extends SceneTree
## Texture budget, full-detail visual equivalence, reuse, and cache invalidation.

const CACHE := preload("res://scripts/stage/scenery/stage_surface_cache.gd")
const RENDERER := preload("res://scripts/stage/scenery/stage_surface_renderer.gd")

class ReferenceSurface extends Node2D:
	var finish: StringName
	var panel_size := Vector2(320.0, 240.0)
	var tint: Color
	var simplified: bool = false

	func _draw() -> void:
		var rect := Rect2(-panel_size * 0.5, panel_size)
		if RENDERER.is_wall_finish(finish):
			RENDERER.draw_wall(self, rect, finish, tint, global_position, Vector2.ONE, true, simplified, simplified)
		else:
			RENDERER.draw_background(self, rect, finish, tint, global_position, Vector2.ONE, true, simplified, simplified)

var _failures: Array[String] = []


func _initialize() -> void:
	call_deferred("_run")


func _run() -> void:
	_test_texture_budget()
	_test_clipped_degenerate_polygon()
	if DisplayServer.get_name() == "headless":
		print("SKIP: texture rendering and invalidation checks require a GUI renderer")
	else:
		for finish: StringName in [&"finish_wall_brick", &"finish_wall_wood", &"finish_background_grass", &"finish_background_concrete", &"finish_background_carpet"]:
			await _test_visual_equivalence(finish)
		await _test_visual_equivalence(&"finish_wall_brick", 0.4)
		await _test_visual_equivalence(&"finish_wall_wood", 0.4)
		await _test_visual_equivalence(&"finish_wall_brick", 0.4, 0.2)
		await _test_invalidation()
		await _test_camera_tile_budget()
		await _test_covered_surfaces()
	if _failures.is_empty():
		print("PASS: full-detail scenery surface texture cache")
	else:
		for failure: String in _failures:
			push_error("FAIL: " + failure)
	quit(0 if _failures.is_empty() else 1)


func _test_texture_budget() -> void:
	for extent: Vector2 in [Vector2(320.0, 240.0), Vector2(100000.0, 80000.0), Vector2(100000.0, 12.0), Vector2(1.0, 1.0)]:
		var pixels: Vector2i = CACHE.texture_size_for(extent, Vector2(3.0, 3.0))
		_expect(pixels.x > 0 and pixels.y > 0 and pixels.x <= CACHE.MAX_TEXTURE_EDGE and pixels.y <= CACHE.MAX_TEXTURE_EDGE, "cache dimensions stay positive and bounded")
		_expect(float(pixels.x) * float(pixels.y) <= CACHE.MAX_TEXTURE_PIXELS, "cache pixel allocation stays bounded")
	_expect(CACHE.texture_size_for(Vector2(320.0, 240.0), Vector2(2.0, 2.0)) == Vector2i(640, 480), "ordinary surfaces rasterize at their current screen resolution")


func _test_clipped_degenerate_polygon() -> void:
	var rect := Rect2(Vector2.ZERO, Vector2(100.0, 100.0))
	var touching := PackedVector2Array([Vector2(-10.0, -10.0), Vector2(0.0, 0.0), Vector2(-10.0, 10.0)])
	_expect(RENDERER._clip_polygon_to_rect(touching, rect).is_empty(), "a polygon touching only the clip edge is discarded")
	var crossing := PackedVector2Array([Vector2(-10.0, 20.0), Vector2(0.0, 20.0), Vector2(30.0, 70.0), Vector2(-10.0, 70.0)])
	var clipped: PackedVector2Array = RENDERER._clip_polygon_to_rect(crossing, rect)
	_expect(clipped.size() >= 3 and not Geometry2D.triangulate_polygon(clipped).is_empty(), "clipped polygons with vertices on the boundary remain triangulatable")


func _make_viewport() -> SubViewport:
	var viewport := SubViewport.new()
	viewport.size = Vector2i(384, 256)
	viewport.transparent_bg = true
	viewport.world_2d = World2D.new()
	viewport.render_target_update_mode = SubViewport.UPDATE_ALWAYS
	root.add_child(viewport)
	return viewport


