extends Object
class_name LevelMaterials

## Shared cel-shaded materials for code-built levels and characters.
##
## Level geometry gets the toon shader with world-space triplanar grid
## (0.5 m cells) tinted per surface; characters get the same toon shading
## over their own textures via convert_to_toon(), plus an inverted-hull
## outline overlay for the inked silhouette.

const GRID_GRAY := "res://assets/textures/prototype/grid_gray.png"
const GRID_DARK := "res://assets/textures/prototype/grid_dark.png"
const TOON_SHADER := "res://assets/shaders/toon.gdshader"
const OUTLINE_SHADER := "res://assets/shaders/toon_outline.gdshader"

## One texture tile = 2 m of world, so one grid cell = 0.5 m.
const WORLD_UNITS_PER_TILE := 2.0

static var _cache: Dictionary = {}
static var _outline_cache: Dictionary = {}


## A tinted toon grid material for level geometry. Cached per (tint, dark) so
## identical surfaces share one material.
static func tinted(tint: Color, dark: bool = false) -> Material:
	var key := "%s|%s" % [tint.to_html(), dark]
	if _cache.has(key):
		return _cache[key]
	var shader: Shader = load(TOON_SHADER)
	var mat := ShaderMaterial.new()
	mat.shader = shader
	var tex_path := GRID_DARK if dark else GRID_GRAY
	var tex: Texture2D = load(tex_path) if ResourceLoader.exists(tex_path) else null
	if tex:
		mat.set_shader_parameter("albedo_texture", tex)
		mat.set_shader_parameter("has_texture", true)
		mat.set_shader_parameter("use_triplanar", true)
		mat.set_shader_parameter("triplanar_tile", WORLD_UNITS_PER_TILE)
	else:
		mat.set_shader_parameter("has_texture", false)
	# The texture is grayscale ~mid value; multiply by ~2x-brightened tint to
	# land near the original flat color while keeping the grid contrast.
	mat.set_shader_parameter("albedo_color", Color(
		minf(tint.r * 1.9, 1.0), minf(tint.g * 1.9, 1.0), minf(tint.b * 1.9, 1.0)))
	# Level surfaces are huge; the toon rim/specular reads as a giant soft
	# "blob" highlight smeared across floors and walls. Keep those effects
	# for characters/props only.
	mat.set_shader_parameter("rim_strength", 0.0)
	mat.set_shader_parameter("specular_strength", 0.0)
	_cache[key] = mat
	return mat


static var _flat_cache: Dictionary = {}

## Flat cel color: toon banding with NO grid texture — the full stylized
## look for dressed maps (vs. tinted()'s greybox grid for blockouts).
## Rim/specular stay off (they blob on large level surfaces).
static func flat(tint: Color) -> Material:
	var key := tint.to_html()
	if _flat_cache.has(key):
		return _flat_cache[key]
	var mat := ShaderMaterial.new()
	mat.shader = load(TOON_SHADER)
	mat.set_shader_parameter("has_texture", false)
	mat.set_shader_parameter("use_triplanar", false)
	mat.set_shader_parameter("albedo_color", tint)
	mat.set_shader_parameter("rim_strength", 0.0)
	mat.set_shader_parameter("specular_strength", 0.0)
	_flat_cache[key] = mat
	return mat


## Toon version of an arbitrary material (usually a character's imported
## StandardMaterial3D): keeps its albedo texture/color, swaps the shading.
static func toonify(src: Material) -> Material:
	var mat := ShaderMaterial.new()
	mat.shader = load(TOON_SHADER)
	var tex: Texture2D = null
	var col := Color.WHITE
	if src is BaseMaterial3D:
		tex = src.albedo_texture
		col = src.albedo_color
	mat.set_shader_parameter("albedo_texture", tex)
	mat.set_shader_parameter("has_texture", tex != null)
	mat.set_shader_parameter("use_triplanar", false)
	mat.set_shader_parameter("albedo_color", col)
	# Fully matte characters: NO specular (even a 2% stepped glint reads as
	# shine sweeping across hair when the camera moves) and only a whisper
	# of rim for silhouette separation.
	mat.set_shader_parameter("rim_strength", 0.05)
	mat.set_shader_parameter("rim_width", 0.28)
	mat.set_shader_parameter("specular_strength", 0.0)
	mat.set_shader_parameter("specular_shininess", 64.0)
	return mat


## Ink used for the line-work an imported character carries in its own mesh.
const CHARACTER_INK := Color(0.07, 0.06, 0.09)


