extends Node2D

@export var speed = 400 # How fast the virus will move (pixels/sec).
@export var attack_range = 200 # virus vision radius (pixels)

# a virus is instantiated as Spawning and transitions (matures) into Spawned
# after a timer timeout, after which it is activated and ready to do its thing.
enum SpawningState {Spawning, Spawned}
# when idle, a virus Waits. if it has already performed some action, it may
# become Blocked for a while. otherwise it might be Running. like a process.
enum ActionState {Blocked, Waiting, Running}

var spawning_state
var action_state

var targets # who the virus will attack

func _ready():
	self.spawning_state = SpawningState.Spawning
	self.action_state = ActionState.Waiting

func _process(delta):
	if self.spawning_state != SpawningState.Spawned:
		return # do nothing if not yet spawned
	if len(self.targets) == 0:
		return # do nothing if no set targets

	# --- determine nearest target
	var nearest_target = self.targets[0] 
	var shortest_distance = 0
	for i in range(1, len(self.targets)):
		var target = self.targets[i]
		var distance = self.position.distance_to(target)
		if distance < shortest_distance:
			shortest_distance = distance
			nearest_target = target

	# --- attack the nearest target, if within range
	if self.action_state != ActionState.Blocked:
		if shortest_distance < self.attack_range:
			self.attack(nearest_target)

	# --- move towards nearest target
	self.position += \
		self.position.direction_to(nearest_target) * self.speed * delta

func attack(target):
	# do attack, block until timer
	self.action_state = ActionState.Blocked

func _on_mature():
	spawning_state = SpawningState.Spawned