#
# Some code for parsing libvirt's capabilities XML
#
# Copyright 2007, 2012-2014 Red Hat, Inc.
# Mark McLoughlin <markmc@redhat.com>
#
# 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 re

from . import util

# Whether a guest can be created with a certain feature on resp. off
FEATURE_ON      = 0x01
FEATURE_OFF     = 0x02


def xpathString(node, path, default=None):
    result = node.xpathEval("string(%s)" % path)
    if len(result) == 0:
        result = default
    return result


class CPUValuesModel(object):
    """
    Single CPU model
    """
    def __init__(self, model):
        self.model = model


class CPUValuesArch(object):
    """
    Single <arch> instance of valid CPUs
    """
    def __init__(self, arch, node=None):
        self.arch = arch
        self.vendors = []
        self.cpus = []

        if node:
            self._parseXML(node)

    def _parseXML(self, node):
        child = node.children
        while child:
            if child.name == "vendor":
                self.vendors.append(child.prop("name"))
            if child.name == "model":
                newcpu = CPUValuesModel(child.prop("name"))
                self.cpus.append(newcpu)

            child = child.next

        self.vendors.sort()

    def get_cpu(self, model):
        for c in self.cpus:
            if c.model == model:
                return c
        raise ValueError(_("Unknown CPU model '%s'") % model)


class _CPUAPIValues(object):
    """
    Lists valid values for cpu models obtained trough libvirt's getCPUModelNames
    """
    def __init__(self):
        self._cpus = None

    def get_cpus(self, arch, conn):
        if self._cpus is not None:
            return self._cpus

        if (conn and conn.check_support(conn.SUPPORT_CONN_CPU_MODEL_NAMES)):
            names = conn.getCPUModelNames(arch, 0)

            # Bindings were broke for a long time, so catch -1
            if names != -1:
                self._cpus = [CPUValuesModel(i) for i in names]
                return self._cpus

        return []


class _CPUMapFileValues(_CPUAPIValues):
    """
    Fallback method to lists cpu models, parsed directly from libvirt's local
    cpu_map.xml
    """
    _cpu_filename = "/usr/share/libvirt/cpu_map.xml"

    def __init__(self):
        _CPUAPIValues.__init__(self)
        self.archmap = {}
        xml = file(self._cpu_filename).read()

        util.parse_node_helper(xml, "cpus",
                                self._parseXML,
                                RuntimeError)

    @staticmethod
    def update_cpu_filename(name):
        _CPUMapFileValues._cpu_filename = name

    def _parseXML(self, node):
        child = node.children
        while child:
            if child.name == "arch":
                arch = child.prop("name")
                self.archmap[arch] = CPUValuesArch(arch, child)

            child = child.next

    def get_cpus(self, arch, conn):
        ignore = conn
        if re.match(r'i[4-9]86', arch):
            arch = "x86"
        elif arch == "x86_64":
            arch = "x86"

        cpumap = self.archmap.get(arch)
        if not cpumap:
            cpumap = CPUValuesArch(arch)
            self.archmap[arch] = cpumap

        return cpumap.cpus


class Features(object):
    """Represent a set of features. For each feature, store a bit mask of
       FEATURE_ON and FEATURE_OFF to indicate whether the feature can
       be turned on or off. For features for which toggling doesn't make sense
       (e.g., 'vmx') store FEATURE_ON when the feature is present."""

    def __init__(self, node=None):
        self.features = {}
        if node is not None:
            self.parseXML(node)

    def __getitem__(self, feature):
        if feature in self.features:
            return self.features[feature]
        return 0

    def names(self):
        return self.features.keys()

    def parseXML(self, node):
        d = self.features

        feature_list = []
        if node.name == "features":
            node_list = node.xpathEval("*")
            for n in node_list:
                feature_list.append(n.name)
        else:
            # New style features
            node_list = node.xpathEval("feature/@name")
            for n in node_list:
                feature_list.append(n.content)

        for feature in feature_list:
            if feature not in d:
                d[feature] = 0

            self._extractFeature(feature, d, n)

    def _extractFeature(self, feature, d, node):
        """Extract the value of FEATURE from NODE and set DICT[FEATURE] to
        its value. Abstract method, must be overridden"""
        raise NotImplementedError("Abstract base class")


class CapabilityFeatures(Features):
    def __init__(self, node=None):
        Features.__init__(self, node)

