import {Logger} from './logger';

import 'rxjs/add/operator/map';


/**
 * Keep an map of indentation => array of indentations based on the level.
 * This is to optimize calculating the prefix based on the indentation itself. Since most logs
 * come from similar levels, and with similar indentation strings, this will be shared by all
 * loggers. Also, string concatenation is expensive so performing concats for every log entries
 * is expensive; this alleviates it.
 */
const indentationMap: {[indentationType: string]: string[]} = {};


export class IndentLogger extends Logger {
  constructor(name: string, parent: Logger | null = null, indentation = '  ') {
    super(name, parent);

    indentationMap[indentation] = indentationMap[indentation] || [''];
    const map = indentationMap[indentation];

    this._observable = this._observable.map(entry => {
      const l = entry.path.length;
      if (l >= map.length) {
        let current = map[map.length - 1];
        while (l >= map.length) {
          current += indentation;
          map.push(current);
        }
      }

      entry.message = map[l] + entry.message;
      return entry;
    });
  }
}