extends Control

## Screen position -> board slot. That's the whole job.
##
## Scoring lives in Phase 2's ScoringEngine. This resolves WHERE, not WHAT IT'S
## WORTH. Keeping them separate means the modifier UI can ship before the
## scoring pipeline exists.
##
## HOW IT WORKS
## ------------
## The raycast returns a `face_index` — which triangle of the trimesh was hit.
## Dartboard maps that face to a material slot name. The material name IS the
## sector.
##
## No trigonometry. No calibration constants. Survives the board being rotated,
## tilted, moved, or having its sectors remapped — because we're reading the
## geometry, not calculating from an assumed layout.
##
## This is only possible because the board has a ConcavePolygonShape3D (trimesh)
## collider. A box or cylinder gives you no face_index.

signal slot_hovered(slot: StringName)
signal slot_dropped(slot: StringName, modifier: Modifier)

const RAY_LENGTH := 1000.0

@export var camera: Camera3D
@export var dartboard: Dartboard

@export_group("Debug")
## Print every hover. Noisy but useful when calibrating.
@export var log_hovers := false

## slot -> Modifier
var applied: Dictionary = {}

var _last_hovered: StringName = &""


func _ready() -> void:
	# The tray's pieces need to receive mouse events. This node is just a
	# service — it must never eat them.
	mouse_filter = Control.MOUSE_FILTER_IGNORE

	if camera == null:
		push_error("DropCatcher: `camera` export is not set.")
	if dartboard == null:
		push_error("DropCatcher: `dartboard` export is not set.")


# --- Public -------------------------------------------------------------

## Which slot is under this screen position? &"" if the board isn't there.
func slot_at_screen_pos(screen_pos: Vector2) -> StringName:
	if camera == null or dartboard == null:
		return &""

	var hit := _raycast(screen_pos)
	if hit.is_empty():
		return &""

	# Only the board counts. The SpiderBody (layer 4) is a bounce surface, not
	# a drop target.
	if hit.get("collider") != dartboard:
		return &""

	var face: int = hit.get("face_index", -1)
	if face < 0:
		push_warning("Raycast returned no face_index. Is the collider a trimesh?")
		return &""

	var slot := dartboard.slot_for_face(face)
	if slot == &"":
		push_warning("Face %d didn't map to any slot." % face)

	return slot


## Called every frame by a piece being dragged, so it can highlight.
func hover(screen_pos: Vector2) -> StringName:
	var slot := slot_at_screen_pos(screen_pos)

	if slot != _last_hovered:
		_last_hovered = slot
		slot_hovered.emit(slot)
		if log_hovers and slot != &"":
			print("hover: %s" % slot)

	return slot


## Drop a modifier at a screen position. True if it landed on a valid target.
func apply_modifier_at_screen_pos(screen_pos: Vector2, modifier: Modifier) -> bool:
	if modifier == null:
		push_warning("DropCatcher: null modifier.")
		return false

	var slot := slot_at_screen_pos(screen_pos)
	if slot == &"":
		return false   # missed the board

	if not _is_valid_target(slot):
		return false   # hit the board, but not somewhere a modifier can go

	dartboard.paint_slot(slot, modifier.texture)
	applied[slot] = modifier
	slot_dropped.emit(slot, modifier)

	print("applied '%s' -> %s" % [modifier.id, slot])
	return true


## Which slots can hold a modifier?
##
## Sectors: yes. Bulls: yes (it's a slot in its own right — the bull modifier
## affects inner and outer together). Flat tire: no — it's the outer band, not
## a scoring region.
func _is_valid_target(slot: StringName) -> bool:
	return dartboard.is_sector(slot) or slot == Dartboard.BULL_SLOT


func modifier_at(slot: StringName) -> Modifier:
	return applied.get(slot)


func clear(slot: StringName) -> void:
	applied.erase(slot)
	dartboard.clear_slot(slot)


func clear_all() -> void:
	applied.clear()
	dartboard.clear_all_slots()


# --- Internals ----------------------------------------------------------

func _raycast(screen_pos: Vector2) -> Dictionary:
	var origin := camera.project_ray_origin(screen_pos)
	var params := PhysicsRayQueryParameters3D.create(
		origin,
		origin + camera.project_ray_normal(screen_pos) * RAY_LENGTH
	)
	params.collide_with_areas = false
	params.collide_with_bodies = true

	# Don't let the dart block the drop. It's on layer 2; the board is layer 1.
	params.collision_mask = 1

	return get_viewport().world_3d.direct_space_state.intersect_ray(params)