ngoninit.ts

  ngOnInit(): void {
    const histories$ = this.route.paramMap.pipe(
      mergeMap(params => {
        const classNames = params.get('class').split(',');
        const methodNames = params.get('method').split(',');
        const metricNames = params.get('metric').split(',');

        const labelMetric = ([className, methodName, metricName]) => {
          if (countBy(metricNames)[metricName] >= 2) {
            if (countBy(methodNames)[methodName] >= 2) {
              return `${className}::${methodName}() #${metricName}`;
            }
            return `${methodName}() #${metricName}`;
          }
          return `#${metricName}`;
        };

        const result = zip(classNames, methodNames, metricNames).map(address => {
          const [className, methodName, metricName] = address;
          return this.metricsService
            .getMetricHistory$(className, methodName, metricName)
            .pipe(map(history => ({history, label: labelMetric(address)})));
        });

        return forkJoin(result);
      }),
    );

    this.chartData$ = histories$.pipe(
      map(histories =>
        histories.map(({label, history}) => ({
          data: history.map(point => point.value),
          label,
        })),
      ),
    );

    this.chartLabels$ = histories$.pipe(
      /* Why is it unknown? */
      map((histories: Array<{history: Array<{time: string}>}>) =>
        histories[0].history.map(point => point.time),
      ),
    );
  }