react-native-epson-escposprinter/src/Discovery.ts

A Turbo Module wrapper for the Epson ePOS Printer SDK.

import EventEmitter from "eventemitter3";
import type { EmitterSubscription } from "react-native";
import {
  asyncIterableIteratorWithResolvers,
  type AsyncIterableWithResolvers,
} from "./asyncIterator";
import { ErrorCode, getEpsonError } from "./errors";
import { events, NativeInterface } from "./NativeInterface";
import { PrinterSeries } from "./PrinterConst";

export const enum FilterDeviceType {
  TYPE_ALL = 0,
  TYPE_PRINTER = 1,
  TYPE_HYBRID_PRINTER = 2,
  TYPE_DISPLAY = 3,
  TYPE_KEYBOARD = 4,
  TYPE_SCANNER = 5,
  TYPE_SERIAL = 6,
  TYPE_CCHANGER = 7,
  TYPE_POS_KEYBOARD = 8,
  TYPE_CAT = 9,
  TYPE_MSR = 10,
  TYPE_OTHER_PERIPHERAL = 11,
  TYPE_GFE = 12,
}

export const enum FilterPortType {
  PORTTYPE_ALL = 0,
  PORTTYPE_TCP = 1,
  PORTTYPE_BLUETOOTH = 2,
  PORTTYPE_USB = 3,
}

export const enum FilterModel {
  MODEL_ALL = 0,
}

export const enum FilterEpson {
  FILTER_NONE = 1,
  FILTER_NAME = 0,
}

export type FilterOptions = {
  deviceType?: FilterDeviceType;
  portType?: FilterPortType;
  boardcast?: string;
  deviceModel?: FilterModel;
  epsonFilter?: FilterEpson;
  bondedDevices?: boolean;
  usbDeviceName?: boolean;
};

export type DiscoveryOptions = {
  verbose?: boolean;
};

export type DeviceInfo = {
  deviceType: FilterDeviceType;
  deviceName: string;
  target: string;
  ipAddress?: string;
  macAddress?: string;
  bdAddress?: string;
  leBdAddress?: string;
};

export const getPrinterSeriesFromDeviceName = (
  name: string,
): PrinterSeries | undefined => {
  switch (name) {
    case "TM-H6000IV":
    case "TM-H6000V":
    case "TM-H6000IV-DT":
      return PrinterSeries.TM_H6000;
    case "TM-L90":
      return PrinterSeries.TM_L90;
    case "TM-L90 Liner-Free Label Printer Model":
      return PrinterSeries.TM_L90LFC;
    case "TM-L100":
      return PrinterSeries.TM_L100;
    case "TM-m10":
      return PrinterSeries.TM_M10;
    case "TM-m30":
      return PrinterSeries.TM_M30;
    case "TM-m30II":
    case "TM-m30II-H":
    case "TM-m30II-NT":
    case "TM-m30II-S":
    case "TM-m30II-SL":
      return PrinterSeries.TM_M30II;
    case "TM-m30III":
    case "TM-m30III-H":
      return PrinterSeries.TM_M30III;
    case "TM-m50":
      return PrinterSeries.TM_M50;
    case "TM-m50II":
    case "TM-m50II-H":
      return PrinterSeries.TM_M50II;
    case "TM-M55":
      return PrinterSeries.TM_M55;
    case "TM-P20":
      return PrinterSeries.TM_P20;
    case "TM-P20II":
      return PrinterSeries.TM_P20II;
    case "TM-P60":
    case "TM-P60 (Receipt/Peeler)":
      return PrinterSeries.TM_P60;
    case "TM-P60II":
    case "TM-P60II (Receipt/Peeler)":
      return PrinterSeries.TM_P60II;
    case "TM-P80":
      return PrinterSeries.TM_P80;
    case "TM-P80II":
      return PrinterSeries.TM_P80II;
    case "TM-T20":
    case "TM-T20II":
    case "TM-T20II-i":
    case "TM-T20III":
    case "TM-T20IIIL":
    case "TM-T20IV-L":
    case "TM-T20X":
    case "TM-T20X-II":
      return PrinterSeries.TM_T20;
    case "TM-T60":
      return PrinterSeries.TM_T60;
    case "TM-T70":
    case "TM-T70-i":
    case "TM-T70II":
    case "TM-T70II-DT":
    case "TM-T70II-DT2":
      return PrinterSeries.TM_T70;
    case "TM-T81II":
    case "TM-T81III":
      return PrinterSeries.TM_T81;
    case "TM-T82":
    case "TM-T82II":
    case "TM-T82II-i":
    case "TM-T82III":
    case "TM-T82IIIL":
    case "TM-T82IV-L":
    case "TM-T82X":
    case "TM-T82X-II":
      return PrinterSeries.TM_T82;
    case "TM-T83II":
    case "TM-T83II-i":
      return PrinterSeries.TM_T83;
    case "TM-T83III":
    case "TM-T83IV":
      return PrinterSeries.TM_T83III;
    case "TM-T88IV":
    case "TM-T88V":
    case "TM-T88VI":
    case "TM-T88V-i":
    case "TM-T88VI-iHUB":
    case "TM-T88V-DT":
    case "TM-T88VI-DT2":
      return PrinterSeries.TM_T88;
    case "TM-T88VII":
      return PrinterSeries.TM_T88VII;
    case "TM-T90":
      return PrinterSeries.TM_T90;
    case "TM-T90KP":
      return PrinterSeries.TM_T90KP;
    case "TM-T100":
      return PrinterSeries.TM_T100;
    case "TM-U220":
    case "TM-U220-i":
      return PrinterSeries.TM_U220;
    case "TM-U220II":
    case "TM-U220IIB-i":
      return PrinterSeries.TM_U220II;
    case "TM-U330":
      return PrinterSeries.TM_U330;
    case "TS-100":
      return PrinterSeries.TS_100;
    case "EU-m30":
      return PrinterSeries.EU_M30;
    default:
      return undefined;
  }
};

