Add server config for mergable extensions

frontend/sync-client/src/services/server-config.ts

@@ -0,0 +1,67 @@
+import { createPromise } from "../utils/create-promise";
+import type { SyncService } from "./sync-service";
+import type { PingResponse } from "./types/PingResponse";
+
+export interface ServerConfigData {
+	mergeableFileExtensions: string[];
+}
+
+export class ServerConfig {
+	private response: Promise<PingResponse> | undefined;
+	private config: ServerConfigData | undefined;
+
+	public constructor(private readonly syncService: SyncService) {}
+
+	public async initialize(): Promise<void> {
+		this.response = this.syncService.ping();
+		this.config = await this.response;
+	}
+
+	public async checkConnection(forceUpdate = false): Promise<{
+		isSuccessful: boolean;
+		message: string;
+	}> {
+		try {
+			let { response } = this;
+			if (!response && !forceUpdate) {
+				throw new Error("ServerConfig not initialized");
+			} else if (forceUpdate) {
+				response = this.response = this.syncService.ping();
+			}
+
+			// eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+			const result: PingResponse = (await response)!; // it must be defined, otherwise we would have thrown above
+			this.config = result;
+
+			if (result.isAuthenticated) {
+				return {
+					isSuccessful: true,
+					message: `Successfully connected to server (version: ${result.serverVersion}) and authenticated`
+				};
+			}
+
+			return {
+				isSuccessful: false,
+				message: `Successfully connected to server (version: ${result.serverVersion}) but failed to authenticate`
+			};
+		} catch (e) {
+			return {
+				isSuccessful: false,
+				message: `Failed to connect to server: ${e}`
+			};
+		}
+	}
+
+	public getConfig(): ServerConfigData {
+		if (!this.config) {
+			throw new Error("ServerConfig not initialized");
+		}
+
+		return this.config;
+	}
+
+	public reset(): void {
+		this.response = undefined;
+		this.config = undefined;
+	}
+}