class_name AnimalAppearance
extends RefCounted
## Shared Blender meshes, per-character palettes and shape weights; no simulation RNG.

const CEL_SHADER := preload("res://world/presentation/materials/character_cel.gdshader")
const KIT := preload("res://assets/characters/woodland_parts.glb")
const PARTS: Array[StringName] = [
	&"Body", &"Head", &"Hair", &"ArmLeft", &"ArmRight", &"LegLeft", &"LegRight", &"Tail"
]

static var _meshes: Dictionary[String, Mesh] = {}


static func apply_to(
	root: Node3D, identity: int, npc_body := false, authored: CharacterAppearanceProfile = null
) -> void:
	_load_kit()
	var profile := (
		authored if authored != null else CharacterAppearanceProfile.for_identity(identity)
	)
	profile = profile.normalized_copy()
	var material := _palette(profile)
	root.set_meta("animal_species", CharacterAppearanceProfile.SPECIES[profile.species])
	root.set_meta("character_appearance", profile)
	var species := CharacterAppearanceProfile.PART_SPECIES[profile.species]
	var arm := "Hiker" if profile.arm_pose == 1 else "Relaxed"
	var choices := [
		"Torso" + CharacterAppearanceProfile.OUTFITS[profile.outfit],
		"Head" + species,
		"Hat" + CharacterAppearanceProfile.HATS[profile.hat] if profile.hat > 0 else "",
		"Arm" + arm + "Left",
		"Arm" + arm + "Right",
		"LegLeft",
		"LegRight",
		"Tail" + species,
	]
	var height := profile.height
	var lift := 0.61 * (profile.leg_length - 1.0) * height
	var shoulder := 0.44 + 0.10 * profile.body_fullness
	var hip := 0.20 + 0.05 * profile.body_fullness
	var pivots := [
		Vector3(0, 1.05, 0),
		Vector3(0, 1.68, 0),
		Vector3(0, 1.68 + 0.22 * profile.head_size, 0),
		Vector3(-shoulder, 1.30, 0),
		Vector3(shoulder, 1.30, 0),
		Vector3(-hip, 0.61, 0),
		Vector3(hip, 0.61, 0),
		Vector3(0, 0.80, -0.22),
	]
	for index in PARTS.size():
		var target_name := "MeshInstance3D" if npc_body and index == 0 else String(PARTS[index])
		var target := root.get_node(target_name) as MeshInstance3D
		_set_part(target, choices[index], material, profile.body_fullness)
		target.position = pivots[index] * height + Vector3.UP * lift
		target.rotation = Vector3.ZERO
		target.scale = Vector3.ONE * height
		if index == 1 or index == 2:
			target.scale *= profile.head_size
		elif index == 3 or index == 4:
			target.scale.x *= 1.0 + 0.15 * profile.body_fullness
		elif index == 5 or index == 6:
			target.scale.x *= 1.0 + 0.20 * profile.body_fullness
			target.scale.y *= profile.leg_length
		target.set_meta("rest_height", target.position.y)
	var body := root.get_node("MeshInstance3D" if npc_body else "Body") as MeshInstance3D
	_child_part(body, "Scarf", "Scarf" if profile.scarf else "", material, profile.body_fullness)
	_child_part(
		body,
		"Bag",
		"Bag" + CharacterAppearanceProfile.BAGS[profile.bag] if profile.bag > 0 else "",
		material,
		profile.body_fullness
	)
	var head := root.get_node("Head") as MeshInstance3D
	var ears := _child_part(head, "Ears", "Ears" + profile.ear_part(), material)
	ears.position.y = 0.52
	ears.scale.y = profile.ear_length
	_child_part(head, "Spectacles", "Spectacles" if profile.spectacles else "", material)
	# Derived from imported bounds, including elongated ears and hats.
	var top := 0.0
	for part in PARTS:
		var path := "MeshInstance3D" if npc_body and part == &"Body" else String(part)
		top = maxf(top, _top(root.get_node(path), Transform3D.IDENTITY))
	root.set_meta("character_top", top)
	root.set_meta("arm_swing", 0.23 if profile.arm_pose == 1 else 1.0)


static func set_profession_color(root: Node3D, color: Color) -> void:
	var body := root.get_node("MeshInstance3D") as MeshInstance3D
	var material := body.material_override as ShaderMaterial
	material.set_shader_parameter("coat_color", color)
	material.set_shader_parameter("profession_tint", 0.28)


static func rest_heights(root: Node3D, npc_body := false) -> Vector3:
	return Vector3(
		root.get_node("MeshInstance3D" if npc_body else "Body").get_meta("rest_height"),
		root.get_node("Head").get_meta("rest_height"),
		root.get_node("Hair").get_meta("rest_height")
	)


static func _load_kit() -> void:
	if not _meshes.is_empty():
		return
	var source := KIT.instantiate()
	for child in source.find_children("*", "MeshInstance3D", true, false):
		_meshes[String(child.name)] = (child as MeshInstance3D).mesh
	source.free()


static func _set_part(
	target: MeshInstance3D, part: String, material: ShaderMaterial, fullness := 0.0
) -> void:
	assert(part.is_empty() or _meshes.has(part), "Missing Blender character part: " + part)
	target.mesh = _meshes.get(part)
	target.visible = target.mesh != null
	target.material_override = material
	if target.mesh != null:
		var shape := target.find_blend_shape_by_name("Stout")
		if shape >= 0:
			target.set_blend_shape_value(shape, fullness)


static func _child_part(
	parent: MeshInstance3D,
	node_name: String,
	part: String,
	material: ShaderMaterial,
	fullness := 0.0
) -> MeshInstance3D:
	var target := parent.get_node_or_null(node_name) as MeshInstance3D
	if target == null:
		target = MeshInstance3D.new()
		target.name = node_name
		parent.add_child(target)
	_set_part(target, part, material, fullness)
	target.transform = Transform3D.IDENTITY
	return target


static func _palette(profile: CharacterAppearanceProfile) -> ShaderMaterial:
	var material := ShaderMaterial.new()
	material.shader = CEL_SHADER
	for channel in ["fur", "muzzle", "outfit", "linen", "scarf", "trousers", "leather"]:
		var parameter: String = channel + "_color"
		material.set_shader_parameter(parameter, profile.get(parameter))
	return material


static func _top(node: Node3D, parent_transform: Transform3D) -> float:
	var transform := parent_transform * node.transform
	var top := 0.0
	if node is MeshInstance3D and node.mesh != null and node.visible:
		var bounds: AABB = transform * node.get_aabb()
		top = bounds.end.y
	for child in node.get_children():
		if child is Node3D:
			top = maxf(top, _top(child, transform))
	return top