class_name OctopusBoss
extends Node2D

signal phase_changed(phase: int)
signal health_changed(current: int, maximum: int)
signal defeated

const EYE_SCENE: PackedScene = preload("res://boss/BossEye.tscn")
const MINION_SCENE: PackedScene = preload("res://boss/BossMinion.tscn")
const RETURN_SCENE: PackedScene = preload("res://boss/BossReturnSignal.tscn")
const LASER_SCENE: PackedScene = preload("res://enemies/EnemyBigLaserBeam.tscn")
const COMBAT_TARGET = preload("res://core/CombatTarget.gd")

enum Phase { MINION_WAVES, LASER_STORM, CORE_EXPOSED, DEFEATED }

const EYE_COUNT: int = 6
const PHASE_TWO_EYES: int = 3
const BODY_RADIUS: float = 86.0
const TENTACLE_LENGTH: float = 235.0
const MAX_ACTIVE_MINIONS: int = 16
const GOLDEN_WAVE_PERIOD: int = 3
const CORE_MAX_HEALTH: int = 36
const REDRAW_INTERVAL: float = 1.0 / 12.0
const ARMOURED_IRIS_COLOR := Color(0.72, 0.22, 1.0)
const ARMOURED_PUPIL_COLOR := Color(0.18, 1.0, 0.62)
const EXPOSED_IRIS_COLOR := Color(1.0, 0.56, 0.08)
const EXPOSED_PUPIL_COLOR := Color(1.0, 0.94, 0.42)

@export var first_wave_delay: float = 1.5
@export var wave_interval: float = 6.0
@export var minions_per_wave: int = 7
@export var laser_interval: float = 2.25
@export var laser_charge_time: float = 0.7
@export var move_speed: float = 115.0
@export var move_acceleration: float = 180.0
@export var preferred_fleet_range: float = 880.0
@export var strafe_speed: float = 72.0

var phase: int = Phase.MINION_WAVES
var wave_timer: float = 0.0
var laser_timer: float = 0.0
var wave_index: int = 0
var eyes: Array = []
var eyes_opened: int = 0
var eyes_destroyed: int = 0
var spawned_minions: Array = []
var return_signals: Array = []
var animation_phase: float = 0.0
var redraw_left: float = 0.0
var total_max_health: int = CORE_MAX_HEALTH
var core_health: int = CORE_MAX_HEALTH
var core_exposed: bool = false
var combat_active: bool = true
var movement_velocity: Vector2 = Vector2.ZERO


func _ready() -> void:
	add_to_group("bosses")
	wave_timer = first_wave_delay
	laser_timer = laser_interval
	_build_eyes()
	queue_redraw()


func _build_eyes() -> void:
	for i in range(EYE_COUNT):
		var eye: Area2D = EYE_SCENE.instantiate()
		eye.position = eye_position(i)
		eye.rotation = eye.position.angle()
		add_child(eye)
		eye.health_changed.connect(_on_eye_health_changed)
		eye.destroyed.connect(_on_eye_destroyed.bind(i))
		eyes.append(eye)
		total_max_health += int(eye.max_hp)


func eye_position(index: int) -> Vector2:
	var angle: float = -PI / 2.0 + TAU * float(index) / float(EYE_COUNT)
	# Alternating reach keeps the silhouette organic without randomising the
	# actual weak-point layout between attempts.
	var reach: float = TENTACLE_LENGTH * (0.88 if index % 2 == 0 else 1.0)
	return Vector2.from_angle(angle) * reach


func _process(delta: float) -> void:
	if phase == Phase.DEFEATED or not combat_active:
		return
	animation_phase += delta
	_move_around_fleet(delta)

	wave_timer -= delta
	if wave_timer <= 0.0:
		spawn_wave()
		wave_timer = wave_interval * (1.25 if phase == Phase.LASER_STORM else 1.0)

	if phase == Phase.LASER_STORM:
		laser_timer -= delta
		if laser_timer <= 0.0:
			fire_laser_volley()
			laser_timer = laser_interval
	redraw_left -= delta
	if redraw_left <= 0.0:
		redraw_left = REDRAW_INTERVAL
		queue_redraw()


