#!/usr/bin/env python3

# Daemon.py - Node daemon
# Part of the Parallel Virtual Cluster (PVC) system
#
#    Copyright (C) 2018  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, 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 <https://www.gnu.org/licenses/>.
#
###############################################################################

version = '0.4'

import kazoo.client
import libvirt
import sys
import os
import signal
import atexit
import socket
import psutil
import subprocess
import uuid
import time
import re
import configparser
import apscheduler.schedulers.background

import pvcd.log as log
import pvcd.zkhandler as zkhandler
import pvcd.common as common

import pvcd.DomainInstance as DomainInstance
import pvcd.NodeInstance as NodeInstance
import pvcd.VXNetworkInstance as VXNetworkInstance

###############################################################################
# PVCD - node daemon startup program
###############################################################################
# 
# The PVC daemon starts a node and configures all the required components for
# the node to run. It determines which of the 3 daemon modes it should be in
# during initial setup based on hostname and the config file, and then starts
# any required services. The 3 daemon modes are:
#  * leader: the cluster leader, follows the Zookeeper leader
#  * coordinator: a Zookeeper cluster member
#  * hypervisor: a hypervisor without any cluster intelligence
#
###############################################################################

###############################################################################
# Daemon functions
###############################################################################

# Create timer to update this node in Zookeeper
def startKeepaliveTimer():
    global update_timer
    interval = int(config['keepalive_interval'])
    logger.out('Starting keepalive timer ({} second interval)'.format(interval), state='s')
    update_timer.add_job(update_zookeeper, 'interval', seconds=interval)
    update_timer.start()

def stopKeepaliveTimer():
    global update_timer
    try:
        update_timer.shutdown()
        logger.out('Stopping keepalive timer', state='s')
    except:
        pass

###############################################################################
# PHASE 1a - Configuration parsing
###############################################################################

# Get the config file variable from the environment
try:
    pvcvd_config_file = os.environ['PVCD_CONFIG_FILE']
except:
    print('ERROR: The "PVCD_CONFIG_FILE" environment variable must be set before starting pvcd.')
    exit(1)

# Set local hostname and domain variables
myfqdn = socket.gethostname()
#myfqdn = 'pvc-hv1.domain.net'
myhostname = myfqdn.split('.', 1)[0]
mydomainname = ''.join(myfqdn.split('.', 1)[1:])
mynodeid = re.findall(r'\d+', myhostname)[-1]

# Gather useful data about our host
# Static data format: 'cpu_count', 'arch', 'os', 'kernel'
staticdata = []
staticdata.append(str(psutil.cpu_count()))
staticdata.append(subprocess.run(['uname', '-r'], stdout=subprocess.PIPE).stdout.decode('ascii').strip())
staticdata.append(subprocess.run(['uname', '-o'], stdout=subprocess.PIPE).stdout.decode('ascii').strip())
staticdata.append(subprocess.run(['uname', '-m'], stdout=subprocess.PIPE).stdout.decode('ascii').strip())

# Create our timer object
update_timer = apscheduler.schedulers.background.BackgroundScheduler()

# Config values dictionary
config_values = [
    'coordinators',
    'dynamic_directory',
    'log_directory',
    'file_logging',
    'keepalive_interval',
    'fence_intervals',
    'suicide_intervals',
    'successful_fence',
    'failed_fence',
    'migration_target_selector',
    'vni_dev',
    'vni_dev_ip',
    'storage_dev',
    'storage_dev_ip',
    'ipmi_hostname',
    'ipmi_username',
    'ipmi_password'
]

# Read and parse the config file
def readConfig(pvcvd_config_file, myhostname):
    print('Loading configuration from file "{}"'.format(pvcvd_config_file))

    o_config = configparser.ConfigParser()
    o_config.read(pvcvd_config_file)
    config = {}

    try:
        entries = o_config[myhostname]
    except:
        try:
            entries = o_config['default']
        except Exception as e:
            print('ERROR: Config file is not valid!')
            exit(1)

    for entry in config_values:
        try:
            config[entry] = entries[entry]
        except:
            try:
                config[entry] = o_config['default'][entry]
            except:
                print('ERROR: Config file missing required value "{}" for this host!'.format(entry))
                exit(1)

