoding = 'utf8'

# The GIT_DIR environment variable must have been set up so that any
# git commands that are executed will operate on the repository we're
# installed in.

changes = []

def connectFailed(error):
    logging.error("Could not connect to %s: %s"
            % (master, error.getErrorMessage()))
    return error


def addChanges(remote, changei):
    logging.debug("addChanges %s, %s" % (repr(remote), repr(changei)))
    def addChange(c):
        logging.info("New revision: %s" % c['revision'][:8])
        for key, value in c.iteritems():
            logging.debug("  %s: %s" % (key, value))

        d = remote.callRemote('addChange', c)
        return d

    finished_d = defer.Deferred()
    def iter():
        try:
            c = changei.next()
            d = addChange(c)
            # handle successful completion by re-iterating, but not immediately
            # as that will blow out the Python stack
            def cb(_):
                reactor.callLater(0, iter)
            d.addCallback(cb)
            # and pass errors along to the outer deferred
            d.addErrback(finished_d.errback)
        except StopIteration:
            remote.broker.transport.loseConnection()
            finished_d.callback(None)

    iter()
    return finished_d


def connected(remote):
    return addChanges(remote, changes.__iter__())


def grab_commit_info(c, rev):
    # Extract information about committer and files using git show
    f = os.popen("git show --raw --pretty=full %s" % rev, 'r')

    files = []

    while True:
        line = f.readline()
        if not line:
            break

        m = re.match(r"^:.*[MAD]\s+(.+)$", line)
        if m:
            logging.debug("Got file: %s" % m.group(1))
            files.append(unicode(m.group(1), encoding=encoding))
            continue

        m = re.match(r"^Author:\s+(.+)$", line)
        if m:
            logging.debug("Got author: %s" % m.group(1))
            c['who'] = unicode(m.group(1), encoding=encoding)

        if re.match(r"^Merge: .*$", line):
            files.append('merge')

    c['files'] = files
    status = f.close()
    if status:
        logging.warning("git show exited with status %d" % status)


def gen_changes(input, branch):
    while True:
        line = input.readline()
        if not line:
            break

        logging.debug("Change: %s" % line)

        m = re.match(r"^([0-9a-f]+) (.*)$", line.strip())
        c = {'revision': m.group(1),
             'comments': unicode(m.group(2), encoding=encoding),
             'branch': unicode(branch, encoding=encoding),
        }

        if category:
            c['category'] = unicode(category, encoding=encoding)

        if repository:
            c['repository'] = unicode(repository, encoding=encoding)

        grab_commit_info(c, m.group(1))
        changes.append(c)


def gen_create_branch_changes(newrev, refname, branch):
    # A new branch has been created. Generate changes for everything
    # up to `newrev' which does not exist in any branch but `refname'.
    #
    # Note that this may be inaccurate if two new branches are created
    # at the same time, pointing to the same commit, or if there are
    # commits that only exists in a common subset of the new branches.

    logging.info("Branch `%s' created" % branch)

    f = os.popen("git rev-parse --not --branches"
            + "| grep -v $(git rev-parse %s)" % refname
            + "| git rev-list --reverse --pretty=oneline --stdin %s" % newrev,
            'r')

    gen_changes(f, branch)

    status = f.close()
    if status:
        logging.warning("git rev-list exited with status %d" % status)


def gen_update_branch_changes(oldrev, newrev, refname, branch):
    # A branch has been updated. If it was a fast-forward update,
    # generate Change events for everything between oldrev and newrev.
    #
    # In case of a forced update, first generate a "fake" Change event
    # rewinding the branch to the common ancestor of oldrev and
    # newrev. Then, generate Change events for each commit between the
    # common ancestor and newrev.

