#!/usr/bin/env python

# Configure clustered Samba nodes

# Copyright (C) Martin Schwenke 2010

# 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/>.

import os
import sys
import optparse # Newer argparse not yet in RHEL5/EPEL.
import ConfigParser
import logging
import re
import subprocess
import errno
import filecmp
import shutil
import glob
import string

lib_dir = "lib"
sys.path.append(lib_dir)

import logging

def process_args():
    usage = "usage: %prog [options] configfile"

    parser = optparse.OptionParser(usage=usage)

    parser.add_option("-t", "--templates",
                      action="store", dest="templates",
                      default="templates/rhel",
                      help="directory containing templates")
    parser.add_option("-f", "--force",
                      action="store_true", dest="force",
                      default=False,
                      help="install configuration files even if unchanged",)
    parser.add_option("-r", "--no-reload",
                      action="store_true", dest="no_reload",
                      default=False,
                      help="""don't run the "reload" script for
services - this is usually done to make services reload their configuration
after any changes""")
    parser.add_option("-n", "--simulate",
                      action="store_true", dest="simulate",
                      default=False,
                      help="""don't actually install configuration
files - this will leave the configuration files in the temporary staging
area - implies -r""")
    parser.add_option("-s", "--staging",
                      action="store", dest="staging",
                      default="staging",
                      help="directory to stage the files to be installed")
    parser.add_option("-v", "--verbose",
                      action="count", dest="verbose",
                      default=0,
                      help="print information and actions taken to stdout")
    parser.add_option("-l", "--log-file",
                      action="store", dest="log_file", default=None,
                      metavar="FILE",
                      help="append information and actions taken to FILE")
    (options, args) = parser.parse_args()

    if len(args) != 1:
        parser.error("configuration file must be specified")

    options.config = args[0]

    return options

def setup_logging():

    global options

    logger = logging.getLogger("cluster-configure")
    logger.setLevel(logging.ERROR)

    sh = logging.StreamHandler(sys.stderr)
    sh.handleError = lambda x : (logging.shutdown(), sys.exit())
    logger.addHandler(sh)

    if options.verbose == 1:
        logger.setLevel(logging.WARNING)
    elif options.verbose == 2:
        logger.setLevel(logging.INFO)
    elif options.verbose >= 3:
        logger.setLevel(logging.DEBUG)

    if options.log_file is not None:
        fh = logging.FileHandler(options.log_file)
        # The formatting option %(funcName)s would be useful here but
        # it only appeared in Python 2.5 and this script will be run
        # on Python 2.4.
        formatter = logging.Formatter(
            "%(asctime)s - %(name)s - %(levelname)s - %(message)s")
        fh.setFormatter(formatter)
        logger.addHandler(fh)

    return logger

def _rpm_parse_version(v):
    ret = []
    for x in re.split("[^A-Za-z0-9]", v):
        try:
            ret.append(int(x))
        except ValueError:
            ret.append(x)
    return ret

config = None
options = None
logger = None

class Package(object):
    def __init__(self, config, directory):
        self.config = config
        self.directory = directory
        self.version = None
        self.platform = None
        self.version_dir = None
        self.files = list()
        self.files_to_install = list()

        m = re.match("\d\d\.(.*)", directory)
        if m is None:
            raise RuntimeError, \
                ("invalid template package directory %s" % directory)
        self.name = m.group(1)
        self.stage = os.path.join(options.staging, self.name)

    def _get_version(self):
        if os.path.exists("/etc/redhat-release"):
            p = subprocess.Popen(["rpm", "-q", self.name],
                                 stdout=subprocess.PIPE)
            out = p.communicate()[0]
            status = p.wait()
            if status == 0:
                out.replace(self.name + "-", "")
                self.version = string.strip(out)
                self.platform = "rpm"
                logger.debug("_get_version: package %s has version %s",
                             self.name, self.version)
                return True
        elif os.path.exists("/etc/debian_version"):
            p = subprocess.Popen(["dpkg-query", "-W", "-f", "${Version}",
                                  self.name],
                                 stdout=subprocess.PIPE,
                                 stderr=subprocess.PIPE)
            out = p.communicate()[0]
            status = p.wait()
            if status == 0 and len(out) > 0:
                self.version = string.strip(out)
                self.platform = "deb"
                logger.debug("_get_version: package %s has version %s",
                             self.name, self.version)
                return True

        logger.info("_get_version: package %s is not installed", self.name)
        return False

