extends Node3D
## Tower attack presentation (G2): target lock marker, crystal bolt in flight and the impact.
## Bolts are requested by LuneTowerView when the rules' attack cycle is about to complete and
## are timed to land on the rules' hit; they only follow the target's view. All objects are
## pooled; nothing here can cause, cancel or duplicate damage or gold.

const Materials = preload("res://scripts/luneraria/view/lune_materials.gd")
const Fx = preload("res://scripts/luneraria/view/lune_fx.gd")
const POOL: int = 24

class Bolt:
	var node: Node3D
	var core: MeshInstance3D
	var trail: MeshInstance3D
	var from: Vector3
	var target: Node3D
	var last_aim: Vector3
	var elapsed: float = 0.0
	var flight: float = .25
	var arc: float = .7
	var team: int = 0
	var heavy: bool = false
	var active: bool = false

var camera: Camera3D
var _bolts: Array[Bolt] = []
var _impacts: Array = []
var _sparks: Array[GPUParticles3D] = []
var _next_spark: int = 0
var _markers: Dictionary = {}
var _materials: Dictionary = {}
var _ring_texture: GradientTexture2D
## Counters for tests and the benchmark (purely informative).
var launched: int = 0
var landed: int = 0

func _ready() -> void:
	name = "TowerFx"

func _material(team: int, kind: String) -> StandardMaterial3D:
	var key: String = "%d:%s" % [team, kind]
	if _materials.has(key):
		return _materials[key]
	var color: Color = Materials.team_color(team, "crystal")
	var material := StandardMaterial3D.new()
	material.shading_mode = BaseMaterial3D.SHADING_MODE_UNSHADED
	material.disable_receive_shadows = true
	match kind:
		"core":
			material.albedo_color = Color(color.r * 2.6 + .4, color.g * 2.6 + .4, color.b * 2.6 + .4)
		"trail":
			material.transparency = BaseMaterial3D.TRANSPARENCY_ALPHA
			material.blend_mode = BaseMaterial3D.BLEND_MODE_ADD
			material.albedo_texture = Fx.soft_texture()
			material.albedo_color = Color(color.r * 1.6, color.g * 1.6, color.b * 1.6, .85)
		"flash":
			material.transparency = BaseMaterial3D.TRANSPARENCY_ALPHA
			material.blend_mode = BaseMaterial3D.BLEND_MODE_ADD
			material.billboard_mode = BaseMaterial3D.BILLBOARD_ENABLED
			material.albedo_texture = Fx.soft_texture()
			material.albedo_color = Color(color.r * 2.0, color.g * 2.0, color.b * 2.0, 1.0)
		"marker":
			material.transparency = BaseMaterial3D.TRANSPARENCY_ALPHA
			material.blend_mode = BaseMaterial3D.BLEND_MODE_ADD
			material.albedo_texture = _ring()
			material.albedo_color = Color(color.r * 1.4, color.g * 1.4, color.b * 1.4, .9)
			material.cull_mode = BaseMaterial3D.CULL_DISABLED
	_materials[key] = material
	return material

func _ring() -> GradientTexture2D:
	if _ring_texture == null:
		var gradient := Gradient.new()
		gradient.offsets = PackedFloat32Array([0.0, .62, .78, .86, .93, 1.0])
		gradient.colors = PackedColorArray([Color(1, 1, 1, 0), Color(1, 1, 1, 0.05), Color(1, 1, 1, .35), Color(1, 1, 1, 1), Color(1, 1, 1, .2), Color(1, 1, 1, 0)])
		_ring_texture = GradientTexture2D.new()
		_ring_texture.gradient = gradient
		_ring_texture.fill = GradientTexture2D.FILL_RADIAL
		_ring_texture.fill_from = Vector2(.5, .5)
		_ring_texture.fill_to = Vector2(1.0, .5)
		_ring_texture.width = 128
		_ring_texture.height = 128
	return _ring_texture

func _new_bolt() -> Bolt:
	var bolt := Bolt.new()
	bolt.node = Node3D.new()
	bolt.node.name = "Bolt"
	add_child(bolt.node)
	bolt.core = MeshInstance3D.new()
	var prism := PrismMesh.new()
	prism.size = Vector3(.16, .5, .16)
	bolt.core.mesh = prism
	bolt.core.cast_shadow = GeometryInstance3D.SHADOW_CASTING_SETTING_OFF
	bolt.node.add_child(bolt.core)
	bolt.trail = MeshInstance3D.new()
	var quad := QuadMesh.new()
	quad.size = Vector2(1, 1)
	quad.center_offset = Vector3(-.5, 0, 0)
	bolt.trail.mesh = quad
	bolt.trail.cast_shadow = GeometryInstance3D.SHADOW_CASTING_SETTING_OFF
	add_child(bolt.trail)
	bolt.node.visible = false
	bolt.trail.visible = false
	return bolt

func _free_bolt() -> Bolt:
	for bolt: Bolt in _bolts:
		if not bolt.active:
			return bolt
	if _bolts.size() < POOL:
		var bolt: Bolt = _new_bolt()
		_bolts.append(bolt)
		return bolt
	return null

