Use Google Calendar Tasks instead of Events

.env.example

@@ -4,11 +4,7 @@ GOOGLE_CLIENT_SECRET=your_google_client_secret
 
 # NextAuth
 NEXTAUTH_URL=http://localhost:3000
-NEXTAUTH_SECRET=your_nextauth_secret  # generate with: openssl rand -base64 32
+NEXTAUTH_SECRET=your_nextauth_secret   # generate with: openssl rand -base64 32
 
-# Firebase Admin (service account JSON, base64-encoded)
-# How to encode: base64 -i serviceAccount.json
-FIREBASE_ADMIN_CREDENTIALS=your_base64_encoded_service_account_json
-
-# Firebase (client-side)
+# Firebase (project ID from Firebase Console → Project Settings)
 NEXT_PUBLIC_FIREBASE_PROJECT_ID=your_project_id

README.md

@@ -1,25 +1,29 @@
-# 🦑 Kalamari
+# 🦑 Kalamari – Tasks variant
 
-Calendar event template manager. Create reusable multi-part event templates and instantly populate your Google Calendar.
+> **Branch: `feature/tasks`**
+> This branch uses **Google Tasks** instead of Google Calendar events.
+> For the Calendar events version, see the [`main`](https://github.com/mortengf/kalamari/tree/main) branch.
+
+Task template manager. Create reusable multi-part task templates and instantly populate your Google Tasks.
 
 ## Concept
 
-Many real-world appointments consist of several related calendar events, e.g.:
+Many real-world appointments consist of several related tasks, e.g.:
 
 - **Squash / haircut**: "Book!", "The appointment", "Book next"
 - **Tickets**: "Buy", "Print", "The event"
 - **Birthdays**: "Buy gift", "Send message", "The day"
 - **Travel**: "Check in online", "Departure", "Return"
 - **Meetings**: "Read material", "The meeting", "Write follow-up"
 
-Kalamari lets you define these as reusable templates and create all related events in one click.
+Kalamari lets you define these as reusable templates and create all related tasks in one click, each with a due date calculated relative to an anchor date.
 
 ## Tech Stack
 
 - [Next.js 14](https://nextjs.org/) (Pages Router)
 - [NextAuth.js](https://next-auth.js.org/) with Google OAuth
-- [Google Calendar API](https://developers.google.com/calendar)
-- [Firebase Firestore](https://firebase.google.com/docs/firestore) (template + event group storage)
+- [Google Tasks API](https://developers.google.com/tasks)
+- [Firebase Firestore](https://firebase.google.com/docs/firestore) (template + task group storage)
 - [Tailwind CSS](https://tailwindcss.com/)
 
 ## Getting Started
@@ -29,38 +33,98 @@ Kalamari lets you define these as reusable templates and create all related even
 ```bash
 git clone https://github.com/mortengf/kalamari.git
 cd kalamari
+git checkout feature/tasks
 npm install
 ```
 
-### 2. Set up Google OAuth
+### 2. Set up Google OAuth and enable APIs
+
+1. Go to [Google Cloud Console](https://console.cloud.google.com/) and create a new project
+2. Go to **APIs & Services → Library** and enable:
+   - **Google Tasks API**
+3. Go to **APIs & Services → Credentials → Create credentials → OAuth 2.0 Client ID**
+   - Application type: Web application
+   - Authorized JavaScript origins: `http://localhost:3000`
+   - Authorized redirect URIs: `http://localhost:3000/api/auth/callback/google`
+4. Go to **APIs & Services → OAuth consent screen**
+   - If the app is in Testing mode, add your Google account under **Test users**
 
-1. Go to [Google Cloud Console](https://console.cloud.google.com/)
-2. Create a new project
-3. Enable the **Google Calendar API**
-4. Create **OAuth 2.0 credentials** (Web application)
-5. Add `http://localhost:3000/api/auth/callback/google` as an authorized redirect URI
+### 3. Set up Firebase Firestore
 
-### 3. Set up Firebase
+1. Go to [Firebase Console](https://console.firebase.google.com/) and create a new project
+2. Go to **Build → Firestore Database → Create database**
+   - Choose **Native mode** (not Datastore mode — Datastore mode will not work)
+   - Choose a region, e.g. `europe-west1`
+3. Go to **Project Settings** and note your **Project ID**
 
-1. Create a project in [Firebase Console](https://console.firebase.google.com/)
-2. Enable **Firestore** in Native mode
-3. Go to Project Settings → Service Accounts → Generate new private key
-4. Base64-encode the JSON: `base64 -i serviceAccount.json`
+### 4. Set up local Google credentials
 
