immutable application settings framework

server/internal/config/application-configuration.ts

@@ -0,0 +1,85 @@
+import { ApplicationSettings, AuthMec } from "@prisma/client";
+import prisma from "../db/database";
+
+class ApplicationConfiguration {
+  // Reference to the currently selected application configuration
+  private currentApplicationSettings: ApplicationSettings;
+  private applicationStateProxy: object;
+  private dirty: boolean = false;
+  private dirtyPromise: Promise<any> | undefined = undefined;
+
+  constructor() {
+    // @ts-expect-error
+    this.currentApplicationSettings = {};
+    this.applicationStateProxy = {};
+  }
+
+  private buildApplicationSettingsProxy() {
+    const appConfig = this;
+    const proxy = new Proxy(this.currentApplicationSettings, {
+      get: (target, key: keyof ApplicationSettings) => {
+        return appConfig.currentApplicationSettings[key];
+      },
+      set: (target, key: keyof ApplicationSettings, value) => {
+        if (JSON.stringify(value) === JSON.stringify(appConfig.currentApplicationSettings[key])) return true;
+        appConfig.currentApplicationSettings[key] = value;
+
+        const deepAppConfigCopy: Omit<ApplicationSettings, "timestamp"> & {
+          timestamp?: Date;
+        } = JSON.parse(JSON.stringify(appConfig.currentApplicationSettings));
+
+        delete deepAppConfigCopy["timestamp"];
+
+        appConfig.dirty = true;
+        appConfig.dirtyPromise = prisma.applicationSettings.create({
+          data: deepAppConfigCopy,
+        });
+        return true;
+      },
+      deleteProperty: (target, key: keyof ApplicationSettings) => {
+        return false;
+      },
+    });
+    this.applicationStateProxy = proxy;
+  }
+
+  // Default application configuration
+  async initialiseConfiguration() {
+    const initialState = await prisma.applicationSettings.create({
+      data: {
+        enabledAuthencationMechanisms: [AuthMec.Simple],
+      },
+    });
+
+    console.log("created configuration");
+
+    this.currentApplicationSettings = initialState;
+    this.buildApplicationSettingsProxy();
+  }
+
+  async pullConfiguration() {
+    const latestState = await prisma.applicationSettings.findFirst({
+      orderBy: {
+        timestamp: "desc",
+      },
+    });
+
+    if (!latestState) throw new Error("No application configuration to pull");
+
+    this.currentApplicationSettings = latestState;
+    this.buildApplicationSettingsProxy();
+    console.log("pulled configuration");
+  }
+
+  async waitForWrite() {
+    if (this.dirty) {
+      await this.dirtyPromise;
+    }
+  }
+
+  useApplicationConfiguration(): ApplicationSettings {
+    return this.applicationStateProxy as ApplicationSettings;
+  }
+}
+
+export const applicationSettings = new ApplicationConfiguration();