extends GPUParticles3D

# Bioluminescent floating particles — only active in abyss zone (player y < -30)

const ABYSS_DEPTH_THRESHOLD: float = -30.0

var _player: Node3D = null


func _ready() -> void:
	amount = 200
	lifetime = 12.0
	one_shot = false
	explosiveness = 0.0
	randomness = 1.0
	visibility_aabb = AABB(Vector3(-30, -25, -30), Vector3(60, 50, 60))

	var process_mat := ParticleProcessMaterial.new()
	process_mat.emission_shape = ParticleProcessMaterial.EMISSION_SHAPE_BOX
	process_mat.emission_box_extents = Vector3(28.0, 20.0, 28.0)

	process_mat.direction = Vector3(0.0, 1.0, 0.0)
	process_mat.spread = 120.0
	process_mat.initial_velocity_min = 0.0
	process_mat.initial_velocity_max = 0.08

	process_mat.linear_accel_min = -0.03
	process_mat.linear_accel_max = 0.03
	process_mat.radial_accel_min = -0.02
	process_mat.radial_accel_max = 0.02

	process_mat.damping_min = 0.4
	process_mat.damping_max = 0.9

	process_mat.scale_min = 0.03
	process_mat.scale_max = 0.12

	# Cyan-green bioluminescent color
	var grad := Gradient.new()
	grad.set_color(0, Color(0.0, 0.8, 0.9, 0.0))
	grad.set_color(1, Color(0.0, 0.8, 0.9, 0.0))
	grad.add_point(0.1, Color(0.1, 0.9, 0.8, 0.7))
	grad.add_point(0.85, Color(0.2, 0.7, 1.0, 0.6))
	var grad_tex := GradientTexture1D.new()
	grad_tex.gradient = grad
	process_mat.color_ramp = grad_tex
	process_mat.color = Color(0.1, 0.9, 0.8, 0.7)

	process_material = process_mat

	var quad := QuadMesh.new()
	quad.size = Vector2(0.08, 0.08)

	var mat := StandardMaterial3D.new()
	mat.shading_mode = BaseMaterial3D.SHADING_MODE_UNSHADED
	mat.transparency = BaseMaterial3D.TRANSPARENCY_ALPHA
	mat.billboard_mode = BaseMaterial3D.BILLBOARD_ENABLED
	mat.emission_enabled = true
	mat.emission = Color(0.2, 0.8, 1.0)
	mat.emission_energy_multiplier = 3.0
	mat.albedo_color = Color(0.1, 0.9, 0.8, 0.7)

	quad.surface_set_material(0, mat)
	draw_pass_1 = quad

	# Start inactive until we detect depth
	emitting = false
	_find_player()


func _find_player() -> void:
	var players := get_tree().get_nodes_in_group("player")
	if players.size() > 0:
		_player = players[0] as Node3D


func _process(_delta: float) -> void:
	if _player == null:
		_find_player()
		return

	var in_abyss: bool = _player.global_position.y < ABYSS_DEPTH_THRESHOLD
	if in_abyss != emitting:
		emitting = in_abyss

	# Follow player horizontally, float at player depth
	if in_abyss:
		global_position = _player.global_position