    # Currently Red Hat specific...
    def _check_version(self, min=None, max=None):
        v = _rpm_parse_version(self.version)
        return min is None or \
            (_rpm_parse_version(min) <= v and \
                 (max is None or v < _rpm_parse_version(max)))

    def find_version_dir(self):
        if self._get_version():
            pdir = os.path.join(options.templates, self.directory)
            versions = sorted(os.listdir(pdir))
            # FIXME: filter out any without #, since they're meaningless.
            versions.reverse()  # bare "#" comes last since it is the default

            for i in versions:
                try:
                    (min, max) = map(lambda x: len(x) and x or None, i.split("#"))
                except ValueError:
                    logger.warn("_find_version_dir: skipping invalid version subdirectory %s" % i)
                    continue
                    
                if self._check_version(min, max):
                    self.version_dir = os.path.join(pdir, i)
                    logger.info("_find_version_dir: found version directory %s" % self.version_dir)
                    return True
        return False

    def _find_template_files(self, fdir):
        """Find the available templates in the given file directory fdir."""
        for (root, dirs, files) in os.walk(fdir):
            for f in files:
                # os.path.relpath is not available in older Python
                frel = os.path.join(root, f).replace(fdir + "/", "", 1)
                logger.debug("_find_template_files: add template file %s" % frel)
                self.files.append(frel)

    def _substitute_template(self, contents):
        """Expand the given template fdir/file into the staging area."""

        logger.debug("_expand_template: subsitute variables into %s", file)

        # Find variables in template and substitute values.
        variables = sorted(set(re.findall("!!((\w+)((=)([^!]*))?)!!",
                                          contents)))
        # r is the default replacement value for v.
        for (a, v, x, e, r) in variables:
            try:
                r = self.config.get("package:" + self.name, v)
            except (ConfigParser.NoSectionError, ConfigParser.NoOptionError), s:
                # This is the equals sign.  if it is there then we have default.
                if e == "":
                    raise

            contents = contents.replace("!!%s!!" % a, r)

        # Find plugin expressions in template and subsitute values.
        exprs = re.findall("!!%([^!]+)!!", contents)
        for e in exprs:
            (m, f, rest) = re.split("[:(]", e, 2)
            foo = 'plugins["%s"].%s(config, "%s", %s' % (m, f, self.name, rest)
            r = eval(foo)
            if r is None:
                return None
            contents = contents.replace("!!%%%s!!" % e, r)

        # Find general python expressions in template and subsitute values.
        exprs = re.findall("!!\|([^!]+)!!", contents)
        for e in exprs:
            r = eval(e)
            if r is None:
                return None
            contents = contents.replace("!!|%s!!" % e, r)

        return contents

    def _expand_template(self, fdir, file):
        """Expand the given template fdir/file into the staging area."""

        logger.debug("_expand_template: subsitute variables into %s", file)

        # Read input file.
        src = os.path.join(fdir, file)
        f = open(src)
        contents = f.read()
        f.close()

        contents = self._substitute_template(contents)

        # Ensure output directory exists in staging area.
        dst = os.path.join(self.stage, file)
        try:
            os.makedirs(os.path.dirname(dst))
        except OSError, exc:
            if exc.errno == errno.EEXIST:
                pass
            else: raise

        # Write output file into staging area, unless it is None,
        # which means to remove the file if it exists.
        if contents is not None:
            f = open(dst, "w")
            f.write(contents)
            f.close()
        else:
            try:
                os.remove(dst)
            except OSError, exc:
                if exc.errno == errno.ENOENT:
                    pass
                else: raise

    def _would_install_file(self, file):
        """Check if a file should be installed from the staging area
        because it is different to the currently installed file (or if
        there is no installed file)."""