    # Handle an empty ipmi_hostname
    if config['ipmi_hostname'] == '':
        config['ipmi_hostname'] = myshorthostname + '-lom.' + mydomainname

    return config

# Get the config object from readConfig()
config = readConfig(pvcvd_config_file, myhostname)

###############################################################################
# PHASE 1b - Prepare filesystem directories
###############################################################################

# Define our dynamic directory schema
# <dynamic_directory>/
#                     dnsmasq/
#                     pdns/
#                     nft/
config['dnsmasq_dynamic_directory'] = config['dynamic_directory'] + '/dnsmasq'
config['pdns_dynamic_directory'] = config['dynamic_directory'] + '/pdns'
config['nft_dynamic_directory'] = config['dynamic_directory'] + '/nft'

# Create our dynamic directories if they don't exist
if not os.path.exists(config['dynamic_directory']):
    os.makedirs(config['dynamic_directory'])
    os.makedirs(config['dnsmasq_dynamic_directory'])
    os.makedirs(config['pdns_dynamic_directory'])
    os.makedirs(config['nft_dynamic_directory'])

# Define our log directory schema
# <log_directory>/
#                 dnsmasq/
#                 pdns/
#                 nft/
config['dnsmasq_log_directory'] = config['log_directory'] + '/dnsmasq'
config['pdns_log_directory'] = config['log_directory'] + '/pdns'
config['nft_log_directory'] = config['log_directory'] + '/nft'

# Create our dynamic directories if they don't exist
if not os.path.exists(config['log_directory']):
    os.makedirs(config['log_directory'])
    os.makedirs(config['dnsmasq_log_directory'])
    os.makedirs(config['pdns_log_directory'])
    os.makedirs(config['nft_log_directory'])

###############################################################################
# PHASE 1c - Set up logging
###############################################################################

logger = log.Logger(config)

# Print our startup messages
logger.out('Parallel Virtual Cluster node daemon v{}'.format(version))
logger.out('FQDN: {}'.format(myfqdn))
logger.out('Host: {}'.format(myhostname))
logger.out('ID: {}'.format(mynodeid))
logger.out('IPMI hostname: {}'.format(config['ipmi_hostname']))
logger.out('Machine details:')
logger.out('  CPUs: {}'.format(staticdata[0]))
logger.out('  Arch: {}'.format(staticdata[3]))
logger.out('  OS: {}'.format(staticdata[2]))
logger.out('  Kernel: {}'.format(staticdata[1]))
logger.out('Starting pvcd on host {}'.format(myfqdn), state='s')

###############################################################################
# PHASE 1d - Prepare sysctl for pvcd
###############################################################################

# Enable routing functions
common.run_os_command('sysctl net.ipv4.ip_forward=1')
common.run_os_command('sysctl net.ipv6.ip_forward=1')

# Send redirects
common.run_os_command('sysctl net.ipv4.conf.all.send_redirects=1')
common.run_os_command('sysctl net.ipv4.conf.default.send_redirects=1')
common.run_os_command('sysctl net.ipv6.conf.all.send_redirects=1')
common.run_os_command('sysctl net.ipv6.conf.default.send_redirects=1')

# Accept source routes
common.run_os_command('sysctl net.ipv4.conf.all.accept_source_route=1')
common.run_os_command('sysctl net.ipv4.conf.default.accept_source_route=1')
common.run_os_command('sysctl net.ipv6.conf.all.accept_source_route=1')
common.run_os_command('sysctl net.ipv6.conf.default.accept_source_route=1')

# Disable RP filtering on the VNI dev interface (to allow traffic pivoting from primary)
common.run_os_command('sysctl net.ipv4.conf.{}.rp_filter=0'.format(config['vni_dev']))
common.run_os_command('sysctl net.ipv6.conf.{}.rp_filter=0'.format(config['vni_dev']))

###############################################################################
# PHASE 2 - Determine coordinator mode and start Zookeeper on coordinators
###############################################################################

