extends Node

## AudioManager autoload singleton (D-068, D-069, D-073).
## 5-bus architecture with directory-scan registry pattern.
## No-op fallback when audio assets absent (D-038).
## Spatial audio positioning for close-range sounds (D-018).

# --- Bus names (D-068) ---
const BUS_MUSIC := "Music"
const BUS_AMBIENT := "Ambient"
const BUS_WORLD_SFX := "WorldSFX"
const BUS_PLAYER_ACTIONS := "PlayerActions"
const BUS_UI_SOUNDS := "UISounds"
const BUSES := [BUS_MUSIC, BUS_AMBIENT, BUS_WORLD_SFX, BUS_PLAYER_ACTIONS, BUS_UI_SOUNDS]

# D-069: Audio dip profiles — dB offsets relative to player slider setting.
# Mid-range of spec values used (e.g. -6 to -8 → -7).
# NOTE: listening_focus requires 30+ stationary ticks before activation (D-069/D-071).
# The tick gate is the caller's responsibility — AudioManager only manages bus volumes.
const DIP_SPECS := {
	"dialogue": {
		"ease_in": 0.3, "ease_out": 0.5,
		"buses": { "Ambient": -7.0 },
	},
	"confrontation": {
		"ease_in": 0.5, "ease_out": 1.0,
		"buses": { "Ambient": -11.0, "WorldSFX": -5.0 },
		"filter_hz": 800.0,
	},
	"listening_focus": {
		"ease_in": 0.5, "ease_out": 0.5,
		"buses": { "WorldSFX": 2.5 },
	},
}

# Low-pass filter default cutoff — effectively bypassed at this value.
const FILTER_CUTOFF_DEFAULT := 20500.0

# Asset registry: filename stem (e.g. "amb_station_base") → AudioStream
var _registry: Dictionary = {}

# Player volume settings per bus (dB). Base for proportional dip calculation.
var _bus_volumes: Dictionary = {}

# Active dip state (D-069)
var _active_dip: String = ""
var _dip_tweens: Array = []

# Low-pass filter on Ambient bus (D-069 confrontation sweep)
var _ambient_filter: AudioEffectLowPassFilter = null

# Ambient loop players keyed by asset_key (D-073 zone crossfade)
var _ambient_players: Dictionary = {}

signal dip_changed(profile: String)


func _ready() -> void:
	_setup_buses()
	_scan_registry()


# --- Bus setup ---

func _setup_buses() -> void:
	for bus_name in BUSES:
		if AudioServer.get_bus_index(bus_name) < 0:
			AudioServer.add_bus()
			var idx := AudioServer.bus_count - 1
			AudioServer.set_bus_name(idx, bus_name)
			AudioServer.set_bus_send(idx, "Master")
		_bus_volumes[bus_name] = 0.0
	# Low-pass filter on Ambient bus — cutoff starts high (bypassed).
	# Confrontation dip sweeps it down to 800 Hz (D-069).
	# Guard: skip if filter already exists (e.g. duplicate _ready in tests).
	var amb_idx := AudioServer.get_bus_index(BUS_AMBIENT)
	if amb_idx >= 0 and _ambient_filter == null:
		_ambient_filter = AudioEffectLowPassFilter.new()
		_ambient_filter.cutoff_hz = FILTER_CUTOFF_DEFAULT
		AudioServer.add_bus_effect(amb_idx, _ambient_filter)