const discoveryErrors = {
  [ErrorCode.ERR_ILLEGAL]: `- Tried to start search when search had been already done.
- Bluetooth is OFF.
- There is no permission for the position information.`,
};

/**
 * A cache of discovered devices.
 *
 * Useful when multiple subscribers are active at the same time, we can only
 * have one active discovery service so we cache and share the result across
 * all subscribers.
 */
const cache = new Map<string, DeviceInfo>();

/**
 * References to active subscribers for sharing the cache.
 */
const iterators = new Set<AsyncIterableWithResolvers<DeviceInfo>>();

/**
 * Reference to active event emitters for sharing the cache.
 */
const emitters = new Set<PrinterDiscovery>();

/**
 * Epson's Discovery service requires a manual cooldown after stopping.
 */
let cooldown: Promise<void> | null = null;

let listener: EmitterSubscription | null = null;

const discoveryStart = async (
  filter: FilterOptions = {},
  options?: DiscoveryOptions,
) => {
  if (iterators.size > 0 || emitters.size > 0) {
    return;
  }

  listener?.remove(); // HMR and React dev mode may cause multiple subscriptions

  listener = events.addListener("deviceFound", (info: DeviceInfo) => {
    for (const it of iterators) {
      it.push(info);
    }

    for (const it of emitters) {
      it.emit("deviceFound", info);
    }

    // [ ] Handles dedupe on network identity conflicts
    cache.set(info.target, info);
  });

  // Let previous stop action to finish before starting a new one.
  await cooldown;

  if (options?.verbose) {
    console.debug(`Starting discovery service...`);
  }

  try {
    await NativeInterface.discoveryStart(filter);
  } catch (error) {
    throw getEpsonError(error, discoveryErrors) || error;
  }
};

const discoveryStop = async (options?: DiscoveryOptions) => {
  if (iterators.size > 0 || emitters.size > 0) {
    return;
  }

  if (!listener) {
    return;
  }

  listener.remove();
  listener = null;

  if (options?.verbose) {
    console.debug(`Stopping discovery service...`);
  }

  cooldown = NativeInterface.discoveryStop()
    .then(
      () => new Promise<void>((r) => setTimeout(r, 100)),
      (error) => {
        throw getEpsonError(error) || error;
      },
    )
    .finally(() => {
      cache.clear();
      cooldown = null;
    });

  return cooldown;
};

/**
 * Event emitter implementation of the printer discovery service.
 */
export class PrinterDiscovery
  extends EventEmitter<{
    deviceFound: [DeviceInfo];
  }>
  implements AsyncDisposable
{
  #startPromise: Promise<void> | null = null;

  constructor(
    filter?: FilterOptions,
    readonly options?: DiscoveryOptions,
  ) {
    super();

    this.#startPromise = discoveryStart(filter, options);

    emitters.add(this);
  }

  async dispose() {
    await this.#startPromise;

    emitters.delete(this);

    await discoveryStop(this.options);
  }

  [Symbol.asyncDispose]() {
    return this.dispose();
  }
}

/**
 * Asynchronous iterator for discovered printers.
 */
export async function discoverPrinters(
  filter?: FilterOptions,
  options?: DiscoveryOptions,
) {
  if (Symbol.asyncIterator === undefined) {
    throw new Error(
      `AsyncIterator is not supported in your runtime, try PrinterDiscovery instead.`,
    );
  }

  const iterator = asyncIterableIteratorWithResolvers<DeviceInfo>({
    dispose: async () => {
      iterators.delete(iterator);

      await discoveryStop(options);
    },
  });

  await discoveryStart(filter, options);

  for (const value of cache.values()) {
    iterator.push(value);
  }

  iterators.add(iterator);

  return iterator;
}