1 files changed, 55 insertions, 0 deletions
diff --git a/src/pybind/mgr/dashboard/frontend/src/app/shared/services/time-diff.service.ts b/src/pybind/mgr/dashboard/frontend/src/app/shared/services/time-diff.service.ts
new file mode 100644
index 000000000..37477658c
--- /dev/null
+++ b/src/pybind/mgr/dashboard/frontend/src/app/shared/services/time-diff.service.ts
@@ -0,0 +1,55 @@
+import { Injectable } from '@angular/core';
+
+import _ from 'lodash';
+
+@Injectable({
+  providedIn: 'root'
+})
+export class TimeDiffService {
+  calculateDuration(startDate: Date, endDate: Date): string {
+    const startTime = +startDate;
+    const endTime = +endDate;
+    const duration = this.getDuration(Math.abs(startTime - endTime));
+    if (startTime > endTime) {
+      return '-' + duration;
+    }
+    return duration;
+  }
+
+  /**
+   * Get the duration in the format '[Nd] [Nh] [Nm]', e.g. '2d 1h 15m'.
+   * @param ms The time in milliseconds.
+   * @return The duration. An empty string is returned if the duration is
+   *   less than a minute.
+   */
+  private getDuration(ms: number): string {
+    const date = new Date(ms);
+    const h = date.getUTCHours();
+    const m = date.getUTCMinutes();
+    const d = Math.floor(ms / (24 * 3600 * 1000));
+
+    const format = (n: number, s: string) => (n ? n + s : n);
+    return [format(d, 'd'), format(h, 'h'), format(m, 'm')].filter((x) => x).join(' ');
+  }
+
+  calculateDate(date: Date, duration: string, reverse?: boolean): Date {
+    const time = +date;
+    if (_.isNaN(time)) {
+      return undefined;
+    }
+    const diff = this.getDurationMs(duration) * (reverse ? -1 : 1);
+    return new Date(time + diff);
+  }
+
+  private getDurationMs(duration: string): number {
+    const d = this.getNumbersFromString(duration, 'd');
+    const h = this.getNumbersFromString(duration, 'h');
+    const m = this.getNumbersFromString(duration, 'm');
+    return ((d * 24 + h) * 60 + m) * 60000;
+  }
+
+  private getNumbersFromString(duration: string, prefix: string): number {
+    const match = duration.match(new RegExp(`[0-9 ]+${prefix}`, 'i'));
+    return match ? parseInt(match[0], 10) : 0;
+  }
+}