extends Node2D

const BUILDING_DEFINITIONS = preload("res://BuildingDefinitions.gd")
const VESSEL_DEFINITIONS = preload("res://VesselDefinitions.gd")

# Space-side building UI. Owns:
#   - the build menu (place a mothership, ship crafter or command centre)
#   - the shared ACTION button, which adapts to whatever the fleet is
#     standing on (craft ships, configure formation, or land). One action
#     fires directly; multiple actions unfold horizontally.
#   - rebuilding a wiped-out fleet at the mothership
#
# Buildings themselves live in GameState (they must outlive the trip to a
# planet's surface); this only drives the UI and spends resources.

@export var prompt_debounce_time: float = 0.15

@onready var fleet: Node2D = get_node("../Fleet")
@onready var building_field: Node2D = get_node("../BuildingField")
@onready var world_map: Control = get_node("../UI/WorldMap")
@onready var build_button: IconButton = get_node("../UI/BuildButton")
@onready var action_button: IconButton = get_node("../UI/BuildActionButton")
@onready var building_action_button: IconButton = get_node("../UI/BuildingActionButton")
@onready var landing_button: IconButton = get_node("../UI/EnterAtmosphereButton")
@onready var landing_controller: Node2D = get_node("../LandingController")

@onready var build_menu: Control = get_node("../UI/BuildMenu")
@onready var build_close_button: IconButton = get_node("../UI/BuildMenu/CloseButton")
@onready var build_status: Label = get_node("../UI/BuildMenu/StatusLabel")
@onready var lab_menu: Control = get_node("../UI/LabMenu")
@onready var lab_vessel_buttons: Array = [
	get_node("../UI/LabMenu/VesselA"), get_node("../UI/LabMenu/VesselB"),
	get_node("../UI/LabMenu/VesselC"), get_node("../UI/LabMenu/VesselD"),
	get_node("../UI/LabMenu/VesselE"), get_node("../UI/LabMenu/VesselF"),
	get_node("../UI/LabMenu/VesselG"),
]
@onready var lab_vessel_label: Label = get_node("../UI/LabMenu/VesselLabel")
@onready var lab_vessel_labels: Array = [
	get_node("../UI/LabMenu/VesselALabel"), get_node("../UI/LabMenu/VesselBLabel"),
	get_node("../UI/LabMenu/VesselCLabel"), get_node("../UI/LabMenu/VesselDLabel"),
	get_node("../UI/LabMenu/VesselELabel"), get_node("../UI/LabMenu/VesselFLabel"),
	get_node("../UI/LabMenu/VesselGLabel"),
]
@onready var lab_detail: Label = get_node("../UI/LabMenu/DetailLabel")
@onready var lab_status: Label = get_node("../UI/LabMenu/StatusLabel")
@onready var lab_buy_button: IconButton = get_node("../UI/LabMenu/BuyButton")
@onready var lab_close_button: IconButton = get_node("../UI/LabMenu/CloseButton")
@onready var lab_upgrade_buttons: Array = [
	get_node("../UI/LabMenu/Upgrade0"), get_node("../UI/LabMenu/Upgrade1"),
	get_node("../UI/LabMenu/Upgrade2"), get_node("../UI/LabMenu/Upgrade3"),
]
@onready var lab_upgrade_labels: Array = [
	get_node("../UI/LabMenu/Upgrade0Label"), get_node("../UI/LabMenu/Upgrade1Label"),
	get_node("../UI/LabMenu/Upgrade2Label"), get_node("../UI/LabMenu/Upgrade3Label"),
]
@onready var craft_shield_button: IconButton = get_node("../UI/CraftMenu/ShieldButton")
@onready var queue_slots: Array = [
	get_node("../UI/CraftMenu/QueueSlot0"), get_node("../UI/CraftMenu/QueueSlot1"),
	get_node("../UI/CraftMenu/QueueSlot2"), get_node("../UI/CraftMenu/QueueSlot3"),
]
@onready var queue_detail: Label = get_node("../UI/CraftMenu/QueueDetail")
@onready var hangar_button: IconButton = get_node("../UI/HangarButton")
@onready var hangar_menu: Control = get_node("../UI/HangarMenu")
@onready var hangar_status: Label = get_node("../UI/HangarMenu/StatusLabel")
@onready var hangar_close_button: IconButton = get_node("../UI/HangarMenu/CloseButton")
@onready var hangar_available_slots: Array = [
	get_node("../UI/HangarMenu/AvailableInterceptor"),
	get_node("../UI/HangarMenu/AvailableShield"),
	get_node("../UI/HangarMenu/AvailableGasBomber"),
	get_node("../UI/HangarMenu/AvailableCarrier"),
	get_node("../UI/HangarMenu/AvailableLaser"),
	get_node("../UI/HangarMenu/AvailableDistorder"),
]
@onready var hangar_available_labels: Array = [
	get_node("../UI/HangarMenu/AvailableInterceptorLabel"),
	get_node("../UI/HangarMenu/AvailableShieldLabel"),
	get_node("../UI/HangarMenu/AvailableGasBomberLabel"),
	get_node("../UI/HangarMenu/AvailableCarrierLabel"),
	get_node("../UI/HangarMenu/AvailableLaserLabel"),
	get_node("../UI/HangarMenu/AvailableDistorderLabel"),
]
@onready var hangar_fleet_slots: Array = [
	get_node("../UI/HangarMenu/FleetInterceptor"),
	get_node("../UI/HangarMenu/FleetShield"),
	get_node("../UI/HangarMenu/FleetGasBomber"),
	get_node("../UI/HangarMenu/FleetCarrier"),
	get_node("../UI/HangarMenu/FleetLaser"),
	get_node("../UI/HangarMenu/FleetDistorder"),
]
@onready var hangar_fleet_labels: Array = [
	get_node("../UI/HangarMenu/FleetInterceptorLabel"),
	get_node("../UI/HangarMenu/FleetShieldLabel"),
	get_node("../UI/HangarMenu/FleetGasBomberLabel"),
	get_node("../UI/HangarMenu/FleetCarrierLabel"),
	get_node("../UI/HangarMenu/FleetLaserLabel"),
	get_node("../UI/HangarMenu/FleetDistorderLabel"),
]
var build_menu_entries: Array = []

