class_name HudGauge
extends HudInstrument

# Generic bar gauge (vertical or horizontal) with a short label and numeric
# readout — used for speed, altitude, and thrust. A dumb display fed by
# HUDController via set_value.

const BG_COLOR := Color(0.05, 0.07, 0.11, 0.55)
const FRAME_COLOR := Color(0.5, 0.85, 1.0, 0.7)
const TEXT_COLOR := Color(0.85, 0.92, 1.0, 0.9)

@export var label := "SPD"
@export var max_value := 100.0
@export var horizontal := false
@export var fill_color := Color(0.5, 0.85, 1.0, 0.85)
# Printf pattern for the numeric readout.
@export var value_format := "%.0f"

var _target := 0.0
var _value := 0.0


func set_value(value: float) -> void:
	_target = value


func _process(delta: float) -> void:
	var t := _smoothing_weight(delta)
	var new_value := lerpf(_value, _target, t)
	# Redraw threshold scales with the gauge's own range so it stays
	# imperceptible whether this is a 0-12 altitude gauge or a 0-100 thrust
	# bar, while skipping the redraw once the lerp has visually settled.
	var changed := absf(new_value - _value) > max_value * 0.001
	_value = new_value
	if changed:
		_throttled_redraw(delta)


func _draw() -> void:
	var font := ThemeDB.fallback_font
	var fraction := clampf(_value / max_value, 0.0, 1.0)
	var reading := value_format % _value

	if horizontal:
		# [label] [======bar======] [value]
		var hbar := Rect2(34, 2, size.x - 74, size.y - 4)
		draw_string(font, Vector2(0, size.y - 4), label, HORIZONTAL_ALIGNMENT_LEFT, -1, 11, TEXT_COLOR)
		draw_rect(hbar, BG_COLOR)
		draw_rect(Rect2(hbar.position, Vector2(hbar.size.x * fraction, hbar.size.y)), fill_color)
		draw_rect(hbar, FRAME_COLOR, false, 1.0)
		draw_string(font, Vector2(hbar.end.x + 6, size.y - 4), reading, HORIZONTAL_ALIGNMENT_LEFT, -1, 11, TEXT_COLOR)
		return

	# label / vertical bar filling upward / value
	var bar := Rect2(size.x / 2.0 - 9, 16, 18, size.y - 34)
	var label_size := font.get_string_size(label, HORIZONTAL_ALIGNMENT_CENTER, -1, 11)
	draw_string(font, Vector2(size.x / 2.0 - label_size.x / 2.0, 12), label,
		HORIZONTAL_ALIGNMENT_CENTER, -1, 11, TEXT_COLOR)
	draw_rect(bar, BG_COLOR)
	var fill_h := bar.size.y * fraction
	draw_rect(Rect2(Vector2(bar.position.x, bar.end.y - fill_h), Vector2(bar.size.x, fill_h)), fill_color)
	draw_rect(bar, FRAME_COLOR, false, 1.0)
	# Quarter tick marks up the side of the bar.
	for i in range(1, 4):
		var y := bar.end.y - bar.size.y * i / 4.0
		draw_line(Vector2(bar.position.x - 3, y), Vector2(bar.position.x, y), FRAME_COLOR, 1.0)
	var reading_size := font.get_string_size(reading, HORIZONTAL_ALIGNMENT_CENTER, -1, 11)
	draw_string(font, Vector2(size.x / 2.0 - reading_size.x / 2.0, size.y - 2), reading,
		HORIZONTAL_ALIGNMENT_CENTER, -1, 11, TEXT_COLOR)