import json
import subprocess
import os, errno

class VMHelper:
	def __init__(self):
		self.config = json.load(open("/root/tmp/config.json"))

	def getPid(self,vmid):
		result = None
		try:
			with open(self.config['kvm']['pidfile'].replace("$VMID", vmid)) as pidfd:
				firstline = pidfd.readline().strip()
				result = int(firstline) if firstline.isdigit() else None
		except IOError:
			pass
		return result
				

	def process_running(self,vmid):

		pid = self.getPid(vmid)
		
		if pid is None:	
			return False

		result = None
		try:
			os.kill(pid,0)
		except OSError as e:
			result = e.errno != errno.ESRCH
		else:
			result = True

		return result

	def startVM(self, vmid):
		self.setupNetwork(vmid)
		cmd = []
		cmd.append(self.config['kvm']['executable'])
		cmd.append(vmid)
		
		cmd.append("-pidfile")
		cmd.append(self.config['kvm']['pidfile'].replace("$VMID", vmid))

		cmd.append("-qmp")
		cmd.append("unix:" + self.config['kvm']['qmpsocket'].replace("$VMID", vmid) + ",server,nowait")

		default_args = self.config['kvm']['default_args'].replace("$VMID", vmid)
		cmd += default_args.split()
		cmd += self.createArguments(vmid).split()
		#print(" ".join(cmd))
		subprocess.Popen(cmd, stdout=open("/dev/null"), stderr=open("/dev/null"))	
		#subprocess.call(cmd)
	
	def createArguments(self, vmid):
		if ('VMs' in self.config) and (vmid in self.config['VMs']):
			config = self.config['VMs'][vmid]
		else:
			raise Exception("No such VM configuration")

		args = ""
		if ('cpu' in config):
			args += " -cpu " + config['cpu']
		if ('smp' in config):
			args += " -smp " + str(config['smp'])
		if ('memory' in config):
			args += " -m " + str(config['memory'])
		if ('disk' in config):
			disk = config['disk']
			if ('file' in disk):
				args += " -drive file=" + disk['file']
				if ('hw' in disk):
					args += ",if=" + disk['hw']
		if ('cdrom' in config):
			args += " -cdrom " + config['cdrom']
		if ('network' in config):
			net = config['network']
			args += " -net nic,vlan=1"
			if ('mac' in net):
				args += ",macaddr=" + net['mac']
			if ('hw' in net):
				args += ",model=" + net['hw']
			args += " -net tap,vlan=1"
			if ('dev' in net):
				args += ",ifname=" + net['dev']
			args += ",script=no,downscript=no"
		if ('vnc' in config):
			vnc = config['vnc']
			if ('display' in vnc):
				args += " -vnc 127.0.0.1:" + str(vnc['display'])
		if ('keyboard' in config):
			args += " -k " + config['keyboard']
		if ('kernel' in config):
			args += " -kernel " + config['kernel']
		if ('append' in config):
			args += " -append \"" + config['append'] + "\""
		return args

	def setupNetwork(self, vmid):
		if ('VMs' in self.config) and (vmid in self.config['VMs']):
			config = self.config['VMs'][vmid]
		else:
			raise Exception("No such VM configuration")
		
		commands = []
		if ('network' in config):
			net = config['network']
			if ('dev' in net):
				commands.append(["tunctl", "-t", net['dev']])
				commands.append(["ip", "link", "set", "dev", net['dev'], "up"])
				commands.append(["ip", "addr", "add", "dev", net['dev'], "0.0.0.0"])

				chain = "VMNET-FWD-" + vmid.upper()

				commands.append(["iptables", "--new-chain", chain])
				if ('ip' in net):
					for ip in net['ip']:
						commands.append(["ip", "route", "add", ip, "dev", net['dev']])
						commands.append(["iptables", "-A", chain, "-i", net['dev'], "-s", ip, "-j", "ACCEPT"])
				commands.append(["iptables", "-A", chain, "-i", net['dev'], "-j", "REJECT", "--reject-with", "icmp-admin-prohibited"])
				commands.append(["iptables", "-A", "FORWARD", "-j", chain])
				
				commands.append(["ip6tables", "--new-chain", chain])
				if ('ipv6' in net):
					for ipv6 in net['ipv6']:
						commands.append( ["ip", "-6", "route", "add", ipv6, "dev", net['dev']])
						commands.append(["ip6tables", "-A", chain, "-i", net['dev'], "-s", ipv6, "-j", "ACCEPT"])
				commands.append(["ip6tables", "-A", chain, "-i", net['dev'], "-j", "REJECT", "--reject-with", "icmp6-adm-prohibited"])
				commands.append(["ip6tables", "-A", "FORWARD", "-j", chain])
		
		for cmd in commands:
			subprocess.call(cmd, stdout=open("/dev/null"))
	
	def teardownNetwork(self, vmid):
		if ('VMs' in self.config) and (vmid in self.config['VMs']):
			config = self.config['VMs'][vmid]
		else:
			raise Exception("No such VM configuration")
		
		commands = []
		if ('network' in config):
			net = config['network']
			if ('dev' in net):
				commands.append(["tunctl", "-d", net['dev']])

				chain = "VMNET-FWD-" + vmid.upper()

				commands.append(["iptables", "-F", chain])
				commands.append(["iptables", "-D", "FORWARD", "-j", chain])
				commands.append(["iptables", "--delete-chain", chain])
				
				commands.append(["ip6tables", "-F", chain])
				commands.append(["ip6tables", "-D", "FORWARD", "-j", chain])
				commands.append(["ip6tables", "--delete-chain", chain])
		
		for cmd in commands:
			subprocess.call(cmd, stdout=open("/dev/null"))