# Which vessel the lab screen is showing, and which visible upgrade card is
# selected. Each vessel gets its own small set of direct cards; the detail and
# Buy controls below them only describe the one the player tapped.
var lab_vessel: String = GameState.VESSEL_INTERCEPTOR
var lab_choice: int = 0
var lab_building_id: int = 0
@onready var planet_field: Node2D = get_node("../PlanetField")
@onready var info_popup: Control = get_node("../UI/BuildMenu/InfoPopup")
@onready var info_title: Label = get_node("../UI/BuildMenu/InfoPopup/Panel/TitleLabel")
@onready var info_message: Label = get_node("../UI/BuildMenu/InfoPopup/Panel/MessageLabel")
@onready var info_cost: NeonNumber = get_node("../UI/BuildMenu/InfoPopup/Panel/CostNumber")
@onready var info_build_button: IconButton = get_node("../UI/BuildMenu/InfoPopup/Panel/BuildButton")
@onready var info_close_button: IconButton = get_node("../UI/BuildMenu/InfoPopup/Panel/CloseButton")

@onready var craft_menu: Control = get_node("../UI/CraftMenu")
@onready var craft_interceptor_button: IconButton = get_node("../UI/CraftMenu/InterceptorButton")
@onready var craft_close_button: IconButton = get_node("../UI/CraftMenu/CloseButton")
@onready var craft_status: Label = get_node("../UI/CraftMenu/StatusLabel")
@onready var craft_interceptor_label: Label = get_node("../UI/CraftMenu/InterceptorLabel")
@onready var craft_shield_label: Label = get_node("../UI/CraftMenu/ShieldLabel")
@onready var craft_gas_bomber_button: IconButton = get_node("../UI/CraftMenu/GasBomberButton")
@onready var craft_gas_bomber_label: Label = get_node("../UI/CraftMenu/GasBomberLabel")
@onready var craft_carrier_button: IconButton = get_node("../UI/CraftMenu/CarrierButton")
@onready var craft_carrier_label: Label = get_node("../UI/CraftMenu/CarrierLabel")
@onready var craft_laser_button: IconButton = get_node("../UI/CraftMenu/LaserButton")
@onready var craft_laser_label: Label = get_node("../UI/CraftMenu/LaserLabel")
@onready var craft_distorder_button: IconButton = get_node("../UI/CraftMenu/DistorderButton")
@onready var craft_distorder_label: Label = get_node("../UI/CraftMenu/DistorderLabel")
@onready var craft_vessel_buttons: Array = [
	craft_interceptor_button, craft_shield_button, craft_gas_bomber_button, craft_carrier_button,
	craft_laser_button, craft_distorder_button,
]
@onready var craft_vessel_labels: Array = [
	craft_interceptor_label, craft_shield_label, craft_gas_bomber_label, craft_carrier_label,
	craft_laser_label, craft_distorder_label,
]

# --- the transfer panel (#24) ---------------------------------------------
# Ore used to be moved from inside whichever panel happened to be open: "load
# ore" lived in the research screen, "store ore here" in the ship crafter.
# Both are now one top-level shortcut beside Build at resource-bearing
# locations and work in both directions, so moving cargo is never buried
# under an unrelated action foldout.
@onready var transfer_button: IconButton = get_node("../UI/TransferButton")
@onready var transfer_menu: Control = get_node("../UI/TransferMenu")
@onready var transfer_status: Label = get_node("../UI/TransferMenu/StatusLabel")
@onready var transfer_close_button: IconButton = get_node("../UI/TransferMenu/CloseButton")
@onready var transfer_list: ResourceTransferList = get_node("../UI/TransferMenu/ResourceList")

# Every building menu carries the same header (#24). Held as a list because
# the only thing any of them needs is to be told which building it is
# reporting on when its panel opens.
@onready var resource_bars: Array = [
	get_node("../UI/CraftMenu/Bar"), get_node("../UI/SkillMenu/Bar"),
	get_node("../UI/LabMenu/Bar"),
]

@onready var skill_menu: Control = get_node("../UI/SkillMenu")
@onready var skill_tree: Control = get_node("../UI/SkillMenu/Tree")
@onready var skill_detail: Label = get_node("../UI/SkillMenu/DetailLabel")
@onready var skill_cost: NeonNumber = get_node("../UI/SkillMenu/CostNumber")
@onready var skill_status: Label = get_node("../UI/SkillMenu/StatusLabel")
@onready var skill_unlock_button: IconButton = get_node("../UI/SkillMenu/UnlockButton")
@onready var skill_close_button: IconButton = get_node("../UI/SkillMenu/CloseButton")

@onready var formation_menu: Control = get_node("../UI/FormationMenu")
@onready var formation_editor: Control = get_node("../UI/FormationMenu/Editor")
@onready var formation_close_button: IconButton = get_node("../UI/FormationMenu/CloseButton")
@onready var formation_reset_button: IconButton = get_node("../UI/FormationMenu/ResetButton")

# Which structure the popup is currently offering to build, or "" when it is
# only explaining something that cannot be built right now.
var pending_build_type: String = ""
# Which crafter the craft menu is showing (see _on_action_pressed).
var craft_building_id: int = 0
# The craft panel refreshes every frame while it is open (so a delivery
# arriving visibly works the queue down). That overwrote any message the
# moment after it was set, which made a working button look dead - the store
# button in particular. Messages therefore have to outlive a refresh.
var craft_message: String = ""
var craft_message_until: int = 0