    def _extractFeature(self, feature, d, n):
        default = xpathString(n, "@default")
        toggle = xpathString(n, "@toggle")

        if default is not None:
            # Format for guest features
            if default == "on":
                d[feature] = FEATURE_ON
            elif default == "off":
                d[feature] = FEATURE_OFF
            else:
                raise RuntimeError("Feature %s: value of default must "
                                   "be 'on' or 'off', but is '%s'" %
                                   (feature, default))
            if toggle == "yes":
                d[feature] |= d[feature] ^ (FEATURE_ON | FEATURE_OFF)
        else:
            # Format for old HOST features, on OLD old guest features
            # back compat is just <$featurename>, like <svm/>
            if feature == "nonpae":
                d["pae"] |= FEATURE_OFF
            else:
                d[feature] |= FEATURE_ON


class CPU(object):
    def __init__(self, node=None):
        # e.g. "i686" or "x86_64"
        self.arch = None
        self.model = None
        self.vendor = None
        self.sockets = 1
        self.cores = 1
        self.threads = 1
        self.features = CapabilityFeatures()

        if node is not None:
            self.parseXML(node)

    def parseXML(self, node):
        newstyle_features = False

        child = node.children
        while child:
            # Do a first pass to try and detect new style features
            if child.name == "feature":
                newstyle_features = True
                break
            child = child.next

        if newstyle_features:
            self.features = CapabilityFeatures(node)

        child = node.children
        while child:
            if child.name == "arch":
                self.arch = child.content
            elif child.name == "model":
                self.model = child.content
            elif child.name == "vendor":
                self.vendor = child.content
            elif child.name == "topology":
                self.sockets = xpathString(child, "@sockets") or 1
                self.cores = xpathString(child, "@cores") or 1
                self.threads = xpathString(child, "@threads") or 1

            elif child.name == "features" and not newstyle_features:
                self.features = CapabilityFeatures(child)

            child = child.next


class Host(object):
    def __init__(self, node=None):
        self.cpu = CPU()
        self.topology = None
        self.secmodels = []

        if node is not None:
            self.parseXML(node)

    def get_secmodel(self):
        return self.secmodels and self.secmodels[0] or None
    secmodel = property(get_secmodel)

    def parseXML(self, node):
        child = node.children
        while child:
            if child.name == "topology":
                self.topology = Topology(child)

            if child.name == "secmodel":
                self.secmodels.append(SecurityModel(child))

            if child.name == "cpu":
                self.cpu = CPU(child)

            child = child.next


class Guest(object):
    def __init__(self, node=None):
        # e.g. "xen" or "hvm"
        self.os_type = None
        # e.g. "i686" or "x86_64"
        self.arch = None

        self.domains = []

        self.features = CapabilityFeatures()

        if node is not None:
            self.parseXML(node)

    def parseXML(self, node):
        child = node.children
        while child:
            if child.name == "os_type":
                self.os_type = child.content
            elif child.name == "features":
                self.features = CapabilityFeatures(child)
            elif child.name == "arch":
                self.arch = child.prop("name")
                machines = []
                emulator = None
                loader = None
                n = child.children
                while n:
                    if n.name == "machine":
                        machines.append(n.content)

                        canon = n.prop("canonical")
                        if canon:
                            machines.append(canon)
                    elif n.name == "emulator":
                        emulator = n.content
                    elif n.name == "loader":
                        loader = n.content
                    n = n.next

                n = child.children
                while n:
                    if n.name == "domain":
                        self.domains.append(Domain(n.prop("type"),
                                            emulator, loader, machines, n))
                    n = n.next

            child = child.next

    def _favoredDomain(self, domains):
        """
        Return the recommended domain for use if the user does not explicitly
        request one.
        """
        if not domains:
            return None

        priority = ["kvm", "xen", "kqemu", "qemu"]

        for t in priority:
            for d in domains:
                if d.hypervisor_type == t:
                    return d