        src = os.path.join(self.stage, file)
        dst = os.path.join("/", file)

        if not os.path.exists(src) and not os.path.exists(dst):
            logger.debug("_would_install_file: skip install of %s (missing)", dst)
            return False

        try: 
            if not options.force and filecmp.cmp(src, dst, shallow=False):
                logger.debug("_would_install_file: skip install of %s (unchanged)", dst)
                return False
        except OSError, exc:
            if exc.errno == errno.ENOENT:
                pass
            else: raise

        logger.info("_would_install_file: would install file %s", dst)
        return True

    def would_install_files(self):
        """For the templates in our packages files area, expand each
        template into the staging area and check if it would be
        installed due to a change.  Return True if any files would be
        installed, False otherwise."""

        fdir = os.path.join(self.version_dir, "files")

        shutil.rmtree(self.stage, ignore_errors=True)

        self._find_template_files(fdir)
        for f in self.files:
            self._expand_template(fdir, f)

        for f in self.files:
            if self._would_install_file(f):
                self.files_to_install.append(f)

        return self.files_to_install

    def _install_file(self, file):
        """Install file from the staging area ."""

        src = os.path.join(self.stage, file)
        dst = os.path.join("/", file)

        if os.path.exists(src):
            logger.info("_install_file: install file %s", dst)
            shutil.copy2(src, dst)
        else:
            logger.info("_install_file: remove file %s", dst)
            try:
                os.remove(dst)
            except OSError, exc:
                if exc.errno == errno.ENOENT:
                    pass
                else: raise

    def install_files(self):
        """Install the list of files from self.files_to_install."""

        for f in self.files_to_install:
            self._install_file(f)

    def run_event(self, event):
        """Run the given event script for the service, if present."""
        es = os.path.join(self.version_dir, "events", event)
        if os.path.exists(es) and os.access(es, os.X_OK):
            p = subprocess.Popen([es],
                                 stdout=subprocess.PIPE,
                                 stderr=subprocess.STDOUT)
            out = p.communicate()[0]
            status = p.wait()
            if status == 0:
                logger.info("_run_event: successfully ran event script %s", es)
            else:
                logger.error("""_run_event: error running event script "%s":
"%s" """,
                             es , string.strip(out))
        else:
            logger.debug("_run_event: no event script %s in %s", event,
                         self.version_dir)
            

plugins = {}

def load_plugins():
    global plugins

    plugin_dir = "plugins"

    sys.path.append(plugin_dir)
    for f in map(lambda x: os.path.splitext(os.path.basename(x))[0],
                 glob.glob(os.path.join(plugin_dir, "*.py"))):
    
        plugins[f] = __import__(f)

def ctdb_socket():

    ret = os.getenv('CTDB_SOCKET')

    if ret is None:
        ctdb = '/usr/bin/ctdb'
        if os.path.exists(ctdb):
            cmd = "strings " + ctdb + " | grep  -E '/ctdbd?\.socket$'"
            p = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE)
            out = p.communicate()[0]
            status = p.wait()
            if status == 0:
                ret = string.rstrip(out)
            else:
                logger.warning('Failed to find socket path in "' + ctdb +
                               '" - falling back to default')
        else:
            logger.warning('Failed to find "' + ctdb +
                           '" - falling back to default')
    if ret is None:
        ret = '/var/run/ctdb/ctdbd.socket'

    return ret

def main():
    global config, options, logger

    options = process_args()

    logger = setup_logging()

    load_plugins()

    os.environ["PATH"] = os.getcwd() + ":" + os.environ["PATH"] 

    logger.debug("main: read configuration from %s", options.config)
    config = ConfigParser.SafeConfigParser()
    config.readfp(open(options.config))

    # Run the check function in every plugin that defines it.
    config_status = True
    for p in plugins.iterkeys():
        func = getattr(plugins[p], "check", None)
        if callable(func):
            if not func(config):
                config_status = False
    if not config_status:
        logger.error("main: exiting due to previous configuration errors")
        return 1

    # Process templates.
    for d in sorted(os.listdir(options.templates)):
        try:
            p = Package(config, d)
            if p.find_version_dir():
                if p.would_install_files() and not options.simulate:
                    p.run_event("pre")
                    p.install_files()
                    p.run_event("post")
        except RuntimeError, s:
            logger.info("main: ignoring %s", s)

    logging.shutdown()


if __name__ == '__main__':
    sys.exit(main())