# Which building the transfer panel is moving ore in and out of. Remembered
# for the same reason craft_building_id is: _process() clears
# current_building while any menu is open, so by the next frame the panel
# would not know which building it belongs to.
var transfer_building_id: int = 0
var transfer_extractor_index: int = -1

var current_building: Node2D = null
var pending_building: Node2D = null
var current_extractor_index: int = -1
var pending_extractor_index: int = -1
var current_landing_planet: Node2D = null
var pending_time: float = 0.0
var context_actions_expanded: bool = false


func _ready() -> void:
	build_button.pressed.connect(_on_build_pressed)
	build_close_button.pressed.connect(_close_build_menu)
	_configure_build_menu_entries()
	lab_close_button.pressed.connect(func(): lab_menu.visible = false)
	lab_buy_button.pressed.connect(_on_lab_buy)
	for i in range(lab_vessel_buttons.size()):
		lab_vessel_buttons[i].pressed.connect(_on_lab_vessel.bind(i))
	for i in range(lab_upgrade_buttons.size()):
		lab_upgrade_buttons[i].pressed.connect(_on_lab_upgrade.bind(i))
	info_close_button.pressed.connect(_close_info)
	info_build_button.pressed.connect(_confirm_build)

	action_button.pressed.connect(_on_context_action_pressed)
	building_action_button.pressed.connect(_on_action_pressed)

	for i in range(mini(craft_vessel_buttons.size(), VESSEL_DEFINITIONS.fleet().size())):
		var definition: Resource = VESSEL_DEFINITIONS.fleet()[i]
		craft_vessel_buttons[i].pressed.connect(_on_craft_vessel.bind(definition.definition_id))
	craft_close_button.pressed.connect(func(): craft_menu.visible = false)

	transfer_button.pressed.connect(_on_transfer_pressed)
	hangar_button.pressed.connect(_on_hangar_pressed)
	hangar_close_button.pressed.connect(func(): hangar_menu.visible = false)
	for i in range(hangar_available_slots.size()):
		hangar_available_slots[i].pressed.connect(_on_hangar_crew_type.bind(i))
		hangar_fleet_slots[i].pressed.connect(_on_hangar_store_type.bind(i))
	for i in range(queue_slots.size()):
		queue_slots[i].pressed.connect(_on_queue_slot.bind(i))
	transfer_close_button.pressed.connect(func(): transfer_menu.visible = false)
	transfer_list.transfer_requested.connect(_on_resource_transfer)

	formation_close_button.pressed.connect(func(): formation_menu.visible = false)
	formation_reset_button.pressed.connect(_on_reset_formation)
	formation_editor.formation_changed.connect(_on_formation_changed)

	skill_close_button.pressed.connect(func(): skill_menu.visible = false)
	skill_unlock_button.pressed.connect(_on_unlock_pressed)
	skill_tree.node_picked.connect(_on_skill_node_picked)

	build_menu.visible = false
	info_popup.visible = false
	craft_menu.visible = false
	formation_menu.visible = false
	skill_menu.visible = false
	lab_menu.visible = false
	transfer_menu.visible = false
	action_button.visible = false
	building_action_button.visible = false
	landing_button.visible = false
	transfer_button.visible = false
	hangar_button.visible = false
	hangar_menu.visible = false
	_layout_context_buttons()


func _configure_build_menu_entries() -> void:
	build_menu_entries.clear()
	for definition in BUILDING_DEFINITIONS.all():
		if definition.menu_button_name == "":
			continue
		var button: IconButton = get_node("../UI/BuildMenu/%s" % definition.menu_button_name)
		var label: Label = get_node("../UI/BuildMenu/%s" % definition.menu_label_name)
		var cost_number: NeonNumber = get_node("../UI/BuildMenu/%s" % definition.menu_cost_name)
		button.icon = definition.menu_icon
		button.pressed.connect(_show_building_info.bind(String(definition.definition_id)))
		label.text = definition.display_name
		cost_number.amount = definition.cost
		build_menu_entries.append([definition.definition_id, button, label, cost_number, definition])


# True while a modal panel owns the shared context controls. A plain building
# prompt is not modal: landing can coexist with its actions in the same foldout.
func is_showing_building_prompt() -> bool:
	return build_menu.visible or craft_menu.visible \
		or formation_menu.visible or skill_menu.visible or transfer_menu.visible \
		or hangar_menu.visible


func _unhandled_input(event: InputEvent) -> void:
	if context_actions_expanded and (event is InputEventScreenTouch and event.pressed \
			or event is InputEventMouseButton and event.pressed and event.button_index == MOUSE_BUTTON_LEFT):
		# Buttons consume their own touch; reaching this handler means the tap
		# landed somewhere else, which dismisses an expanded action list.
		_collapse_context_actions()

	# The formation editor and the skill tree are driven from here rather than
	# via _gui_input, for the same reason as the joystick: a Control that
	# consumes touches through the GUI system swallows them before they get
	# here, which is what made dragging a formation slot silently do nothing.
	if skill_menu.visible:
		if event is InputEventScreenTouch:
			skill_tree.handle_touch(event)
		elif event is InputEventScreenDrag:
			skill_tree.handle_drag(event)
		# Handled either way. A touch that lands on the panel but misses a
		# node is still a touch ON THE PANEL - letting it through moved the
		# fleet and pinch-zoomed the world behind the menu, because
		# GameController sits on the root node and sees whatever this leaves
		# unhandled.
		get_viewport().set_input_as_handled()
		return
	if formation_menu.visible:
		if event is InputEventScreenTouch:
			formation_editor.handle_touch(event)
		elif event is InputEventScreenDrag:
			formation_editor.handle_drag(event)
		get_viewport().set_input_as_handled()
		return
	if build_menu.visible or craft_menu.visible or world_map.visible or lab_menu.visible \
			or transfer_menu.visible or hangar_menu.visible:
		# These panels have no raw-input handler of their own, but the world
		# behind them must still not react.
		get_viewport().set_input_as_handled()


func _process(delta: float) -> void:
	_check_fleet_wipe()

	if build_menu.visible:
		# Keep the greyed state live while the menu is open, so flying onto
		# a planet lights the option up without reopening it.
		_refresh_build_option_states()

	if craft_menu.visible:
		# Live, so a delivery arriving while the menu is open visibly works
		# the queue down instead of looking stuck.
		_refresh_craft_status()

	if transfer_menu.visible:
		# Also live: a hauler banking ore while the panel is open should make
		# the "to fleet" side become available without a reopen.
		_refresh_transfer()

	if world_map.visible or build_menu.visible or craft_menu.visible \
			or formation_menu.visible or skill_menu.visible or lab_menu.visible \
			or transfer_menu.visible or hangar_menu.visible:
		current_building = null
		pending_building = null
		current_extractor_index = -1
		pending_extractor_index = -1
		current_landing_planet = null
		action_button.visible = false
		building_action_button.visible = false
		landing_button.visible = false
		transfer_button.visible = false
		hangar_button.visible = false
		context_actions_expanded = false
		return

