fix: Add functionality for creating recurring events (#1807)

* create recurring event helpers and refactor

* remove unnecessary file

* add documentation and comments

* add tests

* fix comments

* update generateRecurrenceRuleString function

* speed up code

* fix formatting

* format fix

* restore package.json

* fix failing test

* better implementation and faster code

* minor refactoring

* minor correction

* fix imports

* return single recurring instance

* fix failing test

* Revert "return single recurring instance"

This reverts commit 60353fd.

* Reapply "return single recurring instance"

This reverts commit fc12a99.

* test commit

* update test

* fix test

* convert to UTC dates

* test commit with minor change

* limit instance generation date according to the recurrence frequency

* adjust for different timezones

* remove unnecessary code

* remove unnecessary formatting

* change variable names

README.md

@@ -25,11 +25,10 @@ Core features include:
 
 <!-- toc -->
 
-- [Talawa API](#talawa-api)
-  - [Talawa Components](#talawa-components)
-  - [Documentation](#documentation)
-  - [Installation](#installation)
-  - [Image Upload](#image-upload)
+- [Talawa Components](#talawa-components)
+- [Documentation](#documentation)
+- [Installation](#installation)
+- [Image Upload](#image-upload)
 
 <!-- tocstop -->
 
@@ -53,4 +52,4 @@ Core features include:
 
 ## Image Upload
 
-To enable image upload functionalities create an images folder in the root of the project
+To enable image upload functionalities create an images folder in the root of the project

package.json

@@ -86,6 +86,7 @@
     "nodemailer": "^6.9.9",
     "pm2": "^5.2.0",
     "redis": "^4.6.12",
+    "rrule": "^2.8.1",
     "shortid": "^2.2.16",
     "typedoc-plugin-markdown": "^3.17.1",
     "uuid": "^9.0.0",

schema.graphql

@@ -253,7 +253,7 @@ type Event {
   createdAt: DateTime!
   creator: User
   description: String!
-  endDate: Date!
+  endDate: Date
   endTime: Time
   feedback: [Feedback!]!
   isPublic: Boolean!
@@ -376,6 +376,13 @@ input ForgotPasswordData {
   userOtp: String!
 }
 
+enum Frequency {
+  DAILY
+  MONTHLY
+  WEEKLY
+  YEARLY
+}
+
 enum Gender {
   FEMALE
   MALE
@@ -536,7 +543,7 @@ type Mutation {
   createComment(data: CommentInput!, postId: ID!): Comment
   createDirectChat(data: createChatInput!): DirectChat!
   createDonation(amount: Float!, nameOfOrg: String!, nameOfUser: String!, orgId: ID!, payPalId: ID!, userId: ID!): Donation!
-  createEvent(data: EventInput): Event!
+  createEvent(data: EventInput!, recurrenceRuleData: RecurrenceRuleInput): Event!
   createGroupChat(data: createGroupChatInput!): GroupChat!
   createMember(input: UserAndOrganizationInput!): Organization!
   createMessageChat(data: MessageChatInput!): MessageChat!
@@ -898,6 +905,12 @@ enum Recurrance {
   YEARLY
 }
 
+input RecurrenceRuleInput {
+  count: Int
+  frequency: Frequency
+  weekDays: [WeekDays]
+}
+
 enum Status {
   ACTIVE
   BLOCKED
@@ -1207,6 +1220,16 @@ type UsersConnectionResult {
   errors: [ConnectionError!]!
 }
 
+enum WeekDays {
+  FR
+  MO
+  SA
+  SU
+  TH
+  TU
+  WE
+}
+
 input createChatInput {
   organizationId: ID!
   userIds: [ID!]!

src/constants.ts

@@ -529,6 +529,26 @@ export const REDIS_PASSWORD = process.env.REDIS_PASSWORD;
 
 export const MILLISECONDS_IN_A_WEEK = 7 * 24 * 60 * 60 * 1000;
 