# What is the list of coordinator hosts
coordinator_hosts = config['coordinators'].split(',')

if myhostname in coordinator_hosts:
    # We are indeed a coordinator host
    config['daemon_mode'] = 'coordinator'
    # Start the zookeeper service using systemctl
    logger.out('Node is a ' + logger.fmt_blue + 'coordinator' + logger.fmt_end +'; starting Zookeeper daemon', state='i')
    common.run_os_command('systemctl start zookeeper.service')
    time.sleep(1)
else:
    config['daemon_mode'] = 'hypervisor'

###############################################################################
# PHASE 3 - Attempt to connect to the coordinators and start zookeeper client
###############################################################################

# Start the connection to the coordinators
zk_conn = kazoo.client.KazooClient(hosts=config['coordinators'])
try:
    logger.out('Connecting to Zookeeper cluster hosts {}'.format(config['coordinators']), state='i')
    # Start connection
    zk_conn.start()
except Exception as e:
    logger.out('ERROR: Failed to connect to Zookeeper cluster: {}'.format(e), state='e')
    exit(1)

# Handle zookeeper failures
def zk_listener(state):
    global zk_conn, update_timer
    if state == kazoo.client.KazooState.SUSPENDED:
        logger.out('Connection to Zookeeper lost; retrying', state='w')

        # Stop keepalive thread
        if update_timer:
            stopKeepaliveTimer()

        while True:
            try:
                zk_conn.start()
                break
            except:
                time.sleep(1)
    elif state == kazoo.client.KazooState.CONNECTED:
        logger.out('Connection to Zookeeper restarted', state='o')

        # Start keepalive thread
        if update_timer:
            update_timer = createKeepaliveTimer()
    else:
        pass
zk_conn.add_listener(zk_listener)

###############################################################################
# PHASE 4 - Gracefully handle termination
###############################################################################

# Cleanup function
def cleanup():
    global zk_conn, update_timer

    # Stop keepalive thread
    stopKeepaliveTimer()

    logger.out('Terminating pvcd and cleaning up', state='s')

    # Set stop state in Zookeeper
    zkhandler.writedata(zk_conn, { '/nodes/{}/daemonstate'.format(myhostname): 'stop' })

    # Force into secondary network state if needed
    if this_node.name == this_node.primary_node:
        zkhandler.writedata(zk_conn, { '/primary_node': 'none' })

    # Wait for things to flush
    time.sleep(3)

    # Close the Zookeeper connection
    try:
        zk_conn.stop()
        zk_conn.close()
    except:
        pass

# Handle exit gracefully
atexit.register(cleanup)

# Termination function
def term(signum='', frame=''):
    # Exit
    sys.exit(0)

# Handle signals gracefully
signal.signal(signal.SIGTERM, term)
signal.signal(signal.SIGINT, term)
signal.signal(signal.SIGQUIT, term)

###############################################################################
# PHASE 5 - Prepare host in Zookeeper
###############################################################################

# Check if our node exists in Zookeeper, and create it if not
if zk_conn.exists('/nodes/{}'.format(myhostname)):
    logger.out("Node is " + logger.fmt_green + "present" + logger.fmt_end + " in Zookeeper", state='i')
    zkhandler.writedata(zk_conn, { '/nodes/{}/daemonstate'.format(myhostname): 'init' })
    # Update static data just in case it's changed
    zkhandler.writedata(zk_conn, { '/nodes/{}/staticdata'.format(myhostname): ' '.join(staticdata) })
else:
    logger.out("Node is " + logger.fmt_red + "absent" + logger.fmt_end + " in Zookeeper; adding new node", state='i')
    keepalive_time = int(time.time())
    transaction = zk_conn.transaction()
    transaction.create('/nodes/{}'.format(myhostname), config['daemon_mode'].encode('ascii'))
    # Basic state information
    transaction.create('/nodes/{}/daemonmode'.format(myhostname), config['daemon_mode'].encode('ascii'))
    transaction.create('/nodes/{}/daemonstate'.format(myhostname), 'init'.encode('ascii'))
    transaction.create('/nodes/{}/routerstate'.format(myhostname), 'client'.encode('ascii'))
    transaction.create('/nodes/{}/domainstate'.format(myhostname), 'flushed'.encode('ascii'))
    transaction.create('/nodes/{}/staticdata'.format(myhostname), ' '.join(staticdata).encode('ascii'))
    transaction.create('/nodes/{}/memfree'.format(myhostname), '0'.encode('ascii'))
    transaction.create('/nodes/{}/memused'.format(myhostname), '0'.encode('ascii'))
    transaction.create('/nodes/{}/memalloc'.format(myhostname), '0'.encode('ascii'))
    transaction.create('/nodes/{}/vcpualloc'.format(myhostname), '0'.encode('ascii'))
    transaction.create('/nodes/{}/cpuload'.format(myhostname), '0.0'.encode('ascii'))
    transaction.create('/nodes/{}/networkscount'.format(myhostname), '0'.encode('ascii'))
    transaction.create('/nodes/{}/domainscount'.format(myhostname), '0'.encode('ascii'))
    transaction.create('/nodes/{}/runningdomains'.format(myhostname), ''.encode('ascii'))
    # Keepalives and fencing information
    transaction.create('/nodes/{}/keepalive'.format(myhostname), str(keepalive_time).encode('ascii'))
    transaction.create('/nodes/{}/ipmihostname'.format(myhostname), config['ipmi_hostname'].encode('ascii'))
    transaction.create('/nodes/{}/ipmiusername'.format(myhostname), config['ipmi_username'].encode('ascii'))
    transaction.create('/nodes/{}/ipmipassword'.format(myhostname), config['ipmi_password'].encode('ascii'))
    transaction.commit()

