#!/usr/bin/python -t
# 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 Library 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.
#
# rtpatch - a script to check for existance of, fetch, or fetch and apply the
#           latest of Ingo Molnar's -rt kernel patches
#
# Copyright 2006 Clark Williams <williams@redhat.com>
#

import os, sys
import re
import os.path
import urllib
import HTMLParser

from exceptions import IOError, KeyboardInterrupt, ValueError, Exception

url = "http://people.redhat.com/~mingo/realtime-preempt"
gittree = "linus-kernel.git"
patchdir = "sources"

class FileParser(HTMLParser.HTMLParser):
    def __init__(self):
        HTMLParser.HTMLParser.__init__(self)
        self.seen = {}
    def handle_starttag(self, tag, attributes):
        if tag != 'a': return
        for name, value in attributes:
            if name == 'href' and value not in self.seen:
                self.seen[value] = True
                return


class RTpatchError(Exception):
    def __init__(self, args=None):
        self.args = args


def findpatches():
    try:
        s = urllib.urlopen(url)
    except IOError, e:
        print e
        sys.exit(1)
    except KeyboardInterrupt, e:
        sys.exit(1)
    fp = FileParser()
    while True:
        data = s.read(8192)
        if not data: break
        fp.feed(data)
    s.close()
    patches = []
    for thing in fp.seen.keys():
        if thing.find('patch') >= 0:
            patches.append(thing)
    fp = None
    return patches

def check():
    patches = findpatches()
    if len(patches):
        if len(patches) > 1:
            print "Available RT patches:"
        else:
            print "Available RT patch:"
        for p in patches:
            print "    " + p
    else:
        print "No RT patches found"

def reporter(bcount, bsize, fsize):
    done=bcount * bsize
    percent = float(done) / float(fsize) * 100.0
    if percent > 100.0: percent = 100
    sys.stdout.write('\r  Progress: %3.0f%%' % percent)
    sys.stdout.flush()

def fetch(p):
    try:
        print "Downloading %s" % p
        urllib.urlretrieve("%s/%s" % (url, p), p, reporter)
        sys.stdout.write('\n')
    except KeyboardInterrupt, e:
        print "Aborted"
        pass

def usage():
    print "usage: %s [check|get|apply]" % sys.argv[0]
    print "       running with no arguments checks for existance of the patch"
    sys.exit(-1)

def get_version(patchname):
    r = re.compile(r'^patch-(.+)-rt(\d+)$')
    m = r.match(patchname)
    if m == None:
        print "%s is not a valid realtime patch name" % patchname
        return None
    base = m.group(1)
    ver = m.group(2)
    return (base, ver)

def apply(patch):
    if not os.path.exists(gittree):
        print "Can't find Linux git tree: %s" % gittree
        return
    (base, version) = get_version(p)
    if os.path.exists("%s/.git/refs/heads/v%s-rt%s" % (gittree, base, version)):
        print "patch-%s-rt%s already applied to branch v%s-rt%s" % (base, version, base, version)
        return
    if not os.path.exists("%s/.git/refs/tags/v%s" % (gittree, base)):
        print "can't find base v%s in git tree!" % base
        return
    print "about to apply rt patch %s (based on v%s)" % (version, base)
    # first fetch the patch
    here = os.getcwd()
    os.chdir(patchdir)
    fetch(patch)
    os.chdir(here)
    try:
        os.chdir(gittree)
    except:
        print "Can't cd to git tree %s" % gittree
        return
    # now set up the git tree
    run("git checkout -f")
    run("git branch v%s-rt%s v%s" % (base, version, base))
    run("git checkout v%s-rt%s" % (base, version))
    run("cat %s/sources/%s | patch -p1" % (here, patch))
    run("git add")
    run('git commit -a -m "Ingo\'s %s-rt%s realtime patch"' % (base, version))
    os.chdir(here)
    print "patch %s applied and committed" % patch

def run(cmd):
    print "running: %s" % cmd
    retval = os.system(cmd)
    if retval:
        raise RTpatchError, "%s failed with status %d" % (cmd, retval)
    return

###### Main logic
try:
    cmd = sys.argv[1]
except:
    check()
    sys.exit(1)
    
if cmd == "check":
    check()
elif cmd == "get" or cmd == "fetch":
    patches = findpatches()
    for p in patches:
        fetch(p)
elif cmd == "apply":
    patches = findpatches()
    for p in patches:
        apply(p)
else:
    usage()