func _test_visual_equivalence(finish: StringName, zoom: float = 1.0, starting_zoom: float = 1.0) -> void:
	var cached_view := _make_viewport()
	var direct_view := _make_viewport()
	var surface: StageRectSurface = StageWallPanel.new() if RENDERER.is_wall_finish(finish) else StageBackgroundGround.new()
	var reference := ReferenceSurface.new()
	var tint: Color = RENDERER.default_tint(finish)
	var view_transform := Transform2D(Vector2(zoom, 0.0), Vector2(0.0, zoom), Vector2(192.0, 128.0) * (1.0 - zoom))
	cached_view.canvas_transform = Transform2D(Vector2(starting_zoom, 0.0), Vector2(0.0, starting_zoom), Vector2(192.0, 128.0) * (1.0 - starting_zoom))
	direct_view.canvas_transform = view_transform
	surface.position = Vector2(192.0, 128.0)
	surface.configure(Vector2(320.0, 240.0) / zoom, finish, tint)
	cached_view.add_child(surface)
	reference.position = surface.position
	reference.finish = finish
	reference.tint = tint
	reference.panel_size = surface.panel_size
	direct_view.add_child(reference)
	await _settle()
	if not is_equal_approx(starting_zoom, zoom):
		cached_view.canvas_transform = view_transform
		await _settle()
	var cached_image: Image = cached_view.get_texture().get_image()
	var direct_image: Image = direct_view.get_texture().get_image()
	var difference: float = 0.0
	var samples: int = 0
	for y: int in range(16, 240, 2):
		for x: int in range(40, 344, 2):
			var cached_pixel: Color = cached_image.get_pixel(x, y)
			var direct_pixel: Color = direct_image.get_pixel(x, y)
			difference += absf(cached_pixel.r - direct_pixel.r) + absf(cached_pixel.g - direct_pixel.g) + absf(cached_pixel.b - direct_pixel.b)
			samples += 3
	var mean_error: float = difference / float(samples)
	print("%s zoom=%.2f->%.2f cached/reference mean color difference=%.5f" % [finish, starting_zoom, zoom, mean_error])
	# Fractional zoom resamples the cached artwork; compare it with both detailed
	# and simplified references so a flat preview cannot pass as a settled texture.
	var tolerance: float = 0.015 if is_equal_approx(zoom, 1.0) else 0.02
	_expect(mean_error < tolerance, "%s zoom=%.2f->%.2f cache restores full-detail appearance" % [finish, starting_zoom, zoom])
	if zoom < 1.0:
		# Shared immutable bitmaps cannot be changed through a tile's private baker.
		# Draw the simplified reference separately, keeping the full image above.
		reference.simplified = true
		reference.queue_redraw()
		await _settle()
		var simplified_image: Image = direct_view.get_texture().get_image()
		var simplified_difference: float = 0.0
		for y: int in range(16, 240, 2):
			for x: int in range(40, 344, 2):
				var simple_pixel: Color = simplified_image.get_pixel(x, y)
				var full_pixel: Color = direct_image.get_pixel(x, y)
				simplified_difference += absf(simple_pixel.r - full_pixel.r) + absf(simple_pixel.g - full_pixel.g) + absf(simple_pixel.b - full_pixel.b)
		var simple_error: float = simplified_difference / float(samples)
		_expect(mean_error < simple_error * 0.95, "%s normal zoom retains more artwork detail than the flat preview" % finish)
		cached_image.save_png("res://tmp/surface_detail_%s.png" % finish)
	_expect(cached_image.get_pixel(192, 128).a > 0.95, "%s comparison includes visible surface artwork" % finish)
	var tiles: Dictionary = surface.get("_surface_tiles")
	_expect(not tiles.is_empty(), "%s has cached texture tiles" % finish)
	# UPDATE_ONCE is consumed by the rendering server; the node may retain the enum.
	for cache: CACHE in tiles.values():
		_expect(cache.ready_for_display and cache.render_target_update_mode in [SubViewport.UPDATE_ONCE, SubViewport.UPDATE_DISABLED], "%s tile requests a single rasterization" % finish)
	cached_view.queue_free()
	direct_view.queue_free()
	await process_frame