# Check that the primary key exists, and create it with us as master if not
current_primary = zkhandler.readdata(zk_conn, '/primary_node')
if current_primary and current_primary != 'none':
    logger.out('Current primary node is "{}{}{}".'.format(logger.fmt_blue, current_primary, logger.fmt_end), state='i')
else:
    logger.out('No primary node key found; creating with us as primary.', state='i')
    zkhandler.writedata(zk_conn, { '/primary_node': myhostname })

###############################################################################
# PHASE 6 - Create local IP addresses for VNI and Storage networks
###############################################################################

# VNI configuration
vni_dev = config['vni_dev']
vni_dev_ip = config['vni_dev_ip']
logger.out('Setting up VNI network on interface {} with IP {}'.format(vni_dev, vni_dev_ip), state='i')
common.run_os_command('ip link set {} up'.format(vni_dev))
common.run_os_command('ip address add {} dev {}'.format(vni_dev_ip, vni_dev))

# Storage configurationm
storage_dev = config['storage_dev']
storage_dev_ip = config['storage_dev_ip']
logger.out('Setting up Storage network on interface {} with IP {}'.format(storage_dev, storage_dev_ip), state='i')
common.run_os_command('ip link set {} up'.format(storage_dev))
common.run_os_command('ip address add {} dev {}'.format(storage_dev_ip, storage_dev))

###############################################################################
# PHASE 7a - Ensure Libvirt is running on the local host
###############################################################################

# Start the zookeeper service using systemctl
logger.out('Starting Libvirt daemon', state='i')
common.run_os_command('systemctl start libvirtd.service')
time.sleep(1)

# Check that libvirtd is listening TCP
libvirt_check_name = "qemu+tcp://127.0.0.1:16509/system"
logger.out('Connecting to Libvirt daemon at {}'.format(libvirt_check_name), state='i')
try:
    lv_conn = libvirt.open(libvirt_check_name)
    lv_conn.close()
except Exception as e:
    logger.out('ERROR: Failed to connect to Libvirt daemon: {}'.format(e), state='e')
    exit(1)

###############################################################################
# PHASE 7b - Ensure Ceph is running on the local host
###############################################################################

# if coordinator, start ceph-mon
# if hypervisor or coodinator, start ceph-osds

###############################################################################
# PHASE 7c - Ensure NFT is running on the local host
###############################################################################

logger.out("Creating NFT firewall configuration", state='i')

# Create our config dirs
common.run_os_command(
    '/bin/mkdir --parents {}/networks'.format(
        config['nft_dynamic_directory']
     )
)
common.run_os_command(
    '/bin/mkdir --parents {}/static'.format(
        config['nft_dynamic_directory']
     )
)
common.run_os_command(
    '/bin/mkdir --parents {}'.format(
        config['nft_dynamic_directory']
     )
)