-### 4. Configure environment
+The app uses Application Default Credentials to authenticate with Firestore server-side.
+
+```bash
+gcloud auth login
+gcloud auth application-default login
+gcloud auth application-default set-quota-project YOUR_FIREBASE_PROJECT_ID
+```
+
+> **Important:** If you use Google Cloud for other projects, you may have a `GOOGLE_APPLICATION_CREDENTIALS` environment variable set in your shell that points to a different service account. This will override Application Default Credentials and cause authentication errors. Unset it before running the app:
+>
+> ```bash
+> unset GOOGLE_APPLICATION_CREDENTIALS
+> ```
+>
+> You may want to add this to a local `.env` or shell alias for the project.
+
+### 5. Set up IAM permissions
+
+Your Google account needs permission to access Firestore. Go to [Google Cloud Console → IAM](https://console.cloud.google.com/iam-admin/iam), select your Firebase project, and ensure your account has the role:
+
+- **Cloud Datastore User** (`roles/datastore.user`)
+
+### 6. Configure environment
 
 ```bash
 cp .env.example .env.local
-# Fill in all values
 ```
 
-### 5. Run
+Fill in the following values in `.env.local`:
+
+```
+GOOGLE_CLIENT_ID=...
+GOOGLE_CLIENT_SECRET=...
+NEXTAUTH_URL=http://localhost:3000
+NEXTAUTH_SECRET=...                   # required — generate with: openssl rand -base64 32
+NEXT_PUBLIC_FIREBASE_PROJECT_ID=...   # your Firebase project ID
+```
+
+> **Note:** `NEXTAUTH_SECRET` is required even locally. Without it, NextAuth generates a random secret on each server start, which causes session decryption errors every time you restart `npm run dev`.
+
+### 7. Run
 
 ```bash
 npm run dev
 ```
 
-Open [http://localhost:3000](http://localhost:3000).
+Open [http://localhost:3000](http://localhost:3000) and sign in with Google.
+
+> **Note:** After signing in for the first time, sign out and sign back in if you encounter Tasks API errors. This ensures the session token includes the correct OAuth scopes.
+
+## Known setup gotchas
+
+**Firestore index required**
+The first time you load the Templates page, Firestore may return an error saying a composite index is required. The error message contains a direct link to create the index in Firebase Console — click it and wait ~1 minute for the index to build.
+
+**Wrong Google Cloud project**
+If `gcloud config get-value project` shows a different project than your Firebase project, explicitly set the project ID in `.env.local` via `NEXT_PUBLIC_FIREBASE_PROJECT_ID`. The app uses this to connect to the correct Firestore database regardless of your local gcloud config.
+
+## How tasks work
+
+Each template part gets a **due date** calculated by adding its `offsetMinutes` to the anchor date. Since Google Tasks only support due dates (not times), the time component is ignored — only the date matters.
+
+Example with anchor date 2026-03-15:
+- Part with `offsetMinutes: -4320` (−3 days) → due 2026-03-12
+- Part with `offsetMinutes: 0` (anchor) → due 2026-03-15
+- Part with `offsetMinutes: 1440` (+1 day) → due 2026-03-16
 