        # Fallback, just return last item in list
        return domains[-1]

    def bestDomainType(self, dtype=None, machine=None):
        domains = []
        for d in self.domains:
            d.set_recommended_machine(None)

            if dtype and d.hypervisor_type != dtype.lower():
                continue
            if machine and machine not in d.machines:
                continue

            if machine:
                d.set_recommended_machine(machine)
            domains.append(d)

        return self._favoredDomain(domains)


class Domain(object):
    def __init__(self, hypervisor_type,
                 emulator=None, loader=None,
                 machines=None, node=None):
        self.hypervisor_type = hypervisor_type
        self.emulator = emulator
        self.loader = loader
        self.machines = machines

        self._recommended_machine = None

        if node is not None:
            self.parseXML(node)

    def get_recommended_machine(self, conn, capsguest):
        if self._recommended_machine:
            return self._recommended_machine

        if not conn.is_test() and not conn.is_qemu():
            return None

        if capsguest.arch == "ppc64" and "pseries" in self.machines:
            return "pseries"
        if capsguest.arch in ["armv7l", "aarch64"]:
            if "virt" in self.machines:
                return "virt"
            if "vexpress-a15" in self.machines:
                return "vexpress-a15"

        return None

    def set_recommended_machine(self, machine):
        self._recommended_machine = machine

    def parseXML(self, node):
        child = node.children
        machines = []
        while child:
            if child.name == "emulator":
                self.emulator = child.content
            elif child.name == "machine":
                machines.append(child.content)

                canon = child.prop("canonical")
                if canon:
                    machines.append(canon)
                machines.append(child.content)
            child = child.next

        if len(machines) > 0:
            self.machines = machines

    def is_accelerated(self):
        return self.hypervisor_type in ["kvm", "kqemu"]


class Topology(object):
    def __init__(self, node=None):
        self.cells = []

        if node is not None:
            self.parseXML(node)

    def parseXML(self, node):
        child = node.children
        if child.name == "cells":
            for cell in child.children:
                if cell.name == "cell":
                    self.cells.append(TopologyCell(cell))


class TopologyCell(object):
    def __init__(self, node=None):
        self.id = None
        self.cpus = []

        if node is not None:
            self.parseXML(node)

    def parseXML(self, node):
        self.id = int(node.prop("id"))
        for child in node.children:
            if child.name == "cpus":
                for cpu in child.children:
                    if cpu.name == "cpu":
                        self.cpus.append(TopologyCPU(cpu))


class TopologyCPU(object):
    def __init__(self, node=None):
        self.id = None

        if node is not None:
            self.parseXML(node)

    def parseXML(self, node):
        self.id = int(node.prop("id"))


class SecurityModel(object):
    def __init__(self, node=None):
        self.model = None
        self.doi = None
        self.baselabels = {}

        if node is not None:
            self.parseXML(node)

    def parseXML(self, node):
        for child in node.children or []:
            if child.name == "model":
                self.model = child.content
            elif child.name == "doi":
                self.doi = child.content
            elif child.name == "baselabel":
                typ = child.prop("type")
                self.baselabels[typ] = child.content


class Capabilities(object):
    def __init__(self, xml):
        self.host = None
        self.guests = []
        self.xml = xml
        self._topology = None
        self._cpu_values = None

        util.parse_node_helper(self.xml, "capabilities",
                               self.parseXML,
                               RuntimeError)

    def _is_xen(self):
        for g in self.guests:
            if g.os_type != "xen":
                continue

            for d in g.domains:
                if d.hypervisor_type == "xen":
                    return True

        return False

    def no_install_options(self):
        """
        Return True if there are no install options available
        """
        for g in self.guests:
            if len(g.domains) > 0:
                return False

        return True

    def hw_virt_supported(self):
        """
        Return True if the machine supports hardware virtualization.

        For some cases (like qemu caps pre libvirt 0.7.4) this info isn't
        sufficiently provided, so we will return True in cases that we
        aren't sure.
        """
        has_hvm_guests = False
        for g in self.guests:
            if g.os_type == "hvm":
                has_hvm_guests = True
                break

        # Obvious case of feature being specified
        if (self.host.cpu.features["vmx"] == FEATURE_ON or
            self.host.cpu.features["svm"] == FEATURE_ON):
            return True

        # Xen seems to block the vmx/svm feature bits from cpuinfo?
        # so make sure no hvm guests are listed
        if self._is_xen() and has_hvm_guests:
            return True

        # If there is other features, but no virt bit, then HW virt
        # isn't supported
        if len(self.host.cpu.features.names()):
            return False

        # Xen caps have always shown this info, so if we didn't find any
        # features, the host really doesn't have the nec support
        if self._is_xen():
            return False

        # Otherwise, we can't be sure, because there was a period for along
        # time that qemu caps gave no indication one way or the other.
        return True

    def is_kvm_available(self):
        """
        Return True if kvm guests can be installed
        """
        for g in self.guests:
            if g.os_type != "hvm":
                continue

            for d in g.domains:
                if d.hypervisor_type == "kvm":
                    return True

        return False

    def is_xenner_available(self):
        """
        Return True if xenner install option is available
        """
        for g in self.guests:
            if g.os_type != "xen":
                continue

            for d in g.domains:
                if d.hypervisor_type == "kvm":
                    return True

        return False

    def is_bios_virt_disabled(self):
        """
        Try to determine if fullvirt may be disabled in the bios.

