Custom logging service for Angular

logger.ts

import { Injectable } from '@angular/core';
import { BehaviorSubject, Observable } from 'rxjs';

export interface LoggerConfig {
  prefix?: string;
  color?: string;
  enabled: boolean;
}

@Injectable({
  providedIn: 'root'
})
export class LoggerProvider {
  defaultConfig: LoggerConfig = {prefix: '', color: '#76BE43', enabled: true};
  loggedSubj = new BehaviorSubject<any>(null);
  logged$: Observable<any>;
  method: string;
  levelMap = {
    warn: 'warn',
    error: 'error',
    log: 'log',
    info: 'info'
  };
  constructor(private config?: LoggerConfig) {
    this.config = this.config ? {...this.defaultConfig, ...this.config} : this.defaultConfig;
    this.logged$ = this.loggedSubj.asObservable();
  }

  log(...params) {
    this.method = this.levelMap.log;
    this.writeToLog.apply(this, arguments);
  }

  error(...params) {
    this.method = this.levelMap.error;
    this.writeToLog.apply(this, arguments);
  }

  info(...params) {
    this.method = this.levelMap.info;
    this.writeToLog.apply(this, arguments);
  }

  warn(...params) {
    this.method = this.levelMap.warn;
    this.writeToLog.apply(this, arguments);
  }

  writeToLog() {
    const args = [];
    for (let i = 0; i < arguments.length; ++i) {
      args.push(arguments[i]);
    }
    let message = args.map((arg) => {
      if (typeof arg === 'object') {
        return JSON.stringify(arg);
      }
      return arg;
    }).join(', ');
    const logMsg = `${this.config.prefix ? this.config.prefix + ' - ' : ''}${this.method}${message}`;
    console[this.method](`%c${logMsg}`, `color: ${this.config.color}; font-weight: bold;`);
    this.loggedSubj.next({
      prefix: this.config.prefix,
      method: this.method,
      message
    });
  }

}