# --- Asset registry (D-068 directory-scan pattern) ---

func _scan_registry() -> void:
	_scan_dir("res://audio/")
	print("AudioManager: %d assets registered" % _registry.size())


func _scan_dir(path: String) -> void:
	var dir := DirAccess.open(path)
	if dir == null:
		if path == "res://audio/":
			print("AudioManager: res://audio/ not found — all play methods no-op")
		return
	dir.list_dir_begin()
	var file_name := dir.get_next()
	while file_name != "":
		var full_path := path.path_join(file_name)
		if dir.current_is_dir():
			_scan_dir(full_path)
		elif not file_name.ends_with(".import"):
			if file_name.get_extension().to_lower() in ["ogg", "wav", "mp3"]:
				var stream := load(full_path) as AudioStream
				if stream:
					_registry[file_name.get_basename()] = stream
		file_name = dir.get_next()


func has_asset(asset_key: String) -> bool:
	return _registry.has(asset_key)


func get_registry_size() -> int:
	return _registry.size()


# --- Playback: non-spatial ---

## Play a one-shot sound on the given bus. No-ops if asset not in registry.
func play(asset_key: String, bus: String = BUS_UI_SOUNDS) -> void:
	var stream := _get_stream(asset_key)
	if stream == null:
		return
	var player := AudioStreamPlayer.new()
	player.stream = stream
	player.bus = bus
	add_child(player)
	player.finished.connect(player.queue_free)
	player.play()


## Start or replace a looping non-spatial sound. Returns the player or null.
func play_loop(asset_key: String, bus: String = BUS_AMBIENT) -> AudioStreamPlayer:
	var stream := _get_stream(asset_key)
	if stream == null:
		return null
	stop_loop(asset_key)
	var loop_stream := stream.duplicate() as AudioStream
	_enable_loop(loop_stream)
	var player := AudioStreamPlayer.new()
	player.stream = loop_stream
	player.bus = bus
	add_child(player)
	player.play()
	_ambient_players[asset_key] = player
	return player


## Stop a looping sound by asset key.
func stop_loop(asset_key: String) -> void:
	if _ambient_players.has(asset_key):
		var player: AudioStreamPlayer = _ambient_players[asset_key]
		if is_instance_valid(player):
			player.stop()
			player.queue_free()
		_ambient_players.erase(asset_key)


## Stop all looping sounds.
func stop_all_loops() -> void:
	for key in _ambient_players.keys():
		stop_loop(key)


# --- Playback: spatial (D-018 close-range) ---

## Play a one-shot spatial sound at a world position (pixels).
## Added to current_scene for correct AudioListener2D positioning.
func play_at(asset_key: String, world_position: Vector2, bus: String = BUS_WORLD_SFX) -> void:
	var stream := _get_stream(asset_key)
	if stream == null:
		return
	var player := AudioStreamPlayer2D.new()
	player.stream = stream
	player.bus = bus
	player.global_position = world_position
	var scene := get_tree().current_scene
	if scene:
		scene.add_child(player)
	else:
		add_child(player)
	player.finished.connect(player.queue_free)
	player.play()


# --- Audio dip profiles (D-069) ---

## Apply a dip profile. Interrupts any active dip, restoring unaffected buses.
## Profiles: "dialogue", "confrontation", "listening_focus"
func apply_dip(profile: String) -> void:
	if not DIP_SPECS.has(profile):
		push_warning("AudioManager: unknown dip profile '%s'" % profile)
		return
	_kill_tweens()
	_active_dip = profile
	var spec: Dictionary = DIP_SPECS[profile]
	var buses: Dictionary = spec.get("buses", {})
	var ease_in: float = spec.get("ease_in", 0.3)
	# Tween ALL buses — affected ones get offset, unaffected ones restore to base.
	for bus_name in BUSES:
		var offset_db: float = buses.get(bus_name, 0.0)
		var target_db: float = _bus_volumes.get(bus_name, 0.0) + offset_db
		var idx := AudioServer.get_bus_index(bus_name)
		if idx < 0:
			continue
		var current_db := AudioServer.get_bus_volume_db(idx)
		if absf(current_db - target_db) < 0.1:
			continue
		var tween := create_tween()
		tween.tween_method(_make_bus_setter(bus_name), current_db, target_db, ease_in)
		_dip_tweens.append(tween)
	# Confrontation: sweep low-pass filter on Ambient (D-069)
	if spec.has("filter_hz") and _ambient_filter:
		var tween := create_tween()
		tween.tween_property(_ambient_filter, "cutoff_hz", spec["filter_hz"], ease_in)
		_dip_tweens.append(tween)
	elif _ambient_filter and _ambient_filter.cutoff_hz < FILTER_CUTOFF_DEFAULT - 100.0:
		# Leaving confrontation for another dip — restore filter
		var tween := create_tween()
		tween.tween_property(_ambient_filter, "cutoff_hz", FILTER_CUTOFF_DEFAULT, ease_in)
		_dip_tweens.append(tween)
	dip_changed.emit(profile)