 ## Data Model
 
@@ -72,7 +136,6 @@ Open [http://localhost:3000](http://localhost:3000).
   userId: string          // Google email
   name: string
   color: string           // hex
-  defaultCalendarId?: string
   parts: [
     {
       id: string
@@ -96,8 +159,8 @@ Open [http://localhost:3000](http://localhost:3000).
   templateId: string
   templateName: string
   anchorDate: string      // ISO 8601
-  calendarId: string
-  eventIds: string[]      // Google Calendar event IDs
+  calendarId: string      // Google Tasks task list ID
+  eventIds: string[]      // Google Tasks task IDs
   createdAt: string
 }
 ```
@@ -111,6 +174,6 @@ Open [http://localhost:3000](http://localhost:3000).
 | GET | `/api/templates/:id` | Get template |
 | PUT | `/api/templates/:id` | Update template |
 | DELETE | `/api/templates/:id` | Delete template |
-| GET | `/api/event-groups` | List event groups |
-| POST | `/api/event-groups` | Instantiate template → create Calendar events |
-| GET | `/api/calendars` | List user's Google Calendars |
+| GET | `/api/event-groups` | List task groups |
+| POST | `/api/event-groups` | Instantiate template → create Tasks |
+| GET | `/api/calendars` | List user's Google Task lists |

src/lib/auth.ts

@@ -8,22 +8,20 @@ export const authOptions: NextAuthOptions = {
       clientSecret: process.env.GOOGLE_CLIENT_SECRET!,
       authorization: {
         params: {
-          // Request offline access so we get a refresh token
           access_type: 'offline',
           prompt: 'consent',
           scope: [
             'openid',
             'email',
             'profile',
-            'https://www.googleapis.com/auth/calendar',
+            'https://www.googleapis.com/auth/tasks',
           ].join(' '),
         },
       },
     }),
   ],
   callbacks: {
     async jwt({ token, account }) {
-      // Persist the OAuth access_token and refresh_token on first sign-in
       if (account) {
         token.accessToken = account.access_token
         token.refreshToken = account.refresh_token
@@ -32,7 +30,6 @@ export const authOptions: NextAuthOptions = {
       return token
     },
     async session({ session, token }) {
-      // Expose tokens to the client session
       session.accessToken = token.accessToken as string
       return session
     },

src/lib/googleTasks.ts

@@ -0,0 +1,60 @@
+import { google } from 'googleapis'
+import dayjs from 'dayjs'
+
+/**
+ * Returns an authenticated Google Tasks client using the user's access token.
+ */
+export function getTasksClient(accessToken: string) {
+  const auth = new google.auth.OAuth2()
+  auth.setCredentials({ access_token: accessToken })
+  return google.tasks({ version: 'v1', auth })
+}
+
+/**
+ * Fetch all task lists for the authenticated user.
+ */
+export async function listTaskLists(accessToken: string) {
+  const tasks = getTasksClient(accessToken)
+  const res = await tasks.tasklists.list({ maxResults: 100 })
+  return res.data.items ?? []
+}
+
+export interface TaskPart {
+  title: string
+  /** Offset in minutes relative to the anchor date (negative = before, positive = after) */
+  offsetMinutes: number
+  description?: string
+}
+
+/**
+ * Creates multiple tasks from a list of TaskParts and an anchor date.
+ * Returns the created task IDs.
+ */
+export async function createTasksFromParts(
+  accessToken: string,
+  taskListId: string,
+  anchorDate: string, // ISO 8601
+  parts: TaskPart[]
+): Promise<string[]> {
+  const tasks = getTasksClient(accessToken)
+  const anchor = dayjs(anchorDate)
+  const createdIds: string[] = []
+
+  for (const part of parts) {
+    const due = anchor.add(part.offsetMinutes, 'minute')
+
+    const res = await tasks.tasks.insert({
+      tasklist: taskListId,
+      requestBody: {
+        title: part.title,
+        notes: part.description,
+        // Google Tasks due date must be in RFC 3339 format with time set to 00:00:00Z
+        due: due.toDate().toISOString().replace(/T.*/, 'T00:00:00.000Z'),
+      },
+    })
+
+    if (res.data.id) createdIds.push(res.data.id)
+  }
+
+  return createdIds
+}

src/pages/api/calendars.ts

@@ -1,13 +1,13 @@
 import type { NextApiRequest, NextApiResponse } from 'next'
 import { getServerSession } from 'next-auth'
 import { authOptions } from '@/lib/auth'
-import { listCalendars } from '@/lib/googleCalendar'
+import { listTaskLists } from '@/lib/googleTasks'
 
 export default async function handler(req: NextApiRequest, res: NextApiResponse) {
   const session = await getServerSession(req, res, authOptions)
   if (!session?.user?.email || !session.accessToken)
     return res.status(401).json({ error: 'Unauthorized' })
 
-  const calendars = await listCalendars(session.accessToken as string)
-  return res.status(200).json(calendars)
+  const taskLists = await listTaskLists(session.accessToken as string)
+  return res.status(200).json(taskLists)
 }

src/pages/api/event-groups/index.ts

@@ -2,7 +2,7 @@ import type { NextApiRequest, NextApiResponse } from 'next'
 import { getServerSession } from 'next-auth'
 import { authOptions } from '@/lib/auth'
 import { db } from '@/lib/firestore'
-import { createEventsFromParts } from '@/lib/googleCalendar'
+import { createTasksFromParts } from '@/lib/googleTasks'
 import { Template, EventGroup } from '@/types'
 import { v4 as uuidv4 } from 'uuid'
 
@@ -24,7 +24,7 @@ export default async function handler(req: NextApiRequest, res: NextApiResponse)
   }
 
   if (req.method === 'POST') {
-    const { templateId, anchorDate, calendarId } = req.body as {
+    const { templateId, anchorDate, calendarId: taskListId } = req.body as {
       templateId: string
       anchorDate: string
       calendarId: string
@@ -35,15 +35,14 @@ export default async function handler(req: NextApiRequest, res: NextApiResponse)
     if (!tDoc.exists) return res.status(404).json({ error: 'Template not found' })
     const template = tDoc.data() as Template
 
-    // Create all events in Google Calendar
-    const eventIds = await createEventsFromParts(
+    // Create all tasks in Google Tasks
+    const eventIds = await createTasksFromParts(
       accessToken,
-      calendarId,
+      taskListId,
       anchorDate,
       template.parts.map(p => ({
         title: p.title,
         offsetMinutes: p.offsetMinutes,
-        durationMinutes: p.durationMinutes,
         description: p.description,
       }))
     )
@@ -54,7 +53,7 @@ export default async function handler(req: NextApiRequest, res: NextApiResponse)
       templateId,
       templateName: template.name,
       anchorDate,
-      calendarId,
+      calendarId: taskListId,
       eventIds,
       createdAt: new Date().toISOString(),
     }