@meyer/hyperdeck-emulator/src/messageForCode.ts

Typescript Node.js library for emulating a Blackmagic Hyperdeck

import { CRLF } from './constants';
import { ResponseCode, responseNamesByCode, TypesByStringKey } from './types';
import { invariant } from './invariant';
import { camelcaseToSpaceCase } from './utils';
import { Timecode } from './Timecode';

// escape CR/LF and remove colons
const sanitiseMessage = (input: string): string => {
  return input.replace(/\r/g, '\\r').replace(/\n/g, '\\n').replace(/:/g, '');
};

/** For a given code, generate the response message that will be sent to the ATEM */
export const messageForCode = (
  code: ResponseCode,
  params?: Record<string, TypesByStringKey[keyof TypesByStringKey]> | string
): string => {
  if (typeof params === 'string') {
    return code + ' ' + sanitiseMessage(params) + CRLF;
  }

  const firstLine = `${code} ${responseNamesByCode[code]}`;

  // bail if no params
  if (!params) {
    return firstLine + CRLF;
  }

  // filter out params with null/undefined values
  const paramEntries = Object.entries(params).filter(([, value]) => value != null);

  // bail if no params after filtering
  if (paramEntries.length === 0) {
    return firstLine + CRLF;
  }

  // turn the params object into a key/value
  return (
    paramEntries.reduce<string>((prev, [key, value]) => {
      let valueString: string;

      if (typeof value === 'string') {
        valueString = value;
      } else if (typeof value === 'boolean') {
        valueString = value ? 'true' : 'false';
      } else if (typeof value === 'number') {
        valueString = value.toString();
      } else if (value instanceof Timecode) {
        valueString = value.toString();
      } else {
        invariant(
          false,
          'Unhandled value type for key `%s`: `%s`',
          key,
          Array.isArray(value) ? 'array' : typeof value
        );
      }

      // convert camelCase keys to space-separated words
      const formattedKey = camelcaseToSpaceCase(key);

      return prev + formattedKey + ': ' + valueString + CRLF;
    }, firstLine + ':' + CRLF) + CRLF
  );
};