import time
import traceback
import commands
import threading
import json

from datetime import datetime
from collections import defaultdict
from core.models import *
from django.db.models import F, Q
from openstack.manager import OpenStackManager
from util.logger import Logger, logging, logger
#from timeout import timeout

debug_mode = False

logger = Logger(logfile='observer.log', level=logging.INFO)

class StepNotReady(Exception):
	pass

def toposort(g, steps):
	reverse = {}

	for k,v in g.items():
		for rk in v:
			try:
				reverse[rk].append(k)
			except:
				reverse[rk]=k

	sources = []
	for k,v in g.items():
		if not reverse.has_key(k):
			sources.append(k)


	for k,v in reverse.iteritems():
		if (not v):
			sources.append(k)

	order = []
	marked = []
	while sources:
		n = sources.pop()
		try:
			for m in g[n]:
				if m not in marked:
					sources.append(m)
					marked.append(m)
		except KeyError:
			pass
		if (n in steps):
			order.append(n)

	return order

class PlanetStackObserver:
	sync_steps = ['SyncNetworks','SyncNetworkSlivers','SyncSites','SyncSitePrivileges','SyncSlices','SyncSliceMemberships','SyncSlivers','SyncSliverIps']

	def __init__(self):
		self.manager = OpenStackManager()
		# The Condition object that gets signalled by Feefie events
		self.load_sync_steps()
		self.event_cond = threading.Condition()
		self.load_enacted()

	def wait_for_event(self, timeout):
		self.event_cond.acquire()
		self.event_cond.wait(timeout)
		self.event_cond.release()
		
	def wake_up(self):
		logger.info('Wake up routine called. Event cond %r'%self.event_cond)
		self.event_cond.acquire()
		self.event_cond.notify()
		self.event_cond.release()

	def load_sync_steps(self):
		dep_path = Config().pl_dependency_path
		try:
			# This contains dependencies between records, not sync steps
			self.model_dependency_graph = json.loads(open(dep_path).read())
		except Exception,e:
			raise e

		backend_path = Config().backend_dependency_path
		try:
			# This contains dependencies between backend records
			self.backend_dependency_graph = json.loads(open(backend_path).read())
		except Exception,e:
			raise e

		provides_dict = {}
		for s in sync_steps:
			for m in s.provides:
				provides_dict[m]=s.__name__
				
		step_graph = {}
		for k,v in model_dependency_graph.iteritems():
			try:
				source = provides_dict[k]
				for m in v:
					try:
						dest = provides_dict[m]
					except KeyError:
						pass
						# no deps, pass
					step_graph[source]=dest
					
			except KeyError:
				pass
				# no dependencies, pass
		
		if (backend_dependency_graph):
			backend_dict = {}
			for s in sync_steps:
				for m in s.serves:
					backend_dict[m]=s.__name__
					
			for k,v in backend_dependency_graph.iteritems():
				try:
					source = backend_dict[k]
					for m in v:
						try:
							dest = backend_dict[m]
						except KeyError:
							# no deps, pass
							pass
						step_graph[source]=dest
						
				except KeyError:
					pass
					# no dependencies, pass

		dependency_graph = step_graph

		self.ordered_steps = toposort(dependency_graph, steps)
		self.last_run_times={}
		for e in self.ordered_steps:
			self.last_run_times[e.name]=0

	def check_duration(self):
		try:
			if (duration > S.deadline):
				logger.info('Sync step %s missed deadline, took %.2f seconds'%(S.name,duration))
		except AttributeError:
			# S doesn't have a deadline
			pass

	def update_run_time(self, step):
		self.last_run_times[step.name]=time.time()

	def check_schedule(self, step):
		time_since_last_run = time.time() - self.last_run_times[step.name]
		try:
			if (time_since_last_run < step.requested_interval):
				raise StepNotReady
		except AttributeError:
			logger.info('Step %s does not have requested_interval set'%step.name)
			raise StepNotReady
	
	def check_class_dependency(self, step, failed_steps):
		for failed_step in failed_steps:
			if (failed_step in self.dependency_graph[step.name]):
				raise StepNotReady

	def run(self):
		if not self.manager.enabled or not self.manager.has_openstack:
			return

		while True:
			try:
				logger.info('Waiting for event')
				tBeforeWait = time.time()
				self.wait_for_event(timeout=300)
				logger.info('Observer woke up')

				# Set of whole steps that failed
				failed_steps = []

				# Set of individual objects within steps that failed
				failed_step_objects = []

				for S in self.ordered_steps:
					start_time=time.time()
					
					sync_step = S()
					sync_step.dependencies = self.dependencies[sync_step.name]
					sync_step.debug_mode = debug_mode

					should_run = False
					try:
						# Various checks that decide whether
						# this step runs or not
						self.check_class_dependency(sync_step, failed_steps) # dont run Slices if Sites failed
						self.check_schedule(sync_step) # dont run sync_network_routes if time since last run < 1 hour
						should_run = True
					except StepNotReady:
						logging.info('Step not ready: %s'%sync_step.name)
						failed_steps.add(sync_step)
					except:
						failed_steps.add(sync_step)

					if (should_run):
						try:
							duration=time.time() - start_time

							# ********* This is the actual sync step
							failed_objects = sync_step(failed=failed_step_objects)


							check_deadline(sync_step, duration)
							failed_step_objects.extend(failed_objects)
							self.update_run_time(sync_step)
						except:
							failed_steps.add(S)
			except:
				logger.log_exc("Exception in observer run loop")
				traceback.print_exc()