func _move_around_fleet(delta: float) -> void:
	var fleet: Node2D = get_tree().get_first_node_in_group("player_fleet")
	if fleet == null or fleet.ships.is_empty():
		movement_velocity = movement_velocity.move_toward(Vector2.ZERO,
			move_acceleration * delta)
		return
	var from_fleet: Vector2 = global_position - fleet.get_centroid()
	if from_fleet.length_squared() < 1.0:
		from_fleet = Vector2.UP
	var away: Vector2 = from_fleet.normalized()
	# Close or open the range while continuously strafing around the fleet.
	# Acceleration keeps the large creature drifting rather than snapping when
	# the player crosses it, and the speed cap makes its orbit predictable.
	var range_error: float = from_fleet.length() - preferred_fleet_range
	var radial_speed: float = clampf(range_error * 0.8, -move_speed, move_speed)
	var desired_velocity: Vector2 = -away * radial_speed \
		+ away.orthogonal() * strafe_speed
	if phase == Phase.CORE_EXPOSED:
		desired_velocity *= 0.7
	desired_velocity = desired_velocity.limit_length(move_speed)
	movement_velocity = movement_velocity.move_toward(desired_velocity,
		move_acceleration * delta)
	global_position += movement_velocity * delta


func spawn_wave() -> void:
	if not combat_active or phase == Phase.CORE_EXPOSED or phase == Phase.DEFEATED:
		return
	var fleet: Node2D = get_tree().get_first_node_in_group("player_fleet")
	if fleet == null or fleet.ships.is_empty() or get_parent() == null:
		return
	_prune_invalid(spawned_minions)
	var wanted: int = maxi(5,
		minions_per_wave - (2 if phase == Phase.LASER_STORM else 0))
	var count: int = mini(wanted, MAX_ACTIVE_MINIONS - spawned_minions.size())
	if count <= 0:
		return
	# One useful return every third ACTUAL wave. The first contains one so the
	# mechanic teaches itself immediately; the two red-only waves afterwards
	# make the gold target an event rather than permanent scenery.
	var marked_slot: int = wave_index % GOLDEN_WAVE_PERIOD
	if marked_slot != 0:
		marked_slot = -1
	else:
		marked_slot = wave_index % count
	for i in range(count):
		var minion: Area2D = MINION_SCENE.instantiate()
		minion.marked = i == marked_slot
		minion.boss = self
		get_parent().add_child(minion)
		minion.tree_exiting.connect(_forget_minion.bind(minion))
		var angle: float = TAU * float(i) / float(count) + float(wave_index) * 0.47
		# Minions are siblings rather than boss children, so account for the
		# encounter scene's imposing boss scale when placing them off its body.
		var launch_direction := Vector2.from_angle(angle)
		var launch_radius: float = BODY_RADIUS * scale.x + 60.0
		minion.global_position = global_position + launch_direction * launch_radius
		minion.expel(launch_direction, (i + wave_index) % 3 == 0)
		spawned_minions.append(minion)
	wave_index += 1


func accept_marked_kill(from: Vector2) -> void:
	if phase == Phase.DEFEATED or get_parent() == null:
		return
	var returning: Node2D = RETURN_SCENE.instantiate()
	returning.target = self
	get_parent().add_child(returning)
	returning.tree_exiting.connect(_forget_return.bind(returning))
	returning.global_position = from
	return_signals.append(returning)


func open_next_eye() -> bool:
	if phase == Phase.DEFEATED:
		return false
	for eye in eyes:
		if is_instance_valid(eye) and not bool(eye.opened):
			eye.open_eye()
			eyes_opened += 1
			return true
	return false


func _on_eye_destroyed(_index: int) -> void:
	eyes_destroyed += 1
	health_changed.emit(current_health(), max_health())
	if eyes_destroyed >= EYE_COUNT:
		_expose_core()
		return
	if phase == Phase.MINION_WAVES and eyes_destroyed >= PHASE_TWO_EYES:
		phase = Phase.LASER_STORM
		laser_timer = 0.2
		phase_changed.emit(phase)
	queue_redraw()


func _on_eye_health_changed(_current: int, _maximum: int) -> void:
	health_changed.emit(current_health(), max_health())


func current_health() -> int:
	var total: int = core_health
	for eye in eyes:
		if is_instance_valid(eye):
			total += maxi(int(eye.hp), 0)
	return total


func max_health() -> int:
	return total_max_health


func fire_laser_volley() -> void:
	if phase != Phase.LASER_STORM:
		return
	var fleet: Node2D = get_tree().get_first_node_in_group("player_fleet")
	if fleet == null or fleet.ships.is_empty():
		return
	var toward: Vector2 = fleet.get_centroid() - global_position
	if toward.length() < 1.0:
		return
	# Three locked, dodgeable lanes form the second phase's distinct pattern.
	for spread in [-0.17, 0.0, 0.17]:
		var beam: Node2D = LASER_SCENE.instantiate()
		beam.charge_time = laser_charge_time
		beam.infinite_range = true
		beam.beam_half_width = 24.0
		beam.damage = 1
		beam.color = Color(1.0, 0.12, 0.58)
		get_tree().root.add_child(beam)
		beam.add_to_group("boss_lasers")
		beam.launch(global_position, toward.rotated(float(spread)))