## Clear the active dip, restoring all bus volumes to player slider settings.
func clear_dip() -> void:
	if _active_dip.is_empty():
		return
	var spec: Dictionary = DIP_SPECS.get(_active_dip, {})
	var ease_out: float = spec.get("ease_out", 0.5)
	_kill_tweens()
	_active_dip = ""
	for bus_name in BUSES:
		var target_db: float = _bus_volumes.get(bus_name, 0.0)
		var idx := AudioServer.get_bus_index(bus_name)
		if idx < 0:
			continue
		var current_db := AudioServer.get_bus_volume_db(idx)
		if absf(current_db - target_db) < 0.1:
			continue
		var tween := create_tween()
		tween.tween_method(_make_bus_setter(bus_name), current_db, target_db, ease_out)
		_dip_tweens.append(tween)
	# Restore low-pass filter
	if _ambient_filter and _ambient_filter.cutoff_hz < FILTER_CUTOFF_DEFAULT - 100.0:
		var tween := create_tween()
		tween.tween_property(_ambient_filter, "cutoff_hz", FILTER_CUTOFF_DEFAULT, ease_out)
		_dip_tweens.append(tween)
	dip_changed.emit("")


func get_active_dip() -> String:
	return _active_dip


# --- Volume control (player sliders, D-069 proportional base) ---

## Set the player's volume preference for a bus. During active dip, immediately
## recalculates effective volume (proportional to new base).
func set_volume(bus: String, volume_db: float) -> void:
	_bus_volumes[bus] = volume_db
	var idx := AudioServer.get_bus_index(bus)
	if idx < 0:
		return
	if _active_dip.is_empty():
		AudioServer.set_bus_volume_db(idx, volume_db)
	else:
		var spec: Dictionary = DIP_SPECS.get(_active_dip, {})
		var buses: Dictionary = spec.get("buses", {})
		var offset_db: float = buses.get(bus, 0.0)
		AudioServer.set_bus_volume_db(idx, volume_db + offset_db)


func get_volume(bus: String) -> float:
	return _bus_volumes.get(bus, 0.0)


# --- Zone crossfade (D-073 stub) ---

## Handle zone transition. Server sends zone_id per tile in ObserverSnapshot.
## Full crossfade implementation deferred to Sprint 9+ (D-073).
## Stub exists so server integration can call it without conditional checks.
func set_zone(_zone_id: String) -> void:
	pass


# --- Internal helpers ---

func _get_stream(asset_key: String) -> AudioStream:
	return _registry.get(asset_key) as AudioStream


func _make_bus_setter(bus_name: String) -> Callable:
	return func(db: float) -> void:
		var idx := AudioServer.get_bus_index(bus_name)
		if idx >= 0:
			AudioServer.set_bus_volume_db(idx, db)


func _kill_tweens() -> void:
	for tween in _dip_tweens:
		if tween != null and tween.is_valid():
			tween.kill()
	_dip_tweens.clear()


static func _enable_loop(stream: AudioStream) -> void:
	if stream is AudioStreamOggVorbis:
		stream.loop = true
	elif stream is AudioStreamWAV:
		stream.loop_mode = AudioStreamWAV.LOOP_FORWARD
	elif stream is AudioStreamMP3:
		stream.loop = true