## Starts a bolt from `from` that lands on the target view after `flight` simulation seconds.
func launch(from: Vector3, target: Node3D, flight: float, team: int, heavy: bool = false) -> void:
	var bolt: Bolt = _free_bolt()
	if bolt == null or target == null:
		return
	bolt.active = true
	bolt.from = from
	bolt.target = target
	bolt.last_aim = _aim(target)
	bolt.elapsed = 0.0
	bolt.flight = maxf(.05, flight)
	bolt.arc = clampf(from.distance_to(bolt.last_aim) * .08, .15, .9)
	bolt.team = team
	bolt.heavy = heavy
	bolt.core.material_override = _material(team, "core")
	bolt.trail.material_override = _material(team, "trail")
	bolt.core.scale = Vector3.ONE * (1.35 if heavy else 1.0)
	bolt.node.visible = true
	bolt.trail.visible = true
	bolt.node.global_position = from
	launched += 1

func _aim(target: Node3D) -> Vector3:
	if target != null and is_instance_valid(target):
		if target.has_method("aim_point"):
			return target.aim_point()
		return target.global_position + Vector3(0, 1.0, 0)
	return Vector3.ZERO

func _path(bolt: Bolt, t: float) -> Vector3:
	var eased: float = t * t * (3.0 - 2.0 * t) * .35 + t * .65
	return bolt.from.lerp(bolt.last_aim, eased) + Vector3(0, sin(PI * t) * bolt.arc, 0)

## Advances bolts (simulation time, so pause and speed apply) and impact flashes (real time).
func process_fx(delta: float, sim_delta: float) -> void:
	for bolt: Bolt in _bolts:
		if not bolt.active:
			continue
		if bolt.target != null and is_instance_valid(bolt.target):
			bolt.last_aim = _aim(bolt.target)
		bolt.elapsed += sim_delta
		var t: float = clampf(bolt.elapsed / bolt.flight, 0.0, 1.0)
		var at: Vector3 = _path(bolt, t)
		var behind: Vector3 = _path(bolt, maxf(0.0, t - .22))
		var direction: Vector3 = at - behind
		if direction.length() > .001:
			bolt.node.global_transform = Transform3D(Basis.looking_at(direction.normalized(), Vector3.UP) * Basis(Vector3.RIGHT, -PI * .5), at)
		_stretch(bolt.trail, behind, at, .32 if bolt.heavy else .24)
		if t >= 1.0:
			bolt.active = false
			bolt.node.visible = false
			bolt.trail.visible = false
			_impact(bolt.last_aim, bolt.team, bolt.heavy)
			landed += 1
	for index: int in range(_impacts.size() - 1, -1, -1):
		var entry: Array = _impacts[index]
		var flash: MeshInstance3D = entry[0]
		entry[1] = float(entry[1]) + delta
		var k: float = float(entry[1]) / .22
		if k >= 1.0:
			flash.queue_free()
			_impacts.remove_at(index)
			continue
		flash.scale = Vector3.ONE * lerpf(.35, 1.3, k) * float(entry[2])
		flash.transparency = k

## Orients a quad as a ribbon from a to b that faces the camera.
func _stretch(trail: MeshInstance3D, a: Vector3, b: Vector3, width: float) -> void:
	var axis: Vector3 = b - a
	var length: float = axis.length()
	if length < .01 or camera == null:
		trail.visible = false
		return
	trail.visible = true
	var x: Vector3 = axis / length
	var to_camera: Vector3 = (camera.global_position - b).normalized()
	var z: Vector3 = (to_camera - x * to_camera.dot(x))
	if z.length() < .001:
		z = Vector3.UP
	z = z.normalized()
	var y: Vector3 = z.cross(x)
	trail.global_transform = Transform3D(Basis(x * length, y * width, z), b)

func _impact(at: Vector3, team: int, heavy: bool) -> void:
	var flash: MeshInstance3D = Fx.flash_mesh(Color.WHITE, 1.0)
	flash.material_override = _material(team, "flash")
	add_child(flash)
	flash.global_position = at
	_impacts.append([flash, 0.0, 1.35 if heavy else 1.0])
	if _sparks.size() < 8:
		var sparks: GPUParticles3D = Fx.shard_burst(Materials.team_color(team, "crystal"), 10, 3.2)
		sparks.lifetime = .6
		add_child(sparks)
		_sparks.append(sparks)
	var emitter: GPUParticles3D = _sparks[_next_spark % _sparks.size()]
	_next_spark += 1
	Fx.fire(emitter, at)

## Lock-on ring under the current target of a tower; tightens as the shot charges.
func mark(tower_id: String, target: Node3D, charge: float, team: int) -> void:
	var marker: MeshInstance3D = _markers.get(tower_id)
	if target == null or not is_instance_valid(target) or charge <= .02:
		if marker != null:
			marker.visible = false
		return
	if marker == null:
		marker = MeshInstance3D.new()
		marker.name = "Lock_" + tower_id
		var quad := QuadMesh.new()
		quad.size = Vector2(2, 2)
		quad.orientation = PlaneMesh.FACE_Y
		marker.mesh = quad
		marker.material_override = _material(team, "marker")
		marker.cast_shadow = GeometryInstance3D.SHADOW_CASTING_SETTING_OFF
		add_child(marker)
		_markers[tower_id] = marker
	marker.visible = true
	var feet: Vector3 = target.global_position + Vector3(0, .07, 0)
	var size: float = lerpf(1.25, .72, clampf(charge, 0.0, 1.0)) * (target.call("footprint") if target.has_method("footprint") else 1.0)
	marker.global_transform = Transform3D(Basis(Vector3.UP, Time.get_ticks_msec() * .0018) * Basis.from_scale(Vector3(size, 1, size)), feet)
	marker.transparency = 1.0 - clampf(.35 + charge * .65, 0.0, 1.0)

func clear_markers() -> void:
	for id: String in _markers:
		(_markers[id] as MeshInstance3D).visible = false