core/src/core/logger.ts

import dateFmt from 'dateformat';
import util from 'util';

type LogType = 'info' | 'debug' | 'warn' | 'error';

/**
 * Logger for all of Squeebot. Use this instead of console.log/warn/error!
 */
export class Logger {
  private console = [console.log, console.warn, console.error];

  constructor(
    public timestamp = 'dd/mm/yy HH:MM:ss'
  ) {}

  /**
   * Set node.js readline consideration
   * @param rl Readline instance
   */
  public setReadline(rl: any): void {
    for (const index in this.console) {
      const old = this.console[index];
      this.console[index] = (...data: any[]): void => {
        rl.output.write('\x1b[2K\r');
        old(...data);
        rl.prompt(true);
      };
    }
  }

  /**
   * Write out to log
   * @param ltype Logger level
   * @param data Data to log
   */
  private write(ltype: LogType, ...data: any[]): void {
    const message = [];
    let cfunc = this.console[0];

    if (this.timestamp) {
      message.push(`[${dateFmt(new Date(), this.timestamp)}]`);
    }

    switch (ltype) {
    case 'info':
      message.push('[ INFO]');
      break;
    case 'debug':
      message.push('[DEBUG]');
      break;
    case 'warn':
      message.push('[ WARN]');
      cfunc = this.console[1];
      break;
    case 'error':
      message.push('[ERROR]');
      cfunc = this.console[2];
      break;
    }

    // Short dance to apply formatting
    let final = data[0];
    if (data.length > 1) {
      const fargs = data.slice(1);
      final = util.format(data[0], ...fargs);
    }
    message.push(final);
    cfunc(...message);
  }

  /**
   * Logger level: `INFO`
   *
   * See `console.log` for more information.
   */
  public log(...data: any[]): void {
    this.write('info', ...data);
  }

  /**
   * Logger level: `WARN`
   *
   * See `console.warn` for more information.
   */
  public warn(...data: any[]): void {
    this.write('warn', ...data);
  }

  /**
   * Logger level: `INFO`
   *
   * See `console.log` for more information.
   */
  public info(...data: any[]): void {
    this.write('info', ...data);
  }

  /**
   * Logger level: `ERROR`
   *
   * See `console.error` for more information.
   */
  public error(...data: any[]): void {
    this.write('error', ...data);
  }

  /**
   * Logger level: `DEBUG`
   *
   * See `console.log` for more information.
   */
  public debug(...data: any[]): void {
    this.write('debug', ...data);
  }
}

// Create singleton for Logger to be used anywhere
const logger = new Logger();
export { logger };