import virtualbox
from contextlib import contextmanager
from tests.system.tools import waituntil
import logging
log = logging.getLogger(__name__)


class VirtualBoxInstance(object):

	cpus = 1
	memory = 256

	def __init__(self, image, name, arch, release):
		self.image = image
		self.name = name
		self.arch = arch
		self.release = release
		self.vbox = virtualbox.VirtualBox()
		manager = virtualbox.Manager()
		self.session = manager.get_session()

	def create(self):
		log.debug('Creating vbox machine `{name}\''.format(name=self.name))
		# create machine
		os_type = {'x86': 'Debian',
		           'amd64': 'Debian_64'}.get(self.arch)
		self.machine = self.vbox.create_machine(settings_file='', name=self.name,
		                                        groups=[], os_type_id=os_type, flags='')
		self.machine.cpu_count = self.cpus
		self.machine.memory_size = self.memory
		self.machine.save_settings()  # save settings, so that we can register it
		self.vbox.register_machine(self.machine)

		# attach image
		log.debug('Attaching SATA storage controller to vbox machine `{name}\''.format(name=self.name))
		with lock(self.machine, self.session) as machine:
			strg_ctrl = machine.add_storage_controller('SATA Controller',
			                                           virtualbox.library.StorageBus.sata)
			strg_ctrl.port_count = 1
			machine.attach_device(name='SATA Controller', controller_port=0, device=0,
			                      type_p=virtualbox.library.DeviceType.hard_disk,
			                      medium=self.image.medium)
			machine.save_settings()

		# redirect serial port
		log.debug('Enabling serial port on vbox machine `{name}\''.format(name=self.name))
		with lock(self.machine, self.session) as machine:
			serial_port = machine.get_serial_port(0)
			serial_port.enabled = True
			import tempfile
			handle, self.serial_port_path = tempfile.mkstemp()
			import os
			os.close(handle)
			serial_port.path = self.serial_port_path
			serial_port.host_mode = virtualbox.library.PortMode.host_pipe
			serial_port.server = True  # Create the socket on startup
			machine.save_settings()

	def boot(self):
		log.debug('Booting vbox machine `{name}\''.format(name=self.name))
		self.machine.launch_vm_process(self.session, 'headless').wait_for_completion(-1)
		from tests.system.tools import read_from_socket
		# Gotta figure out a more reliable way to check when the system is done booting.
		# Maybe bootstrapped unit test images should have a startup script that issues
		# a callback to the host.
		from bootstrapvz.common.releases import wheezy
		if self.release <= wheezy:
			termination_string = 'INIT: Entering runlevel: 2'
		else:
			termination_string = 'Debian GNU/Linux'
		self.console_output = read_from_socket(self.serial_port_path, termination_string, 120)

	def shutdown(self):
		log.debug('Shutting down vbox machine `{name}\''.format(name=self.name))
		self.session.console.power_down().wait_for_completion(-1)
		if not waituntil(lambda: self.machine.session_state == virtualbox.library.SessionState.unlocked):
			raise LockingException('Timeout while waiting for the machine to become unlocked')

	def destroy(self):
		log.debug('Destroying vbox machine `{name}\''.format(name=self.name))
		if hasattr(self, 'machine'):
			try:
				log.debug('Detaching SATA storage controller from vbox machine `{name}\''.format(name=self.name))
				with lock(self.machine, self.session) as machine:
					machine.detach_device(name='SATA Controller', controller_port=0, device=0)
					machine.save_settings()
			except virtualbox.library.VBoxErrorObjectNotFound:
				pass
			log.debug('Unregistering and removing vbox machine `{name}\''.format(name=self.name))
			self.machine.unregister(virtualbox.library.CleanupMode.unregister_only)
			self.machine.remove(delete=True)
		else:
			log.debug('vbox machine `{name}\' was not created, skipping destruction'.format(name=self.name))


@contextmanager
def lock(machine, session):
	if machine.session_state != virtualbox.library.SessionState.unlocked:
		msg = ('Acquiring lock on machine failed, state was `{state}\' '
		       'instead of `Unlocked\'.'.format(state=str(machine.session_state)))
		raise LockingException(msg)

	machine.lock_machine(session, virtualbox.library.LockType.write)
	yield session.machine

	if machine.session_state != virtualbox.library.SessionState.locked:
		if not waituntil(lambda: machine.session_state == virtualbox.library.SessionState.unlocked):
			msg = ('Error before trying to release lock on machine, state was `{state}\' '
			       'instead of `Locked\'.'.format(state=str(machine.session_state)))
			raise LockingException(msg)

	session.unlock_machine()

	if not waituntil(lambda: machine.session_state == virtualbox.library.SessionState.unlocked):
		msg = ('Timeout while trying to release lock on machine, '
		       'last state was `{state}\''.format(state=str(machine.session_state)))
		raise LockingException(msg)


class LockingException(Exception):
	pass