"""
This is the TaskManager python package.  It provides a system for running any number of
predefined tasks in separate threads in an organized and controlled manner.

A task in this package is a class derived from the Task class.  The task should have a run
method that, when called, performs some task.

The Scheduler class is the organizing object.  It manages the addition, execution, deletion,
and well being of a number of tasks.  Once you have created your task class, you call the Scheduler to
get it added to the tasks to be run.

"""



from threading import Thread, Event
from TaskHandler import TaskHandler
from time import time, sleep
from exceptions import IOError

class Scheduler(Thread):
	"""
	The top level class of the TaskManager system.  The Scheduler is a thread that 
	handles organizing and running tasks.  The Sheduler class should be instantiated 
	to start a TaskManager sessions.  It's run method should be called to start the 
	TaskManager.  It's stop method should be called to end the TaskManager session.
	"""

	## Init ##

	def __init__(self, daemon=1):
		Thread.__init__(self)
		self._notifyEvent = Event()
		self._nextTime = None
		self._scheduled = {}
		self._running = {}
		self._onDemand = {}
		self._isRunning = 0
		if daemon: self.setDaemon(1)


	## Event Methods ##

	def wait(self, seconds=None):
		"""
		Our own version of wait.
		When called, it waits for the specified number of seconds, or until it is
		notified that it needs to wake up, through the notify event.
		"""
		try:
			self._notifyEvent.wait(seconds)
		except IOError, e:
			pass
		self._notifyEvent.clear()


	## Attributes ##
	
	def runningTasks(self):
		return self._running

	def running(self, name, default=None):
		"""
		Returns a task with the given name from the "running" list, 
		if it is present there.
		"""
		return self._running.get(name, default)
			
	def hasRunning(self, name):
		"""
		Check to see if a task with the given name is currently running.
		"""
		return self._running.has_key(name)

	def setRunning(self, handle):
		"""
		Add a task to the running dictionary.
		Used internally only.
		"""
		self._running[handle.name()] = handle

	def delRunning(self, name):
		"""
		Delete a task from the running list.
		Used Internally.
		"""
		try:
			handle = self._running[name]
			del self._running[name]
			return handle
		except:
			return None

	def scheduledTasks(self):
		return self._scheduled

	def scheduled(self, name, default=None):
		"""
		Returns a task from the scheduled list.
		"""			
		return self._scheduled.get(name, default)
					
	def hasScheduled(self, name):
		"""
		Is the task with he given name in the scheduled list?
		"""
		return self._scheduled.has_key(name)

	def setScheduled(self, handle):
		"""
		Add the given task to the scheduled list.
		"""
		self._scheduled[handle.name()] = handle

	def delScheduled(self, name):
		"""
		Deleted a task with the given name from the scheduled list.
		"""
		try:
			handle = self._scheduled[name]
			del self._scheduled[name]
			return handle
		except:
			return None

	def onDemandTasks(self):
		return self._onDemand
		
	def onDemand(self, name, default=None):
		"""
		Returns a task from the onDemand list.
		"""
		return self._onDemand.get(name, default)

	def hasOnDemand(self, name):
		"""
		Is the task with he given name in the onDemand list?
		"""		
		return self._onDemand.has_key(name)

	def setOnDemand(self, handle):
		"""
		Add the given task to the onDemand list.
		"""
		self._onDemand[handle.name()] = handle

	def delOnDemand(self, name):
		"""
		Deleted a task with the given name from the onDemand list.
		"""
		try:
			handle = self._onDemand[name]
			del self._onDemand[name]
			return handle
		except:
			return None

	def nextTime(self):
		return self._nextTime

	def setNextTime(self, time):
		self._nextTime = time

	def isRunning(self):
		return self._isRunning


	## Adding Tasks ##

	def addTimedAction(self, time, task, name):
		"""
		This method is used to add an action to be run once, at a specific time.
		"""
		handle = self.unregisterTask(name)
		if not handle:
			handle = TaskHandler(self, time, 0, task, name)
		else:
			handle.reset(time, 0, task, 1)
		self.scheduleTask(handle)

	def addActionOnDemand(self, task, name):
		"""
		This method is used to add a task to the scheduler that will not be scheduled 
		until specifically requested.
		"""
		handle = self.unregisterTask(name)
		if not handle:
			handle = TaskHandler(self, time(), 0, task, name)
		else:
			handle.reset(time(), 0, task, 1)
		self.setOnDemand(handle)

	def addDailyAction(self, hour, minute, task, name):
		"""		
		This method is used to add an action to be run every day at a specific time.
		If a task with the given name is already registered with the scheduler, that task 
		will be removed from the scheduling queue and registered anew as a periodic task.
			