	# Debounced exactly like the enter-atmosphere prompt, so the action
	# button can't flicker while the fleet drifts on the interact boundary.
	var detected: Node2D = building_field.get_building_fleet_is_on()
	var detected_extractor: int = -1
	if detected == null:
		var planet: Node2D = _planet_under_fleet()
		if planet != null:
			detected_extractor = GameState.extractor_index_at(planet.planet_id)

	if detected != pending_building or detected_extractor != pending_extractor_index:
		pending_building = detected
		pending_extractor_index = detected_extractor
		pending_time = 0.0
	else:
		pending_time += delta

	var detected_landing_planet: Node2D = landing_controller.current_planet
	if pending_time < prompt_debounce_time or (pending_building == current_building \
			and pending_extractor_index == current_extractor_index \
			and detected_landing_planet == current_landing_planet):
		return

	current_building = pending_building
	current_extractor_index = pending_extractor_index
	current_landing_planet = detected_landing_planet
	context_actions_expanded = false
	hangar_button.visible = false
	building_action_button.visible = false
	landing_button.visible = false
	transfer_button.visible = _has_transfer_context()
	var actions: Array = _context_action_buttons()
	action_button.visible = not actions.is_empty()
	if current_building != null:
		building_action_button.icon = int(current_building.definition.action_icon)
		building_action_button.queue_redraw()
	if not actions.is_empty():
		action_button.icon = int(actions[0].icon) if actions.size() == 1 else IconButton.Icon.ACTION_MENU
		action_button.queue_redraw()
	_layout_context_buttons()


func _layout_context_buttons() -> void:
	# Build is permanently under the resource counter. The contextual berth
	# directly below it is compact until it has more than one real choice.
	action_button.offset_top = 324
	action_button.offset_bottom = 472
	var buttons: Array = _context_action_buttons()
	if not context_actions_expanded:
		for button in buttons:
			button.visible = false
		return
	# Expand sideways so the controls stay in the same visual band instead of
	# pushing the player down a vertical stack. Three actions fit across the
	# 720px phone layout with the same generous 148px touch targets.
	for i in range(buttons.size()):
		var button: Control = buttons[i]
		button.visible = true
		button.offset_left = 188 + i * 164
		button.offset_right = button.offset_left + 148
		button.offset_top = 324
		button.offset_bottom = 472


func _context_action_buttons() -> Array:
	var buttons: Array = []
	if current_building != null:
		for action in current_building.available_actions():
			var button: IconButton = _button_for_building_action(action)
			if button != null and button not in buttons:
				buttons.append(button)
	if current_landing_planet != null:
		buttons.append(landing_button)
	return buttons


func _has_transfer_context() -> bool:
	if current_extractor_index >= 0:
		return true
	return current_building != null and current_building.available_actions().has("transfer")


func _button_for_building_action(action: String) -> IconButton:
	if action == "transfer":
		return null
	if action == "hangar":
		return hangar_button
	return building_action_button


func _on_context_action_pressed() -> void:
	if current_building == null and current_extractor_index < 0 \
			and current_landing_planet == null:
		return
	var actions: Array = _context_action_buttons()
	if actions.size() == 1:
		if actions[0] == landing_button:
			landing_controller._on_enter_pressed()
		elif actions[0] == hangar_button:
			_on_hangar_pressed()
		else:
			_on_action_pressed()
		return
	context_actions_expanded = not context_actions_expanded
	_layout_context_buttons()


func _collapse_context_actions() -> void:
	if not context_actions_expanded:
		return
	context_actions_expanded = false
	_layout_context_buttons()


func _check_fleet_wipe() -> void:
	if not fleet.ships.is_empty():
		return
	# Whole fleet destroyed: rebuild a single vessel at the mothership, or
	# at the world origin when none has been built yet.
	var spawn_pos: Variant = GameState.get_mothership_position()
	fleet.spawn_ships(1, spawn_pos if spawn_pos != null else Vector2.ZERO)


func _on_action_pressed() -> void:
	if current_building == null:
		return
	# Whichever panel opens, its header reports on the building it was opened
	# from. Set once here rather than in each branch, so a new building menu
	# cannot forget to do it and silently show a blank HERE column.
	for bar in resource_bars:
		bar.building_id = current_building.building_id

	var action: String = current_building.primary_action()
	if action == "research":
		skill_menu.visible = true
		skill_tree.reset_scroll()
		_refresh_skill_menu()
	elif action == "craft":
		# Remembered explicitly: _process() clears current_building while any
		# menu is open, so by the next frame the panel would no longer know
		# which crafter it belongs to. Losing this line makes every button in
		# the panel bail out at its `== 0` guard while the panel itself still
		# opens - which reads as "the buttons do nothing".
		craft_building_id = current_building.building_id
		craft_menu.visible = true
		_refresh_craft_status()
	elif action == "lab":
		lab_building_id = current_building.building_id
		lab_menu.visible = true
		_refresh_lab()
	elif action == "formation":
		formation_menu.visible = true
		formation_editor.queue_redraw()


func _on_build_pressed() -> void:
	build_menu.visible = true
	info_popup.visible = false
	pending_build_type = ""
	_refresh_build_status()


func _planet_under_fleet() -> Node2D:
	# An extractor mines a specific planet, so one has to be within reach.
	return planet_field.get_planet_fleet_is_on()


