feat: Automatic invite reminder email (#3354)

* feat: Add user flags concept, for tracking bits on a user

* feat: Example flag usage for user invite resend abuse

* wip

* test

* fix: Set correct flag

server/queues/tasks/InviteReminderTask.ts

@@ -0,0 +1,67 @@
+import { subDays } from "date-fns";
+import { Op } from "sequelize";
+import { sequelize } from "@server/database/sequelize";
+import InviteReminderEmail from "@server/emails/templates/InviteReminderEmail";
+import { APM } from "@server/logging/tracing";
+import { User } from "@server/models";
+import { UserFlag } from "@server/models/User";
+import BaseTask, { TaskPriority } from "./BaseTask";
+
+type Props = undefined;
+
+@APM.trace()
+export default class InviteReminderTask extends BaseTask<Props> {
+  public async perform() {
+    const users = await User.scope("invited").findAll({
+      attributes: ["id"],
+      where: {
+        createdAt: {
+          [Op.lt]: subDays(new Date(), 2),
+          [Op.gt]: subDays(new Date(), 3),
+        },
+      },
+    });
+    const userIds = users.map((user) => user.id);
+
+    for (const userId of userIds) {
+      await sequelize.transaction(async (transaction) => {
+        const user = await User.scope("withTeam").findByPk(userId, {
+          lock: {
+            level: transaction.LOCK.UPDATE,
+            of: User,
+          },
+          transaction,
+        });
+
+        const invitedBy = user?.invitedById
+          ? await User.findByPk(user?.invitedById, { transaction })
+          : undefined;
+
+        if (
+          user &&
+          invitedBy &&
+          user.getFlag(UserFlag.InviteReminderSent) === 0
+        ) {
+          await InviteReminderEmail.schedule({
+            to: user.email,
+            name: user.name,
+            actorName: invitedBy.name,
+            actorEmail: invitedBy.email,
+            teamName: user.team.name,
+            teamUrl: user.team.url,
+          });
+
+          user.incrementFlag(UserFlag.InviteReminderSent);
+          await user.save({ transaction });
+        }
+      });
+    }
+  }
+
+  public get options() {
+    return {
+      attempts: 1,
+      priority: TaskPriority.Background,
+    };
+  }
+}