		Can we make this addCalendarAction?  What if we want to run something once a week?
		We probably don't need that for Webware, but this is a more generally useful module.
		This could be a difficult function, though.  Particularly without mxDateTime.
		"""
		import time
		current = time.localtime(time.time())
		currHour = current[3]
		currMin = current[4]

		if hour > currHour:
			hourDifference = hour - currHour
			if minute > currMin:
				minuteDifference = minute - currMin
			elif minute < currMin:
				minuteDifference = 60 - currMin + minute
				hourDifference -= 1
			else:
				minuteDifference = 0
		elif hour < currHour:
			hourDifference = 24 - currHour + hour
			if minute > currMin:
				minuteDifference = minute - currMin
			elif minute < currMin:
				minuteDifference = 60 - currMin + minute
				hourDifference -= 1
			else:
				minuteDifference = 0
		else:
			if minute > currMin:
				hourDifference = 0
				minuteDifference = minute - currMin
			elif minute < currMin:
				minuteDifference = 60 - currMin + minute
				hourDifference = 23
			else:
				hourDifference = 0
				minuteDifference = 0

		delay = (minuteDifference + (hourDifference * 60)) * 60
		self.addPeriodicAction(time.time()+delay, 24*60*60, task, name)


	def addPeriodicAction(self, start, period, task, name):
		"""
		This method is used to add an action to be run at a specific initial time, 
		and every period thereafter.

		The scheduler will not reschedule a task until the last scheduled instance 
		of the task has completed.

		If a task with the given name is already registered with the scheduler, 
		that task will be removed from the scheduling queue and registered
		anew as a periodic task.
		"""
		
		handle = self.unregisterTask(name)
		if not handle:
			handle = TaskHandler(self, start, period, task, name)
		else:
			handle.reset(start, period, task, 1)
		self.scheduleTask(handle)


	## Task methods ##

	def unregisterTask(self, name):
		"""
		This method unregisters the named task so that it can be rescheduled with 
		different parameters, or simply removed.
		"""
		handle = None
		if self.hasScheduled(name):
			handle = self.delScheduled(name)
		if self.hasOnDemand(name):
			handle = self.delOnDemand(name)
		if handle:
			handle.unregister()
		return handle

	def runTaskNow(self, name):
		"""
		This method is provided to allow a registered task to be immediately executed.
		
		Returns 1 if the task is either currently running or was started, or 0 if the 
		task could not be found in the list of currently registered tasks.
		"""
		if self.hasRunning(name):
			return 1
		handle = self.scheduled(name)
		if not handle:
			handle = self.onDemand(name)
		if not handle:
			return 0
		self.runTask(handle)
		return 1
	
	def demandTask(self, name):
		"""
		This method is provided to allow the server to request that a task listed as being 
		registered on-demand be run as soon as possible.
		
		If the task is currently running, it will be flagged to run again as soon as the 
		current run completes. 

		Returns 0 if the task name could not be found on the on-demand or currently running lists.
		"""
		if  not self.hasRunning(name) and not self.hasOnDemand(name):
			return 0
		else:
			handle = self.running(name)
			if handle:
				handle.runOnCompletion()
				return 1
			handle = self.onDemand(name)
			if not handle:
				return 0			
			self.runTask(handle)
			return 1

	def stopTask(self, name):
		"""
		This method is provided to put an immediate halt to a running background task.
		
