# This file is part of Gajim.
#
# SPDX-License-Identifier: GPL-3.0-only

from __future__ import annotations

from typing import Any

import inspect
import logging
import operator
import traceback
from collections.abc import Callable

from nbxmpp import NodeProcessed

from gajim.common import app
from gajim.common.events import ApplicationEvent

log = logging.getLogger('gajim.c.ged')

PRECORE = 10
CORE = 20
POSTCORE = 30
PREGUI = 40
PREGUI1 = 50
GUI1 = 60
POSTGUI1 = 70
PREGUI2 = 80
GUI2 = 90
POSTGUI2 = 100
POSTGUI = 110


HandlerFuncT = Callable[[Any], Any]
EventHandlerT = tuple[str, int, HandlerFuncT]


class GlobalEventsDispatcher:

    def __init__(self):
        self.handlers: dict[str, list[tuple[int, HandlerFuncT]]] = {}

    def register_event_handler(self,
                               event_name: str,
                               priority: int,
                               handler: HandlerFuncT) -> None:

        if event_name not in self.handlers:
            self.handlers[event_name] = [(priority, handler)]
            return

        handlers_list = self.handlers[event_name]
        if (priority, handler) in handlers_list:
            # Don’t register same handler/prio multiple times
            return

        handlers_list.append((priority, handler))
        handlers_list.sort(key=operator.itemgetter(0))

    def remove_event_handler(self,
                             event_name: str,
                             priority: int,
                             handler: HandlerFuncT) -> None:

        if event_name in self.handlers:
            try:
                self.handlers[event_name].remove((priority, handler))
            except ValueError as error:
                log.warning(
                    '''Function (%s) with priority "%s" never
                    registered as handler of event "%s".
                    Error: %s''', handler, priority, event_name, error)

    def raise_event(self, event_obj: ApplicationEvent) -> Any:
        event_name = event_obj.name
        log.debug('Raise event: %s', event_name)
        if event_name in self.handlers:
            node_processed = False
            # Iterate over a copy of the handlers list, so while iterating
            # the original handlers list can be modified
            for _priority, handler in list(self.handlers[event_name]):
                try:
                    if inspect.ismethod(handler):
                        log.debug('Call handler %s on %s',
                                  handler.__name__,
                                  handler.__self__)
                    else:
                        log.debug('Call handler %s', handler.__name__)
                    if handler(event_obj):
                        return True
                except NodeProcessed:
                    node_processed = True
                except Exception:
                    log.error('Error while running an event handler: %s',
                              handler)
                    traceback.print_exc()
            if node_processed:
                raise NodeProcessed


class EventHelper:
    def __init__(self):
        self.__event_handlers: list[EventHandlerT] = []

    def has_events_registered(self) -> bool:
        return bool(self.__event_handlers)

    def register_event(self,
                       event_name: str,
                       priority: int,
                       handler: HandlerFuncT) -> None:

        if (event_name, priority, handler) in self.__event_handlers:
            return

        self.__event_handlers.append((event_name, priority, handler))
        app.ged.register_event_handler(event_name, priority, handler)

    def register_events(self, events: list[EventHandlerT]) -> None:
        for handler in events:
            if handler in self.__event_handlers:
                continue
            self.__event_handlers.append(handler)
            app.ged.register_event_handler(*handler)

    def unregister_event(self,
                         event_name: str,
                         priority: int,
                         handler: HandlerFuncT) -> None:

        self.__event_handlers.remove((event_name, priority, handler))
        app.ged.register_event_handler(event_name, priority, handler)

    def unregister_events(self) -> None:
        for handler in self.__event_handlers:
            app.ged.remove_event_handler(*handler)
        self.__event_handlers.clear()
