extends Object
class_name UITheme

## The one UI theme: high-voltage anime. Built once, applied to the root Window,
## inherited by every Control in every scene.
##
## The look is a charged cel comic — near-black violet ink, hot papaya, and a
## lightning yellow that only ever appears at the moment something is pressed.
## Three rules hold it together:
##
##   INK EVERYTHING     every panel, chip and letter carries a heavy dark edge.
##                      It is what makes flat colour read as drawn rather than
##                      as flat, and it is why text stays legible over a 3D
##                      scene without a scrim behind it.
##   LEAN               chips are cut with two sharp corners and two round ones,
##                      on a diagonal. A uniformly rounded button reads calm; the
##                      same shape leaning reads fast, and it costs nothing.
##   VOLT MEANS NOW     yellow is reserved for the pressed state and the bolt.
##                      Spend it anywhere else and the moment of input stops
##                      standing out.
##
## Everything here is static. Screens ask for `apply_global` once and then use
## the helpers — `heading`, `card`, `divider`, `chip_button` — instead of
## hand-rolling styleboxes, which is how the pause menu drifted 900 lines away
## from the rest of the game's look.

const FONT_PATH := "res://assets/ui/fonts/Bangers-Regular.ttf"

# ── The voltage palette ──────────────────────────────────────────────────────
const INK := Color(0.045, 0.040, 0.075)
const INK_SOFT := Color(0.105, 0.095, 0.165)
const PANEL := Color(0.075, 0.068, 0.125, 0.94)
const PANEL_DEEP := Color(0.045, 0.040, 0.085, 0.97)
const PAPER := Color(0.97, 0.96, 0.99)
const PAPER_DIM := Color(0.60, 0.58, 0.68)
const PAPAYA := Color(1.00, 0.47, 0.10)
const PAPAYA_HOT := Color(1.00, 0.64, 0.20)
## Reserved for the instant of input, and for the bolt. See VOLT MEANS NOW.
const VOLT := Color(1.00, 0.93, 0.22)
const CYAN := Color(0.22, 0.94, 1.00)
const MAGENTA := Color(1.00, 0.18, 0.52)
## Older screens name the accent `TEAL`; it is the electric cyan now.
const TEAL := CYAN

## How far a chip leans. Applied as opposite corners round and the other two
## nearly square, which is as close to a skew as a StyleBoxFlat can get.
const LEAN := 18

static var _theme: Theme = null


## A leaning comic chip: flat fill, heavy ink edge, hard offset shadow.
##
## Kept at its original name and argument order — main_menu and match_hud both
## call it — with the lean added on top.
static func box(bg: Color, border: Color = INK, radius: int = 10,
		border_w: int = 3, shadow: bool = true) -> StyleBoxFlat:
	var sb := StyleBoxFlat.new()
	sb.bg_color = bg
	sb.border_color = border
	sb.set_border_width_all(border_w)
	sb.corner_radius_top_left = radius + LEAN
	sb.corner_radius_bottom_right = radius + LEAN
	sb.corner_radius_top_right = 3
	sb.corner_radius_bottom_left = 3
	sb.content_margin_left = 22
	sb.content_margin_right = 22
	sb.content_margin_top = 9
	sb.content_margin_bottom = 9
	if shadow:
		sb.shadow_color = Color(INK.r, INK.g, INK.b, 0.7)
		sb.shadow_size = 3
		sb.shadow_offset = Vector2(5, 5)
	return sb


## A panel: same ink edge, but square-shouldered so it reads as a surface to put
## things on rather than as a very large button.
static func panel(bg: Color = PANEL, border: Color = INK,
		border_w: int = 4) -> StyleBoxFlat:
	var sb := StyleBoxFlat.new()
	sb.bg_color = bg
	sb.border_color = border
	sb.set_border_width_all(border_w)
	sb.set_corner_radius_all(6)
	sb.content_margin_left = 20
	sb.content_margin_right = 20
	sb.content_margin_top = 16
	sb.content_margin_bottom = 16
	sb.shadow_color = Color(INK.r, INK.g, INK.b, 0.55)
	sb.shadow_size = 4
	sb.shadow_offset = Vector2(6, 6)
	return sb


static func build() -> Theme:
	if _theme:
		return _theme
	var t := Theme.new()
	var font: Font = load(FONT_PATH) if ResourceLoader.exists(FONT_PATH) else null
	if font:
		t.default_font = font
	t.default_font_size = 26

