import logging
import os
import sys
import time
import threading

from neco.util import guid
from neco.util.timefuncs import strfnow, strfdiff, strfvalid 
from neco.execution.resource import ResourceFactory, ResourceAction, \
        ResourceState
from neco.execution.scheduler import HeapScheduler, Task, TaskStatus
from neco.util.parallel import ParallelRun

# TODO: use multiprocessing instead of threading

class ExperimentController(object):
    def __init__(self, root_dir = "/tmp", loglevel = 'error'): 
        super(ExperimentController, self).__init__()
        # root directory to store files
        self._root_dir = root_dir

        # generator of globally unique ids
        self._guid_generator = guid.GuidGenerator()
        
        # Resource managers
        self._resources = dict()

        # Resource managers
        self._group = dict()

        # Scheduler
        self._scheduler = HeapScheduler()

        # Tasks
        self._tasks = dict()

        # Event processing thread
        self._stop = False
        self._cond = threading.Condition()
        self._thread = threading.Thread(target = self._process)
        self._thread.start()

        # Logging
        self._logger = logging.getLogger("neco.execution.ec")
        self._logger.setLevel(getattr(logging, loglevel.upper()))

    def get_task(self, tid):
        return self._tasks.get(tid)

    def get_resource(self, guid):
        return self._resources.get(guid)

    @property
    def resources(self):
        return self._resources.keys()

    def register_resource(self, rtype, guid = None):
        # Get next available guid
        guid = self._guid_generator.next(guid)
        
        # Instantiate RM
        rm = ResourceFactory.create(rtype, self, guid)

        # Store RM
        self._resources[guid] = rm

        return guid

    def create_group(self, *args):
        guid = self._guid_generator.next(guid)

        grp = [arg for arg in args]

        self._resources[guid] = grp

        return guid
 

    def get_attributes(self, guid):
        rm = self.get_resource(guid)
        return rm.get_attributes()

    def get_filters(self, guid):
        rm = self.get_resource(guid)
        return rm.get_filters()

    def register_connection(self, guid1, guid2):
        rm1 = self.get_resource(guid1)
        rm2 = self.get_resource(guid2)

        rm1.connect(guid2)
        rm2.connect(guid1)

    def register_condition(self, group1, action, group2, state,
            time = None):
        """ Registers an action START or STOP for all RM on group1 to occur 
            time 'time' after all elements in group2 reached state 'state'.

            :param group1: List of guids of RMs subjected to action
            :type group1: list

            :param action: Action to register (either START or STOP)
            :type action: ResourceAction

            :param group2: List of guids of RMs to we waited for
            :type group2: list

            :param state: State to wait for on RMs (STARTED, STOPPED, etc)
            :type state: ResourceState

            :param time: Time to wait after group2 has reached status 
            :type time: string

        """
        if isinstance(group1, int):
            group1 = [group1]
        if isinstance(group2, int):
            group2 = [group2]

        for guid1 in group1:
            rm = self.get_resource(guid1)
            rm.register_condition(action, group2, state, time)

    def discover(self, guid, filters):
        rm = self.get_resource(guid)
        return rm.discover(filters)

    def provision(self, guid, filters):
        rm = self.get_resource(guid)
        return rm.provision(filters)

    def get(self, guid, name):
        rm = self.get_resource(guid)
        return rm.get(name)

    def set(self, guid, name, value):
        rm = self.get_resource(guid)
        return rm.set(name, value)

    def state(self, guid):
        rm = self.get_resource(guid)
        return rm.state

    def stop(self, guid):
        rm = self.get_resource(guid)
        return rm.stop()

    def start(self, guid):
        rm = self.get_resource(guid)
        return rm.start()

    def set_with_conditions(self, name, value, group1, group2, state,
            time = None):
        """ Set value 'value' on attribute with name 'name' on all RMs of
            group1 when 'time' has elapsed since all elements in group2 
            have reached state 'state'.