func set_combat_active(active: bool) -> void:
	combat_active = active
	if active:
		wave_timer = first_wave_delay
		laser_timer = laser_interval


func _expose_core() -> void:
	if core_exposed or phase == Phase.DEFEATED:
		return
	core_exposed = true
	phase = Phase.CORE_EXPOSED
	COMBAT_TARGET.register(self, COMBAT_TARGET.DANGER_PRIORITY)
	$CoreCollision.set_deferred("disabled", false)
	phase_changed.emit(phase)
	queue_redraw()


func take_damage(amount: int) -> bool:
	if not core_exposed or phase == Phase.DEFEATED:
		return false
	core_health = maxi(core_health - maxi(amount, 1), 0)
	health_changed.emit(current_health(), max_health())
	if core_health > 0:
		queue_redraw()
		return false
	_defeat()
	return true


func _forget_minion(minion: Node) -> void:
	spawned_minions.erase(minion)


func _forget_return(returning: Node) -> void:
	return_signals.erase(returning)


func _prune_invalid(nodes: Array) -> void:
	for i in range(nodes.size() - 1, -1, -1):
		if not is_instance_valid(nodes[i]) or nodes[i].is_queued_for_deletion():
			nodes.remove_at(i)


func _defeat() -> void:
	if phase == Phase.DEFEATED:
		return
	phase = Phase.DEFEATED
	core_health = 0
	remove_from_group(COMBAT_TARGET.GROUP)
	$CoreCollision.set_deferred("disabled", true)
	for minion in spawned_minions:
		if is_instance_valid(minion):
			minion.retire()
	for returning in return_signals:
		if is_instance_valid(returning):
			returning.queue_free()
	EnemyExplosionVFX.spawn(get_tree().root, global_position)
	Sfx.play(get_tree(), Sfx.ENEMY_DEATH)
	visible = false
	phase_changed.emit(phase)
	defeated.emit()


func suppress_as_defeated() -> void:
	phase = Phase.DEFEATED
	core_health = 0
	combat_active = false
	visible = false
	set_process(false)


func _draw() -> void:
	if phase == Phase.DEFEATED:
		return
	var flesh := Color(0.95, 0.18, 0.58)
	var phase_color := Color(1.0, 0.1, 0.32) if phase == Phase.LASER_STORM \
		else flesh
	var dark := Color(0.075, 0.004, 0.05)
	for i in range(EYE_COUNT):
		var end: Vector2 = eye_position(i)
		var angle: float = end.angle()
		var side := Vector2.from_angle(angle + PI / 2.0)
		var points := PackedVector2Array()
		for step in range(9):
			var t: float = float(step) / 8.0
			var sway: float = sin(animation_phase * 1.7 + float(i) * 1.4 + t * PI * 2.0)
			points.append(end * t + side * sway * 18.0 * sin(t * PI))
		NeonDraw.draw_glowing_path(self, points, phase_color, 0.8, 0.8, dark)

	var body := PackedVector2Array()
	for i in range(28):
		var angle: float = TAU * float(i) / 28.0
		var pulse: float = 1.0 + 0.045 * sin(animation_phase * 2.4 + float(i) * 1.9)
		body.append(Vector2.from_angle(angle) * BODY_RADIUS * pulse)
	NeonDraw.draw_glowing_polygon(self, body, phase_color, 0.92, dark)
	# The central eye watches but is armoured; only tentacle eyes opened by a
	# returning marked minion join the combat-target group.
	draw_set_transform(Vector2.ZERO, 0.0, Vector2(0.72, 1.0))
	var core_color := EXPOSED_IRIS_COLOR if core_exposed else ARMOURED_IRIS_COLOR
	NeonDraw.draw_glowing_circle(self, Vector2.ZERO, 31.0,
		core_color, 0.8 + 0.2 * sin(animation_phase * 3.0), dark)
	NeonDraw.draw_glowing_circle(self, Vector2.ZERO, 12.0,
		EXPOSED_PUPIL_COLOR if core_exposed else ARMOURED_PUPIL_COLOR,
		1.0, dark)
	draw_set_transform(Vector2.ZERO, 0.0, Vector2.ONE)