class_name RhythmConductor
extends AudioStreamPlayer

@export var bpm: float = 120.0
@export var measures: int = 4
@export var beat_offset: float = 0.0
@export var perfect_window: float = 0.060
@export var good_window: float = 0.120
@export var bad_window: float = 0.200
@export var starts_on_ready := true

var song_position := 0.0
var song_position_in_beats := 0
var sec_per_beat := 0.5
var last_reported_beat := -1
var current_measure := 1
var running := false

var _start_time_usec := 0
var _uses_fallback_clock := false

signal beat(position: int)
signal measure(position: int)
signal action_judged(action_name: String, rating: Dictionary)


func _ready() -> void:
	add_to_group("rhythm_conductor")
	sec_per_beat = 60.0 / bpm
	if is_inside_tree():
		_event_bus().connect("rhythm_action_requested", _on_rhythm_action_requested)
	if starts_on_ready:
		start()


func _physics_process(_delta: float) -> void:
	if not running:
		return
	song_position = get_current_song_position()
	var adjusted_position: float = _apply_beat_offset(song_position)
	song_position_in_beats = int(floor(adjusted_position / sec_per_beat))
	_report_beat()


func start() -> void:
	running = true
	_uses_fallback_clock = stream == null
	_start_time_usec = Time.get_ticks_usec()
	song_position = 0.0
	song_position_in_beats = 0
	last_reported_beat = -1
	current_measure = 1
	if not _uses_fallback_clock:
		play()


func stop_conductor() -> void:
	if playing:
		stop()
	running = false


func get_current_song_position() -> float:
	if running and playing:
		var current_position: float = get_playback_position() + AudioServer.get_time_since_last_mix()
		current_position -= AudioServer.get_output_latency()
		return maxf(0.0, current_position)
	if running:
		return float(Time.get_ticks_usec() - _start_time_usec) / 1000000.0
	return song_position


func judge_action(action_name: String) -> Dictionary:
	var rating := get_current_rating()
	rating["action"] = action_name
	emit_signal("action_judged", action_name, rating)
	var bus := _event_bus()
	bus.emit_signal("judgement_made", StringName(str(rating.get("label", "miss"))), float(rating.get("diff", INF)) * 1000.0)
	bus.emit_signal("action_judged", StringName(action_name), rating)
	return rating


func get_current_rating() -> Dictionary:
	return get_rating_for_time(get_current_song_position())


func get_rating_for_time(time_seconds: float) -> Dictionary:
	var adjusted_time: float = _apply_beat_offset(time_seconds)
	if adjusted_time < 0.0:
		return _rating_result("miss", Color("ff0055"), 0, 0.0, INF, INF)
	
	var nearest_beat: int = int(round(adjusted_time / sec_per_beat))
	var nearest_beat_time: float = nearest_beat * sec_per_beat
	var diff: float = adjusted_time - nearest_beat_time
	var abs_diff: float = absf(diff)
	
	if abs_diff <= perfect_window:
		return _rating_result("perfect", Color("00f2ff"), nearest_beat, nearest_beat_time, diff, abs_diff)
	if abs_diff <= good_window:
		return _rating_result("good", Color("ffffff"), nearest_beat, nearest_beat_time, diff, abs_diff)
	if abs_diff <= bad_window:
		return _rating_result("bad", Color("ffaa00"), nearest_beat, nearest_beat_time, diff, abs_diff)
	return _rating_result("miss", Color("ff0055"), nearest_beat, nearest_beat_time, diff, abs_diff)


func get_current_beat_progress() -> float:
	return get_beat_progress_for_time(get_current_song_position())


func get_beat_progress_for_time(time_seconds: float) -> float:
	var adjusted_time: float = _apply_beat_offset(time_seconds)
	if adjusted_time < 0.0:
		return 0.0
	return fposmod(adjusted_time, sec_per_beat) / sec_per_beat


func get_time_to_nearest_beat(time_seconds: float) -> float:
	var adjusted_time: float = _apply_beat_offset(time_seconds)
	if adjusted_time < 0.0:
		return INF
	var nearest_beat_time: float = round(adjusted_time / sec_per_beat) * sec_per_beat
	return adjusted_time - nearest_beat_time


func _report_beat() -> void:
	if last_reported_beat < song_position_in_beats:
		if current_measure > measures:
			current_measure = 1
		emit_signal("beat", song_position_in_beats)
		emit_signal("measure", current_measure)
		_event_bus().emit_signal("beat_ticked", song_position_in_beats)
		last_reported_beat = song_position_in_beats
		current_measure += 1


func _on_rhythm_action_requested(action_name: StringName) -> void:
	judge_action(str(action_name))


func _event_bus() -> Node:
	var root := get_tree().root
	var bus := root.get_node_or_null("EventBus")
	if bus == null:
		bus = load("res://autoload/event_bus.gd").new()
		bus.name = "EventBus"
		root.add_child(bus)
	return bus


func _apply_beat_offset(time_seconds: float) -> float:
	return time_seconds + beat_offset


func _rating_result(label: String, color: Color, nearest_beat: int, nearest_beat_time: float, diff: float, abs_diff: float) -> Dictionary:
	return {
		"label": label,
		"color": color,
		"nearest_beat": nearest_beat,
		"nearest_beat_time": nearest_beat_time,
		"diff": diff,
		"abs_diff": abs_diff,
	}


func _format_signed_ms(seconds: float) -> String:
	if is_inf(seconds):
		return "--"
	return "%+.0f" % (seconds * 1000.0)