class_name Fahrplan extends Node3D

## easy graph: <station> : [Track1Train1 (next halt), Track1Train2], [Track2Train1(next halt), ...]
## CAVEAT: These must be direct children of the fahrplan!
@onready var fahrplan : Dictionary[Station, Array] = {
	$hirschfeld: [["u2", $uni_mensa, "u1", $parity_square],[]],
	$uni_mensa : [["u2", $uni_main],[]],
	$uni_main: [["u2", $ministry],["u8", $rosenthal, "u2", $uni_mensa, "u1", $saint_exupery]],
	$parity_square : [["u4", $saint_exupery, "u1", $saint_exupery], []],
	$saint_exupery : [["u4", $rosenthal], ["u1", $uni_main]],

	$ministry : ["", null, "", null], # Endstation
	$rosenthal : ["", null, "", null], # Endstation
}

## List of all registered station nodes, used to unparent them
@onready var stations : Array[Station] = fahrplan.keys()
@onready var tracks : Array[Dolly] = [%Track0Dolly, %Track1Dolly]

@export var empty_train_random_delay : Vector2 = Vector2(5.0, 20.0)

func _set_signage_texts(group: StringName, message: String) -> void:
	get_tree().call_group(group, "set_text", "")
	for i in range(len(message)):
		get_tree().call_group(group, "set_text", message.substr(0, i+1))
		await get_tree().create_timer(0.05).timeout

func _ready() -> void:
	await get_tree().process_frame

	tracks[0].train_left.connect(_player_train_left)
	tracks[1].train_left.connect(_player_train_left)
	_unparent_all_stations_except($hirschfeld)
	enter_station(current)


## The current station
var current : Station
var stop := false

var destinations : Array[Station] = [null, null]

## Begins the scheduled traffic (looping through the list of destinations) on a given track
func _begin_traffic_loop(track: Dolly, cancel: Array) -> void:
	if not track.player_on_board and fahrplan[current][track.index] == null: # empty trains dont arrive at endstation
		track.arrive(true)
		_set_signage_texts(track.signage_group, "Endstation")
		return

	var routes : Array = fahrplan[current][track.index]
	if routes.is_empty():
		_set_signage_texts(track.signage_group, "Verkehr z. Zt.\nunregelmäßig")
		return

	while true:
		if cancel.is_empty(): return # abort the loop

		var line : StringName = routes.pop_front()
		var next : Station = routes.pop_front()

		routes.append(line) # It's a ring buffer
		routes.append(next) # It's a ring buffer

		destinations[track.index] = next
		track.set_line(line)
		_set_signage_texts(track.signage_group, current.get_label(line, next)) # TODO: load nice string

		# Vary our schedule a little by making empty trains wait a random amount of time
		if not track.player_on_board:
			await get_tree().create_timer(randf_range(empty_train_random_delay.x, empty_train_random_delay.y)).timeout

		if cancel.is_empty(): return # abort the loop
		await track.cycle() # arrive and depart


var cancellation_token : Array

func enter_station(station: Station):
	prints("------------", "ENTER STATION", station, station.name, "------------")
	remove_child(current)
	current = station
	add_child(station)

	cancellation_token = ["go"] # Allocate a new stopping token
	_begin_traffic_loop(tracks[0], cancellation_token)
	_begin_traffic_loop(tracks[1], cancellation_token)


func _player_train_left(track: Dolly) -> void:
	cancellation_token.clear()
	enter_station(destinations[track.index])

func _unparent_all_stations_except(except : Node3D):
	for station in stations:
		assert(station.get_parent() == self, "A station that isn't a child of Fahrplan is in the Fahrplan: %s" % station.name)
		station.visible = true # Make visible by default, parenting handles visibility and collision
		if station == except:
			current = station
			continue
		remove_child(station)