extends Node

const SHADER_INTERACTOR_LIMIT := 8
const CLEARING_LIMIT := 4

@export var grass_material: ShaderMaterial
@export_range(1, SHADER_INTERACTOR_LIMIT, 1) var max_interactors := 8
@export_range(0.02, 0.5, 0.01) var update_interval := 0.08
@export var path_clearings: Array[NodePath] = []
@export var actor_root_path := NodePath("../../..")
@export var foliage_root_path := NodePath("../..")
@export var simulation_manager_path := NodePath("../../../SimulationManager")
@export var primary_interactor_path := NodePath("../../../Player")

var _elapsed := 0.0
var _trail_map := FoliageTrailMap.new()


func _ready() -> void:
	# JajceWorld first isolates its mutable materials in the parent's _ready().
	call_deferred("_configure_interaction")


func _configure_interaction() -> void:
	_configure_path_clearings()
	var simulation := get_node_or_null(simulation_manager_path)
	if simulation != null and simulation.has_signal("state_restored"):
		simulation.connect("state_restored", reset_interaction)
	if is_processing():
		_refresh_interactors(0.0)


func set_interaction_enabled(enabled: bool) -> void:
	set_process(enabled)
	reset_interaction()
	_elapsed = update_interval


func reset_interaction() -> void:
	_trail_map.clear()
	if grass_material != null:
		grass_material.set_shader_parameter("interactor_count", 0)
	_bind_trail_materials(false)


func _configure_path_clearings() -> void:
	if grass_material == null:
		return
	var segments := PackedVector4Array()
	segments.resize(CLEARING_LIMIT)
	var widths := Vector4.ZERO
	var count := 0
	for path in path_clearings.slice(0, CLEARING_LIMIT):
		var strip := get_node_or_null(path) as MeshInstance3D
		if strip == null or not strip.mesh is BoxMesh:
			continue
		var box := strip.mesh as BoxMesh
		var half_length := strip.global_basis.z * box.size.z * 0.5
		var start := strip.global_position - half_length
		var end := strip.global_position + half_length
		segments[count] = Vector4(start.x, start.z, end.x, end.z)
		widths[count] = strip.global_basis.x.length() * box.size.x * 0.5 + 0.12
		count += 1
	grass_material.set_shader_parameter("clearing_count", count)
	grass_material.set_shader_parameter("clearing_segments", segments)
	grass_material.set_shader_parameter("clearing_half_widths", widths)


func _process(delta: float) -> void:
	_elapsed += delta
	if _elapsed < update_interval:
		return
	_refresh_interactors(_elapsed)
	_elapsed = 0.0


func _refresh_interactors(delta: float = 0.08) -> void:
	if grass_material == null:
		return
	var camera := get_viewport().get_camera_3d()
	var origin := camera.global_position if camera != null else Vector3.ZERO
	var actor_root := get_node_or_null(actor_root_path)
	var primary := get_node_or_null(primary_interactor_path)
	var nearest: Array[Node3D] = []
	var limit := clampi(max_interactors, 1, SHADER_INTERACTOR_LIMIT)
	for value in get_tree().get_nodes_in_group("grass_interactors"):
		var candidate := value as Node3D
		if (
			candidate == null
			or candidate.is_queued_for_deletion()
			or not candidate.is_visible_in_tree()
			or candidate.get_viewport() != get_viewport()
			or (actor_root != null and not actor_root.is_ancestor_of(candidate))
		):
			continue
		var insert_at := nearest.size()
		var candidate_distance := origin.distance_squared_to(candidate.global_position)
		for index in nearest.size():
			if (
				candidate == primary
				or (
					nearest[index] != primary
					and (
						candidate_distance
						< origin.distance_squared_to(nearest[index].global_position)
					)
				)
			):
				insert_at = index
				break
		nearest.insert(insert_at, candidate)
		if nearest.size() > limit:
			nearest.pop_back()

	var positions := PackedVector3Array()
	positions.resize(SHADER_INTERACTOR_LIMIT)
	for index in SHADER_INTERACTOR_LIMIT:
		positions[index] = Vector3(0.0, -1000.0, 0.0)
	var trail_positions: Dictionary[int, Vector3] = {}
	for index in nearest.size():
		positions[index] = nearest[index].global_position
		trail_positions[nearest[index].get_instance_id()] = positions[index]
	grass_material.set_shader_parameter("interactor_count", nearest.size())
	grass_material.set_shader_parameter("interactor_positions", positions)
	_trail_map.advance(delta, origin, trail_positions)
	_bind_trail_materials(true)


func _bind_trail_materials(enabled: bool) -> void:
	if grass_material != null:
		grass_material.set_shader_parameter("foliage_trail_map", _trail_map.texture)
		grass_material.set_shader_parameter("foliage_trail_rect", _trail_map.world_rect)
		grass_material.set_shader_parameter("foliage_trails_enabled", enabled)
	var foliage_root := get_node_or_null(foliage_root_path)
	if foliage_root == null:
		return
	for value in get_tree().get_nodes_in_group("interactive_foliage"):
		var patch := value as StylizedBerryPatch
		if patch != null and foliage_root.is_ancestor_of(patch):
			patch.set_contact_field(_trail_map.texture, _trail_map.world_rect, enabled)
			if grass_material != null:
				patch.set_contact_actors(
					grass_material.get_shader_parameter("interactor_positions"),
					int(grass_material.get_shader_parameter("interactor_count")) if enabled else 0
				)