#!/usr/bin/python
# mclu (mini cluster)
# Copyright (C) 2014 Red Hat Inc.
#
# 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 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

import os
import subprocess
import libvirt

import config

class Node:
    def __init__ (self, name, host, mac, uri):
        self.name = name
        self.host = host
        self.mac = mac
        self.uri = uri

    def ping (self, force = False):
        """Test if node is up."""
        if not force:
            if hasattr (self, 'up'):
                return self.up

        devnull = open (os.devnull, "w")
        r = subprocess.call (["ping", "-c", "1", self.host],
                             stdout = devnull, stderr = devnull)
        self.up = r == 0
        return self.up

    def ssh_ping (self):
        """Test if we can open an SSH connection"""
        if self.ping ():
            devnull = open (os.devnull, "w")
            r = subprocess.call ([config.SSH, "-l", "root", self.host, ":"],
                                 stdout = devnull, stderr = devnull)
            return r == 0
        else:
            return False

    def libvirt_ping (self):
        """Test if we can open a libvirt connection"""
        if self.ping():
            conn = libvirt.openReadOnly (self.uri)
            return conn != None
        else:
            return False

    def wake (self):
        if not self.ping ():
            devnull = open (os.devnull, "w")
            subprocess.check_call ([config.WOL, self.mac],
                                   stdout = devnull, stderr = devnull)

    def shutdown (self):
        if self.ping ():
            devnull = open (os.devnull, "w")
            r = subprocess.call ([config.SSH, "-l", "root", self.host,
                                  "/sbin/poweroff"],
                                 stdout = devnull, stderr = devnull)
            # returns a non-zero exit status, for unknown reasons

    def guests (self):
        """Return the list of VMs running on this node"""
        guests = []
        if self.ping ():
            conn = self.get_connection ()
            for id in conn.listDomainsID():
                try:
                    dom = conn.lookupByID (id)
                except:
                    continue
                guests.append (dom)
        return guests

    def get_connection (self):
        """Return cached libvirt connection, fail if not possible."""
        if not self.ping ():
            sys.exit ("error: node %s is not awake" % self.name)
        if hasattr (self, 'conn'):
            return self.conn
        conn = libvirt.open (self.uri)
        if conn == None:
            sys.exit ("error: could not open a libvirt connection to %s (URI: %s)" %
                      (self.host, self.uri))
        self.conn = conn
        return self.conn