extends Node3D
## VR start screen UI panel.
## Renders a 2D UI in a SubViewport on a QuadMesh in VR space.
## Allows user to enter server URL/port, connect, and launch AR mode.
## Includes an in-VR numpad since the Quest system keyboard doesn't work in XR mode.

signal connect_requested(host: String, port: int)
signal launch_ar_requested()

@onready var ui_mesh: MeshInstance3D = $UIMesh
@onready var viewport: SubViewport = $UIMesh/SubViewport
@onready var host_input: LineEdit = $UIMesh/SubViewport/PanelContainer/MarginContainer/VBox/ServerRow/HostInput
@onready var port_input: LineEdit = $UIMesh/SubViewport/PanelContainer/MarginContainer/VBox/PortRow/PortInput
@onready var connect_button: Button = $UIMesh/SubViewport/PanelContainer/MarginContainer/VBox/ConnectButton
@onready var status_label: Label = $UIMesh/SubViewport/PanelContainer/MarginContainer/VBox/StatusLabel
@onready var launch_ar_button: Button = $UIMesh/SubViewport/PanelContainer/MarginContainer/VBox/LaunchARButton
@onready var vbox: VBoxContainer = $UIMesh/SubViewport/PanelContainer/MarginContainer/VBox

var _is_connected: bool = false
var _numpad_container: VBoxContainer
var _active_input: LineEdit  # Which input field the numpad types into


func _ready() -> void:
	add_to_group("start_screen")
	connect_button.pressed.connect(_on_connect_pressed)
	launch_ar_button.pressed.connect(_on_launch_ar_pressed)

	# Show numpad when input fields are focused
	host_input.focus_entered.connect(_on_input_focused.bind(host_input))
	port_input.focus_entered.connect(_on_input_focused.bind(port_input))

	# Build the in-VR numpad
	_build_numpad()

	# Set up the mesh material to display the SubViewport
	var material := StandardMaterial3D.new()
	material.shading_mode = BaseMaterial3D.SHADING_MODE_UNSHADED
	material.albedo_texture = viewport.get_texture()
	material.transparency = BaseMaterial3D.TRANSPARENCY_DISABLED
	ui_mesh.material_override = material

	print("[StartScreen] Ready")


func _build_numpad() -> void:
	_numpad_container = VBoxContainer.new()
	_numpad_container.add_theme_constant_override("separation", 6)
	_numpad_container.visible = false

	# Button rows: [1,2,3] [4,5,6] [7,8,9] [.,0,<-] [Clear, Done]
	var rows := [
		["1", "2", "3"],
		["4", "5", "6"],
		["7", "8", "9"],
		[".", "0", "<"],
		["Clear", "Done"],
	]

	for row in rows:
		var hbox := HBoxContainer.new()
		hbox.add_theme_constant_override("separation", 6)
		hbox.alignment = BoxContainer.ALIGNMENT_CENTER
		for key in row:
			var btn := Button.new()
			btn.text = key
			btn.custom_minimum_size = Vector2(80, 55)
			btn.size_flags_horizontal = Control.SIZE_EXPAND_FILL
			if key == "Clear" or key == "Done":
				btn.custom_minimum_size = Vector2(130, 55)
			btn.add_theme_font_size_override("font_size", 26)
			btn.pressed.connect(_on_numpad_key.bind(key))
			hbox.add_child(btn)
		_numpad_container.add_child(hbox)

	# Insert numpad after the PortRow
	var port_row_idx := port_input.get_parent().get_index()
	vbox.add_child(_numpad_container)
	vbox.move_child(_numpad_container, port_row_idx + 1)


func _on_input_focused(input: LineEdit) -> void:
	_active_input = input
	_numpad_container.visible = true


func _on_numpad_key(key: String) -> void:
	if _active_input == null:
		return

	if key == "<":
		# Backspace
		var t := _active_input.text
		if t.length() > 0:
			_active_input.text = t.substr(0, t.length() - 1)
			_active_input.caret_column = _active_input.text.length()
	elif key == "Clear":
		_active_input.text = ""
		_active_input.caret_column = 0
	elif key == "Done":
		_numpad_container.visible = false
		_active_input.release_focus()
		_active_input = null
	else:
		_active_input.text += key
		_active_input.caret_column = _active_input.text.length()


func _on_connect_pressed() -> void:
	# Hide numpad if open
	_numpad_container.visible = false

	var host := host_input.text.strip_edges()
	if host.is_empty():
		update_status("Please enter a server address")
		return

	var port := int(port_input.text.strip_edges())
	if port <= 0 or port > 65535:
		update_status("Invalid port number")
		return

	update_status("Connecting to %s:%d..." % [host, port])
	connect_requested.emit(host, port)


func _on_launch_ar_pressed() -> void:
	launch_ar_requested.emit()


func update_status(text: String) -> void:
	status_label.text = text


func set_connected(connected: bool) -> void:
	_is_connected = connected
	if connected:
		update_status("Connected!")
		connect_button.text = "Disconnect"
	else:
		if connect_button.text == "Disconnect":
			update_status("Disconnected")
		connect_button.text = "Connect to Server"


func show_screen() -> void:
	visible = true


func hide_screen() -> void:
	visible = false