gamestream-webtransport-proxy/frontend/src/lib/input.ts

import { Input } from "$lib/proto/input-event"
import { InputEvent } from "$lib/proto/input"
import { Builder } from "flatbuffers";

export enum KeyAction {
  DOWN,
  UP,
}

export async function sendKeyboardEvent(
  writer: WritableStreamDefaultWriter,
  event: KeyboardEvent,
  keyAction: KeyAction,
) {
  const builder = new Builder(1024);

  InputEvent.KeyboardInput.startKeyboardInput(builder);
  // Have to use keyCode even though it's deprecated beacuse .code is a unhelpful string :sigh:
  InputEvent.KeyboardInput.addKeyCode(builder, event.keyCode);
  InputEvent.KeyboardInput.addKeyAction(builder, keyAction);
  const modifierState = InputEvent.ModifierState.createModifierState(
    builder,
    event.shiftKey,
    event.ctrlKey,
    event.altKey,
    event.metaKey
  );

  InputEvent.KeyboardInput.addModifiers(builder, modifierState);
  const keyboardInput = InputEvent.KeyboardInput.endKeyboardInput(builder);

  // Create InputEvent table with union
  InputEvent.InputEvent.startInputEvent(builder);
  InputEvent.InputEvent.addInputType(builder, Input.Keyboard);
  InputEvent.InputEvent.addInput(builder, keyboardInput);
  const inputEvent = InputEvent.InputEvent.endInputEvent(builder);

  // Finish the buffer
  builder.finish(inputEvent);

  // Get the buffer data
  const bufferData = builder.asUint8Array();

  // Create size prefix as big-endian u32
  const sizePrefix = new Uint8Array(4);
  const size = bufferData.length;
  sizePrefix[0] = (size >> 24) & 0xFF;  // Most significant byte
  sizePrefix[1] = (size >> 16) & 0xFF;
  sizePrefix[2] = (size >> 8) & 0xFF;
  sizePrefix[3] = size & 0xFF;          // Least significant byte

  // Create combined buffer with size prefix + flatbuffer data
  const combined = new Uint8Array(sizePrefix.length + bufferData.length);
  combined.set(sizePrefix, 0);
  combined.set(bufferData, sizePrefix.length);

  // Write to stream
  await writer.write(combined);
}

export async function sendMouseMoveEvent(
  writer: WritableStreamDefaultWriter,
  event: MouseEvent,
) {
  const builder = new Builder(1024);

  const mouseMovement = InputEvent.MouseMovement.createMouseMovement(builder, event.movementX, event.movementY);

  // Create InputEvent table with union
  InputEvent.InputEvent.startInputEvent(builder);
  InputEvent.InputEvent.addInputType(builder, Input.MouseMovement);
  InputEvent.InputEvent.addInput(builder, mouseMovement);
  const inputEvent = InputEvent.InputEvent.endInputEvent(builder);

  // Finish the buffer
  builder.finish(inputEvent);

  // Get the buffer data
  const bufferData = builder.asUint8Array();

  // Create size prefix as big-endian u32
  const sizePrefix = new Uint8Array(4);
  const size = bufferData.length;
  sizePrefix[0] = (size >> 24) & 0xFF;  // Most significant byte
  sizePrefix[1] = (size >> 16) & 0xFF;
  sizePrefix[2] = (size >> 8) & 0xFF;
  sizePrefix[3] = size & 0xFF;          // Least significant byte

  // Create combined buffer with size prefix + flatbuffer data
  const combined = new Uint8Array(sizePrefix.length + bufferData.length);
  combined.set(sizePrefix, 0);
  combined.set(bufferData, sizePrefix.length);

  // Write to stream
  await writer.write(combined);
}

export async function sendMouseInputEvent(
  writer: WritableStreamDefaultWriter,
  event: MouseEvent,
  keyAction: KeyAction,
) {
  const builder = new Builder(1024);

  var mouseButton: InputEvent.MouseButton;

  switch (event.button) {
    case 0:
      mouseButton = InputEvent.MouseButton.LEFT;
      break;
    case 1:
      mouseButton = InputEvent.MouseButton.MIDDLE;
      break;
    case 2:
      mouseButton = InputEvent.MouseButton.RIGHT;
      break;
    default:
      console.log(`Unknown mouse button ${event.button}, defaulting to LEFT`);
      mouseButton = InputEvent.MouseButton.LEFT;
      break;
  }

  const mouseInput = InputEvent.MouseInput.createMouseInput(builder, mouseButton, keyAction);

  // Create InputEvent table with union
  InputEvent.InputEvent.startInputEvent(builder);
  InputEvent.InputEvent.addInputType(builder, Input.MouseInput);
  InputEvent.InputEvent.addInput(builder, mouseInput);
  const inputEvent = InputEvent.InputEvent.endInputEvent(builder);

  // Finish the buffer
  builder.finish(inputEvent);

  // Get the buffer data
  const bufferData = builder.asUint8Array();

  // Create size prefix as big-endian u32
  const sizePrefix = new Uint8Array(4);
  const size = bufferData.length;
  sizePrefix[0] = (size >> 24) & 0xFF;  // Most significant byte
  sizePrefix[1] = (size >> 16) & 0xFF;
  sizePrefix[2] = (size >> 8) & 0xFF;
  sizePrefix[3] = size & 0xFF;          // Least significant byte

  // Create combined buffer with size prefix + flatbuffer data
  const combined = new Uint8Array(sizePrefix.length + bufferData.length);
  combined.set(sizePrefix, 0);
  combined.set(bufferData, sizePrefix.length);

  // Write to stream
  await writer.write(combined);
}