@tool
extends Control

signal layout_saved
signal save_failed
signal load_failed

const CATALOG = preload("res://scripts/layout_catalog.gd")
const STORE = preload("res://scripts/layout_store.gd")

@export var grid_size := Vector2i(32, 18)
@export var panel_gap := 16.0:
	set(value):
		panel_gap = maxf(value, 0.0)
		if is_node_ready():
			arrange_items()
@export var config_path := ""
@export var legacy_config_path := ""
var edit_mode := false
var selected: Control
var _items: Array[Control] = []
var _defaults: Dictionary = {}
var _operation := ""
var _origin := Rect2i()
var _candidate := Rect2i()
var _offset := Vector2.ZERO

@onready var overlay: Control = $EditOverlay

func _ready() -> void:
	for child in get_children():
		if child.has_method("arrange_content"):
			if child.element_type.is_empty():
				child.element_type = child.panel_id
			_items.append(child)
			_defaults[child.panel_id] = child.cell_rect
	resized.connect(arrange_items)
	get_window().focus_exited.connect(cancel_interaction)
	$EditOverlay/Actions/Resize.gui_input.connect(_resize_input)
	$EditOverlay/Actions/Delete.pressed.connect(delete_selected)
	arrange_items()

func cell_size() -> Vector2:
	return size / Vector2(grid_size)

func arrange_items() -> void:
	for item in _items:
		item.padding = panel_gap / 2
		item.position = Vector2(item.cell_rect.position) * cell_size()
		item.size = Vector2(item.cell_rect.size) * cell_size()
		item.arrange_content()
	_update_overlay()

func set_edit_mode(active: bool) -> void:
	cancel_interaction()
	edit_mode = active
	for item in _items:
		item.mouse_behavior_recursive = Control.MOUSE_BEHAVIOR_DISABLED if active else Control.MOUSE_BEHAVIOR_INHERITED
	if not active:
		selected = null
	overlay.visible = active
	_update_overlay()

func handle_grid_input(event: InputEvent) -> void:
	if not edit_mode:
		return
	if event is InputEventMouseButton and event.button_index == MOUSE_BUTTON_LEFT and event.pressed:
		var point: Vector2 = event.position
		selected = null
		for item in _items:
			if item.visible and Rect2(item.position, item.size).has_point(point):
				selected = item
				break
		if selected != null:
			_begin_interaction("move", point)
		_update_overlay()

func _input(event: InputEvent) -> void:
	if not edit_mode or _operation.is_empty():
		return
	if event is InputEventMouseMotion:
		update_interaction(get_global_transform_with_canvas().affine_inverse() * event.position)
		get_viewport().set_input_as_handled()
	elif event is InputEventMouseButton and event.button_index == MOUSE_BUTTON_LEFT and not event.pressed:
		finish_interaction()

func _resize_input(event: InputEvent) -> void:
	if event is InputEventMouseButton and event.button_index == MOUSE_BUTTON_LEFT and event.pressed and selected != null:
		var button: Control = $EditOverlay/Actions/Resize
		var point: Vector2 = get_global_transform_with_canvas().affine_inverse() * button.get_global_transform_with_canvas() * event.position
		_begin_interaction("resize", point)
		$EditOverlay/Actions/Resize.accept_event()

func _begin_interaction(operation: String, point: Vector2) -> void:
	_operation = operation
	_origin = selected.cell_rect
	_candidate = _origin
	_offset = point / cell_size()
	_update_overlay()

func update_interaction(point: Vector2) -> void:
	if selected == null or _operation.is_empty():
		return
	var delta := Vector2i((point / cell_size() - _offset).round())
	_candidate = Rect2i(_origin.position + delta, _origin.size) if _operation == "move" else Rect2i(_origin.position, _origin.size + delta)
	if can_place(selected, _candidate):
		selected.cell_rect = _candidate
		arrange_items()
	_update_overlay()

