#!/usr/bin/python
#
# Authors:
#   Rob Crittenden <rcritten@redhat.com>
#
# Copyright (C) 2009  Red Hat
# see file 'COPYING' for use and warranty information
#
# 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 3 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, see <http://www.gnu.org/licenses/>.

"""
Upgrade configuration files to a newer template.
"""

import sys
try:
    from ipapython import ipautil
    import krbV
    import re
    import os
    import shutil
    import fileinput
except ImportError:
    print >> sys.stderr, """\
There was a problem importing one of the required Python modules. The
error was:

    %s
""" % sys.exc_value
    sys.exit(1)

def backup_file(filename, ext):
    """Make a backup of filename using ext as the extension. Do not overwrite
       previous backups."""
    if not os.path.isabs(filename):
        raise ValueError("Absolute path required")

    backupfile = filename + ".bak"
    (reldir, file) = os.path.split(filename)

    while os.path.exists(backupfile):
        backupfile = backupfile + "." + str(ext)

    shutil.copy2(filename, backupfile)

def update_conf(sub_dict, filename, template_filename):
    template = ipautil.template_file(template_filename, sub_dict)
    fd = open(filename, "w")
    fd.write(template)
    fd.close()

def find_hostname():
    """Find the hostname currently configured in ipa-rewrite.conf"""
    filename="/etc/httpd/conf.d/ipa-rewrite.conf"

    if not ipautil.file_exists(filename):
        return None

    pattern = "^[\s#]*.*https:\/\/([A-Za-z0-9\.\-]*)\/.*"
    p = re.compile(pattern)
    for line in fileinput.input(filename):
        if p.search(line):
            fileinput.close()
            return p.search(line).group(1)
    fileinput.close()

    raise RuntimeError("Unable to determine the fully qualified hostname from %s" % filename)

def find_version(filename):
    """Find the version of a configuration file"""
    if os.path.exists(filename):
        pattern = "^[\s#]*VERSION\s+([0-9]+)\s+.*"
        p = re.compile(pattern)
        for line in fileinput.input(filename):
            if p.search(line):
                fileinput.close()
                return p.search(line).group(1)
        fileinput.close()

        # no VERSION found
        return 0
    else:
        return -1

def upgrade(sub_dict, filename, template):
    old = int(find_version(filename))
    new = int(find_version(template))

    if old < 0:
        print "%s not found." % filename
        sys.exit(1)

    if new < 0:
        print "%s not found." % template

    if old < new:
        backup_file(filename, new)
        update_conf(sub_dict, filename, template)
        print "Upgraded %s to version %d" % (filename, new)

def check_certs():
    """Check ca.crt is in the right place, and try to fix if not"""
    if not os.path.exists("/usr/share/ipa/html/ca.crt"):
        ca_file = "/etc/httpd/alias/cacert.asc"
        if os.path.exists(ca_file):
            old_umask = os.umask(022)   # make sure its readable by httpd
            try:
                shutil.copyfile(ca_file, "/usr/share/ipa/html/ca.crt")
            finally:
                os.umask(old_umask)
        else:
            print "Missing Certification Authority file."
            print "You should place a copy of the CA certificate in /usr/share/ipa/html/ca.crt"

def main():
    """
    Get some basics about the system. If getting those basics fail then
    this is likely because the machine isn't currently an IPA server so
    exit gracefully.
    """

    try:
        krbctx = krbV.default_context()
    except krbV.Krb5Error, e:
        # Unable to get default kerberos realm
        sys.exit(0)

    fqdn = find_hostname()
    if fqdn is None:
        # ipa-rewrite.conf doesn't exist, nothing to do
        sys.exit(0)

    # Ok, we are an IPA server, do the additional tests

    check_certs()

    sub_dict = { "REALM" : krbctx.default_realm, "FQDN": fqdn }

    upgrade(sub_dict, "/etc/httpd/conf.d/ipa.conf", ipautil.SHARE_DIR + "ipa.conf")
    upgrade(sub_dict, "/etc/httpd/conf.d/ipa-rewrite.conf", ipautil.SHARE_DIR + "ipa-rewrite.conf")

try:
    if __name__ == "__main__":
        sys.exit(main())
except SystemExit, e:
    sys.exit(e)
except KeyboardInterrupt, e:
    sys.exit(1)