ft (Wip): FSM behaviour prey

evolve-die-repeat/shared/state_machine.gd

@@ -0,0 +1,39 @@
+class_name StateMachine extends Node
+
+@export var initial_state: State = null
+
+# use first child as 'active' state
+@onready var state: State = (func get_initial_state() -> State:
+	return initial_state if initial_state != null else get_child(0)
+).call()
+
+# Connect states on ready, then wait.
+func _ready() -> void:
+	for node: State in find_children("*", "State"):
+		node.finished.connect(_transition_to_next_state)
+
+	await owner.ready
+	state.enter("")
+
+#  pass unhandled input to state.
+func _unhandled_input(event: InputEvent) -> void:
+	state.handle_input(event)
+
+# Pass process tick to state.
+func _process(delta: float) -> void:
+	state.update(delta)
+
+# Pass physics tick to state.
+func _physics_process(delta: float) -> void:
+	state.physics_update(delta)
+
+# Transition to next state
+func _transition_to_next_state(target_path: String, data: Dictionary = {}) -> void:
+	if not has_node(target_path):
+		printerr(owner.name + ": Trying to transition to state " + target_path + ", which does not exist.")
+		return
+
+	var previous_state_path := state.name
+	state.exit()
+	state = get_node(target_path)
+	state.enter(previous_state_path, data)