security-game/src/game/audio_feedback.gd

class_name AudioFeedback
extends Node
## Procedural audio feedback (PLAN.md: Polish and Accessibility). Generates
## short tones for confirmation prompts, radio responses, and escalation
## feedback without requiring audio assets. Headless-safe: in headless mode
## the AudioServer is a dummy and playback is a no-op.

const SAMPLE_RATE := 22050.0

var _players: Array[AudioStreamPlayer] = []
var _bed_player: AudioStreamPlayer = null
## Observable state so headless tests and the HUD can see what was requested.
var crowd_level: float = 0.0
var bed_playing := false
var radio_crackles := 0
var footsteps := 0
var landings := 0
var precision_ticks := 0

func _ready() -> void:
	# Pre-create a few players so overlapping cues don't cut each other off.
	for i in 4:
		var player := AudioStreamPlayer.new()
		add_child(player)
		_players.append(player)

## Play a short confirmation beep (single high tone).
func play_confirm() -> void:
	_play_tone(880.0, 0.12, 0.5)

## Play a radio-response cue (two quick tones).
func play_radio_response() -> void:
	_play_tone(660.0, 0.10, 0.5)
	_play_tone(990.0, 0.10, 0.5, 0.12)

## Play an escalation warning cue (low descending tone).
func play_escalation(level: int) -> void:
	var freq := 440.0 - float(level) * 40.0
	_play_tone(maxf(freq, 180.0), 0.18, 0.6)

## Start the looping crowd bed (low murmur). Called once per shift; safe to call
## again. Volume then follows `set_crowd_level`.
func start_crowd_bed() -> void:
	if _bed_player == null:
		_bed_player = AudioStreamPlayer.new()
		_bed_player.name = "CrowdBed"
		add_child(_bed_player)
		_bed_player.stream = _build_crowd_stream()
		_bed_player.volume_db = _level_to_db(crowd_level)
	_bed_player.play()
	bed_playing = true

func stop_crowd_bed() -> void:
	if _bed_player:
		_bed_player.stop()
	bed_playing = false

## Crowd mood (0..1) drives the bed volume: quiet when calm, louder when the
## street is agitated or panicking.
func set_crowd_level(mood: float) -> void:
	crowd_level = clampf(mood, 0.0, 1.0)
	if _bed_player:
		_bed_player.volume_db = _level_to_db(crowd_level)

static func _level_to_db(mood: float) -> float:
	return lerpf(-34.0, -12.0, clampf(mood, 0.0, 1.0))

## Radio open cue: a short burst of filtered crackle.
func play_radio_open() -> void:
	radio_crackles += 1
	_play_noise(0.09, 0.35)

## Radio close cue: a lower, shorter click.
func play_radio_close() -> void:
	radio_crackles += 1
	_play_noise(0.06, 0.25, 1400.0)

## Surface-aware footstep: a short filtered burst, lower on asphalt, brighter on
## the stone entrance steps.
func play_footstep(surface: String) -> void:
	footsteps += 1
	var cutoff := 2600.0
	match surface:
		"asphalt":
			cutoff = 1500.0
		"stone":
			cutoff = 3400.0
		_:
			cutoff = 2400.0
	_play_noise(0.045, 0.22, cutoff)

## Landing thump after a step or drop.
func play_land() -> void:
	landings += 1
	_play_tone(92.0, 0.09, 0.4)

## Quiet tick when the precision-walk modifier engages.
func play_precision_tick() -> void:
	precision_ticks += 1
	_play_tone(1180.0, 0.035, 0.22)

## Play a denial/error cue (low buzz).
func play_deny() -> void:
	_play_tone(220.0, 0.20, 0.5)

## Generate a sine-wave tone and play it on a free player.
func _play_tone(freq: float, duration: float, volume: float, delay: float = 0.0) -> void:
	var player := _free_player()
	if player == null:
		return
	var stream := AudioStreamGenerator.new()
	stream.mix_rate = SAMPLE_RATE
	stream.buffer_length = duration + 0.05
	player.stream = stream
	player.volume_db = linear_to_db(volume)
	player.play()
	# Fill the generator buffer with a sine wave.
	var playback: AudioStreamGeneratorPlayback = player.get_stream_playback()
	var frames := int(SAMPLE_RATE * duration)
	for i in frames:
		var t := float(i) / SAMPLE_RATE
		var sample := sin(TAU * freq * t) * 0.6
		playback.push_frame(Vector2(sample, sample))

## Deterministic low murmur for the crowd bed: filtered noise plus a low drone.
func _build_crowd_stream() -> AudioStreamWAV:
	const SECONDS := 4.0
	var frames := int(SAMPLE_RATE * SECONDS)
	var data := PackedByteArray()
	data.resize(frames * 2)
	var rng := RandomNumberGenerator.new()
	rng.seed = 20261031
	var smooth := 0.0
	for i in frames:
		var t := float(i) / SAMPLE_RATE
		# Low-passed noise (a simple one-pole filter) sounds like distant talking.
		smooth = lerpf(smooth, rng.randf_range(-1.0, 1.0), 0.02)
		var drone := sin(TAU * 68.0 * t) * 0.25 + sin(TAU * 103.0 * t) * 0.12
		var sample := (smooth * 2.2 + drone) * 0.35
		var v := int(clampf(sample, -1.0, 1.0) * 32767.0)
		data[i * 2] = v & 0xFF
		data[i * 2 + 1] = (v >> 8) & 0xFF
	var stream := AudioStreamWAV.new()
	stream.format = AudioStreamWAV.FORMAT_16_BITS
	stream.mix_rate = int(SAMPLE_RATE)
	stream.stereo = false
	stream.data = data
	stream.loop_mode = AudioStreamWAV.LOOP_FORWARD
	stream.loop_begin = 0
	stream.loop_end = frames
	return stream

## Short filtered noise burst used for the radio crackle.
func _play_noise(duration: float, volume: float, cutoff_hz: float = 3200.0) -> void:
	var player := _free_player()
	if player == null:
		return
	var frames := int(SAMPLE_RATE * duration)
	var data := PackedByteArray()
	data.resize(frames * 2)
	var rng := RandomNumberGenerator.new()
	rng.seed = 7
	var smooth := 0.0
	var alpha := clampf(cutoff_hz / SAMPLE_RATE, 0.01, 0.9)
	for i in frames:
		smooth = lerpf(smooth, rng.randf_range(-1.0, 1.0), alpha)
		var env := 1.0 - float(i) / float(maxi(frames, 1))
		var v := int(clampf(smooth * env, -1.0, 1.0) * 32767.0)
		data[i * 2] = v & 0xFF
		data[i * 2 + 1] = (v >> 8) & 0xFF
	var stream := AudioStreamWAV.new()
	stream.format = AudioStreamWAV.FORMAT_16_BITS
	stream.mix_rate = int(SAMPLE_RATE)
	stream.stereo = false
	stream.data = data
	player.stream = stream
	player.volume_db = linear_to_db(volume)
	player.play()

func _free_player() -> AudioStreamPlayer:
	if _players.is_empty():
		return null
	for player in _players:
		if not player.playing:
			return player
	return _players[0]