            :param name: Name of attribute to set in RM
            :type name: string

            :param value: Value of attribute to set in RM
            :type name: string

            :param group1: List of guids of RMs subjected to action
            :type group1: list

            :param action: Action to register (either START or STOP)
            :type action: ResourceAction

            :param group2: List of guids of RMs to we waited for
            :type group2: list

            :param state: State to wait for on RMs (STARTED, STOPPED, etc)
            :type state: ResourceState

            :param time: Time to wait after group2 has reached status 
            :type time: string

        """
        if isinstance(group1, int):
            group1 = [group1]
        if isinstance(group2, int):
            group2 = [group2]

        for guid1 in group1:
            rm = self.get_resource(guid)
            rm.set_with_conditions(name, value, group2, state, time)

    def stop_with_conditions(self, guid):
        rm = self.get_resource(guid)
        return rm.stop_with_conditions()

    def start_with_conditions(self, guid):
        rm = self.get_resource(guid)
        return rm.start_with_condition()

    def deploy(self, group = None, wait_all_deployed = True):
        """ Deploy all resource manager in group

        :param group: List of guids of RMs to deploy
        :type group: list

        :param wait_all_deployed: Wait until all RMs are deployed in
            order to start the RMs
        :type guid: int

        """
        def steps(rm):
            rm.deploy()
            rm.start_with_conditions()

            # Only if the RM has STOP consitions we
            # schedule a stop. Otherwise the RM will stop immediately
            if rm.conditions.get(ResourceAction.STOP):
                rm.stop_with_conditions()

        if not group:
            group = self.resources

        threads = []
        for guid in group:
            rm = self.get_resource(guid)

            if wait_all_deployed:
                towait = list(group)
                towait.remove(guid)
                self.register_condition(guid, ResourceAction.START, 
                        towait, ResourceState.DEPLOYED)

            thread = threading.Thread(target = steps, args = (rm,))
            threads.append(thread)
            thread.start()

        for thread in threads:
            thread.join()

    def release(self, group = None):
        if not group:
            group = self.resources

        threads = []
        for guid in group:
            rm = self.get_resource(guid)
            thread = threading.Thread(target=rm.release)
            threads.append(thread)
            thread.start()

        for thread in threads:
            thread.join()

    def shutdown(self):
        self.release()
        
        self._stop = True
        self._cond.acquire()
        self._cond.notify()
        self._cond.release()
        if self._thread.is_alive():
           self._thread.join()

    def schedule(self, date, callback, track = False):
        """ Schedule a callback to be executed at time date.

            date    string containing execution time for the task.
                    It can be expressed as an absolute time, using
                    timestamp format, or as a relative time matching
                    ^\d+.\d+(h|m|s|ms|us)$

            callback    code to be executed for the task. Must be a
                        Python function, and receives args and kwargs
                        as arguments.

            track   if set to True, the task will be retrivable with
                    the get_task() method
        """
        timestamp = strfvalid(date)
        
        task = Task(timestamp, callback)
        task = self._scheduler.schedule(task)

        if track:
            self._tasks[task.id] = task
  
        # Notify condition to wake up the processing thread
        self._cond.acquire()
        self._cond.notify()
        self._cond.release()

        return task.id
     
    def _process(self):
        runner = ParallelRun(maxthreads = 50)
        runner.start()

        try:
            while not self._stop:
                self._cond.acquire()
                task = self._scheduler.next()
                self._cond.release()

                if not task:
                    # It there are not tasks in the tasks queue we need to 
                    # wait until a call to schedule wakes us up
                    self._cond.acquire()
                    self._cond.wait()
                    self._cond.release()
                else: 
                    # If the task timestamp is in the future the thread needs to wait
                    # until time elapse or until another task is scheduled
                    now = strfnow()
                    if now < task.timestamp:
                        # Calculate time difference in seconds
                        timeout = strfdiff(task.timestamp, now)
                        # Re-schedule task with the same timestamp
                        self._scheduler.schedule(task)
                        # Sleep until timeout or until a new task awakes the condition
                        self._cond.acquire()
                        self._cond.wait(timeout)
                        self._cond.release()
                    else:
                        # Process tasks in parallel
                        runner.put(self._execute, task)
        except:  
            import traceback
            err = traceback.format_exc()
            self._logger.error("Error while processing tasks in the EC: %s" % err)

    def _execute(self, task):
        # Invoke callback
        task.status = TaskStatus.DONE

        try:
            task.result = task.callback()
        except:
            import traceback
            err = traceback.format_exc()
            self._logger.error("Error while executing event: %s" % err)

            task.result = err
            task.status = TaskStatus.ERROR