    """
    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]

            #minute difference
            if minute > currMin:
                minuteDifference = minute - currMin
            elif minute < currMin:
                minuteDifference = 60 - currMin + minute
            else: #equal
                minuteDifference = 0

            #hourDifference
            if hour > currHour:
                hourDifference = hour - currHour
            elif hour < currHour:
                hourDifference = 24 - currHour + hour
            else: #equal
                hourDifference = 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)