+// recurring event frequencies
+export const RECURRENCE_FREQUENCIES = ["YEARLY", "MONTHLY", "WEEKLY", "DAILY"];
+
+// recurring instance generation date limit in years based on it's frequency
+export const RECURRING_EVENT_INSTANCES_DAILY_LIMIT = 1;
+export const RECURRING_EVENT_INSTANCES_WEEKLY_LIMIT = 2;
+export const RECURRING_EVENT_INSTANCES_MONTHLY_LIMIT = 5;
+export const RECURRING_EVENT_INSTANCES_YEARLY_LIMIT = 10;
+
+// recurring event days
+export const RECURRENCE_WEEKDAYS = [
+  "MONDAY",
+  "TUESDAY",
+  "WEDNESDAY",
+  "THURSDAY",
+  "FRIDAY",
+  "SATURDAY",
+  "SUNDAY",
+];
+
 export const key = ENV.ENCRYPTION_KEY as string;
 export const iv = crypto.randomBytes(16).toString("hex");
 

src/helpers/event/createEventHelpers/createRecurringEvent.ts

@@ -0,0 +1,101 @@
+import type mongoose from "mongoose";
+import type { InterfaceEvent } from "../../../models";
+import { Event } from "../../../models";
+import type { MutationCreateEventArgs } from "../../../types/generatedGraphQLTypes";
+import {
+  generateRecurrenceRuleString,
+  getRecurringInstanceDates,
+  createRecurrenceRule,
+  generateRecurringEventInstances,
+} from "../recurringEventHelpers";
+
+/**
+ * This function creates the instances of a recurring event upto a certain date.
+ * @param args - payload of the createEvent mutation
+ * @param creatorId - _id of the creator
+ * @param organizationId - _id of the organization the events belongs to
+ * @remarks The following steps are followed:
+ * 1. Create a default recurrenceRuleData.
+ * 2. Generate a recurrence rule string based on the recurrenceRuleData.
+ * 3. Create a baseRecurringEvent on which recurring instances would be based.
+ * 4. Get the dates for recurring instances.
+ * 5. Create a recurrenceRule document.
+ * 6. Generate recurring instances according to the recurrence rule.
+ * @returns Created recurring event instance
+ */
+
+export const createRecurringEvent = async (
+  args: MutationCreateEventArgs,
+  creatorId: string,
+  organizationId: string,
+  session: mongoose.ClientSession
+): Promise<InterfaceEvent> => {
+  const { data } = args;
+  let { recurrenceRuleData } = args;
+
+  if (!recurrenceRuleData) {
+    // create a default weekly recurrence rule
+    recurrenceRuleData = {
+      frequency: "WEEKLY",
+    };
+  }
+
+  // generate a recurrence rule string which would be used to generate rrule object
+  // and get recurrence dates
+  const recurrenceRuleString = generateRecurrenceRuleString(
+    recurrenceRuleData,
+    data?.startDate,
+    data?.endDate
+  );
+
+  // create a base recurring event first, based on which all the
+  // recurring instances would be dynamically generated
+  const baseRecurringEvent = await Event.create(
+    [
+      {
+        ...data,
+        recurring: true,
+        isBaseRecurringEvent: true,
+        creatorId,
+        admins: [creatorId],
+        organization: organizationId,
+      },
+    ],
+    { session }
+  );
+
+  // get the dates for the recurringInstances, and the date of the last instance
+  // to be generated in this operation (rest would be generated dynamically during query)
+  const recurringInstanceDates = getRecurringInstanceDates(
+    recurrenceRuleString,
+    data.startDate,
+    data.endDate
+  );
+
+  // get the date for the latest created instance
+  const latestInstanceDate =
+    recurringInstanceDates[recurringInstanceDates.length - 1];
+  // create a recurrenceRule document that would contain the recurrence pattern
+  const recurrenceRule = await createRecurrenceRule(
+    recurrenceRuleString,
+    data.startDate,
+    data.endDate,
+    organizationId,
+    baseRecurringEvent[0]?._id.toString(),
+    latestInstanceDate,
+    session
+  );
+
+  // generate the recurring instances and get an instance back
+  const recurringEventInstance = await generateRecurringEventInstances({
+    data,
+    baseRecurringEventId: baseRecurringEvent[0]?._id.toString(),
+    recurrenceRuleId: recurrenceRule?._id.toString(),
+    recurringInstanceDates,
+    creatorId,
+    organizationId,
+    session,
+  });
+
+  return recurringEventInstance;
+};