# Grid geometry, shared with the layout below. Rows of two, and the menu is
# rebuilt from whatever is currently researched (#21) rather than being a
# fixed arrangement with holes punched in it.
const MENU_ROW_TOPS: Array = [-300.0, -77.0, 146.0, 369.0]
const MENU_COL_X: float = 140.0
const MENU_BUTTON_HALF: float = 64.0
const MENU_BUTTON_H: float = 100.0
const MENU_LABEL_HALF: float = 150.0
const MENU_LABEL_H: float = 52.0
const MENU_COST_HALF: float = 60.0
const MENU_COST_H: float = 44.0
# Gaps from each row's own top to where the label/cost start, sized to the
# shrunk MENU_*_H values above (#54: fitting a 4th row meant tightening
# MENU_ROW_TOPS' spacing to 223px, less than the original 256px a row's
# button+label+cost needed - shrinking those closed the gap without
# resorting to a scrollable menu).
const MENU_LABEL_OFFSET: float = 106.0
const MENU_COST_OFFSET: float = 162.0


func _place_entry(node: Control, cx: float, top: float, half: float, height: float) -> void:
	node.offset_left = cx - half
	node.offset_right = cx + half
	node.offset_top = top
	node.offset_bottom = top + height


func _layout_build_menu() -> void:
	# Structures the player has not researched are hidden outright (#21), and
	# what remains is repacked so there are no gaps where they used to be.
	# This reverses the earlier decision to always list everything greyed
	# out; an option you cannot explain is apparently worse than one you
	# cannot see yet.
	var shown: Array = []
	for entry in build_menu_entries:
		var visible: bool = GameState.is_building_unlocked(entry[0])
		entry[1].visible = visible
		entry[2].visible = visible
		entry[3].visible = visible
		if visible:
			shown.append(entry)

	for i in range(shown.size()):
		var row: int = i / 2
		# Centred when it is the only one on its row, rather than hanging in
		# the left column looking like something is missing beside it.
		var alone: bool = (i == shown.size() - 1) and (i % 2 == 0)
		var cx: float = 0.0 if alone else (-MENU_COL_X if i % 2 == 0 else MENU_COL_X)
		var top: float = MENU_ROW_TOPS[mini(row, MENU_ROW_TOPS.size() - 1)]
		_place_entry(shown[i][1], cx, top, MENU_BUTTON_HALF, MENU_BUTTON_H)
		_place_entry(shown[i][2], cx, top + MENU_LABEL_OFFSET, MENU_LABEL_HALF, MENU_LABEL_H)
		_place_entry(shown[i][3], cx, top + MENU_COST_OFFSET, MENU_COST_HALF, MENU_COST_H)


func _refresh_build_status() -> void:
	_layout_build_menu()
	# Researched but not usable right here is still shown, greyed: an
	# extractor needs a planet under the fleet, which is a "not now" rather
	# than a "not yet".
	_refresh_build_option_states()

	# Prices are shown under each option now, so this only needs to say
	# whether the fleet is somewhere an extractor could go.
	var planet: Node2D = _planet_under_fleet()
	if planet == null:
		build_status.text = ""
	elif not GameState.is_planet_conquered(planet.planet_id):
		build_status.text = "Over %s - capture it before building an extractor" % planet.planet_name
	else:
		build_status.text = "Over %s - an extractor can be built here" % planet.planet_name


func _refresh_build_option_states() -> void:
	for entry in build_menu_entries:
		var definition: Resource = entry[4]
		var enabled: bool = GameState.is_building_unlocked(definition.definition_id)
		if definition.placement_mode == "planet":
			var planet: Node2D = _planet_under_fleet()
			enabled = enabled and planet != null and GameState.is_planet_conquered(planet.planet_id)
		entry[1].enabled = enabled
		entry[1].queue_redraw()


func _close_build_menu() -> void:
	# The popup is a child panel of this menu; leaving it "open" while its
	# parent is hidden is what blocked every button in the game.
	info_popup.visible = false
	pending_build_type = ""
	build_menu.visible = false


func cost_of(type: String) -> int:
	var definition: Resource = BUILDING_DEFINITIONS.get_definition(type)
	return int(definition.cost) if definition != null else 0


func _show_building_info(type: String) -> void:
	var definition: Resource = BUILDING_DEFINITIONS.get_definition(type)
	if definition == null:
		return
	var cost: int = int(definition.cost)
	var lines: Array = [definition.description]
	var can_build: bool = true

	# Locked structures still list themselves, greyed, so the player can see
	# what exists and what research would open it up.
	if not GameState.is_building_unlocked(type):
		lines.append("Locked. Research %s at your mothership." % GameState.research_for_building(type))
		can_build = false

	# Anything that would stop this particular placement is spelled out in
	# the same popup, rather than silently failing after the press.
	if can_build and definition.placement_mode == "planet":
		var planet: Node2D = _planet_under_fleet()
		if planet == null:
			lines.append("No planet in reach - fly over one.")
			can_build = false
		elif not GameState.is_planet_conquered(planet.planet_id):
			lines.append("%s is not captured yet - take all its capture points." % planet.planet_name)
			can_build = false
		elif GameState.has_extractor_at(planet.planet_id):
			lines.append("%s already has an extractor." % planet.planet_name)
			can_build = false
		else:
			lines.append("Will mine %s from %s." % [GameState.resource_name(planet.resource_type), planet.planet_name])
	elif can_build and definition.unique and GameState.has_building_of_type(type):
		lines.append("WARNING: only one may exist - this destroys your current one.")

	if can_build and not GameState.can_afford(cost):
		lines.append("Not enough rocks - needs %d, you have %d." % [cost, GameState.rocks])
		can_build = false

	info_title.text = definition.display_name
	info_message.text = "\n\n".join(lines)
	info_cost.amount = cost
	info_build_button.visible = can_build
	pending_build_type = type if can_build else ""
	info_popup.visible = true


func _close_info() -> void:
	info_popup.visible = false
	pending_build_type = ""


func _confirm_build() -> void:
	var type: String = pending_build_type
	if type == "":
		return
	pending_build_type = ""
	info_popup.visible = false

	# Everything is re-checked here rather than trusted from when the popup
	# opened: the fleet keeps flying while it is up, so it can drift off the
	# planet an extractor was going to mine.
	if not GameState.is_building_unlocked(type):
		return
	var definition: Resource = BUILDING_DEFINITIONS.get_definition(type)
	if definition == null:
		return

	if definition.placement_mode == "planet":
		var planet: Node2D = _planet_under_fleet()
		if planet == null or GameState.has_extractor_at(planet.planet_id):
			build_status.text = "No planet in reach any more"
			return
		if not GameState.is_planet_conquered(planet.planet_id):
			build_status.text = "%s is not captured yet" % planet.planet_name
			return
		if not GameState.spend(definition.cost):
			build_status.text = "Not enough rocks (need %d, have %d)" % [definition.cost, GameState.rocks]
			return
		GameState.add_extractor(planet.planet_name, planet.position, planet.resource_type, planet.planet_id)
		build_menu.visible = false
		return

	if definition.unique and GameState.has_building_of_type(type):
		if not GameState.can_afford(definition.cost):
			build_status.text = "Not enough rocks (need %d, have %d)" % [
				definition.cost, GameState.rocks
			]
			return
		# Only now is the old one destroyed - never before the new one is
		# known to be affordable, or the player would be left with none.
		GameState.remove_buildings_of_type(type)
		building_field.rebuild_all()

