#===============================================================================
# This module stores events that can happen during the game. A procedure can
# subscribe to an event by adding itself to the event. It will then be called
# whenever the event occurs. Existing events are:
#-------------------------------------------------------------------------------
#   :on_game_map_setup - When a Game_Map is set up. Typically changes map data.
#   :on_new_spriteset_map - When a Spriteset_Map is created. Adds more things to
#     show in the overworld.
#   :on_frame_update - Once per frame. Various frame/time counters.
#   :on_leave_map - When leaving a map. End weather/expired effects.
#   :on_enter_map - Upon entering a new map. Set up new effects, end expired
#     effects.
#   :on_map_or_spriteset_change - Upon entering a new map or when spriteset was
#     made. Show things on-screen.
#-------------------------------------------------------------------------------
#   :on_player_change_direction - When the player turns in a different direction.
#   :on_leave_tile - When any event or the player starts to move from a tile.
#   :on_step_taken - When any event or the player finishes a step.
#   :on_player_step_taken - When the player finishes a step/ends surfing, except
#     as part of a move route. Step-based counters.
#   :on_player_step_taken_can_transfer - When the player finishes a step/ends
#     surfing, except as part of a move route. Step-based effects that can
#     transfer the player elsewhere.
#   :on_player_interact - When the player presses the Use button in the
#     overworld.
#-------------------------------------------------------------------------------
#   :on_trainer_load - When an NPCTrainer is generated (to battle against or as
#     a registered partner). Various modifications to that trainer and their
#     Pokémon.
#   :on_wild_species_chosen - When a species/level have been chosen for a wild
#     encounter. Changes the species/level (e.g. roamer, Poké Radar chain).
#   :on_wild_pokemon_created - When a Pokemon object has been created for a wild
#     encounter. Various modifications to that Pokémon.
#   :on_calling_wild_battle - When a wild battle is called. Prevents that wild
#     battle and instead starts a different kind of battle (e.g. Safari Zone).
#   :on_start_battle - Just before a battle starts. Memorize/reset information
#     about party Pokémon, which is used after battle for evolution checks.
#   :on_end_battle - Just after a battle ends. Evolution checks, Pickup/Honey
#     Gather, blacking out.
#   :on_wild_battle_end - After a wild battle. Updates Poké Radar chain info.
#===============================================================================
module EventHandlers
  @@events = {}

  # Add a named callback for the given event.
  def self.add(event, key, proc)
    @@events[event] = NamedEvent.new if !@@events.has_key?(event)
    @@events[event].add(key, proc)
  end

  # Remove a named callback from the given event.
  def self.remove(event, key)
    @@events[event]&.remove(key)
  end

  # Clear all callbacks for the given event.
  def self.clear(key)
    @@events[key]&.clear
  end

  # Trigger all callbacks from an Event if it has been defined.
  def self.trigger(event, *args)
    return @@events[event]&.trigger(*args)
  end
end