# -*- coding: utf-8 -*-

from threading import Lock
from traceback import print_exc

class EventManager:
    """
    Handles all event-related tasks, also stores an event queue for clients, so they can retrieve them later.

    **Known Events:**
    Most addon methods exist as events. These are some additional known events.

    ===================== ================ ===========================================================
    Name                      Arguments      Description
    ===================== ================ ===========================================================
    event                 eventName, *args Called for every event, with eventName and original args
    download:preparing    fid              A download was just queued and will be prepared now.
    download:start        fid              A plugin will immediately start the download afterwards.
    download:allProcessed                  All links were handled, pyLoad would idle afterwards.
    download:allFinished                   All downloads in the queue are finished.
    config:changed        sec, opt, value  The config was changed.
    ===================== ================ ===========================================================

    | Notes:
    |    download:allProcessed is *always* called before download:allFinished.
    """

    def __init__(self, core):
        self.core = core
        self.log = core.log

        # uuid : list of events
        self.clients = {}
        self.events = {"event": []}

        self.lock = Lock()

    def getEvents(self, uuid):
        """ Get accumulated events for uuid since last call, this also registers a new client """
        if uuid not in self.clients:
            self.clients[uuid] = Client()
        return self.clients[uuid].get()

    def addEvent(self, event, func):
        """Adds an event listener for event name"""
        if event in self.events:
            if func in self.events[event]:
                self.log.debug("Function already registered %s" % func)
            else:
                self.events[event].append(func)
        else:
            self.events[event] = [func]

    def removeEvent(self, event, func):
        """removes previously added event listener"""
        if event in self.events:
            self.events[event].remove(func)

    def removeFromEvents(self, func):
        """ Removes func from all known events """
        for name, events in self.events.iteritems():
            if func in events:
                events.remove(func)

    def dispatchEvent(self, event, *args):
        """dispatches event with args"""
        for f in self.events["event"]:
            try:
                f(event, *args)
            except Exception, e:
                self.log.warning("Error calling event handler %s: %s, %s, %s"
                % ("event", f, args, str(e)))
                if self.core.debug:
                    print_exc()

        if event in self.events:
            for f in self.events[event]:
                try:
                    f(*args)
                except Exception, e:
                    self.log.warning("Error calling event handler %s: %s, %s, %s"
                    % (event, f, args, str(e)))
                    if self.core.debug:
                        print_exc()