node-web-serial/index.ts

import { EventEmitter } from "events";
import * as SerialPortStream from "serialport";

// TODO: stream/web 使う https://nodejs.org/en/blog/release/v16.5.0/#experimental-web-streams-api
import { Writable, Readable } from "stream";

type ConnectEventHandler = () => {};
type DisconnectEventHandler = () => {};

interface SerialPortMetadata {
  /** Serial Number */
  serialNumber?: string;
  /** Manufacturer */
  manufacturer?: string;
  /** Location ID */
  locationId?: number | string;
  /** Vendor ID */
  vendorId?: number | string;
  /** Vendor */
  vendor?: string;
  /** Product ID */
  productId?: number | string;
  /** Product */
  product?: string;
  /** PNP ID. Different from Web Serial API specification. */
  pnpId?: string;
  /** Path. Different from Web Serial API specification. */
  path?: string;
}

export interface SerialPortRequestOptions {
  filters?: Array<SerialPortMetadata>;
}

export interface SerialPortInfo extends Map<string, undefined | string> {
}

interface Parity {
  /** No parity bit is sent for each data word. */
  none: never;
  /** Data word plus parity bit has even parity. */
  even: never;
  /** Data word plus parity bit has odd parity. */
  odd: never;
  /** Parity bit has a mark symbol (logical one). */
  mark: never;
  /** Parity bit has a space symbol (logical zero). */
  space: never;
}

type ParityType = keyof Parity;

export interface SerialOptions {
  baudrate?:
  | 115200
  | 57600
  | 38400
  | 19200
  | 9600
  | 4800
  | 2400
  | 1800
  | 1200
  | 600
  | 300
  | 200
  | 150
  | 134
  | 110
  | 75
  | 50;
  databits?: 8 | 7 | 6 | 5;
  stopbits?: 1 | 2;
  parity?: ParityType;
  buffersize?: number;
  rtscts?: boolean;
  xon?: boolean;
  xoff?: boolean;
  xany?: boolean;
}

export class SerialPort {
  #portInfo: SerialPortStream.PortInfo
  #port?: SerialPortStream;

  constructor(portInfo: SerialPortStream.PortInfo) {
    this.#portInfo = portInfo;
  }

  getInfo(): SerialPortInfo {
    return new Map(Object.entries(this.#portInfo));
  }

  async open(options: SerialOptions): Promise<void> {
    return new Promise((resolve, reject) => {
      this.#port = new SerialPortStream(this.#portInfo.path, options, (error) => {
        if (error) return reject(error);

        return resolve();
      })
    })
  }

  get in(): Writable {

  }

  get out(): Readable {
    return this.#port?.readable
  }
}

const filterKeys: Array<
  & keyof SerialPortMetadata
  & keyof SerialPortStream.PortInfo
> = [
    "serialNumber",
    "manufacturer",
    "locationId",
    "vendorId",
    "productId",
    "pnpId",
    "path"
  ];

const matchPort = (filters: SerialPortRequestOptions["filters"]) => (
  portInfo: SerialPortStream.PortInfo
) => {
  if (filters == null) return true;

  return filters.some(filter =>
    filterKeys
      .flatMap(key => filter[key] == null ? [] : [[filter[key], portInfo[key]]])
      .every(([param, info]) => {
        if (typeof param === "number") {
          return info === param.toString(16);
        }

        return info === param;
      })
  );
};

export class Serial extends EventEmitter {
  onconnect?: ConnectEventHandler;
  ondisconnect?: DisconnectEventHandler;
  #ports: Array<SerialPort>;

  constructor() {
    super();
    this.on("connect", () => {
      if (this.onconnect != null) this.onconnect();
    });
    this.on("disconnect", () => {
      if (this.ondisconnect != null) this.ondisconnect();
    });
    this.#ports = []
  }

  async getPorts(): Promise<Array<SerialPort>> {
    return this.#ports;
  }

  async requestPort({ filters }: SerialPortRequestOptions = {}): Promise<SerialPort> {
    const portInfo = await SerialPortStream.list();
    const ports = portInfo.filter(matchPort(filters));

    if (ports.length === 0) {
      throw new Error("Serial port not found.");
    }

    const port = new SerialPort(ports[0]);
    this.#ports = [...this.#ports, port]
    return port;
  }
}