#!/usr/bin/env python3

# common.py - PVC client function library, common fuctions
# Part of the Parallel Virtual Cluster (PVC) system
#
#    Copyright (C) 2018-2021 Joshua M. Boniface <joshua@boniface.me>
#
#    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, version 3.
#
#    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 <https://www.gnu.org/licenses/>.
#
###############################################################################

import time
import uuid
import lxml
import subprocess
import signal
from json import loads
from re import match as re_match
from distutils.util import strtobool
from threading import Thread
from shlex import split as shlex_split


###############################################################################
# Supplemental functions
###############################################################################

#
# Run a local OS daemon in the background
#
class OSDaemon(object):
    def __init__(self, command_string, environment, logfile):
        command = shlex_split(command_string)
        # Set stdout to be a logfile if set
        if logfile:
            stdout = open(logfile, 'a')
        else:
            stdout = subprocess.PIPE

        # Invoke the process
        self.proc = subprocess.Popen(
            command,
            env=environment,
            stdout=stdout,
            stderr=stdout,
        )

    # Signal the process
    def signal(self, sent_signal):
        signal_map = {
            'hup': signal.SIGHUP,
            'int': signal.SIGINT,
            'term': signal.SIGTERM,
            'kill': signal.SIGKILL
        }
        self.proc.send_signal(signal_map[sent_signal])


def run_os_daemon(command_string, environment=None, logfile=None):
    daemon = OSDaemon(command_string, environment, logfile)
    return daemon


#
# Run a local OS command via shell
#
def run_os_command(command_string, background=False, environment=None, timeout=None):
    command = shlex_split(command_string)
    if background:
        def runcmd():
            try:
                subprocess.run(
                    command,
                    env=environment,
                    timeout=timeout,
                    stdout=subprocess.PIPE,
                    stderr=subprocess.PIPE,
                )
            except subprocess.TimeoutExpired:
                pass
        thread = Thread(target=runcmd, args=())
        thread.start()
        return 0, None, None
    else:
        try:
            command_output = subprocess.run(
                command,
                env=environment,
                timeout=timeout,
                stdout=subprocess.PIPE,
                stderr=subprocess.PIPE,
            )
            retcode = command_output.returncode
        except subprocess.TimeoutExpired:
            retcode = 128
        except Exception:
            retcode = 255

        try:
            stdout = command_output.stdout.decode('ascii')
        except Exception:
            stdout = ''
        try:
            stderr = command_output.stderr.decode('ascii')
        except Exception:
            stderr = ''
        return retcode, stdout, stderr


#
# Validate a UUID
#
def validateUUID(dom_uuid):
    try:
        uuid.UUID(dom_uuid)
        return True
    except Exception:
        return False


#
# Parse a Domain XML object
#
def getDomainXML(zkhandler, dom_uuid):
    try:
        xml = zkhandler.read(('domain.xml', dom_uuid))
    except Exception:
        return None

    # Parse XML using lxml.objectify
    parsed_xml = lxml.objectify.fromstring(xml)
    return parsed_xml


#
# Get the main details for a VM object from XML
#
def getDomainMainDetails(parsed_xml):
    # Get the information we want from it
    duuid = str(parsed_xml.uuid)
    try:
        ddescription = str(parsed_xml.description)
    except AttributeError:
        ddescription = "N/A"
    dname = str(parsed_xml.name)
    dmemory = str(parsed_xml.memory)
    dmemory_unit = str(parsed_xml.memory.attrib.get('unit'))
    if dmemory_unit == 'KiB':
        dmemory = int(int(dmemory) / 1024)
    elif dmemory_unit == 'GiB':
        dmemory = int(int(dmemory) * 1024)
    dvcpu = str(parsed_xml.vcpu)
    try:
        dvcputopo = '{}/{}/{}'.format(parsed_xml.cpu.topology.attrib.get('sockets'), parsed_xml.cpu.topology.attrib.get('cores'), parsed_xml.cpu.topology.attrib.get('threads'))
    except Exception:
        dvcputopo = 'N/A'

