Remove NotificationSettings table (#5036

* helper

* Add script to move notification settings

* wip, removal of NotificationSettings

* event name

* iteration

* test

* test

* Remove last of NotificationSettings model

* refactor

* More fixes

* snapshots

* Change emails to class instances for type safety

* test

* docs

* Update migration for self-hosted

* tsc

server/models/helpers/NotificationSettingsHelper.ts

@@ -0,0 +1,45 @@
+import crypto from "crypto";
+import {
+  NotificationEventDefaults,
+  NotificationEventType,
+} from "@shared/types";
+import env from "@server/env";
+import User from "../User";
+
+/**
+ * Helper class for working with notification settings
+ */
+export default class NotificationSettingsHelper {
+  /**
+   * Get the default notification settings for a user
+   *
+   * @returns The default notification settings
+   */
+  public static getDefaults() {
+    return NotificationEventDefaults;
+  }
+
+  /**
+   * Get the unsubscribe URL for a user and event type. This url allows the user
+   * to unsubscribe from a specific event without being signed in, for one-click
+   * links in emails.
+   *
+   * @param user The user to unsubscribe
+   * @param eventType The event type to unsubscribe from
+   * @returns The unsubscribe URL
+   */
+  public static unsubscribeUrl(user: User, eventType: NotificationEventType) {
+    return `${
+      env.URL
+    }/api/notifications.unsubscribe?token=${this.unsubscribeToken(
+      user,
+      eventType
+    )}&userId=${user.id}&eventType=${eventType}`;
+  }
+
+  public static unsubscribeToken(user: User, eventType: NotificationEventType) {
+    const hash = crypto.createHash("sha256");
+    hash.update(`${user.id}-${env.SECRET_KEY}-${eventType}`);
+    return hash.digest("hex");
+  }
+}