	_try_place(type, cost_of(type))


func _try_place(type: String, cost: int) -> void:
	if not GameState.spend(cost):
		build_status.text = "Not enough rocks (need %d, have %d)" % [cost, GameState.rocks]
		return
	building_field.place(type, fleet.get_centroid())
	build_menu.visible = false


# --- research (the mothership's skill tree) --------------------------------

func _on_skill_node_picked(id: String) -> void:
	_refresh_skill_menu(id)


func _refresh_skill_menu(id: String = "") -> void:
	if id == "":
		id = skill_tree.selected_id
	if id == "":
		# Nothing chosen yet: point the player at the tree rather than
		# leaving the panel blank, which reads as broken.
		skill_detail.text = "Select a node to see what it unlocks."
		skill_cost.amount = 0
		skill_status.text = "Fleet capacity %d" % GameState.max_fleet_size()
		skill_unlock_button.visible = false
		return

	var node: Dictionary = GameState.skill_node(id)
	if node.is_empty():
		return
	skill_detail.text = "%s\n%s" % [node.name, node.desc]
	skill_cost.amount = int(node.cost)

	if GameState.is_unlocked(id):
		skill_status.text = "Researched"
		skill_unlock_button.visible = false
	elif not GameState.prerequisite_met(id):
		skill_status.text = "Needs %s first" % GameState.skill_node(node.requires).name
		skill_unlock_button.visible = false
	elif not GameState.can_afford(int(node.cost)):
		skill_status.text = "Not enough rocks - you have %d" % GameState.rocks
		skill_unlock_button.visible = false
	else:
		skill_status.text = ""
		skill_unlock_button.visible = true


func _on_unlock_pressed() -> void:
	var id: String = skill_tree.selected_id
	if id == "":
		return
	if not GameState.unlock(id):
		# Re-check rather than trust the button: rocks can be spent elsewhere
		# while this menu is open, since haulers keep delivering.
		_refresh_skill_menu(id)
		return
	# A capacity upgrade has to reach the fleet that is already flying, not
	# just ones rebuilt later.
	if int(GameState.skill_node(id).get("fleet_bonus", 0)) > 0:
		fleet.apply_formation()
	skill_tree.queue_redraw()
	_refresh_skill_menu(id)


func _say(message: String) -> void:
	craft_message = message
	craft_message_until = Time.get_ticks_msec() + 3000
	_refresh_craft_status()


func _format_costs(costs: Dictionary) -> String:
	var parts: PackedStringArray = PackedStringArray()
	for resource_type in GameState.resource_types():
		var amount: int = int(costs.get(resource_type, 0))
		if amount > 0:
			parts.append("%d %s" % [amount, GameState.resource_name(resource_type).to_lower()])
	return " · ".join(parts) if not parts.is_empty() else "free"


func _format_missing_costs(costs: Dictionary) -> String:
	var parts: PackedStringArray = PackedStringArray()
	for resource_type in GameState.resource_types():
		var amount: int = int(costs.get(resource_type, 0))
		if amount > 0:
			parts.append("%d more %s" % [amount,
				GameState.resource_name(resource_type).to_lower()])
	return " · ".join(parts)


func _refresh_craft_status() -> void:
	# Prices live with the buttons they describe. The top of the screen is
	# intentionally reserved for the shared resource bar and a short action
	# message; repeating fleet, queue and transport counts here buried the UI.
	craft_status.text = ""
	var definitions: Array = VESSEL_DEFINITIONS.fleet()
	for i in range(mini(definitions.size(), craft_vessel_buttons.size())):
		var definition: Resource = definitions[i]
		var button: IconButton = craft_vessel_buttons[i]
		craft_vessel_labels[i].text = "%s\n%s" % [definition.display_name,
			_format_costs(GameState.product_costs(definition.definition_id))]
		button.icon = definition.icon
		button.glow_color = definition.glow_color
		button.enabled = GameState.vessel_is_unlocked(definition.definition_id)
		button.queue_redraw()
	_refresh_queue()
	if craft_message != "":
		if Time.get_ticks_msec() < craft_message_until:
			craft_status.text = "%s\n%s" % [craft_message, craft_status.text]
		else:
			craft_message = ""


func _on_craft_interceptor() -> void:
	_on_craft_vessel(GameState.VESSEL_INTERCEPTOR)


func _on_craft_vessel(vessel: String) -> void:
	if craft_building_id == 0:
		_say("No crafter selected - reopen this panel from the building")
		return
	var definition: Resource = VESSEL_DEFINITIONS.get_definition(vessel)
	if definition == null:
		return
	if not GameState.queue_order(craft_building_id, vessel):
		if not GameState.vessel_is_unlocked(vessel):
			_say("%s must be unlocked at a ship lab first" % definition.display_name)
		return
	_report_order(vessel)


func _report_order(product: String) -> void:
	var missing: Dictionary = GameState.outstanding_costs(craft_building_id)
	if not missing.is_empty():
		_say("%s queued - deliver %s here" % [GameState.vessel_name(product),
			_format_missing_costs(missing)])
	else:
		_say("%s ordered - building now" % GameState.vessel_name(product))


