[8.x] [Automatic import] refactor merge (#193270) (#193291)

# Backport

This will backport the following commits from `main` to `8.x`:
- [[Automatic import] refactor merge
(#193270)](#193270)

<!--- Backport version: 9.4.3 -->

### Questions ?
Please refer to the [Backport tool
documentation](https://github.com/sqren/backport)

<!--BACKPORT [{"author":{"name":"Hanna
Tamoudi","email":"[email protected]"},"sourceCommit":{"committedDate":"2024-09-18T13:05:13Z","message":"[Automatic
import] refactor merge
(#193270)","sha":"af01e511734aba4687bee6ca9122ac1186e31ee1","branchLabelMapping":{"^v9.0.0$":"main","^v8.16.0$":"8.x","^v(\\d+).(\\d+).\\d+$":"$1.$2"}},"sourcePullRequest":{"labels":["enhancement","release_note:skip","v9.0.0","backport:prev-minor","Team:Security-Scalability","Feature:AutomaticImport"],"title":"[Automatic
import] refactor
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import] refactor merge
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BACKPORT-->

Co-authored-by: Hanna Tamoudi <[email protected]>

x-pack/plugins/integration_assistant/server/util/samples.test.ts

@@ -0,0 +1,116 @@
+/*
+ * 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 { merge } from './samples';
+
+describe('merge', () => {
+  it('Should return source if target is empty', async () => {
+    const target = {};
+    const source = { target: 'user.name', confidence: 0.9, type: 'string', date_formats: [] };
+
+    const result = merge(target, source);
+
+    expect(result).toEqual(source);
+  });
+
+  it('Should return target if source is empty', async () => {
+    const target = { hostname: '0.0.0.0', 'teleport.internal/resource-id': '1234' };
+    const source = {};
+
+    const result = merge(target, source);
+
+    expect(result).toEqual(target);
+  });
+
+  it('Should return one result', async () => {
+    const target = {
+      aaa: {
+        ei: 0,
+        event: 'cert.create',
+        uid: '1234',
+        cluster_name: 'cluster.com',
+        identity: { user: 'teleport-admin' },
+        server_labels: { hostname: 'some-hostname' },
+      },
+    };
+    const source = {
+      aaa: {
+        ei: 0,
+        event: 'session.start',
+        uid: '4567',
+        cluster_name: 'cluster.com',
+        user: 'teleport-admin',
+        server_labels: { hostname: 'some-other-hostname', id: '1234' },
+      },
+    };
+
+    const result = merge(target, source);
+
+    expect(result).toEqual({
+      aaa: {
+        ei: 0,
+        event: 'cert.create',
+        uid: '1234',
+        cluster_name: 'cluster.com',
+        identity: { user: 'teleport-admin' },
+        server_labels: { hostname: 'some-hostname', id: '1234' },
+        user: 'teleport-admin',
+      },
+    });
+  });
+
+  it('Should not merge built-in properties of neither target nor source', async () => {
+    const target = {
+      __proto__: 'some properties',
+      constructor: 'some other properties',
+      hostname: '0.0.0.0',
+      'teleport.internal/resource-id': '1234',
+    };
+    const source = {
+      __proto__: 'some properties of source',
+      constructor: 'some other properties of source',
+    };
+
+    const result = merge(target, source);
+
+    expect(result).toEqual({ hostname: '0.0.0.0', 'teleport.internal/resource-id': '1234' });
+  });
+
+  it('Should keep source object if it collides with target key that is not an object', async () => {
+    const target = {
+      hostname: '',
+      'teleport.internal/resource-id': '1234',
+      date_formats: 'format',
+    };
+    const source = {
+      target: 'user.name',
+      confidence: 0.9,
+      type: 'string',
+      date_formats: { key: 'value' },
+    };
+
+    const result = merge(target, source);
+
+    expect(result).toEqual({
+      'teleport.internal/resource-id': '1234',
+      target: 'user.name',
+      confidence: 0.9,
+      type: 'string',
+      hostname: '',
+      date_formats: { key: 'value' },
+    });
+  });
+
+  it('Should copy array into the result', async () => {
+    const target = { date_formats: ['a', 'b'] };
+    const source = { target: 'user.name', confidence: 0.9, type: 'string', date_formats: ['c'] };
+
+    const result = merge(target, source);
+
+    expect(result).toEqual(source);
+  });
+});

x-pack/plugins/integration_assistant/server/util/samples.ts

@@ -163,39 +163,61 @@ export function generateFields(mergedDocs: string): string {
   return yaml.safeDump(fieldsStructure, { sortKeys: false });
 }
 
-function isEmptyValue(value: unknown): boolean {
-  return (
-    value === null ||
-    value === undefined ||
-    (typeof value === 'object' && !Array.isArray(value) && Object.keys(value).length === 0) ||
-    (Array.isArray(value) && value.length === 0)
-  );
-}
-
 export function merge(
   target: Record<string, any>,
   source: Record<string, any>
 ): Record<string, unknown> {
+  const filteredTarget = filterOwnProperties(target);
   for (const [key, sourceValue] of Object.entries(source)) {
-    const targetValue = target[key];
-    if (Array.isArray(sourceValue)) {
-      // Directly assign arrays
-      target[key] = sourceValue;
-    } else if (
-      typeof sourceValue === 'object' &&
-      sourceValue !== null &&
-      !Array.isArray(targetValue)
-    ) {
-      if (typeof targetValue !== 'object' || isEmptyValue(targetValue)) {
-        target[key] = merge({}, sourceValue);
-      } else {
-        target[key] = merge(targetValue, sourceValue);
+    if (!isBuiltInProperties(key, source)) {
+      const targetValue = filteredTarget[key];
+      if (Array.isArray(sourceValue)) {
+        // Directly assign arrays
+        filteredTarget[key] = sourceValue;
+      } else if (isObject(sourceValue) && !Array.isArray(targetValue)) {
+        if (!isObject(targetValue) || isEmptyValue(targetValue)) {
+          filteredTarget[key] = merge({}, sourceValue);
+        } else {
+          filteredTarget[key] = merge(targetValue, sourceValue);
+        }
+      } else if (
+        !(key in filteredTarget) ||
+        (isEmptyValue(targetValue) && !isEmptyValue(sourceValue))
+      ) {
+        filteredTarget[key] = sourceValue;
       }
-    } else if (!(key in target) || (isEmptyValue(targetValue) && !isEmptyValue(sourceValue))) {
-      target[key] = sourceValue;
     }
   }
-  return target;
+  return filteredTarget;
+}
+
+function isEmptyValue(value: unknown): boolean {
+  if (value == null) return true;
+  if (isObject(value)) {
+    if (Array.isArray(value)) return value.length === 0;
+    return value && Object.keys(value).length === 0;
+  }
+  return false;
+}
+
+function isObject(value: any): boolean {
+  return typeof value === 'object' && value !== null;
+}
+
+function isBuiltInProperties(key: string, obj: Record<string, any>): boolean {
+  return key === 'constructor' || !Object.prototype.hasOwnProperty.call(obj, key);
+}
+
+function filterOwnProperties(obj: Record<string, any>): Record<string, any> {
+  const ownProps: Record<string, any> = {};
+
+  for (const key of Object.getOwnPropertyNames(obj)) {
+    if (!isBuiltInProperties(key, obj)) {
+      ownProps[key] = (obj as any)[key];
+    }
+  }
+
+  return ownProps;
 }
 
 export function mergeSamples(objects: any[]): string {