func _test_invalidation() -> void:
	var viewport := _make_viewport()
	var surface := StageWallPanel.new()
	surface.position = Vector2(192.0, 128.0)
	surface.configure(Vector2(1600.0, 1200.0), &"finish_wall_brick", Color("#B95F3D"))
	viewport.add_child(surface)
	await _settle()
	var initial_tiles: Dictionary = (surface.get("_surface_tiles") as Dictionary).duplicate()
	var initial_builds: int = int(CACHE.get_stats(surface).get("builds", 0))
	surface.queue_redraw()
	await _settle()
	_expect(int(CACHE.get_stats(surface).get("builds", 0)) == initial_builds, "unchanged surfaces reuse the rasterized texture")
	viewport.canvas_transform.origin = Vector2(-16.0, 0.0)
	await _settle()
	_expect((surface.get("_surface_tiles") as Dictionary).size() == initial_tiles.size() and int(CACHE.get_stats(surface).get("builds", 0)) == initial_builds, "small camera pans reuse cached tiles")
	viewport.canvas_transform.origin = Vector2(-300.0, 0.0)
	await _settle()
	var tiles: Dictionary = surface.get("_surface_tiles")
	var reused: int = 0
	for key: Variant in initial_tiles:
		if tiles.get(key) == initial_tiles[key]:
			reused += 1
	_expect(reused > 0, "large pans retain the same repeating material")
	viewport.canvas_transform = Transform2D(Vector2(2.0, 0.0), Vector2(0.0, 2.0), Vector2.ZERO)
	await _settle()
	tiles = surface.get("_surface_tiles")
	for cache: CACHE in tiles.values():
		if cache.wanted:
			_expect(cache.ready_for_display and cache.source_scale.is_equal_approx(Vector2(2.0, 2.0)), "zoom keeps the same full-resolution mipmapped material")
	viewport.size = Vector2i(512, 384)
	await _settle()
	_expect(_pending_tiles(root) == 0, "window resizing completes newly exposed tiles")
	surface.set_preview_tint(Color("#22C6FF"))
	await _settle()
	for cache: CACHE in (surface.get("_surface_tiles") as Dictionary).values():
		_expect(cache.get("_tint") == Color("#22C6FF"), "temporary color edits refresh the tiles")
	surface.clear_preview_tint()
	await _settle()
	for cache: CACHE in (surface.get("_surface_tiles") as Dictionary).values():
		_expect(cache.get("_tint") == surface.tint, "canceling a color preview restores tile colors")
	viewport.canvas_transform = Transform2D.IDENTITY
	var retained_material: CACHE = (surface.get("_surface_tiles") as Dictionary).values()[0] as CACHE
	surface.configure(Vector2(48.0, 64.0), surface.finish_id, surface.tint)
	await _settle()
	for cache: CACHE in (surface.get("_surface_tiles") as Dictionary).values():
		_expect(cache == retained_material, "shrinking a panel keeps the shared material and changes only clipping")
	surface.position += Vector2(30.0, 20.0)
	await _settle()
	for cache: CACHE in (surface.get("_surface_tiles") as Dictionary).values():
		_expect(cache == retained_material, "moving a panel keeps the material and changes only pattern coordinates")
	surface.configure(surface.panel_size, &"finish_wall_wood", Color("#C87137"))
	await _settle()
	for cache: CACHE in (surface.get("_surface_tiles") as Dictionary).values():
		_expect(cache.get("_finish") == &"finish_wall_wood", "changing finish replaces cached artwork")
	viewport.queue_free()
	await process_frame