	# ── Buttons ──────────────────────────────────────────────────────────
	# Dark chip with a papaya edge at rest; the chip FILLS papaya on hover and
	# flashes volt on press. The press state drops its shadow, so the chip
	# visibly slams down into the page rather than just changing colour.
	_button_look(t, "Button")
	for cls in ["OptionButton", "MenuButton", "CheckBox", "CheckButton",
			"LinkButton"]:
		# Godot theme types do not inherit styling from Button, so each one has
		# to be told the same thing.
		_button_look(t, cls)

	# ── Labels: ink outline everywhere, for readability straight over 3D ──
	t.set_color("font_color", "Label", PAPER)
	t.set_color("font_outline_color", "Label", INK)
	t.set_constant("outline_size", "Label", 8)

	t.set_color("default_color", "RichTextLabel", PAPER)
	t.set_color("font_outline_color", "RichTextLabel", INK)
	t.set_constant("outline_size", "RichTextLabel", 6)

	# ── Inputs ───────────────────────────────────────────────────────────
	t.set_stylebox("normal", "LineEdit", box(INK_SOFT, PAPAYA, 4, 3, false))
	t.set_stylebox("focus", "LineEdit", box(INK_SOFT, CYAN, 4, 3, false))
	t.set_color("font_color", "LineEdit", PAPER)
	t.set_color("caret_color", "LineEdit", VOLT)
	t.set_color("font_placeholder_color", "LineEdit", PAPER_DIM)

	# ── Sliders: the filled part is the charged part ─────────────────────
	t.set_stylebox("slider", "HSlider", box(INK_SOFT, INK, 2, 2, false))
	t.set_stylebox("grabber_area", "HSlider", box(PAPAYA, INK, 2, 2, false))
	t.set_stylebox("grabber_area_highlight", "HSlider", box(VOLT, INK, 2, 2, false))

	# ── Panels / lists ───────────────────────────────────────────────────
	t.set_stylebox("panel", "PanelContainer", panel())
	t.set_stylebox("panel", "Panel", panel())
	t.set_stylebox("panel", "ItemList", panel(PANEL_DEEP, INK, 3))
	t.set_color("font_color", "ItemList", PAPER)
	t.set_color("font_selected_color", "ItemList", INK)
	t.set_stylebox("selected", "ItemList", box(PAPAYA, INK, 4, 2, false))
	t.set_stylebox("selected_focus", "ItemList", box(PAPAYA_HOT, CYAN, 4, 2, false))
	t.set_stylebox("hovered", "ItemList", box(INK_SOFT, PAPAYA, 4, 2, false))

	# ── Tabs ─────────────────────────────────────────────────────────────
	t.set_stylebox("panel", "TabContainer", panel())
	t.set_stylebox("tab_selected", "TabContainer", box(PAPAYA, INK, 6, 3, false))
	t.set_stylebox("tab_unselected", "TabContainer", box(INK_SOFT, INK, 6, 3, false))
	t.set_stylebox("tab_hovered", "TabContainer", box(PAPAYA_HOT, INK, 6, 3, false))
	t.set_color("font_selected_color", "TabContainer", INK)
	t.set_color("font_unselected_color", "TabContainer", PAPER_DIM)
	t.set_color("font_hovered_color", "TabContainer", INK)

	# ── Popups (OptionButton dropdowns) ──────────────────────────────────
	t.set_stylebox("panel", "PopupMenu", panel(PANEL_DEEP, PAPAYA, 3))
	t.set_stylebox("hover", "PopupMenu", box(PAPAYA, INK, 4, 0, false))
	t.set_color("font_color", "PopupMenu", PAPER)
	t.set_color("font_hover_color", "PopupMenu", INK)

	# ── Dialogs ──────────────────────────────────────────────────────────
	t.set_stylebox("panel", "AcceptDialog", panel(PANEL_DEEP, PAPAYA, 4))
	t.set_stylebox("embedded_border", "Window", panel(PANEL_DEEP, PAPAYA, 4))
	t.set_color("title_color", "Window", VOLT)

