feat(utils): added merging util

package.json

@@ -1,6 +1,6 @@
 {
   "name": "hawk.api",
-  "version": "1.1.29",
+  "version": "1.1.30",
   "main": "index.ts",
   "license": "UNLICENSED",
   "scripts": {
@@ -21,6 +21,8 @@
   "devDependencies": {
     "@shelf/jest-mongodb": "^1.2.2",
     "@types/jest": "^26.0.8",
+    "@types/lodash.clonedeep": "^4.5.9",
+    "@types/lodash.mergewith": "^4.6.9",
     "eslint": "^6.7.2",
     "eslint-config-codex": "1.2.4",
     "eslint-plugin-import": "^2.19.1",
@@ -37,7 +39,8 @@
     "@graphql-tools/schema": "^8.5.1",
     "@graphql-tools/utils": "^8.9.0",
     "@hawk.so/nodejs": "^3.1.1",
-    "@hawk.so/types": "^0.1.31",
+    "@hawk.so/types": "^0.1.33",
+    "@n1ru4l/json-patch-plus": "^0.2.0",
     "@types/amqp-connection-manager": "^2.0.4",
     "@types/bson": "^4.0.5",
     "@types/debug": "^4.1.5",
@@ -70,6 +73,8 @@
     "graphql-upload": "^13",
     "jsonwebtoken": "^8.5.1",
     "lodash": "^4.17.15",
+    "lodash.clonedeep": "^4.5.0",
+    "lodash.mergewith": "^4.6.2",
     "migrate-mongo": "^7.0.1",
     "mime-types": "^2.1.25",
     "mongodb": "^3.7.3",

src/utils/merge.ts

@@ -0,0 +1,115 @@
+import mergeWith from 'lodash.mergewith';
+import cloneDeep from 'lodash.clonedeep';
+import { patch } from '@n1ru4l/json-patch-plus';
+import { GroupedEventDBScheme, RepetitionDBScheme } from '@hawk.so/types';
+
+/**
+ * One of the features of the events is that their repetition is the difference
+ * between the original, which greatly optimizes storage. So we need to restore
+ * the original repetition payload using the very first event and its difference
+ * between its repetition
+ *
+ * @param originalEvent - the very first event we received
+ * @param repetition - the difference with its repetition, for the repetition we want to display
+ * @returns fully assembled payload of the current repetition
+ */
+export function repetitionAssembler(originalEvent: Record<string, any>, repetition: { [key: string]: any }): any {
+  const customizer = (originalParam: any, repetitionParam: any): any => {
+    if (repetitionParam === null) {
+      return originalParam;
+    }
+
+    if (typeof repetitionParam === 'object' && typeof originalParam === 'object') {
+      /**
+       * If original event has null but repetition has some value, we need to return repetition value
+       */
+      if (originalParam === null) {
+        return repetitionParam;
+        /**
+         * Otherwise, we need to recursively merge original and repetition values
+         */
+      } else {
+        return repetitionAssembler(originalParam, repetitionParam);
+      }
+    }
+
+    return repetitionParam;
+  };
+
+  return mergeWith(cloneDeep(originalEvent), cloneDeep(repetition), customizer);
+}
+
+function parsePayloadField(payload: any, field: string) {
+  if (payload && payload[field] && typeof payload[field] === 'string') {
+    payload[field] = JSON.parse(payload[field]);
+  }
+
+  return payload;
+}
+
+function stringifyPayloadField(payload: any, field: string) {
+  if (payload && payload[field]) {
+    payload[field] = JSON.stringify(payload[field]);
+  }
+
+  return payload;
+}
+
+/**
+ * Helps to merge original event and repetition due to delta format,
+ * in case of old delta format, we need to patch the payload
+ * in case of new delta format, we need to assemble the payload
+ *
+ * @param originalEvent {HawkEvent} - The original event
+ * @param repetition {HawkEventRepetition} - The repetition to process
+ * @returns {HawkEvent} Updated event with processed repetition payload
+ */
+export function composeFullRepetitionEvent(originalEvent: GroupedEventDBScheme, repetition: RepetitionDBScheme | undefined): GroupedEventDBScheme {
+  /**
+   * Make a deep copy of the original event, because we need to avoid mutating the original event
+   */
+  const event = cloneDeep(originalEvent);
+
+  if (!repetition) {
+    return event;
+  }
+
+  /**
+   * New delta format (repetition.delta is not null)
+   */
+  if (repetition.delta) {
+    /**
+     * Parse addons and context fields from string to object before patching
+     */
+    event.payload = parsePayloadField(event.payload, 'addons');
+    event.payload = parsePayloadField(event.payload, 'context');
+
+    event.payload = patch({
+      left: event.payload,
+      delta: JSON.parse(repetition.delta),
+    });
+
+    /**
+     * Stringify addons and context fields from object to string after patching
+     */
+    event.payload = stringifyPayloadField(event.payload, 'addons');
+    event.payload = stringifyPayloadField(event.payload, 'context');
+
+    return event;
+  }
+
+  /**
+   * New delta format (repetition.payload is null) and repetition.delta is null (there is no delta between original and repetition)
+   */
+  if (!repetition.payload) {
+    return event;
+  }
+
+  /**
+   * Old delta format (repetition.payload is not null)
+   * @todo remove after July 5 2025
+   */
+  event.payload = repetitionAssembler(event.payload, repetition.payload);
+
+  return event;
+}