    return duuid, dname, ddescription, dmemory, dvcpu, dvcputopo


#
# Get long-format details
#
def getDomainExtraDetails(parsed_xml):
    dtype = str(parsed_xml.os.type)
    darch = str(parsed_xml.os.type.attrib['arch'])
    dmachine = str(parsed_xml.os.type.attrib['machine'])
    dconsole = str(parsed_xml.devices.console.attrib['type'])
    demulator = str(parsed_xml.devices.emulator)

    return dtype, darch, dmachine, dconsole, demulator


#
# Get CPU features
#
def getDomainCPUFeatures(parsed_xml):
    dfeatures = []
    try:
        for feature in parsed_xml.features.getchildren():
            dfeatures.append(feature.tag)
    except Exception:
        pass

    return dfeatures


#
# Get disk devices
#
def getDomainDisks(parsed_xml, stats_data):
    ddisks = []
    for device in parsed_xml.devices.getchildren():
        if device.tag == 'disk':
            disk_attrib = device.source.attrib
            disk_target = device.target.attrib
            disk_type = device.attrib.get('type')
            disk_stats_list = [x for x in stats_data.get('disk_stats', []) if x.get('name') == disk_attrib.get('name')]
            try:
                disk_stats = disk_stats_list[0]
            except Exception:
                disk_stats = {}

            if disk_type == 'network':
                disk_obj = {
                    'type': disk_attrib.get('protocol'),
                    'name': disk_attrib.get('name'),
                    'dev': disk_target.get('dev'),
                    'bus': disk_target.get('bus'),
                    'rd_req': disk_stats.get('rd_req', 0),
                    'rd_bytes': disk_stats.get('rd_bytes', 0),
                    'wr_req': disk_stats.get('wr_req', 0),
                    'wr_bytes': disk_stats.get('wr_bytes', 0)
                }
            elif disk_type == 'file':
                disk_obj = {
                    'type': 'file',
                    'name': disk_attrib.get('file'),
                    'dev': disk_target.get('dev'),
                    'bus': disk_target.get('bus'),
                    'rd_req': disk_stats.get('rd_req', 0),
                    'rd_bytes': disk_stats.get('rd_bytes', 0),
                    'wr_req': disk_stats.get('wr_req', 0),
                    'wr_bytes': disk_stats.get('wr_bytes', 0)
                }
            else:
                disk_obj = {}
            ddisks.append(disk_obj)

    return ddisks


#
# Get a list of disk devices
#
def getDomainDiskList(zkhandler, dom_uuid):
    domain_information = getInformationFromXML(zkhandler, dom_uuid)
    disk_list = []
    for disk in domain_information['disks']:
        disk_list.append(disk['name'])

    return disk_list


#
# Get domain information from XML
#
def getInformationFromXML(zkhandler, uuid):
    """
    Gather information about a VM from the Libvirt XML configuration in the Zookeper database
    and return a dict() containing it.
    """
    domain_state = zkhandler.read(('domain.state', uuid))
    domain_node = zkhandler.read(('domain.node', uuid))
    domain_lastnode = zkhandler.read(('domain.last_node', uuid))
    domain_failedreason = zkhandler.read(('domain.failed_reason', uuid))

    try:
        domain_node_limit = zkhandler.read(('domain.meta.node_limit', uuid))
    except Exception:
        domain_node_limit = None
    try:
        domain_node_selector = zkhandler.read(('domain.meta.node_selector', uuid))
    except Exception:
        domain_node_selector = None
    try:
        domain_node_autostart = zkhandler.read(('domain.meta.autostart', uuid))
    except Exception:
        domain_node_autostart = None
    try:
        domain_migration_method = zkhandler.read(('domain.meta.migrate_method', uuid))
    except Exception:
        domain_migration_method = None

