from contextlib import contextmanager
from bootstrapvz.remote import register_deserialization_handlers
import logging
log = logging.getLogger(__name__)

# Register deserialization handlers for objects
# that will pass between server and client
register_deserialization_handlers()


@contextmanager
def boot_manifest(manifest_data, boot_vars={}):
	from bootstrapvz.common.tools import load_data
	build_servers = load_data('build-servers.yml')
	from bootstrapvz.remote.build_servers import pick_build_server
	build_server = pick_build_server(build_servers, manifest_data)

	manifest_data = build_server.apply_build_settings(manifest_data)
	from bootstrapvz.base.manifest import Manifest
	manifest = Manifest(data=manifest_data)

	bootstrap_info = None
	log.info('Connecting to build server')
	with build_server.connect() as connection:
		log.info('Building manifest')
		bootstrap_info = connection.run(manifest)

	log.info('Creating and booting instance')
	from ..images import initialize_image
	image = initialize_image(manifest, build_server, bootstrap_info)
	try:
		with image.get_instance(**boot_vars) as instance:
			yield instance
	finally:
		image.destroy()


def waituntil(predicate, timeout=5, interval=0.05):
	import time
	threshhold = time.time() + timeout
	while time.time() < threshhold:
		if predicate():
			return True
		time.sleep(interval)
	return False


def read_from_socket(socket_path, termination_string, timeout, read_timeout=0.5):
		import socket
		import select
		import errno
		console = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
		console.connect(socket_path)
		console.setblocking(0)

		from timeit import default_timer
		start = default_timer()

		output = ''
		ptr = 0
		continue_select = True
		while continue_select:
			read_ready, _, _ = select.select([console], [], [], read_timeout)
			if console in read_ready:
				while True:
					try:
						output += console.recv(1024)
						if termination_string in output[ptr:]:
							continue_select = False
						else:
							ptr = len(output) - len(termination_string)
						break
					except socket.error, e:
						if e.errno != errno.EWOULDBLOCK:
							raise Exception(e)
						continue_select = False
			if default_timer() - start > timeout:
				from exceptions import SocketReadTimeout
				msg = ('Reading from socket `{path}\' timed out after {seconds} seconds.\n'
				       'Here is the output so far:\n{output}'
				       .format(path=socket_path, seconds=timeout, output=output))
				raise SocketReadTimeout(msg)
		console.close()
		return output