func _settle() -> void:
	for frame: int in 1000:
		await process_frame
		await RenderingServer.frame_post_draw
		if frame >= 3 and _pending_tiles(root) == 0:
			return
	_expect(false, "progressive tile builds complete")


func _test_camera_tile_budget() -> void:
	var viewport := _make_viewport()
	var surface := StageWallPanel.new()
	surface.position = Vector2(192.0, 128.0)
	surface.configure(Vector2(12000.0, 6000.0), &"finish_wall_brick", Color("#B95F3D"))
	viewport.add_child(surface)
	await _settle()
	var original: Dictionary = (surface.get("_surface_tiles") as Dictionary).duplicate()
	# Camera zoom uses mipmaps from the same material image.
	for scale: float in [0.95, 0.9, 0.85]:
		viewport.canvas_transform = Transform2D(Vector2(scale, 0.0), Vector2(0.0, scale), Vector2.ZERO)
		await _settle()
	for key: Variant in original:
		_expect((surface.get("_surface_tiles") as Dictionary).get(key) == original[key], "wheel steps reuse the same material image")
	var builds_by_frame: Dictionary = {}
	for index: int in 28:
		var builds_before: int = int(CACHE.get_stats(surface).get("builds", 0))
		viewport.canvas_transform.origin = Vector2(-float(index) * 220.0, -float(index % 5) * 70.0)
		await process_frame
		await RenderingServer.frame_post_draw
		var frame: int = Engine.get_process_frames()
		var tiles: Dictionary = surface.get("_surface_tiles")
		_expect(tiles.size() <= surface.MAX_RESIDENT_TILES, "camera traversal keeps the tile cache bounded")
		# Eviction also emits updated; count actual shared bitmap builds instead.
		builds_by_frame[frame] = int(CACHE.get_stats(surface).get("builds", 0)) - builds_before
		# Queued work is metadata only; all tiles share a single GPU viewport.
		for cache: CACHE in tiles.values():
			if not cache.ready_for_display and not cache.get("_building"):
				_expect(cache.get_texture() == null and int(CACHE.get_stats(surface).get("bakers", 0)) <= 1, "unbuilt tiles share one render target during camera input")
		_expect(frame >= 0, "camera traversal advances frames")
	await _settle()
	for count: int in builds_by_frame.values():
		_expect(count <= 1, "the shared queue admits at most one tile build per frame")
	viewport.queue_free()
	await process_frame


func _test_covered_surfaces() -> void:
	var viewport := _make_viewport()
	var back := StageWallPanel.new()
	back.position = Vector2(192.0, 128.0)
	back.configure(Vector2(1600.0, 1200.0), &"finish_wall_wood", Color("#C87137"))
	viewport.add_child(back)
	var front := StageWallPanel.new()
	front.position = back.position
	front.configure(Vector2(2000.0, 1600.0), &"finish_wall_brick", Color("#B95F3D"))
	viewport.add_child(front)
	await _settle()
	_expect((back.get("_surface_tiles") as Dictionary).is_empty(), "fully covered walls do not prepare hidden texture tiles")
	front.hide()
	await _settle()
	_expect(not (back.get("_surface_tiles") as Dictionary).is_empty(), "revealing a wall resumes its tile preparation")
	front.show()
	front.modulate.a = 0.5
	await _settle()
	_expect(not back.call("_covered_by_surface"), "transparent walls keep underlying artwork visible")
	front.modulate.a = 1.0
	await _settle()
	_expect(back.call("_covered_by_surface"), "opaque coverage is detected again after transparency is removed")
	viewport.queue_free()
	await process_frame


func _pending_tiles(node: Node) -> int:
	var count: int = 0
	if node is StageRectSurface:
		for cache: CACHE in (node.get("_surface_tiles") as Dictionary).values():
			if cache.wanted and not cache.ready_for_display:
				count += 1
		return count
	for child: Node in node.get_children():
		count += _pending_tiles(child)
	return count


func _expect(condition: bool, message: String) -> void:
	if not condition:
		_failures.append(message)