    if not domain_node_limit:
        domain_node_limit = None
    else:
        domain_node_limit = domain_node_limit.split(',')

    if not domain_node_autostart:
        domain_node_autostart = None

    try:
        domain_profile = zkhandler.read(('domain.profile', uuid))
    except Exception:
        domain_profile = None

    try:
        domain_vnc = zkhandler.read(('domain.console.vnc', uuid))
        domain_vnc_listen, domain_vnc_port = domain_vnc.split(':')
    except Exception:
        domain_vnc_listen = 'None'
        domain_vnc_port = 'None'

    parsed_xml = getDomainXML(zkhandler, uuid)

    try:
        stats_data = loads(zkhandler.read(('domain.stats', uuid)))
    except Exception:
        stats_data = {}

    domain_uuid, domain_name, domain_description, domain_memory, domain_vcpu, domain_vcputopo = getDomainMainDetails(parsed_xml)
    domain_networks = getDomainNetworks(parsed_xml, stats_data)

    domain_type, domain_arch, domain_machine, domain_console, domain_emulator = getDomainExtraDetails(parsed_xml)

    domain_features = getDomainCPUFeatures(parsed_xml)
    domain_disks = getDomainDisks(parsed_xml, stats_data)
    domain_controllers = getDomainControllers(parsed_xml)

    if domain_lastnode:
        domain_migrated = 'from {}'.format(domain_lastnode)
    else:
        domain_migrated = 'no'

    domain_information = {
        'name': domain_name,
        'uuid': domain_uuid,
        'state': domain_state,
        'node': domain_node,
        'last_node': domain_lastnode,
        'migrated': domain_migrated,
        'failed_reason': domain_failedreason,
        'node_limit': domain_node_limit,
        'node_selector': domain_node_selector,
        'node_autostart': bool(strtobool(domain_node_autostart)),
        'migration_method': domain_migration_method,
        'description': domain_description,
        'profile': domain_profile,
        'memory': int(domain_memory),
        'memory_stats': stats_data.get('mem_stats', {}),
        'vcpu': int(domain_vcpu),
        'vcpu_topology': domain_vcputopo,
        'vcpu_stats': stats_data.get('cpu_stats', {}),
        'networks': domain_networks,
        'type': domain_type,
        'arch': domain_arch,
        'machine': domain_machine,
        'console': domain_console,
        'vnc': {
            'listen': domain_vnc_listen,
            'port': domain_vnc_port
        },
        'emulator': domain_emulator,
        'features': domain_features,
        'disks': domain_disks,
        'controllers': domain_controllers,
        'xml': lxml.etree.tostring(parsed_xml, encoding='ascii', method='xml').decode().replace('\"', '\'')
    }

    return domain_information


#
# Get network devices
#
def getDomainNetworks(parsed_xml, stats_data):
    dnets = []
    for device in parsed_xml.devices.getchildren():
        if device.tag == 'interface':
            try:
                net_type = device.attrib.get('type')
            except Exception:
                net_type = None
            try:
                net_mac = device.mac.attrib.get('address')
            except Exception:
                net_mac = None
            try:
                net_bridge = device.source.attrib.get(net_type)
            except Exception:
                net_bridge = None
            try:
                net_model = device.model.attrib.get('type')
            except Exception:
                net_model = None
            try:
                net_stats_list = [x for x in stats_data.get('net_stats', []) if x.get('bridge') == net_bridge]
                net_stats = net_stats_list[0]
            except Exception:
                net_stats = {}
            net_rd_bytes = net_stats.get('rd_bytes', 0)
            net_rd_packets = net_stats.get('rd_packets', 0)
            net_rd_errors = net_stats.get('rd_errors', 0)
            net_rd_drops = net_stats.get('rd_drops', 0)
            net_wr_bytes = net_stats.get('wr_bytes', 0)
            net_wr_packets = net_stats.get('wr_packets', 0)
            net_wr_errors = net_stats.get('wr_errors', 0)
            net_wr_drops = net_stats.get('wr_drops', 0)
            if net_type in ['direct', 'hostdev']:
                net_vni = device.source.attrib.get('dev')
            else:
                net_vni = re_match(r'[vm]*br([0-9a-z]+)', net_bridge).group(1)
            net_obj = {
                'type': net_type,
                'vni': net_vni,
                'mac': net_mac,
                'source': net_bridge,
                'model': net_model,
                'rd_bytes': net_rd_bytes,
                'rd_packets': net_rd_packets,
                'rd_errors': net_rd_errors,
                'rd_drops': net_rd_drops,
                'wr_bytes': net_wr_bytes,
                'wr_packets': net_wr_packets,
                'wr_errors': net_wr_errors,
                'wr_drops': net_wr_drops
            }
            dnets.append(net_obj)