# --- ship lab (#5) --------------------------------------------------------

func _lab_options() -> Array:
	# The shield VESSEL unlock is offered on the shield page as an extra
	# entry, because unlocking the type and upgrading it belong in the same
	# place - and its upgrades are pointless until it exists.
	var options: Array = []
	var definition: Resource = VESSEL_DEFINITIONS.get_definition(lab_vessel)
	if definition == null:
		return options
	if not GameState.vessel_is_unlocked(lab_vessel):
		options.append({"unlock": true, "id": definition.unlock_id,
			"name": definition.unlock_name, "desc": definition.unlock_description,
			"costs": GameState.research_costs(definition.unlock_id),
			"icon": definition.unlock_icon if definition.unlock_icon >= 0 else definition.icon})
		return options
	for u in GameState.upgrades_for(lab_vessel):
		options.append({"unlock": false, "id": u.id, "name": u.name, "desc": u.desc})
	return options


func _on_lab_vessel(index: int) -> void:
	var definitions: Array = VESSEL_DEFINITIONS.all()
	if index < 0 or index >= definitions.size():
		return
	lab_vessel = definitions[index].definition_id
	lab_choice = 0
	_refresh_lab()


func _on_lab_upgrade(index: int) -> void:
	if index < 0 or index >= _lab_options().size():
		return
	lab_choice = index
	lab_status.text = ""
	_refresh_lab()


func _on_lab_buy() -> void:
	var options: Array = _lab_options()
	if options.is_empty():
		return
	var choice: Dictionary = options[lab_choice]
	var id: String = String(choice.id)
	if not GameState.queue_lab_research(lab_building_id, id):
		lab_status.text = "Research is already queued or complete"
		return
	lab_status.text = "%s queued - deliver %s to this lab" % [choice.name,
		_format_costs(GameState.research_costs(id))]
	_refresh_lab()


func _refresh_lab() -> void:
	var definitions: Array = VESSEL_DEFINITIONS.all()
	for i in range(mini(lab_vessel_buttons.size(), definitions.size())):
		var definition: Resource = definitions[i]
		var this_vessel: String = definition.definition_id
		lab_vessel_buttons[i].enabled = true
		lab_vessel_buttons[i].icon = definition.icon
		lab_vessel_buttons[i].glow_color = definition.glow_color
		lab_vessel_labels[i].text = definition.display_name
		lab_vessel_buttons[i].highlighted = this_vessel == lab_vessel
		lab_vessel_buttons[i].queue_redraw()
	lab_vessel_label.text = "%s research" % GameState.vessel_name(lab_vessel)

	var options: Array = _lab_options()
	for i in range(lab_upgrade_buttons.size()):
		var visible: bool = i < options.size()
		lab_upgrade_buttons[i].visible = visible
		lab_upgrade_labels[i].visible = visible
		if not visible:
			continue
		var option: Dictionary = options[i]
		var price_text: String = _format_costs(option.costs if bool(option.unlock) \
			else GameState.research_costs(option.id))
		if not bool(option.unlock) and GameState.upgrade_maxed(option.id):
			price_text = "MAX"
		var level_note: String = "" if bool(option.unlock) else "  %d/%d" % [
			GameState.upgrade_level(option.id), int(GameState.upgrade_def(option.id).max_level)]
		lab_upgrade_labels[i].text = "%s%s\n%s" % [option.name, level_note, price_text]
		lab_upgrade_buttons[i].icon = _upgrade_icon(option)
		lab_upgrade_buttons[i].glow_color = _vessel_colour(lab_vessel)
		lab_upgrade_buttons[i].highlighted = i == lab_choice
		lab_upgrade_buttons[i].enabled = true
		lab_upgrade_buttons[i].queue_redraw()
	if options.is_empty():
		lab_detail.text = ""
		lab_buy_button.enabled = false
		lab_buy_button.queue_redraw()
		return
	lab_choice = clampi(lab_choice, 0, options.size() - 1)

	var choice: Dictionary = options[lab_choice]
	lab_detail.text = "%s\n%s" % [choice.name, choice.desc]
	var queued: Dictionary = GameState.lab_research_order(lab_building_id)
	lab_buy_button.enabled = queued.is_empty() and (choice.unlock or not GameState.upgrade_maxed(choice.id))
	if not queued.is_empty():
		lab_status.text = "%s %d%%" % ["Researching" if bool(queued.started) else "Waiting for resources", int(100.0 * float(queued.elapsed) / maxf(GameState.lab_research_time(), 0.001))]
	lab_buy_button.queue_redraw()


func _upgrade_icon(option: Dictionary) -> IconButton.Icon:
	return int(option.get("icon", IconButton.Icon.SHIP_LAB))


func _on_craft_shield() -> void:
	_on_craft_vessel(GameState.VESSEL_SHIELD)


# --- moving ore, in both directions, at any building (#24) ----------------

# Sentinel for the "All" buttons. The transfer primitives cap what they move
# by what is actually there, so asking for more than could possibly exist is
# how you say "everything" without the UI having to work out how much that
# is first - and the answer cannot go stale between the read and the press.
const ALL: int = 1 << 30


func _on_transfer_pressed() -> void:
	if current_building == null and current_extractor_index < 0:
		return
	transfer_building_id = current_building.building_id if current_building != null else 0
	transfer_extractor_index = current_extractor_index
	for bar in resource_bars:
		bar.building_id = transfer_building_id
	transfer_menu.visible = true
	transfer_status.text = ""
	_refresh_transfer()


func _on_transfer(to_building: bool, amount: int) -> void:
	_on_resource_transfer(GameState.RESOURCE_ORE, to_building, amount)


func _on_resource_transfer(resource_type: String, to_building: bool, amount: int = ALL) -> void:
	if transfer_building_id == 0 and transfer_extractor_index < 0:
		transfer_status.text = "No resource store selected - reopen this panel from its action"
		return

	var moved: int
	if transfer_extractor_index >= 0:
		moved = GameState.transfer_resource_to_extractor(transfer_extractor_index, resource_type, amount) \
			if to_building else GameState.transfer_resource_from_extractor(transfer_extractor_index, resource_type, amount)
	else:
		moved = GameState.transfer_resource_to_building(transfer_building_id, resource_type, amount) \
			if to_building else GameState.transfer_resource_to_fleet(transfer_building_id, resource_type, amount)
	var resource_name: String = GameState.resource_name(resource_type).to_lower()

