extends Area2D

# #101 (#97c): the part of a structure a wave can actually hit.
#
# A Building is a plain Node2D, so nothing could collide with it - enemies
# flew through the mothership without noticing. This gives it a body in the
# same shape the rest of the game already understands: an Area2D in a group,
# exactly like a Ship or an asteroid, so EnemyProjectile needed one extra
# branch rather than a new concept.
#
# Damage is applied on a TICK rather than on area_entered. Entry fires once,
# which is right for a rammer - it dies on the first strike - but would let
# a sniper that drifted inside sit there scratch-free for ever. On a tick,
# an enemy parked on a structure is besieging it, which is what #97 asks
# for.

const STRIKE_INTERVAL: float = 0.7
var _strike_timer: float = 0.0


func _ready() -> void:
	add_to_group("player_buildings")


func building_id() -> int:
	var building: Node = get_parent()
	return 0 if building == null else int(building.building_id)


# Called by EnemyProjectile, which knows nothing about buildings beyond this
# name - the same call it makes on a Ship.
func take_damage(amount: int) -> void:
	GameState.damage_building(building_id(), amount)


func _physics_process(delta: float) -> void:
	_strike_timer -= delta
	if _strike_timer > 0.0:
		return
	_strike_timer = STRIKE_INTERVAL
	var id: int = building_id()
	if id == 0:
		return
	for area in get_overlapping_areas():
		if not is_instance_valid(area) or not area.is_in_group("enemies"):
			continue
		var damage: int = area.contact_damage() if area.has_method("contact_damage") else 6
		# The structure is told first, for the same reason Ship tells the
		# enemy first: resolving the enemy's own death can free it, and a
		# rammer must still land its hit on the way out.
		GameState.damage_building(id, damage)
		if area.has_method("collide_with_player_building"):
			area.collide_with_player_building()