ScriptBase.js

class CommandParser {
  constructor(trigger) {
    this.trigger = trigger;
    this.defaultCmd;
    this.subCmds = {};
  }

  default(action) {
    this.defaultCmd = { action };
    return this;
  }

  command(name, action) {
    this.subCmds[name] = { action };
    return this;
  }

  handleMessage(msg) {
    if (msg.type !== 'api') return;
    let content = msg.content.trim();
    if (!content.startsWith(this.trigger)) return;
    let [_trigger, subCommand, ...args] = content.split(' ');
    if (
      !subCommand ||
      subCommand.startsWith('--') ||
      !(subCommand in this.subCmds)
    ) {
      if (this.defaultCmd) {
        const opts = this.parseArgs([subCommand, ...args]);
        this.defaultCmd.action(opts, msg);
      } else {
        this.showHelp();
      }
    } else {
      if (subCommand in this.subCmds) {
        const opts = this.parseArgs(args);
        this.subCmds[subCommand].action(opts, msg);
      } else {
        this.showHelp();
      }
    }
  }

  parseArgs(args) {
    let options = args.reduce(
      (opts, arg) => {
        if (!arg) return opts;
        if (arg.startsWith('--')) {
          let [key, val] = arg.slice(2).split('=');
          return { ...opts, [key]: val === undefined ? true : val };
        }
        return {
          ...opts,
          _: [...opts._, arg],
        };
      },
      { _: [] }
    );

    return options;
  }

  showHelp() {}
}

const ScriptBase = ({ name, version, stateKey = name, initialState = {} }) =>
  class {
    version = version;
    name = name;

    get state() {
      if (!state[stateKey]) {
        state[stateKey] = initialState;
      }
      return state[stateKey];
    }

    onMessage = (msg) => {
      if (!this.parser) return;
      try {
        this.parser.handleMessage(msg);
      } catch (err) {
        log(`${name} ERROR: ${err.message}`);
        sendChat(
          `${name} ERROR:`,
          `/w ${msg.who.replace(/\(GM\)/, '').trim()} ${err.message}`
        );
      }
    };

    constructor() {
      on('chat:message', this.onMessage);
      on('ready', () => {
        log(`\n[====== ${name} v${version} ======]`);
      });
    }

    resetState(newState = initialState) {
      state[stateKey] = newState;
    }
  };

ScriptBaseExample.js

class _MyCoolScript extends ScriptBase({
  name: 'MyCoolScript',
  version: '0.1.0',
  stateKey: 'MY_COOL_SCRIPT',
  initialState: { favoriteColor: 'blue' },
}) {
  constructor() {
    super();
    // Here is where you can register additional event handlers:
    // on('change:graphic', this.onChangeGraphic);
  }
  
  parser = new CommandParser('!cool-script')
    .default(() => {
      sendChat(this.name, `My favorite color is ${this.state.favoriteColor}`);
    })
    .command('set', this.setColor);
  
  setColor = (opts, msg) => {
    // CommandParser puts arguments into the `opts` parameter. If the argument
    // is a flag like `--name=Bob`, opts will be an object like `{ name: 'Bob', _: [] }`
    // If the argument is NOT a flag, it will go into the array like `{ _: ['First', 'Second'] }`
    
    // Here, the usage is `!cool-script set blue`, so opts looks like `{ _: ['blue'] }`
    const newColor = opts._[0];
    
    if (!newColor) {
      throw new Error("Please specify a color!")
    }
    
    this.state.favoriteColor = newColor;
  }
}

const MyCoolScript = new _MyCoolScript();