# Set up the basic features of the nftables firewall
nftables_base_rules = """# Base rules
flush ruleset
# Add the filter table and chains
add table inet filter
add chain inet filter forward {{ type filter hook forward priority 0; }}
add chain inet filter input {{ type filter hook input priority 0; }}
# Include static rules and network rules
include "{rulesdir}/static/*"
include "{rulesdir}/networks/*"
""".format(
    rulesdir=config['nft_dynamic_directory']
)

# Write the basic firewall config
nftables_base_filename = '{}/base.nft'.format(config['nft_dynamic_directory'])
nftables_update_filename = '{}/update'.format(config['nft_dynamic_directory'])
with open(nftables_base_filename, 'w') as nfbasefile:
    nfbasefile.write(nftables_base_rules)
    # Notify a reload of the firewall rules on next keepalive update
    open(nftables_update_filename, 'a').close()

###############################################################################
# PHASE 8 - Set up our objects
###############################################################################

logger.out('Setting up objects', state='i')

d_node = dict()
d_network = dict()
d_domain = dict()
node_list = []
network_list = []
domain_list = []

# Node objects
@zk_conn.ChildrenWatch('/nodes')
def update_nodes(new_node_list):
    global node_list, d_node

    # Add any missing nodes to the list
    for node in new_node_list:
        if not node in node_list:
            d_node[node] = NodeInstance.NodeInstance(node, myhostname, zk_conn, config, logger, d_node, d_network, d_domain)

    # Remove any deleted nodes from the list
    for node in node_list:
        if not node in new_node_list:
            # Delete the object
            del(d_node[node])

    # Update and print new list
    node_list = new_node_list
    logger.out('{}Node list:{} {}'.format(logger.fmt_blue, logger.fmt_end, ' '.join(node_list)), state='i')

    # Update node objects' list
    for node in d_node:
        d_node[node].update_node_list(d_node)

# Alias for our local node (passed to network and domain objects)
this_node = d_node[myhostname]

# Network objects
@zk_conn.ChildrenWatch('/networks')
def update_networks(new_network_list):
    global network_list, d_network

    # Add any missing networks to the list
    for network in new_network_list:
        if not network in network_list:
            d_network[network] = VXNetworkInstance.VXNetworkInstance(network, zk_conn, config, logger, this_node)
            # Start primary functionality
            if this_node.router_state == 'primary':
                d_network[network].createGatewayAddress()
                d_network[network].startDHCPServer()

    # Remove any deleted networks from the list
    for network in network_list:
        if not network in new_network_list:
            # Stop primary functionality
            if this_node.router_state == 'primary':
                d_network[network].stopDHCPServer()
                d_network[network].removeGatewayAddress()
            # Stop general functionality
            d_network[network].removeFirewall()
            d_network[network].removeNetwork()
            # Delete the object
            del(d_network[network])

    # Update and print new list
    network_list = new_network_list
    logger.out('{}Network list:{} {}'.format(logger.fmt_blue, logger.fmt_end, ' '.join(network_list)), state='i')

    # Update node objects' list
    for node in d_node:
        d_node[node].update_network_list(d_network)

# VM domain objects
@zk_conn.ChildrenWatch('/domains')
def update_domains(new_domain_list):
    global domain_list, d_domain

    # Add any missing domains to the list
    for domain in new_domain_list:
        if not domain in domain_list:
            d_domain[domain] = DomainInstance.DomainInstance(domain, zk_conn, config, logger, this_node);

    # Remove any deleted domains from the list
    for domain in domain_list:
        if not domain in new_domain_list:
            # Delete the object
            del(d_domain[domain])

    # Update and print new list
    domain_list = new_domain_list
    logger.out('{}Domain list:{} {}'.format(logger.fmt_blue, logger.fmt_end, ' '.join(domain_list)), state='i')

    # Update node objects' list
    for node in d_node:
        d_node[node].update_domain_list(d_domain)

###############################################################################
# PHASE 9 - Run the daemon
###############################################################################

# Set up our update function
update_zookeeper = this_node.update_zookeeper

# Start keepalive thread and immediately update Zookeeper
startKeepaliveTimer()
update_zookeeper()

# Tick loop
while True:
    try:
        time.sleep(1)
    except:
        break