FF-3407 spike on client-side edge code

src/edge/edge-init.ts

@@ -0,0 +1,48 @@
+import { applicationLogger } from '..';
+import ApiEndpoints from '../api-endpoints';
+import { DEFAULT_REQUEST_TIMEOUT_MS } from '../constants';
+import FetchHttpClient from '../http-client';
+import { Variation } from '../interfaces';
+import { AttributeType } from '../types';
+
+import { EppoClientEdge } from './eppo-client-edge';
+
+type VariationValue = Variation['value'] | object;
+
+export interface IEdgeConfig {
+  apiKey: string;
+  subjectKey: string;
+  subjectAttributes: Record<string, AttributeType>;
+  throwOnFailedInitialization?: boolean;
+  baseUrl?: string;
+}
+
+export async function commonEdgeInit(
+  config: IEdgeConfig,
+  sdkName: string,
+  sdkVersion: string,
+): Promise<EppoClientEdge> {
+  const { apiKey, baseUrl, throwOnFailedInitialization } = config;
+  try {
+    const apiEndpoints = new ApiEndpoints({
+      baseUrl,
+      queryParams: { apiKey, sdkName, sdkVersion },
+    });
+    const httpClient = new FetchHttpClient(apiEndpoints, DEFAULT_REQUEST_TIMEOUT_MS);
+    const assignments = await httpClient.rawGet<Record<string, VariationValue>>(
+      apiEndpoints.endpoint('/flag-config/v1/edge-config'),
+    );
+    if (!assignments) {
+      throw new Error('Unable to get assignments');
+    }
+    return new EppoClientEdge(assignments);
+  } catch (error) {
+    applicationLogger.warn(
+      'Eppo SDK encountered an error initializing, assignment calls will return the default value',
+    );
+    if (throwOnFailedInitialization) {
+      throw error;
+    }
+    return new EppoClientEdge({});
+  }
+}

src/edge/eppo-client-edge.ts

@@ -0,0 +1,39 @@
+import { Variation } from '../interfaces';
+
+type VariationValue = Variation['value'] | object;
+
+export class EppoClientEdge {
+  constructor(private cachedAssignments: Record<string, VariationValue>) {}
+
+  getAssignments() {
+    return this.cachedAssignments;
+  }
+
+  getStringAssignment(flagKey: string, defaultValue: string): string {
+    if (typeof this.cachedAssignments[flagKey] === 'string') {
+      return this.cachedAssignments[flagKey];
+    }
+    return defaultValue;
+  }
+
+  getBooleanAssignment(flagKey: string, defaultValue: boolean): boolean {
+    if (typeof this.cachedAssignments[flagKey] === 'boolean') {
+      return this.cachedAssignments[flagKey];
+    }
+    return defaultValue;
+  }
+
+  getNumericAssignment(flagKey: string, defaultValue: number): number {
+    if (typeof this.cachedAssignments[flagKey] === 'number') {
+      return this.cachedAssignments[flagKey];
+    }
+    return defaultValue;
+  }
+
+  getJSONAssignment(flagKey: string, defaultValue: object): object {
+    if (typeof this.cachedAssignments[flagKey] === 'object') {
+      return this.cachedAssignments[flagKey];
+    }
+    return defaultValue;
+  }
+}