#! /usr/bin/env python

# This script is meant to run from hooks/post-receive in the git
# repository. It 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.
#
# Largely based on contrib/hooks/post-receive-email from git.

import commands, logging, os, re, sys

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

from buildbot.scripts import runner
from optparse import OptionParser

# Modify this to fit your setup

master = "localhost:9989"

# 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 addChange(dummy, remote, changei):
    logging.debug("addChange %s, %s" % (repr(remote), repr(changei)))
    try:
        c = changei.next()
    except StopIteration:
        remote.broker.transport.loseConnection()
        return None

    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)
    d.addCallback(addChange, remote, changei)
    return d

def connected(remote):
    return addChange(None, 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(m.group(1))
            continue

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

    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': m.group(2),
                'branch': branch }
        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': branch, '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(file)

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

        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.")
    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)

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