src/helpers/event/createEventHelpers/createSingleEvent.ts

@@ -0,0 +1,66 @@
+import type mongoose from "mongoose";
+import type { InterfaceEvent } from "../../../models";
+import { Event, EventAttendee, User } from "../../../models";
+import type { MutationCreateEventArgs } from "../../../types/generatedGraphQLTypes";
+import { cacheEvents } from "../../../services/EventCache/cacheEvents";
+
+/**
+ * This function generates a single non-recurring event.
+ * @param args - the arguments provided for the createEvent mutation.
+ * @param creatorId - _id of the current user.
+ * @param organizationId - _id of the current organization.
+ * @remarks The following steps are followed:
+ * 1. Create an event document.
+ * 2. Associate the event with the user
+ * 3. Cache the event.
+ * @returns The created event.
+ */
+
+export const createSingleEvent = async (
+  args: MutationCreateEventArgs,
+  creatorId: string,
+  organizationId: string,
+  session: mongoose.ClientSession
+): Promise<InterfaceEvent> => {
+  // create the single event
+  const createdEvent = await Event.create(
+    [
+      {
+        ...args.data,
+        creatorId,
+        admins: [creatorId],
+        organization: organizationId,
+      },
+    ],
+    { session }
+  );
+
+  // associate event with the user
+  await EventAttendee.create(
+    [
+      {
+        userId: creatorId,
+        eventId: createdEvent[0]?._id,
+      },
+    ],
+    { session }
+  );
+  await User.updateOne(
+    {
+      _id: creatorId,
+    },
+    {
+      $push: {
+        eventAdmin: createdEvent[0]?._id,
+        createdEvents: createdEvent[0]?._id,
+        registeredEvents: createdEvent[0]?._id,
+      },
+    },
+    { session }
+  );
+
+  // cache the event
+  await cacheEvents([createdEvent[0]]);
+
+  return createdEvent[0];
+};

src/helpers/event/createEventHelpers/index.ts

@@ -0,0 +1,2 @@
+export { createSingleEvent } from "./createSingleEvent";
+export { createRecurringEvent } from "./createRecurringEvent";

src/helpers/event/recurringEventHelpers/createRecurrenceRule.ts

@@ -0,0 +1,65 @@
+import type mongoose from "mongoose";
+import { rrulestr } from "rrule";
+import type { InterfaceRecurrenceRule } from "../../../models/RecurrenceRule";
+import { RecurrenceRule } from "../../../models/RecurrenceRule";
+import {
+  RECURRENCE_FREQUENCIES,
+  RECURRENCE_WEEKDAYS,
+} from "../../../constants";
+
+/**
+ * This function generates the recurrenceRule document.
+ * @param recurrenceRuleString - the rrule string containing the rules that the instances would follow.
+ * @param recurrenceStartDate - start date of recurrence.
+ * @param recurrenceEndDate - end date of recurrence.
+ * @param organizationId - _id of the current organization.
+ * @param baseRecurringEventId - _id of the base recurring event.
+ * @param latestInstanceDate - start date of the last instance generated during this operation.
+ * @remarks The following steps are followed:
+ * 1. Create an rrule object from the rrule string.
+ * 2. Get the fields for the RecurrenceRule document.
+ * 3. Create the RecurrenceRuleDocument.
+ * @returns The recurrence rule document.
+ */
+
+export const createRecurrenceRule = async (
+  recurrenceRuleString: string,
+  recurrenceStartDate: Date,
+  recurrenceEndDate: Date | null,
+  organizationId: string,
+  baseRecurringEventId: string,
+  latestInstanceDate: Date,
+  session: mongoose.ClientSession
+): Promise<InterfaceRecurrenceRule> => {
+  const recurrenceRuleObject = rrulestr(recurrenceRuleString);
+
+  const { freq, byweekday } = recurrenceRuleObject.options;
+
+  const weekDays: string[] = [];
+  if (byweekday) {
+    for (const weekday of byweekday) {
+      weekDays.push(RECURRENCE_WEEKDAYS[weekday]);
+    }
+  }
+
+  const frequency = RECURRENCE_FREQUENCIES[freq];
+
+  const recurrenceRule = await RecurrenceRule.create(
+    [
+      {
+        organizationId,
+        baseRecurringEventId,
+        recurrenceRuleString,
+        startDate: recurrenceStartDate,
+        endDate: recurrenceEndDate,
+        frequency,
+        count: recurrenceRuleObject.options.count,
+        weekDays,
+        latestInstanceDate,
+      },
+    ],
+    { session }
+  );
+
+  return recurrenceRule[0].toObject();
+};