func can_place(item: Control, rect: Rect2i) -> bool:
	if rect.position.x < 0 or rect.position.y < 0 or rect.end.x > grid_size.x or rect.end.y > grid_size.y:
		return false
	if rect.size.x < item.minimum_cells.x or rect.size.y < item.minimum_cells.y:
		return false
	for other in _items:
		if other != item and other.visible and rect.intersects(other.cell_rect):
			return false
	return true

func finish_interaction() -> void:
	if selected == null or _operation.is_empty():
		return
	selected.cell_rect = _candidate if can_place(selected, _candidate) else _origin
	var changed: bool = selected.cell_rect != _origin
	_operation = ""
	arrange_items()
	if changed:
		save_layout()

func cancel_interaction() -> void:
	if selected != null and not _operation.is_empty():
		selected.cell_rect = _origin
	_operation = ""
	if is_node_ready():
		arrange_items()

func delete_selected() -> void:
	if selected == null:
		return
	cancel_interaction()
	selected.hide()
	selected = null
	_update_overlay()
	save_layout()

func reset_layout() -> void:
	cancel_interaction()
	selected = null
	_remove_dynamic_items()
	for item in _items:
		item.cell_rect = _defaults[item.panel_id]
		item.show()
	arrange_items()
	save_layout()

func add_element(element_type: String) -> Control:
	if not edit_mode or not CATALOG.ENTRIES.has(element_type):
		return null
	cancel_interaction()
	var entry: Dictionary = CATALOG.ENTRIES[element_type]
	var item: Control
	for candidate in _items:
		if not candidate.visible and candidate.element_type == element_type:
			item = candidate
			break
	var minimum: Vector2i = item.minimum_cells if item != null else entry.minimum
	var preferred: Vector2i = Vector2i(entry.size).max(minimum)
	var rect := _first_free(preferred)
	if rect.size == Vector2i.ZERO:
		rect = _first_free(minimum)
	if rect.size == Vector2i.ZERO:
		return null
	if item == null:
		var id := element_type
		var suffix := 2
		while _find_item(id) != null:
			id = "%s_%d" % [element_type, suffix]
			suffix += 1
		item = CATALOG.create_item(element_type, id, rect)
		add_child(item)
		_items.append(item)
	item.cell_rect = rect
	item.show()
	item.mouse_behavior_recursive = Control.MOUSE_BEHAVIOR_DISABLED
	selected = item
	arrange_items()
	save_layout()
	return item

func _first_free(dimensions: Vector2i) -> Rect2i:
	for y in range(grid_size.y - dimensions.y + 1):
		for x in range(grid_size.x - dimensions.x + 1):
			var rect := Rect2i(Vector2i(x, y), dimensions)
			var free := true
			for item in _items:
				if item.visible and rect.intersects(item.cell_rect):
					free = false
					break
			if free:
				return rect
	return Rect2i()

func _find_item(id: String) -> Control:
	for item in _items:
		if item.panel_id == id:
			return item
	return null

func _remove_dynamic_items() -> void:
	for item in _items.duplicate():
		if not _defaults.has(item.panel_id):
			_items.erase(item)
			remove_child(item)
			item.queue_free()

func _record(item: Control, rect: Rect2i) -> Dictionary:
	return {"id": item.panel_id, "type": item.element_type,
		"rect": [rect.position.x, rect.position.y, rect.size.x, rect.size.y]}

func save_layout() -> void:
	if config_path.is_empty():
		return
	var elements: Array = []
	for item in _items:
		if item.visible:
			elements.append(_record(item, item.cell_rect))
	var document := {"version": 1, "grid": [grid_size.x, grid_size.y], "elements": elements}
	if STORE.write_json(config_path, document) != OK:
		save_failed.emit()
	else:
		layout_saved.emit()

func load_layout() -> void:
	if config_path.is_empty():
		return
	if not FileAccess.file_exists(config_path):
		_migrate_legacy()
		return
	var decoded := _decode_document(STORE.read_json(config_path))
	if decoded.is_empty():
		load_failed.emit()
		return
	_apply_records(decoded.records)

