# Duane's Dungeon - a rogue-like game
# Copyright (C) 2023 Duane Robertson

# state.gd - basic finite machine state

# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.

# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.

# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>.


# States can stack by adding children.
# If state has a child, it defers to the child.
# If state has no child, it accepts input and updates itself.
# still need to enable/disable controls
# two types of input: player commands and buttons
# All interface components belong to a state.


extends Node2D
class_name State


var game:Node2D
var sname := 'state'
var stacked


func _unhandled_input(event):
	if stacked:
		return

	input(event)

	# Only one state should be taking input.
	get_viewport().set_input_as_handled()


func _ready():
	game = get_node('/root/Game')


func enter():
	pass


func exit(state=null):
	# A stacked state calls exit with no argument, to return.
	if state == null:
		get_parent().stacked = null
	else:
		###########################################
		# This allows gui changes before creating a dungeon.
		# It might be better to create it in a thread, but
		#  the dungeon isn't thread-safe.
		###########################################
		await RenderingServer.frame_post_draw
		###########################################
		get_parent().add_child(state.new())

	get_tree().queue_delete(self)


func input(_event):
	pass


func stack(state):
	var new_state = state.new()
	add_child(new_state)
	stacked = new_state