extends Node

# ============================================================================
# 探针 P1 —— Godot 4.7 hint_screen_texture / SCREEN_TEXTURE 语义
# 架构依据：§11 P1 / §5.2（ADR-2 单趟 fused 后处理的 CanvasLayer 拓扑）
# 实测手册：docs/engineering/2026-10-19-f-w1-probe-p1-manual.md
# 结论回填：docs/engineering/probes/P1-result.md
#
# 三问：
#   ① 背景/世界色是否含入 SCREEN_TEXTURE 采样（后处理 L1 能否看见 L0）
#   ② CanvasLayer 排序语义（L1 后处理在 L0 世界之上、L2 UI 之下）
#   ③ UI 层是否被后处理污染（UI 保持 crisp、不被 shader 调制）
#
# 场景在 _ready() 中代码化搭建（不手写 .tscn 降低出错面）。
# 键位：1 直通 | 2 反色 | 3 红染 | 4 纯绿 | V 显/隐后处理层 | S 截图 user:// | Esc 退出
# ============================================================================

enum PostMode { PASSTHROUGH, INVERT, RED_TINT, SOLID_GREEN }

var _post: ColorRect
var _post_visible := true
var _mode: int = PostMode.PASSTHROUGH
var _mat: ShaderMaterial
var _hud: Label
var _shot_n := 0


func _ready() -> void:
	_build_world()
	_build_post()
	_build_ui()
	_print_environment()


func _build_world() -> void:
	var world := CanvasLayer.new()
	world.name = "L0_World"
	world.layer = 0
	add_child(world)

	var bg := ColorRect.new()
	bg.name = "Background"
	bg.color = Color("#23384F") # 已知底色：后处理里能看见它 = 世界含入采样
	bg.set_anchors_preset(Control.PRESET_FULL_RECT)
	world.add_child(bg)

	var marker := ColorRect.new()
	marker.name = "WorldMarker"
	marker.color = Color("#D08A2E")
	marker.position = Vector2(400, 240)
	marker.size = Vector2(480, 240)
	world.add_child(marker)

	var world_label := Label.new()
	world_label.name = "WorldLabel"
	world_label.text = "L0 World: bg #23384F + marker #D08A2E"
	world_label.position = Vector2(24, 180)
	world_label.add_theme_color_override("font_color", Color.WHITE)
	world.add_child(world_label)


func _build_post() -> void:
	var post_layer := CanvasLayer.new()
	post_layer.name = "L1_PostProcess"
	post_layer.layer = 1
	add_child(post_layer)

	var sh := load("res://tests/probe_p1_screen_texture/probe_p1.gdshader") as Shader
	_mat = ShaderMaterial.new()
	_mat.shader = sh
	_mat.set_shader_parameter("mode", PostMode.PASSTHROUGH)

	_post = ColorRect.new()
	_post.name = "PostProcessRect"
	_post.material = _mat
	_post.mouse_filter = Control.MOUSE_FILTER_IGNORE
	_post.set_anchors_preset(Control.PRESET_FULL_RECT)
	post_layer.add_child(_post)


func _build_ui() -> void:
	var ui_layer := CanvasLayer.new()
	ui_layer.name = "L2_UI"
	ui_layer.layer = 2
	add_child(ui_layer)

	var root := Control.new()
	root.name = "UIRoot"
	root.set_anchors_preset(Control.PRESET_FULL_RECT)
	ui_layer.add_child(root)