## Second pass for IMPORTED CHARACTER models (the anime GLB skins), run right
## after apply_toon_recursive. Two things those models need that props don't:
##
## 1. Their line-work is part of the mesh, as extra UNTEXTURED surfaces, and it
##    splits into two kinds that need opposite treatment:
##
##    * The body/hair OUTLINE HULL (Taila's "FullBlack" and "material") is a
##      duplicated shell. Its skin weights do not track the base mesh through a
##      deep bend, so during a run it tears into spikes and stretches sheets
##      between the ankles — that is what made the ankle cuffs look welded
##      together. It is also redundant: characters already get an inverted-hull
##      overlay from apply_toon_recursive AND the screen-space ink_edge pass.
##      So it is HIDDEN outright, which removes the artefact and the redundancy
##      in one go.
##
##    * The EYE cards ("EyesFullBlack" lashes, "EyesInvL", "EyesHL" highlight)
##      are real facial features, not a hull, and they are kept — flat, because
##      the glTF import hands every untextured surface a default near-white
##      albedo and toon-LIGHTING the black ones was the thin white rim that used
##      to trace every hair strand.
##
## 2. Their textures are ALREADY painted with cel shading. Stacking the hard
##    3-tone break on top read as gloss — a bright stripe sliding across the
##    hair as the camera moved. Characters get a soft terminator and an
##    almost-invisible second step so the painted shading carries the form.
##
## Props and level geometry keep the crisp banding they were calibrated with.
static func apply_character_look(root: Node) -> void:
	for mi in root.find_children("*", "MeshInstance3D", true, false):
		if not mi.mesh:
			continue
		for s in range(mi.mesh.get_surface_count()):
			var src: BaseMaterial3D = mi.mesh.surface_get_material(s) as BaseMaterial3D
			if src == null:
				continue
			if src.albedo_texture == null:
				# Untextured surface on a character = the model's own line-work.
				var name := src.resource_name.to_lower()
				var flat := StandardMaterial3D.new()
				flat.shading_mode = BaseMaterial3D.SHADING_MODE_UNSHADED
				flat.cull_mode = src.cull_mode
				if not name.begins_with("eyes"):
					# The outline HULL: hide it (see above). Fully transparent
					# rather than deleted so the surface indices, and therefore
					# the mesh's own skin bindings, stay exactly as imported.
					flat.transparency = BaseMaterial3D.TRANSPARENCY_ALPHA
					flat.albedo_color = Color(0, 0, 0, 0)
				else:
					# An eye card. "HL" marks the highlight (the glint in the
					# pupil) — that one really is meant to be white.
					flat.albedo_color = Color.WHITE if name.contains("hl") \
						else CHARACTER_INK
				mi.set_surface_override_material(s, flat)
				continue
			var toon: ShaderMaterial = mi.get_surface_override_material(s) as ShaderMaterial
			if toon == null:
				continue
			toon.set_shader_parameter("band_softness", 0.16)
			toon.set_shader_parameter("mid_tone", 0.92)
			# Shadow tint measured off the Sketchfab reference render: sampling
			# Taila's hair there, shadow/midtone lands near (0.63, 0.53, 0.70).
			# Green drops hardest, and that is what keeps copper hair COPPER in
			# shadow — the level default (0.62, 0.65, 0.78) lifts green above
			# red and washes ginger toward a dull brown.
			toon.set_shader_parameter("shadow_color", Color(0.64, 0.56, 0.72))


## Swap every mesh surface under `node` to toon shading and add an
## inverted-hull outline overlay. Safe on skinned meshes (material_overlay
## re-renders the same deformed mesh).
static func apply_toon_recursive(node: Node, outline_width: float = 0.005) -> void:
	if node is MeshInstance3D:
		var mi := node as MeshInstance3D
		var surface_count: int = mi.mesh.get_surface_count() if mi.mesh else 0
		for s in range(surface_count):
			var src := mi.get_active_material(s)
			if src and not (src is ShaderMaterial):
				mi.set_surface_override_material(s, toonify(src))
		if outline_width > 0.0:
			mi.material_overlay = outline(outline_width)
	for child in node.get_children():
		apply_toon_recursive(child, outline_width)


static func outline(width: float = 0.005) -> ShaderMaterial:
	var key := "%.4f" % width
	if _outline_cache.has(key):
		return _outline_cache[key]
	var mat := ShaderMaterial.new()
	mat.shader = load(OUTLINE_SHADER)
	mat.set_shader_parameter("outline_width", width)
	_outline_cache[key] = mat
	return mat