		Returns 1 if the task was either not running, or was running and was told to stop.
		"""
		handle = self.running(name)
		if not handle:
			return 0
		handle.stop()
		return 1


	def stopAllTasks(self):
		"""
		Terminate all running tasks.
		"""
		for i in self._running.keys():
			print "Stopping ",i
			self.stopTask(i)

	def disableTask(self, name):
		"""
		This method is provided to specify that a task be suspended. Suspended tasks will 
		not be scheduled until later enabled. If the task is currently running, it will 
		not be interfered with, but the task will not be scheduled for execution in future 
		until re-enabled.
		
		Returns 1 if the task was found and disabled.
		"""
		handle = self.running(name)
		if not handle:
			handle = self.scheduled(name)
		if not handle:
			return 0
		handle.disable()
		return 1

	def enableTask(self, name):
		"""
		This method is provided to specify that a task be re-enabled after a suspension.
		A re-enabled task will be scheduled for execution according to its original schedule, 
		with any runtimes that would have been issued during the time the task was suspended 
		simply skipped.

		Returns 1 if the task was found and enabled
		"""
		
		handle = self.running(name)
		if not handle:
			handle = self.scheduled(name)
		if not handle:
			return 0
		handle.enable()
		return 1

	def runTask(self, handle):
		"""
		This method is used by the Scheduler thread's main loop to put a task in 
		the scheduled hash onto the run hash.
		"""
		name = handle.name()
		if self.delScheduled(name) or self.delOnDemand(name):
			self.setRunning(handle)
			handle.runTask()

	def scheduleTask(self, handle):
		"""
		This method takes a task that needs to be scheduled and adds it to the scheduler. 
		All scheduling additions or changes are handled by this method. This is the only 
		Scheduler method that can notify the run() method that it may need to wake up early 
		to handle a newly registered task.
		"""
		self.setScheduled(handle)
		if not self.nextTime() or handle.startTime() < self.nextTime():
			self.setNextTime(handle.startTime())
			self.notify()


	## Misc Methods ##

	def notifyCompletion(self, handle):
		"""
		This method is used by instances of TaskHandler to let the Scheduler thread know 
		when their tasks have run to completion.
		This method is responsible for rescheduling the task if it is a periodic task.
		"""
		name = handle.name()
		if self.hasRunning(name):
			self.delRunning(name)
			if handle.startTime() and handle.startTime() > time():
				self.scheduleTask(handle)
			else:
				if handle.reschedule():
					self.scheduleTask(handle)
				elif not handle.startTime():
					self.setOnDemand(handle)
					if handle.runAgain():
						self.runTask(handle)

	def notify(self):
		self._notifyEvent.set()

	def stop(self):
		"""
		This method terminates the scheduler and its associated tasks.
		"""
		self._isRunning = 0
		self.notify()
		self.stopAllTasks()
		self.join()	 # jdh: wait until the scheduler thread exits; otherwise
					 # it's possible for the interpreter to exit before this thread
					 # has a chance to shut down completely, which causes a traceback


	## Main Method ##

	def run(self):
		"""
		This method is responsible for carrying out the scheduling work of this class 
		on a background thread. The basic logic is to wait until the next action is due to 
		run, move the task from our scheduled list to our running list, and run it. Other
		synchronized methods such as runTask(), scheduleTask(), and notifyCompletion(), may 
		be called while this method is waiting for something to happen. These methods modify 
		the data structures that run() uses to determine its scheduling needs.
		"""
		self._isRunning = 1
		while 1:
			if not self._isRunning:
				return
			if not self.nextTime():
				self.wait()
			else:
				nextTime = self.nextTime()
				currentTime = time()
				if currentTime < nextTime:
					sleepTime = nextTime - currentTime
					self.wait(sleepTime)
				if not self._isRunning: return
				currentTime = time()
				if currentTime >= nextTime:
					toRun = []
					nextRun = None
					for handle in self._scheduled.values():
						startTime = handle.startTime()
						if startTime <= currentTime:
							toRun.append(handle)
						else:
							if not nextRun:
								nextRun = startTime
							elif startTime < nextRun:
								nextRun = startTime
					self.setNextTime(nextRun)
					for handle in toRun:
						self.runTask(handle)