class_name HudAttitudeIndicator
extends HudInstrument

# Aircraft-style attitude indicator (artificial horizon): the sky/ground disc
# rolls and the pitch ladder scrolls behind a fixed ship symbol, so pitch and
# roll are readable at a glance. Pure _draw code — no textures. A dumb display:
# HUDController pushes values in via set_attitude; it never reads the ship.

const SKY_COLOR := Color(0.10, 0.24, 0.42, 0.9)
const GROUND_COLOR := Color(0.22, 0.15, 0.10, 0.9)
const LINE_COLOR := Color(0.85, 0.92, 1.0, 0.9)
const SHIP_SYMBOL_COLOR := Color(1.0, 0.8, 0.2)
const RING_COLOR := Color(0.5, 0.85, 1.0, 0.7)

# Instrument scale: degrees of pitch visible from centre to rim.
const PITCH_RANGE := 45.0

var _target_pitch := 0.0
var _target_roll := 0.0
var _pitch := 0.0
var _roll := 0.0


func set_attitude(pitch_deg: float, roll_deg: float) -> void:
	_target_pitch = pitch_deg
	_target_roll = roll_deg


# Below this, both axes have visually settled — skip the redraw.
const REDRAW_EPSILON_DEG := 0.05

func _process(delta: float) -> void:
	var t := _smoothing_weight(delta)
	var new_pitch := lerpf(_pitch, _target_pitch, t)
	var new_roll := lerp_angle_deg(_roll, _target_roll, t)
	var changed := absf(new_pitch - _pitch) > REDRAW_EPSILON_DEG \
		or absf(angle_delta_deg(_roll, new_roll)) > REDRAW_EPSILON_DEG
	_pitch = new_pitch
	_roll = new_roll
	if changed:
		_throttled_redraw(delta)


func _draw() -> void:
	var center := size / 2.0
	var radius := minf(size.x, size.y) / 2.0 - 10.0
	var px_per_deg := radius / PITCH_RANGE
	# Screen y grows downward, so nose-up (positive pitch) pushes the horizon
	# down the instrument (+y) and reveals more sky.
	var horizon_y := clampf(_pitch * px_per_deg, -radius, radius)
	var roll_rad := deg_to_rad(_roll)

	# Everything inside the dial is drawn in the horizon frame: rotated
	# opposite to roll so the horizon stays level while the instrument banks.
	draw_set_transform(center, -roll_rad, Vector2.ONE)

	# Ground disc, then the sky as the circle segment above the horizon chord.
	draw_circle(Vector2.ZERO, radius, GROUND_COLOR)
	var sky := PackedVector2Array()
	for i in 97:
		# Start sampling at the bottom of the circle (excluded region) so the
		# kept arc through the top is contiguous.
		var ang := PI / 2.0 + float(i) * TAU / 96.0
		var p := Vector2(cos(ang), sin(ang)) * radius
		if p.y < horizon_y:
			sky.append(p)
	if sky.size() >= 3:
		draw_colored_polygon(sky, SKY_COLOR)

	# Horizon line, clipped to the dial.
	if absf(horizon_y) < radius:
		var half_chord := sqrt(radius * radius - horizon_y * horizon_y)
		draw_line(Vector2(-half_chord, horizon_y), Vector2(half_chord, horizon_y), LINE_COLOR, 2.0)

	# Pitch ladder: rungs every 10 degrees, labelled, scrolling with pitch.
	var font := ThemeDB.fallback_font
	for ladder_deg: int in [-30, -20, -10, 10, 20, 30]:
		var y := horizon_y - ladder_deg * px_per_deg
		if absf(y) > radius - 12.0:
			continue
		var half_w := 22.0 if ladder_deg % 20 == 0 else 14.0
		draw_line(Vector2(-half_w, y), Vector2(half_w, y), LINE_COLOR, 1.0)
		draw_string(font, Vector2(half_w + 4.0, y + 4.0), str(absi(ladder_deg)),
			HORIZONTAL_ALIGNMENT_LEFT, -1, 10, LINE_COLOR)

	# Roll pointer: triangle at the dial's top edge in the horizon frame, so
	# it swings against the fixed tick marks as the ship banks.
	draw_colored_polygon(PackedVector2Array([
		Vector2(0, -radius + 2.0), Vector2(-5, -radius + 12.0), Vector2(5, -radius + 12.0),
	]), SHIP_SYMBOL_COLOR)

	# Back to the instrument frame for the fixed furniture.
	draw_set_transform(center, 0.0, Vector2.ONE)

	# Roll scale ticks at 0, +/-30, +/-60 degrees around the top of the dial.
	for tick_deg: int in [-60, -30, 0, 30, 60]:
		var ang := deg_to_rad(float(tick_deg)) - PI / 2.0
		var dir := Vector2(cos(ang), sin(ang))
		var tick_len := 8.0 if tick_deg == 0 else 5.0
		draw_line(dir * radius, dir * (radius + tick_len), RING_COLOR, 2.0)

	# Fixed ship symbol: wings + centre dot, what the ladder is read against.
	draw_line(Vector2(-34, 0), Vector2(-10, 0), SHIP_SYMBOL_COLOR, 3.0)
	draw_line(Vector2(10, 0), Vector2(34, 0), SHIP_SYMBOL_COLOR, 3.0)
	draw_line(Vector2(-10, 0), Vector2(0, 5), SHIP_SYMBOL_COLOR, 3.0)
	draw_line(Vector2(0, 5), Vector2(10, 0), SHIP_SYMBOL_COLOR, 3.0)

	draw_arc(Vector2.ZERO, radius, 0.0, TAU, 96, RING_COLOR, 2.0, true)