    logging.info("Branch `%s' updated %s .. %s"
            % (branch, oldrev[:8], newrev[:8]))

    baserev = commands.getoutput("git merge-base %s %s" % (oldrev, newrev))
    logging.debug("oldrev=%s newrev=%s baserev=%s" % (oldrev, newrev, baserev))
    if baserev != oldrev:
        c = {'revision': baserev,
             'comments': "Rewind branch",
             'branch': unicode(branch, encoding=encoding),
             'who': "dummy",
        }
        logging.info("Branch %s was rewound to %s" % (branch, baserev[:8]))
        files = []
        f = os.popen("git diff --raw %s..%s" % (oldrev, baserev), 'r')
        while True:
            line = f.readline()
            if not line:
                break

            file = re.match(r"^:.*[MAD]\s*(.+)$", line).group(1)
            logging.debug("  Rewound file: %s" % file)
            files.append(unicode(file, encoding=encoding))

        status = f.close()
        if status:
            logging.warning("git diff exited with status %d" % status)

        if category:
            c['category'] = unicode(category, encoding=encoding)

        if repository:
            c['repository'] = unicode(repository, encoding=encoding)

        if files:
            c['files'] = files
            changes.append(c)

    if newrev != baserev:
        # Not a pure rewind
        f = os.popen("git rev-list --reverse --pretty=oneline %s..%s"
                % (baserev, newrev), 'r')
        gen_changes(f, branch)

        status = f.close()
        if status:
            logging.warning("git rev-list exited with status %d" % status)


def cleanup(res):
    reactor.stop()


def process_changes():
    # Read branch updates from stdin and generate Change events
    while True:
        line = sys.stdin.readline()
        if not line:
            break

        [oldrev, newrev, refname] = line.split(None, 2)

        # We only care about regular heads, i.e. branches
        m = re.match(r"^refs\/heads\/(.+)$", refname)
        if not m:
            logging.info("Ignoring refname `%s': Not a branch" % refname)
            continue

        branch = m.group(1)

        # Find out if the branch was created, deleted or updated. Branches
        # being deleted aren't really interesting.
        if re.match(r"^0*$", newrev):
            logging.info("Branch `%s' deleted, ignoring" % branch)
            continue
        elif re.match(r"^0*$", oldrev):
            gen_create_branch_changes(newrev, refname, branch)
        else:
            gen_update_branch_changes(oldrev, newrev, refname, branch)

    # Submit the changes, if any
    if not changes:
        logging.warning("No changes found")
        return

    host, port = master.split(':')
    port = int(port)

    f = pb.PBClientFactory()
    d = f.login(credentials.UsernamePassword("change", "changepw"))
    reactor.connectTCP(host, port, f)

    d.addErrback(connectFailed)
    d.addCallback(connected)
    d.addBoth(cleanup)

    reactor.run()


def parse_options():
    parser = OptionParser()
    parser.add_option("-l", "--logfile", action="store", type="string",
            help="Log to the specified file")
    parser.add_option("-v", "--verbose", action="count",
            help="Be more verbose. Ignored if -l is not specified.")
    master_help = ("Build master to push to. Default is %(master)s" % 
                   { 'master' : master })
    parser.add_option("-m", "--master", action="store", type="string",
            help=master_help)
    parser.add_option("-c", "--category", action="store",
                      type="string", help="Scheduler category to notify.")
    parser.add_option("-r", "--repository", action="store",
                      type="string", help="Git repository URL to send.")
    encoding_help = ("Encoding to use when converting strings to "
                     "unicode. Default is %(encoding)s." % 
                     { "encoding" : encoding })
    parser.add_option("-e", "--encoding", action="store", type="string", 
                      help=encoding_help)
    options, args = parser.parse_args()
    return options


# Log errors and critical messages to stderr. Optionally log
# information to a file as well (we'll set that up later.)
stderr = logging.StreamHandler(sys.stderr)
fmt = logging.Formatter("git_buildbot: %(levelname)s: %(message)s")
stderr.setLevel(logging.ERROR)
stderr.setFormatter(fmt)
logging.getLogger().addHandler(stderr)
logging.getLogger().setLevel(logging.DEBUG)

try:
    options = parse_options()
    level = logging.WARNING
    if options.verbose:
        level -= 10 * options.verbose
        if level < 0:
            level = 0

    if options.logfile:
        logfile = logging.FileHandler(options.logfile)
        logfile.setLevel(level)
        fmt = logging.Formatter("%(asctime)s %(levelname)s: %(message)s")
        logfile.setFormatter(fmt)
        logging.getLogger().addHandler(logfile)

    if options.master:
        master=options.master

    if options.category:
        category = options.category

    if options.repository:
        repository = options.repository

    if options.encoding:
        encoding = options.encoding

    process_changes()
except SystemExit:
    pass
except:
    logging.exception("Unhandled exception")
    sys.exit(1)
