extends MeshInstance3D
## Displays JPEG webcam frames received from the robot on a quad mesh.
## The quad is positioned in front of the user's view (child of XRCamera3D).
##
## Receives JPEG bytes via the webcam_frame_received signal from TeleopClient.

## Display settings
@export var default_color := Color(0.1, 0.1, 0.1, 0.8)

## State
var _texture: ImageTexture
var _material: StandardMaterial3D
var _frame_count: int = 0
var _last_frame_time: int = 0
var _fps: float = 0.0
var _fps_update_timer: float = 0.0
var _has_received_frame: bool = false


func _ready() -> void:
	# Always create a fresh material — instanced scenes share sub_resources,
	# so we must not reuse the scene's material or all quads show the same texture
	_material = StandardMaterial3D.new()
	_material.shading_mode = BaseMaterial3D.SHADING_MODE_UNSHADED
	_material.albedo_color = default_color
	_material.transparency = BaseMaterial3D.TRANSPARENCY_ALPHA
	material_override = _material

	# Create initial texture (will be replaced on first frame)
	_texture = ImageTexture.new()

	print("[WebcamDisplay] %s ready, waiting for frames..." % name)


func _process(delta: float) -> void:
	# Update FPS counter
	_fps_update_timer += delta
	if _fps_update_timer >= 1.0:
		_fps = _frame_count / _fps_update_timer
		_frame_count = 0
		_fps_update_timer = 0.0


## Called when a JPEG webcam frame is received from the server.
## Connected via signal from TeleopClient in Main.gd.
func _on_webcam_frame(jpeg_bytes: PackedByteArray) -> void:
	if jpeg_bytes.size() < 2:
		return

	var image := Image.new()
	var err := image.load_jpg_from_buffer(jpeg_bytes)
	if err != OK:
		if _frame_count == 0:
			printerr("[WebcamDisplay] Failed to decode JPEG frame (size=%d, err=%d)" % [jpeg_bytes.size(), err])
		return

	# Update texture from decoded image
	if _texture.get_image() == null or _texture.get_width() != image.get_width() or _texture.get_height() != image.get_height():
		_texture = ImageTexture.create_from_image(image)
		_material.albedo_texture = _texture
		_material.albedo_color = Color.WHITE  # Full brightness once we have a real image
		print("[WebcamDisplay] Texture created: %dx%d" % [image.get_width(), image.get_height()])
	else:
		_texture.update(image)

	_frame_count += 1
	_last_frame_time = Time.get_ticks_msec()

	if not _has_received_frame:
		_has_received_frame = true
		print("[WebcamDisplay] First frame received!")


## Get display FPS
func get_fps() -> float:
	return _fps


## Check if frames are being received
func is_receiving() -> bool:
	if not _has_received_frame:
		return false
	# Consider stale if no frame for 2 seconds
	return (Time.get_ticks_msec() - _last_frame_time) < 2000