class_name AimedFleetAbilityController
extends Node2D

const COMBAT_TARGET = preload("res://core/CombatTarget.gd")

# Shared press-drag-release input and camera behavior for manually aimed fleet
# abilities. Subclasses provide the component, ammunition, target calculation,
# shot effect, and effect visuals.

const AIM_DEADZONE: float = 22.0

@export var minimum_zoom: float = 0.4
@onready var fleet: Node2D = get_node("../Fleet")
@onready var camera: Camera2D = get_node("../Camera2D")

var button: IconButton
var status: Label
var status_message_until: int = 0
var aiming: bool = false
var aim_touch: int = -1
var aim_start_screen: Vector2 = Vector2.ZERO
var aim_screen: Vector2 = Vector2.ZERO
var aim_target: Vector2 = Vector2.ZERO
var saved_zoom: float = 1.0
var restoring_zoom: bool = false


func _ready() -> void:
	button = get_node(_button_path())
	status = get_node(_status_path())
	button.visible = false
	status.text = ""
	queue_redraw()


func _process(delta: float) -> void:
	var had_visuals: bool = aiming or _has_effect_visuals()
	# #122: "there's no action button available, only movements". Checked
	# here rather than by the director reaching in, because this line runs
	# every frame and would put the button straight back.
	button.visible = fleet.has_capability(_component_id()) and not GameState.intro_active
	button.enabled = _next_ready_ship() != null and _can_afford_shot()
	if not button.visible and aiming:
		_cancel_aim()
	if status.text != "" and Time.get_ticks_msec() >= status_message_until:
		status.text = ""

	if restoring_zoom and not aiming:
		var zoom: float = move_toward(camera.zoom.x, saved_zoom,
			maxf(saved_zoom, 0.1) * delta * 5.0)
		camera.zoom = Vector2(zoom, zoom)
		if is_equal_approx(zoom, saved_zoom):
			restoring_zoom = false

	_advance_effects(delta)
	if aiming or _has_effect_visuals() or had_visuals:
		queue_redraw()


func can_begin_aim() -> bool:
	# An unaffordable shot still claims the press so the status label can
	# explain what is missing instead of silently passing the touch through.
	return button.visible and not button._blocked_by_modal() \
		and not aiming and _next_ready_ship() != null


# Fires immediately at a world point, with no press-drag-release. The mouse
# path (#80) has a crosshair already - it does not need to be dragged into
# existence - so it aims and fires in one call rather than pretending to be
# a touch.
func fire_at(world_target: Vector2) -> bool:
	if not button.visible or button._blocked_by_modal() or _next_ready_ship() == null:
		return false
	if not _can_afford_shot():
		_say(_unaffordable_message())
		return false
	# Recorded before firing because _fire() ends by restoring it, and a stale
	# value from an earlier aim would snap the camera somewhere unrelated.
	saved_zoom = camera.zoom.x
	restoring_zoom = false
	aim_target = world_target
	_fire()
	return true


func handle_touch(event: InputEventScreenTouch) -> bool:
	if event.pressed:
		if not can_begin_aim() \
				or not Rect2(button.global_position, button.size).has_point(event.position):
			return false
		if not _can_afford_shot():
			_say(_unaffordable_message())
			return true
		aiming = true
		aim_touch = event.index
		aim_start_screen = event.position
		aim_screen = event.position
		saved_zoom = camera.zoom.x
		restoring_zoom = false
		button.pressed_down = true
		button.queue_redraw()
		_update_aim()
		return true
	if event.index != aim_touch:
		return false
	if aim_start_screen.distance_to(aim_screen) >= AIM_DEADZONE:
		_fire()
	elif _aim_at_nearest_enemy():
		# Tapping the button used to do nothing at all - the press was claimed,
		# the aim began, and releasing without dragging simply threw it away.
		# A tap now fires at the nearest enemy in range; dragging remains the
		# way to place a shot precisely.
		_fire()
	else:
		_say("Nothing in range - drag from the button to aim")
		_cancel_aim()
	return true