	# Nothing moving is the common case at an empty end, and a silent no-op
	# is the dead-button problem this panel exists to remove. Say which side
	# was empty rather than just refusing.
	if moved <= 0:
		if to_building:
			transfer_status.text = "The fleet is carrying nothing to unload (no %s)" % resource_name
		else:
			transfer_status.text = "%s has no %s to load" % [_transfer_place_name().capitalize(), resource_name]
	elif to_building:
		transfer_status.text = "Moved %d %s into %s" % [moved, resource_name, _transfer_place_name()]
	else:
		transfer_status.text = "Loaded %d %s into the fleet" % [moved, resource_name]
	_refresh_transfer()

func _on_gas_transfer(to_building: bool) -> void:
	_on_resource_transfer(GameState.RESOURCE_GAS, to_building)


func _transfer_place_name() -> String:
	if transfer_extractor_index >= 0:
		return "the extractor"
	var b: Dictionary = GameState.find_building(transfer_building_id)
	if b.is_empty():
		return "this building"
	if b.type == GameState.BUILDING_MOTHERSHIP:
		# Worth naming as the bank rather than as a structure: this is the
		# one building where unloading makes the ore spendable everywhere.
		return "the bank"
	return "this building"


func _refresh_transfer() -> void:
	if transfer_extractor_index >= 0:
		transfer_list.set_extractor_destination(transfer_extractor_index, "Planet extractor")
		return
	var building: Dictionary = GameState.find_building(transfer_building_id)
	var heading: String = "This building"
	if not building.is_empty() and building.type == GameState.BUILDING_MOTHERSHIP:
		heading = "Mothership bank"
	transfer_list.set_destination(transfer_building_id, heading)


func _refresh_queue() -> void:
	# The queue down the right of the craft panel: one slot per pending
	# vessel, the first being the one actually under construction. Tapping a
	# slot cancels it (#23).
	var orders: Array = GameState.order_list(craft_building_id)
	for i in range(queue_slots.size()):
		var slot: IconButton = queue_slots[i]
		slot.visible = i < orders.size()
		if not slot.visible:
			continue
		var order: Dictionary = orders[i]
		var definition: Resource = VESSEL_DEFINITIONS.get_definition(String(order.product))
		slot.icon = definition.icon
		slot.glow_color = _vessel_colour(String(order.product))
		# Only the one under construction reads as active; the rest are
		# waiting, and greyed says so without needing a caption each.
		slot.enabled = bool(order.started)
		slot.queue_redraw()

	if orders.is_empty():
		queue_detail.text = "Nothing queued"
		return
	var head: Dictionary = orders[0]
	if bool(head.started):
		queue_detail.text = "Building %s  %d%%\nTap to cancel" % [
			GameState.vessel_name(String(head.product)),
			int(round(float(head.progress) * 100.0)),
		]
	else:
		queue_detail.text = "%s waiting for resources\nTap to cancel" % \
			GameState.vessel_name(String(head.product))


func _vessel_colour(product: String) -> Color:
	var definition: Resource = VESSEL_DEFINITIONS.get_definition(product)
	return definition.glow_color if definition != null else Color(0.25, 0.85, 1.0)


func _on_queue_slot(index: int) -> void:
	var orders: Array = GameState.order_list(craft_building_id)
	if index >= orders.size():
		return
	var vessel: String = GameState.vessel_name(String(orders[index].product))
	var refunded: bool = bool(orders[index].started)
	if not GameState.cancel_order(craft_building_id, index):
		return
	_say("%s cancelled%s" % [vessel, "  - resources refunded here" if refunded else ""])
	_refresh_queue()


# --- hangar (#23) ---------------------------------------------------------

func _on_hangar_pressed() -> void:
	hangar_status.text = ""
	hangar_menu.visible = true
	_refresh_hangar()


func _on_hangar_crew_type(index: int) -> void:
	var type: String = _hangar_types()[index]
	if fleet.ships.size() >= GameState.max_fleet_size():
		hangar_status.text = "Fleet is full (%d/%d) - research capacity at the mothership" % [
			fleet.ships.size(), GameState.max_fleet_size()
		]
		return
	var stored_index: int = GameState.stored_vessels.find(type)
	if stored_index < 0:
		hangar_status.text = "No %s available" % GameState.vessel_name(type)
		return
	if not fleet.add_ship(GameState.take_stored_vessel(stored_index)):
		hangar_status.text = "Could not crew that vessel"
		return
	hangar_status.text = "%s joined the fleet" % GameState.vessel_name(type)
	_refresh_hangar()


func _on_hangar_store_type(index: int) -> void:
	var type: String = _hangar_types()[index]
	var ship_index: int = -1
	for i in range(fleet.ships.size()):
		if String(fleet.ships[i].vessel_type) == type:
			ship_index = i
			break
	if ship_index < 0:
		hangar_status.text = "No %s in the fleet" % GameState.vessel_name(type)
		return
	var stored: String = fleet.store_ship(ship_index)
	if stored == "":
		hangar_status.text = "Keep one ship deployed"
		return
	GameState.stored_vessels.append(stored)
	hangar_status.text = "%s stored in the hangar" % GameState.vessel_name(stored)
	_refresh_hangar()


func _hangar_types() -> Array:
	var types: Array = []
	for definition in VESSEL_DEFINITIONS.fleet():
		types.append(definition.definition_id)
	return types


func _refresh_hangar() -> void:
	var types: Array = _hangar_types()
	for i in range(types.size()):
		var type: String = types[i]
		var definition: Resource = VESSEL_DEFINITIONS.get_definition(type)
		var available: int = GameState.stored_vessels.count(type)
		var deployed: int = 0
		for ship in fleet.ships:
			if is_instance_valid(ship) and String(ship.vessel_type) == type:
				deployed += 1
		hangar_available_labels[i].text = "%s\n%d available" % [definition.display_name, available]
		hangar_fleet_labels[i].text = "%s\n%d in fleet" % [definition.display_name, deployed]
		hangar_available_slots[i].icon = definition.icon
		hangar_fleet_slots[i].icon = definition.icon
		hangar_available_slots[i].glow_color = definition.glow_color
		hangar_fleet_slots[i].glow_color = definition.glow_color
		hangar_available_slots[i].enabled = available > 0 and fleet.ships.size() < GameState.max_fleet_size()
		hangar_fleet_slots[i].enabled = deployed > 0 and fleet.ships.size() > 1
		hangar_available_slots[i].queue_redraw()
		hangar_fleet_slots[i].queue_redraw()


func _on_formation_changed() -> void:
	fleet.apply_formation()


func _on_reset_formation() -> void:
	GameState.reset_formation()
	fleet.apply_formation()
	formation_editor.queue_redraw()