	# UI 样本：四色板 + 一块纯白。被后处理污染 = 颜色变了/出现着色/纸纹
	var chip_colors := [
		Color("#1A1614"), Color("#EDE6D8"), Color("#B03A2E"),
		Color("#3A5A6B"), Color("#FFFFFF"),
	]
	var chip_names := ["墨 #1A1614", "骨白 #EDE6D8", "朱砂 #B03A2E", "靛 #3A5A6B", "纯白 #FFFFFF"]
	for i in chip_colors.size():
		var chip := ColorRect.new()
		chip.name = "Chip%d" % i
		chip.color = chip_colors[i]
		chip.size = Vector2(200, 40)
		chip.position = Vector2(960, 48 + i * 56)
		root.add_child(chip)
		var lbl := Label.new()
		lbl.name = "ChipLabel%d" % i
		lbl.text = chip_names[i]
		lbl.position = Vector2(1010, 54 + i * 56)
		if chip_colors[i].get_luminance() > 0.5:
			lbl.add_theme_color_override("font_color", Color.BLACK)
		else:
			lbl.add_theme_color_override("font_color", Color.WHITE)
		root.add_child(lbl)

	_hud = Label.new()
	_hud.name = "HUDHelp"
	_hud.text = _help_text()
	_hud.position = Vector2(24, 648)
	_hud.add_theme_color_override("font_color", Color.WHITE)
	root.add_child(_hud)


func _help_text() -> String:
	var mode_names := ["PASS直通", "INVERT反色", "RED红染", "GREEN纯绿"]
	# 条件表达式含数组下标 → Variant；`:=` 推断触发 INFERENCE_ON_VARIANT（4.7.2 按错误）→ 显式标注
	var mode_name: String = mode_names[_mode] if _mode >= 0 and _mode < mode_names.size() else "?"
	return "探针 P1 | 1 直通 2 反色 3 红染 4 纯绿 | V 显/隐后处理层（当前:%s）| S 截图到 user:// | Esc 退出 | 当前 mode=%s" % [
		"显示" if _post_visible else "隐藏", mode_name]


func _input(event: InputEvent) -> void:
	var key_event := event as InputEventKey
	if key_event != null and key_event.pressed and not key_event.echo:
		match key_event.keycode:
			KEY_1:
				_set_mode(PostMode.PASSTHROUGH)
			KEY_2:
				_set_mode(PostMode.INVERT)
			KEY_3:
				_set_mode(PostMode.RED_TINT)
			KEY_4:
				_set_mode(PostMode.SOLID_GREEN)
			KEY_V:
				_post_visible = not _post_visible
				_post.visible = _post_visible
				_hud.text = _help_text()
			KEY_S:
				_screenshot()
			KEY_ESCAPE:
				get_tree().quit()


func _set_mode(m: int) -> void:
	_mode = m
	_mat.set_shader_parameter("mode", m)
	_hud.text = _help_text()
	var mode_names := ["PASS直通", "INVERT反色", "RED红染", "GREEN纯绿"]
	print("P1 mode → %d（%s）" % [m, mode_names[m] if m >= 0 and m < mode_names.size() else "?"])


func _screenshot() -> void:
	var tex := get_viewport().get_texture()
	if tex == null:
		push_warning("P1: viewport texture 为空，回退：请用系统截图（Win+Shift+S）")
		return
	var img := tex.get_image()
	if img == null:
		push_warning("P1: get_image() 失败，回退：请用系统截图（Win+Shift+S）")
		return
	var path := "user://p1_mode_%d_%02d.png" % [_mode, _shot_n]
	_shot_n += 1
	var err := img.save_png(path)
	print("P1 screenshot → ", path, " err=", err)


func _print_environment() -> void:
	var v := Engine.get_version_info()
	print("=== P1 probe 环境（截图请连同此段一起归档）===")
	print("godot: %d.%d.%d %s" % [int(v.major), int(v.minor), int(v.patch), str(v.status)])
	print("rendering_method: ", ProjectSettings.get_setting("rendering/renderer/rendering_method"))
	print("adapter: ", RenderingServer.get_video_adapter_name())
	print("viewport: ", get_viewport().get_visible_rect().size)
	print("stretch: ", ProjectSettings.get_setting("display/window/stretch/mode"), " / ", ProjectSettings.get_setting("display/window/stretch/aspect"))
	print("=== 键位：1 直通 | 2 反色 | 3 红染 | 4 纯绿 | V 显隐后处理 | S 截图 | Esc 退出 ===")