    return dnets


#
# Get controller devices
#
def getDomainControllers(parsed_xml):
    dcontrollers = []
    for device in parsed_xml.devices.getchildren():
        if device.tag == 'controller':
            controller_type = device.attrib.get('type')
            try:
                controller_model = device.attrib.get('model')
            except KeyError:
                controller_model = 'none'
            controller_obj = {'type': controller_type, 'model': controller_model}
            dcontrollers.append(controller_obj)

    return dcontrollers


#
# Verify node is valid in cluster
#
def verifyNode(zkhandler, node):
    return zkhandler.exists(('node', node))


#
# Get the primary coordinator node
#
def getPrimaryNode(zkhandler):
    failcount = 0
    while True:
        try:
            primary_node = zkhandler.read('base.config.primary_node')
        except Exception:
            primary_node == 'none'

        if primary_node == 'none':
            raise
            time.sleep(1)
            failcount += 1
            continue
        else:
            break

        if failcount > 2:
            return None

    return primary_node


#
# Find a migration target
#
def findTargetNode(zkhandler, dom_uuid):
    # Determine VM node limits; set config value if read fails
    try:
        node_limit = zkhandler.read(('domain.meta.node_limit', dom_uuid)).split(',')
        if not any(node_limit):
            node_limit = None
    except Exception:
        node_limit = None

    # Determine VM search field or use default; set config value if read fails
    try:
        search_field = zkhandler.read(('domain.meta.node_selector', dom_uuid))
    except Exception:
        search_field = None

    # If our search field is invalid, use the default
    if search_field is None or search_field == 'None':
        search_field = zkhandler.read('base.config.migration_target_selector')

    # Execute the search
    if search_field == 'mem':
        return findTargetNodeMem(zkhandler, node_limit, dom_uuid)
    if search_field == 'load':
        return findTargetNodeLoad(zkhandler, node_limit, dom_uuid)
    if search_field == 'vcpus':
        return findTargetNodeVCPUs(zkhandler, node_limit, dom_uuid)
    if search_field == 'vms':
        return findTargetNodeVMs(zkhandler, node_limit, dom_uuid)

    # Nothing was found
    return None


#
# Get the list of valid target nodes
#
def getNodes(zkhandler, node_limit, dom_uuid):
    valid_node_list = []
    full_node_list = zkhandler.children('base.node')
    current_node = zkhandler.read(('domain.node', dom_uuid))

    for node in full_node_list:
        if node_limit and node not in node_limit:
            continue

        daemon_state = zkhandler.read(('node.state.daemon', node))
        domain_state = zkhandler.read(('node.state.domain', node))

        if node == current_node:
            continue

        if daemon_state != 'run' or domain_state != 'ready':
            continue

        valid_node_list.append(node)

    return valid_node_list


#
# via free memory (relative to allocated memory)
#
def findTargetNodeMem(zkhandler, node_limit, dom_uuid):
    most_provfree = 0
    target_node = None