# Points aim_target at the closest enemy within reach, or reports that there
# is none. Both aimed abilities read only the aim_target when they fire - the
# laser takes its DIRECTION and always extends to full range, the gas bomb
# takes the point itself - so setting it here is all auto-aim has to do, and
# each ability keeps its own meaning for it.
func _aim_at_nearest_enemy() -> bool:
	var origin: Vector2 = _aim_origin()
	var reach: float = _aim_max_range()
	var nearest: Node2D = null
	var nearest_distance: float = INF
	for enemy in get_tree().get_nodes_in_group(COMBAT_TARGET.GROUP):
		if not is_instance_valid(enemy) or not (enemy is Node2D):
			continue
		var distance: float = origin.distance_to((enemy as Node2D).global_position)
		if distance > reach or distance >= nearest_distance:
			continue
		nearest_distance = distance
		nearest = enemy
	if nearest == null:
		return false
	aim_target = nearest.global_position
	queue_redraw()
	return true


func handle_drag(event: InputEventScreenDrag) -> bool:
	if not aiming or event.index != aim_touch:
		return false
	aim_screen = event.position
	_update_aim()
	return true


func _update_aim() -> void:
	var origin: Vector2 = _aim_origin()
	aim_target = _calculate_aim_target(aim_screen - aim_start_screen, origin)
	_update_aim_zoom(origin, aim_target)
	queue_redraw()


func _update_aim_zoom(origin: Vector2, target: Vector2) -> void:
	var displacement: Vector2 = target - origin
	var half_screen: Vector2 = get_viewport_rect().size * 0.5 - Vector2(54.0, 54.0)
	var padding: float = _aim_padding()
	var fit_x: float = saved_zoom if absf(displacement.x) < 1.0 \
		else half_screen.x / (absf(displacement.x) + padding)
	var fit_y: float = saved_zoom if absf(displacement.y) < 1.0 \
		else half_screen.y / (absf(displacement.y) + padding)
	var desired: float = clampf(minf(saved_zoom, minf(fit_x, fit_y)),
		minimum_zoom, saved_zoom)
	camera.zoom = Vector2(desired, desired)


func _finish_aim() -> void:
	aiming = false
	aim_touch = -1
	button.pressed_down = false
	button.queue_redraw()
	restoring_zoom = true


func _cancel_aim() -> void:
	_finish_aim()
	queue_redraw()


func _fire() -> void:
	var ship: Node2D = _next_ready_ship()
	if ship == null:
		_cancel_aim()
		return
	if not _can_afford_shot():
		_say(_unaffordable_message())
		_cancel_aim()
		return
	var component: Node = ship.get_component(_component_id())
	if component == null or not _consume_shot(component):
		_cancel_aim()
		return
	GameState.withdraw_fleet_resource(_ammo_resource(), _ammo_cost())
	_perform_shot(ship, component)
	_finish_aim()
	button.enabled = _next_ready_ship() != null and _can_afford_shot()


func _next_ready_ship() -> Node2D:
	for ship in fleet.ships:
		if not is_instance_valid(ship):
			continue
		var component: Node = ship.get_component(_component_id())
		if component != null and component.is_ready():
			return ship
	return null


func _can_afford_shot() -> bool:
	return GameState.fleet_resource(_ammo_resource()) >= _ammo_cost()


func _unaffordable_message() -> String:
	var resource_type: String = _ammo_resource()
	return "Need %d %s in the fleet hold to fire (have %d)" % [
		_ammo_cost(), GameState.resource_name(resource_type).to_lower(),
		GameState.fleet_resource(resource_type),
	]


func _say(message: String) -> void:
	status.text = message
	status_message_until = Time.get_ticks_msec() + 3000


func _aim_origin() -> Vector2:
	return fleet.get_centroid()


# Subclass hooks.
func _button_path() -> NodePath: return NodePath()
func _status_path() -> NodePath: return NodePath()
func _component_id() -> String: return ""
func _ammo_resource() -> String: return ""
func _ammo_cost() -> int: return 0
func _aim_padding() -> float: return 0.0
# How far this ability can reach, for auto-aim and for the aim guide.
func _aim_max_range() -> float: return 0.0
func _has_effect_visuals() -> bool: return false
func _advance_effects(_delta: float) -> void: pass
func _consume_shot(_component: Node) -> bool: return false
func _perform_shot(_ship: Node2D, _component: Node) -> void: pass
func _calculate_aim_target(_drag: Vector2, origin: Vector2) -> Vector2: return origin