	_theme = t
	return t


static func _button_look(t: Theme, cls: String) -> void:
	t.set_stylebox("normal", cls, box(INK_SOFT, PAPAYA))
	t.set_stylebox("hover", cls, box(PAPAYA, INK))
	t.set_stylebox("pressed", cls, box(VOLT, INK, 10, 3, false))
	t.set_stylebox("focus", cls, box(INK_SOFT, CYAN))
	t.set_stylebox("disabled", cls, box(Color(0.10, 0.10, 0.14, 0.85), Color(0.28, 0.27, 0.33)))
	t.set_color("font_color", cls, PAPER)
	t.set_color("font_hover_color", cls, INK)
	t.set_color("font_pressed_color", cls, INK)
	t.set_color("font_focus_color", cls, PAPER)
	t.set_color("font_disabled_color", cls, Color(0.42, 0.41, 0.48))
	t.set_color("font_outline_color", cls, INK)
	t.set_constant("outline_size", cls, 5)


## Apply the theme to the whole root window. Idempotent, and cheap enough that
## every screen should just call it in `_ready` rather than assuming some other
## screen already did — which is exactly what left the pause menu unstyled
## whenever it was opened before the HUD had loaded.
static func apply_global(tree: SceneTree) -> void:
	if tree and tree.root and tree.root.theme != build():
		tree.root.theme = build()


# ── Widgets ──────────────────────────────────────────────────────────────────


## The wordmark treatment: papaya on a heavy ink outline, tilted off true.
##
## The tilt is the cheapest energy in the whole theme. Two and a half degrees is
## enough for the eye to register that the type is not sitting square and not
## enough to read as broken.
static func title(text: String, size: int = 64, tilt: float = -2.5) -> Label:
	var l := Label.new()
	l.text = text
	l.add_theme_font_size_override("font_size", size)
	l.add_theme_color_override("font_color", PAPAYA)
	l.add_theme_color_override("font_outline_color", INK)
	l.add_theme_constant_override("outline_size", int(maxf(8.0, size * 0.16)))
	l.rotation_degrees = tilt
	l.pivot_offset = Vector2(0, size * 0.5)
	return l


## A section heading — smaller, paper-coloured, no tilt.
static func heading(text: String, size: int = 32) -> Label:
	var l := Label.new()
	l.text = text
	l.add_theme_font_size_override("font_size", size)
	l.add_theme_color_override("font_color", PAPER)
	l.add_theme_color_override("font_outline_color", INK)
	l.add_theme_constant_override("outline_size", 8)
	return l


## A bolt-struck rule, for separating sections.
static func divider(strike_at: float = 0.34) -> BoltRule:
	var b := BoltRule.new()
	b.line_color = PAPAYA
	b.bolt_color = VOLT
	b.ink = INK
	b.strike_at = strike_at
	return b


## A panel to put things on, already themed.
static func card() -> PanelContainer:
	var p := PanelContainer.new()
	p.add_theme_stylebox_override("panel", panel())
	return p


## Sounds and the hover kick for every button under `root` (recursive).
##
## The kick is a 4% scale-up on hover and a snap back on exit. It is small on
## purpose: the theme already changes the chip's fill colour, and a big scale on
## top of that reads as the button wobbling rather than as it responding.
static func wire_sounds(root: Node) -> void:
	if root == null or not root.is_inside_tree():
		return
	var am = root.get_tree().root.get_node_or_null("AudioManager")
	for btn in root.find_children("*", "BaseButton", true, false):
		if btn.has_meta("ui_sfx_wired"):
			continue
		btn.set_meta("ui_sfx_wired", true)
		if am:
			btn.mouse_entered.connect(func(): am.play_ui("ui_hover"))
			btn.pressed.connect(func(): am.play_ui("ui_click"))
		_wire_kick(btn)


static func _wire_kick(btn: Control) -> void:
	btn.mouse_entered.connect(func(): _kick(btn, 1.04))
	btn.mouse_exited.connect(func(): _kick(btn, 1.0))
	btn.focus_entered.connect(func(): _kick(btn, 1.04))
	btn.focus_exited.connect(func(): _kick(btn, 1.0))


static func _kick(btn: Control, to: float) -> void:
	if not is_instance_valid(btn) or not btn.is_inside_tree():
		return
	# Scale about the chip's own centre, or it grows off to one side. The pivot
	# is set every time because a container can resize the button after it was
	# wired, and a stale pivot is what makes a hover look like a lurch.
	btn.pivot_offset = btn.size * 0.5
	var tw := btn.create_tween()
	# The menu runs while the tree is paused, so the tween has to as well.
	tw.set_pause_mode(Tween.TWEEN_PAUSE_PROCESS)
	tw.set_trans(Tween.TRANS_BACK).set_ease(Tween.EASE_OUT)
	tw.tween_property(btn, "scale", Vector2(to, to), 0.12)