Add utility functions to event log plugin

x-pack/plugins/event_log/common/index.ts

@@ -6,3 +6,4 @@
  */
 
 export const BASE_EVENT_LOG_API_PATH = '/internal/event_log';
+export { millisToNanos, nanosToMillis } from './lib';

x-pack/plugins/event_log/common/lib/index.ts

@@ -0,0 +1,9 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0; you may not use this file except in compliance with the Elastic License
+ * 2.0.
+ */
+
+export { millisToNanos } from './millis_to_nanos';
+export { nanosToMillis } from './nanos_to_millis';

x-pack/plugins/event_log/common/lib/millis_to_nanos.test.ts

@@ -0,0 +1,22 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0; you may not use this file except in compliance with the Elastic License
+ * 2.0.
+ */
+
+import { millisToNanos } from './millis_to_nanos';
+
+describe('millisToNanos', () => {
+  test('should return "0" when passing 0 millis', () => {
+    expect(millisToNanos(0)).toEqual('0');
+  });
+
+  test('should return "1000000" when passing in 1 millis', () => {
+    expect(millisToNanos(1)).toEqual('1000000');
+  });
+
+  test('should return "9007199254740991000000" when passing in 9007199254740991 (Number.MAX_SAFE_INTEGER)', () => {
+    expect(millisToNanos(9007199254740991)).toEqual('9007199254740991000000');
+  });
+});

x-pack/plugins/event_log/common/lib/millis_to_nanos.ts

@@ -0,0 +1,13 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0; you may not use this file except in compliance with the Elastic License
+ * 2.0.
+ */
+
+export function millisToNanos(millis: number): string {
+  if (millis === 0) {
+    return '0';
+  }
+  return `${millis}000000`;
+}

x-pack/plugins/event_log/common/lib/nanos_to_millis.test.ts

@@ -0,0 +1,26 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0; you may not use this file except in compliance with the Elastic License
+ * 2.0.
+ */
+
+import { nanosToMillis } from './nanos_to_millis';
+
+describe('nanosToMillis', () => {
+  test('should return 0 when passing in "0" nanos', () => {
+    expect(nanosToMillis('0')).toEqual(0);
+  });
+
+  test('should drop decimals when passing in "1" nanos', () => {
+    expect(nanosToMillis('1')).toEqual(0);
+  });
+
+  test('should drop decimals when passing in "1000001" nanos', () => {
+    expect(nanosToMillis('1000001')).toEqual(1);
+  });
+
+  test('should return 9007199254740991 (Number.MAX_SAFE_INTEGER) when passing in "9007199254740991000000" nanos', () => {
+    expect(nanosToMillis('9007199254740991000000')).toEqual(9007199254740991);
+  });
+});

x-pack/plugins/event_log/common/lib/nanos_to_millis.ts

@@ -0,0 +1,12 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0; you may not use this file except in compliance with the Elastic License
+ * 2.0.
+ */
+
+const ONE_MILLION = BigInt(1000 * 1000);
+
+export function nanosToMillis(nanos: string): number {
+  return Number(BigInt(nanos) / ONE_MILLION);
+}

x-pack/plugins/event_log/tsconfig.json

@@ -12,7 +12,7 @@
     "generated/*",
     // have to declare *.json explicitly due to https://github.com/microsoft/TypeScript/issues/25636
     "generated/*.json",
-    "common/*"
+    "common/**/*"
   ],
   "references": [
     { "path": "../../../src/core/tsconfig.json" },