func _decode_document(document: Variant) -> Dictionary:
	if not document is Dictionary or document.get("version") != 1:
		return {}
	var dimensions = document.get("grid")
	if not STORE.integer_array(dimensions, 2) or (dimensions[0] != grid_size.x or dimensions[1] != grid_size.y):
		return {}
	var elements = document.get("elements")
	if not elements is Array or elements.size() > grid_size.x * grid_size.y:
		return {}
	var ids: Dictionary = {}
	var occupied: Array[Rect2i] = []
	var records: Array = []
	for record in elements:
		if not record is Dictionary:
			return {}
		var id = record.get("id")
		var element_type = record.get("type")
		var coordinates = record.get("rect")
		if not id is String or id.length() > 64 or not id.is_valid_identifier() or ids.has(id):
			return {}
		if not element_type is String or not CATALOG.ENTRIES.has(element_type) or not STORE.integer_array(coordinates, 4):
			return {}
		for coordinate in coordinates:
			if absf(float(coordinate)) > maxi(grid_size.x, grid_size.y):
				return {}
		var rect := Rect2i(coordinates[0], coordinates[1], coordinates[2], coordinates[3])
		var existing := _find_item(id)
		if existing != null and existing.element_type != element_type:
			return {}
		var minimum: Vector2i = existing.minimum_cells if existing != null else CATALOG.ENTRIES[element_type].minimum
		if rect.position.x < 0 or rect.position.y < 0 or rect.end.x > grid_size.x or rect.end.y > grid_size.y or rect.size.x < minimum.x or rect.size.y < minimum.y:
			return {}
		for other in occupied:
			if rect.intersects(other):
				return {}
		occupied.append(rect)
		ids[id] = true
		records.append({"id": id, "type": element_type, "rect": rect})
	return {"records": records}

func _apply_records(records: Array) -> void:
	cancel_interaction()
	selected = null
	_remove_dynamic_items()
	for item in _items:
		item.hide()
	for record in records:
		var item := _find_item(record.id)
		if item == null:
			item = CATALOG.create_item(record.type, record.id, record.rect)
			add_child(item)
			_items.append(item)
		item.cell_rect = record.rect
		item.show()
		item.mouse_behavior_recursive = Control.MOUSE_BEHAVIOR_DISABLED if edit_mode else Control.MOUSE_BEHAVIOR_INHERITED
	arrange_items()

func _migrate_legacy() -> void:
	if legacy_config_path.is_empty() or not FileAccess.file_exists(legacy_config_path):
		return
	var config := ConfigFile.new()
	if config.load(legacy_config_path) != OK or config.get_value("layout", "grid") != grid_size:
		load_failed.emit()
		return
	var elements: Array = []
	for item in _items:
		if not _defaults.has(item.panel_id):
			continue
		var rect = config.get_value(item.panel_id, "rect", _defaults[item.panel_id])
		var enabled = config.get_value(item.panel_id, "visible", true)
		if not rect is Rect2i or not enabled is bool:
			load_failed.emit()
			return
		if enabled:
			elements.append(_record(item, rect))
	var decoded := _decode_document({"version": 1, "grid": [grid_size.x, grid_size.y], "elements": elements})
	if decoded.is_empty():
		load_failed.emit()
		return
	_apply_records(decoded.records)
	save_layout()

func _update_overlay() -> void:
	if not is_instance_valid(overlay):
		return
	var actions: Control = $EditOverlay/Actions
	actions.visible = edit_mode and selected != null
	if selected != null:
		overlay.selected_rect = Rect2(selected.position, selected.size)
		overlay.candidate_rect = Rect2(Vector2(_candidate.position) * cell_size(), Vector2(_candidate.size) * cell_size())
		overlay.candidate_valid = can_place(selected, _candidate)
		actions.position = selected.position + Vector2(selected.size.x - 116, 4)
	overlay.show_candidate = not _operation.is_empty()
	overlay.queue_redraw()