extends Node2D

# Forgejo #79: a small "+N" with the resource's own mark, rising and fading
# where the fleet picked something up.
#
# Collecting used to be entirely silent - a rock vanished and a number in the
# corner of the screen changed. Which number, and by how much, was left for
# the player to notice on their own. This says it at the point it happened,
# in the resource's own colour, and gets out of the way.
#
# Built from the SAME glyph scene the resource tables and transfer rows use
# (ResourceDefinition.glyph_scene), so a new material added to the catalog
# gets a correct pickup mark with no work here - and can never end up with
# one mark in the HUD and a different one in the world.

const RESOURCE_DEFINITIONS = preload("res://ResourceDefinitions.gd")
# Deliberately NO class_name, and the constructor below loads this file by
# path rather than naming the class. A global class-name identifier - even a
# script's own, inside its own static function - needs the class cache already
# warm, and it is not when this is reached indirectly through a preview scene
# loading Main.tscn. That failed to compile outright, taking Rock and the gas
# vents down with it. Callers preload the path too; see Rock.gd.
const SELF_PATH: String = "res://ResourcePickupVFX.gd"

const RISE_DISTANCE: float = 46.0
const DURATION: float = 0.85
const GLYPH_SIZE: float = 22.0
const DIGIT_HEIGHT: float = 20.0
# Held fully opaque for the first part of its life, so the eye has time to
# catch it before it starts going.
const FADE_START: float = 0.45

var age: float = 0.0
var colour: Color = Color.WHITE
var start_y: float = 0.0


static func spawn(parent: Node, world_position: Vector2, resource_type: String,
		amount: int) -> void:
	if amount <= 0:
		return
	var vfx: Node2D = (load(SELF_PATH) as GDScript).new()
	vfx.position = world_position
	vfx.build(resource_type, amount)
	parent.add_child(vfx)


func build(resource_type: String, amount: int) -> void:
	var definition: Resource = RESOURCE_DEFINITIONS.get_definition(resource_type)
	colour = definition.color if definition != null else Color.WHITE

	if definition != null and definition.glyph_scene != null:
		var glyph: Control = definition.glyph_scene.instantiate()
		glyph.colour = definition.color
		# Anchors first. The glyph scenes are authored as full-rect Controls
		# for the panels that host them, and Godot recomputes the size of any
		# Control with non-equal opposite anchors right after _ready() - so
		# assigning size without this is overwritten, with a warning, the
		# moment it enters the tree.
		glyph.set_anchors_preset(Control.PRESET_TOP_LEFT)
		glyph.size = Vector2(GLYPH_SIZE, GLYPH_SIZE)
		glyph.position = Vector2(-2.0, -GLYPH_SIZE * 0.5)
		add_child(glyph)

	# show_icon off: the resource's own glyph is already beside it, and
	# NeonNumber's built-in mark is the ore hexagon whatever the amount is.
	var number := NeonNumber.new()
	number.show_icon = false
	number.amount = amount
	number.digit_height = DIGIT_HEIGHT
	number.glow_color = colour
	number.core_color = colour.darkened(0.8)
	number.size = Vector2(60.0, DIGIT_HEIGHT)
	number.position = Vector2(GLYPH_SIZE + 4.0, -DIGIT_HEIGHT * 0.5)
	add_child(number)

	start_y = position.y
	z_index = 40


func _process(delta: float) -> void:
	age += delta
	var t: float = age / DURATION
	if t >= 1.0:
		queue_free()
		return
	# Eases out: quick off the mark, drifting by the end.
	position.y = start_y - RISE_DISTANCE * (1.0 - pow(1.0 - t, 2.0))
	modulate.a = 1.0 if t < FADE_START else 1.0 - (t - FADE_START) / (1.0 - FADE_START)
	queue_redraw()


func _draw() -> void:
	# The plus sign, drawn here rather than as a third child - it is two
	# strokes and giving it its own node would cost more than it saves.
	var centre := Vector2(-12.0, 0.0)
	var arm: float = 5.0
	NeonDraw.draw_glowing_line(self, centre - Vector2(arm, 0.0), centre + Vector2(arm, 0.0),
		colour, 1.0, 0.5, colour.darkened(0.8))
	NeonDraw.draw_glowing_line(self, centre - Vector2(0.0, arm), centre + Vector2(0.0, arm),
		colour, 1.0, 0.5, colour.darkened(0.8))