    node_list = getNodes(zkhandler, node_limit, dom_uuid)
    for node in node_list:
        memprov = int(zkhandler.read(('node.memory.provisioned', node)))
        memused = int(zkhandler.read(('node.memory.used', node)))
        memfree = int(zkhandler.read(('node.memory.free', node)))
        memtotal = memused + memfree
        provfree = memtotal - memprov

        if provfree > most_provfree:
            most_provfree = provfree
            target_node = node

    return target_node


#
# via load average
#
def findTargetNodeLoad(zkhandler, node_limit, dom_uuid):
    least_load = 9999.0
    target_node = None

    node_list = getNodes(zkhandler, node_limit, dom_uuid)
    for node in node_list:
        load = float(zkhandler.read(('node.cpu.load', node)))

        if load < least_load:
            least_load = load
            target_node = node

    return target_node


#
# via total vCPUs
#
def findTargetNodeVCPUs(zkhandler, node_limit, dom_uuid):
    least_vcpus = 9999
    target_node = None

    node_list = getNodes(zkhandler, node_limit, dom_uuid)
    for node in node_list:
        vcpus = int(zkhandler.read(('node.vcpu.allocated', node)))

        if vcpus < least_vcpus:
            least_vcpus = vcpus
            target_node = node

    return target_node


#
# via total VMs
#
def findTargetNodeVMs(zkhandler, node_limit, dom_uuid):
    least_vms = 9999
    target_node = None

    node_list = getNodes(zkhandler, node_limit, dom_uuid)
    for node in node_list:
        vms = int(zkhandler.read(('node.count.provisioned_domains', node)))

        if vms < least_vms:
            least_vms = vms
            target_node = node

    return target_node


#
# Connect to the primary node and run a command
#
def runRemoteCommand(node, command, become=False):
    import paramiko
    import hashlib
    import dns.resolver
    import dns.flags

    # Support doing SSHFP checks
    class DnssecPolicy(paramiko.client.MissingHostKeyPolicy):
        def missing_host_key(self, client, hostname, key):
            sshfp_expect = hashlib.sha1(key.asbytes()).hexdigest()
            ans = dns.resolver.query(hostname, 'SSHFP')
            if not ans.response.flags & dns.flags.DO:
                raise AssertionError('Answer is not DNSSEC signed')
            for answer in ans.response.answer:
                for item in answer.items:
                    if sshfp_expect in item.to_text():
                        client._log(paramiko.common.DEBUG, 'Found {} in SSHFP for host {}'.format(key.get_name(), hostname))
                        return
            raise AssertionError('SSHFP not published in DNS')

    if become:
        command = 'sudo ' + command

    ssh_client = paramiko.client.SSHClient()
    ssh_client.load_system_host_keys()
    ssh_client.set_missing_host_key_policy(DnssecPolicy())
    ssh_client.connect(node)
    stdin, stdout, stderr = ssh_client.exec_command(command)
    return stdout.read().decode('ascii').rstrip(), stderr.read().decode('ascii').rstrip()


#
# Reload the firewall rules of the system
#
def reload_firewall_rules(rules_file, logger=None):
    if logger is not None:
        logger.out('Reloading firewall configuration', state='o')

    retcode, stdout, stderr = run_os_command('/usr/sbin/nft -f {}'.format(rules_file))
    if retcode != 0 and logger is not None:
        logger.out('Failed to reload configuration: {}'.format(stderr), state='e')


#
# Create an IP address
#
def createIPAddress(ipaddr, cidrnetmask, dev):
    run_os_command(
        'ip address add {}/{} dev {}'.format(
            ipaddr,
            cidrnetmask,
            dev
        )
    )
    run_os_command(
        'arping -P -U -W 0.02 -c 2 -i {dev} -S {ip} {ip}'.format(
            dev=dev,
            ip=ipaddr
        )
    )


#
# Remove an IP address
#
def removeIPAddress(ipaddr, cidrnetmask, dev):
    run_os_command(
        'ip address delete {}/{} dev {}'.format(
            ipaddr,
            cidrnetmask,
            dev
        )
    )