import { Pixel } from "@systemic-games/pixels-core-connect";

import BleSession from "./BleSession";
import { PixelsDevices } from "./PixelsDevices";

const _pixels = new Map<string, Pixel>();

function getOrCreatePixel(device: BluetoothDevice): Pixel {
  // Keep Pixel instances
  let pixel = _pixels.get(device.id);
  if (!pixel) {
    const session = new BleSession(device.id);
    pixel = new Pixel(session);
    _pixels.set(device.id, pixel);
  }
  return pixel;
}

/**
 * Request the user to select a Pixels die to connect to.
 * When supported the browser will display the list of Pixels dice
 * that are currently available to be connected to.
 *
 * The same {@link Pixel} instance is returned if the a die is selected
 * again.
 *
 * @returns A promise that resolves to a {@link Pixel} instance.
 *
 * @remarks
 * - See {@link getBluetoothCapabilities} to check Bluetooth availability.
 * - See {@link getPixel} to directly get the instance of a Pixels die
 *   previously authorized the user.
 *
 * @category Pixels
 */
export async function requestPixel(): Promise<Pixel> {
  const device = await PixelsDevices.requestDevice();
  return getOrCreatePixel(device);
}

/**
 * Returns the {@link Pixel} instance corresponding to the given system id.
 * The latter is assigned by the system to Bluetooth devices,
 * see {@link Pixel.systemId}.
 *
 * This function doesn't check the actual availability nor the connection state
 * of the die. The later might be turned off, available or already connected.
 *
 * As of Chrome 122, only Pixels dice authorized by the user during the current
 * browser session may be returned.
 *
 * With the "Use the new permissions backend for Web Bluetooth" flag enabled in
 * Chrome, Pixels dice authorized by the user in previous browser sessions (and
 * not revoked since) will also be returned.
 * To enable this flag, open the following address in Chrome:
 * `chrome://flags/#enable-web-bluetooth-new-permissions-backend` and toggle the flag
 * to `Enabled`.
 *
 * The returned promise will resolve to undefined when there is no authorized
 * Pixel with the given system id.
 *
 * @param systemId A string assigned by the system that uniquely identifies
 *                 a Pixel die.
 * @returns
 * A promise that resolves to a {@link Pixel} instance if the Bluetooth device
 * was previously authorized, or undefined.
 *
 * @remarks
 * - See {@link getBluetoothCapabilities} to check Bluetooth availability and
 *   if the new permissions backend is enabled.
 * - See {@link requestPixel} to request the user to give access to a new Pixels
 *   die.
 *
 * @category Pixels
 */
export async function getPixel(systemId: string): Promise<Pixel | undefined> {
  const pixel = _pixels.get(systemId);
  if (pixel) {
    return pixel;
  } else {
    const device = await PixelsDevices.getDevice(systemId);
    return device ? getOrCreatePixel(device) : undefined;
  }
}