        Check is basically:
            - We support HW virt
            - We appear to be xen
            - There are no HVM install options

        We don't do this check for KVM, since no KVM options may mean
        KVM isn't installed or the module isn't loaded (and loading the
        module will give an appropriate error
        """
        if not self.hw_virt_supported():
            return False

        if not self._is_xen():
            return False

        for g in self.guests:
            if g.os_type == "hvm":
                return False

        return True

    def support_pae(self):
        for g in self.guests:
            if "pae" in g.features.names():
                return True
        return False

    def _guestForOSType(self, typ=None, arch=None):
        if self.host is None:
            return None

        if arch is None:
            archs = [self.host.cpu.arch, None]
        else:
            archs = [arch]

        for a in archs:
            for g in self.guests:
                if (typ is None or g.os_type == typ) and \
                   (a is None or g.arch == a):
                    return g

    def parseXML(self, node):
        child = node.children
        while child:
            if child.name == "host":
                self.host = Host(child)
            elif child.name == "guest":
                self.guests.append(Guest(child))
            child = child.next

    def get_cpu_values(self, conn, arch):
        if not arch:
            return []
        if self._cpu_values:
            return self._cpu_values.get_cpus(arch, conn)

        # Iterate over the available methods until a set of CPU models is found
        for mode in (_CPUAPIValues, _CPUMapFileValues):
            cpu_values = mode()
            cpus = cpu_values.get_cpus(arch, conn)
            if len(cpus) > 0:
                self._cpu_values = cpu_values
                return cpus

        return []

    def guest_lookup(self, os_type=None, arch=None, typ=None, machine=None):
        """
        Simple virtualization availability lookup

        Convenience function for looking up 'Guest' and 'Domain' capabilities
        objects for the desired virt type. If type, arch, or os_type are none,
        we return the default virt type associated with those values. These are
        typically:

            - os_type : hvm, then xen
            - typ     : kvm over plain qemu
            - arch    : host arch over all others

        Otherwise the default will be the first listed in the capabilities xml.
        This function throws C{ValueError}s if any of the requested values are
        not found.

        @param typ: Virtualization type ('hvm', 'xen', ...)
        @param arch: Guest architecture ('x86_64', 'i686' ...)
        @param os_type: Hypervisor name ('qemu', 'kvm', 'xen', ...)
        @param machine: Optional machine type to emulate

        @returns: A (Capabilities Guest, Capabilities Domain) tuple
        """
        guest = self._guestForOSType(os_type, arch)
        if not guest:
            archstr = _("for arch '%s'") % arch
            if not arch:
                archstr = ""

            osstr = _("virtualization type '%s'") % os_type
            if not os_type:
                osstr = _("any virtualization options")

            raise ValueError(_("Host does not support %(virttype)s %(arch)s") %
                               {'virttype' : osstr, 'arch' : archstr})

        domain = guest.bestDomainType(dtype=typ, machine=machine)
        if domain is None:
            machinestr = " with machine '%s'" % machine
            if not machine:
                machinestr = ""
            raise ValueError(_("Host does not support domain type %(domain)s"
                               "%(machine)s for virtualization type "
                               "'%(virttype)s' arch '%(arch)s'") %
                               {'domain': typ, 'virttype': guest.os_type,
                                'arch': guest.arch, 'machine': machinestr})

        return (guest, domain)

    def build_virtinst_guest(self, conn, guest, domain):
        from .guest import Guest as VMGuest
        gobj = VMGuest(conn)
        gobj.type = domain.hypervisor_type
        gobj.os.os_type = guest.os_type
        gobj.os.arch = guest.arch
        gobj.os.loader = domain.loader
        gobj.emulator = domain.emulator
        gobj.os.machine = domain.get_recommended_machine(conn, guest)

        return gobj
