#!/usr/bin/python2 -O

'''
Qubes OS
'''

__author__ = 'Invisible Things Lab'
__license__ = 'GPLv2 or later'
__version__ = 'R3'

import qubes._pluginloader

class QubesException(Exception):
    '''Exception that can be shown to the user'''
    pass

class QubesVMMConnection(object):
    '''Connection to Virtual Machine Manager (libvirt)'''
    def __init__(self):
        self._libvirt_conn = None
        self._xs = None
        self._xc = None
        self._offline_mode = False

    @property
    def offline_mode(self):
        '''Check or enable offline mode (do not actually connect to vmm)'''
        return self._offline_mode

    @offline_mode.setter
    def offline_mode(self, value):
        if value and self._libvirt_conn is not None:
            raise QubesException("Cannot change offline mode while already connected")

        self._offline_mode = value

    def _libvirt_error_handler(self, ctx, error):
        pass

    def init_vmm_connection(self):
        '''Initialise connection

        This method is automatically called when getting'''
        if self._libvirt_conn is not None:
            # Already initialized
            return
        if self._offline_mode:
            # Do not initialize in offline mode
            raise QubesException("VMM operations disabled in offline mode")

        if 'xen.lowlevel.xs' in sys.modules:
            self._xs = xen.lowlevel.xs.xs()
        self._libvirt_conn = libvirt.open(defaults['libvirt_uri'])
        if self._libvirt_conn == None:
            raise QubesException("Failed connect to libvirt driver")
        libvirt.registerErrorHandler(self._libvirt_error_handler, None)
        atexit.register(self._libvirt_conn.close)

    @property
    def libvirt_conn(self):
        '''Connection to libvirt'''
        self.init_vmm_connection()
        return self._libvirt_conn

    @property
    def xs(self):
        '''Connection to Xen Store

        This property in available only when running on Xen.'''

        if 'xen.lowlevel.xs' not in sys.modules:
            return None

        self.init_vmm_connection()
        return self._xs

vmm = QubesVMMConnection()


class QubesHost(object):
    '''Basic information about host machine'''
    def __init__(self):
        (model, memory, cpus, mhz, nodes, socket, cores, threads) = vmm.libvirt_conn.getInfo()
        self._total_mem = long(memory)*1024
        self._no_cpus = cpus

#        print "QubesHost: total_mem  = {0}B".format (self.xen_total_mem)
#        print "QubesHost: free_mem   = {0}".format (self.get_free_xen_memory())
#        print "QubesHost: total_cpus = {0}".format (self.xen_no_cpus)

    @property
    def memory_total(self):
        '''Total memory, in bytes'''
        return self._total_mem

    @property
    def no_cpus(self):
        '''Noumber of CPUs'''
        return self._no_cpus

    # TODO
    def get_free_xen_memory(self):
        ret = self.physinfo['free_memory']
        return long(ret)

    # TODO
    def measure_cpu_usage(self, previous=None, previous_time = None,
            wait_time=1):
        """measure cpu usage for all domains at once"""
        if previous is None:
            previous_time = time.time()
            previous = {}
            info = vmm.xc.domain_getinfo(0, qubes_max_qid)
            for vm in info:
                previous[vm['domid']] = {}
                previous[vm['domid']]['cpu_time'] = (
                        vm['cpu_time'] / vm['online_vcpus'])
                previous[vm['domid']]['cpu_usage'] = 0
            time.sleep(wait_time)

        current_time = time.time()
        current = {}
        info = vmm.xc.domain_getinfo(0, qubes_max_qid)
        for vm in info:
            current[vm['domid']] = {}
            current[vm['domid']]['cpu_time'] = (
                    vm['cpu_time'] / max(vm['online_vcpus'], 1))
            if vm['domid'] in previous.keys():
                current[vm['domid']]['cpu_usage'] = (
                    float(current[vm['domid']]['cpu_time'] -
                        previous[vm['domid']]['cpu_time']) /
                    long(1000**3) / (current_time-previous_time) * 100)
                if current[vm['domid']]['cpu_usage'] < 0:
                    # VM has been rebooted
                    current[vm['domid']]['cpu_usage'] = 0
            else:
                current[vm['domid']]['cpu_usage'] = 0

        return (current_time, current)