1. Set Up Your Supabase Project

• Go to the Supabase website and log in or create an account if you don't have one.
• Create a new project by clicking on the "New Project" button and following the prompts.
• Note down the project URL and the API keys provided; you'll need these in later steps.
• Enable Database and Auth features in your project settings if they are not already enabled.

2. Initialize Your Database

• Once the project is created, go to the "Database" section in the Supabase dashboard.
• Click on "Table Editor" and create a new table called "subscriptions".
• Add the following fields to the table:
  • id (primary key, type: uuid, default: gen_random_uuid())
  • user\_id (type: uuid, foreign key referencing the users table)
  • plan (type: text)
  • status (type: text)
  • valid\_until (type: timestamp)

3. Install Supabase Client Library

• If you're using Node.js, run npm install @supabase/supabase-js
• If you're using other environments like React or Angular, install the appropriate supabase client library as per your environment.

4. Initialize Supabase Client

• In your project, import and initialize the Supabase client:

  import { createClient } from '@supabase/supabase-js';
  
  const supabaseUrl = 'YOUR_SUPABASE_URL';
  const supabaseKey = 'YOUR_SUPABASE_KEY';
  const supabase = createClient(supabaseUrl, supabaseKey);

  
  

5. Implement Signup and Login Functionality

• Use Supabase's Auth API for signing up and logging in users:

  // Sign up
  const { user, session, error } = await supabase.auth.signUp({
    email: '[email protected]',
    password: 'your-password'
  });
  
  // Log in
  const { user, session, error } = await supabase.auth.signIn({
    email: 'user@example.com',
    password: 'your-password'
  });

  
  

6. Create Subscription Logic

• Write a function to handle user subscriptions:

  async function createSubscription(userId, plan) {
    const { data, error } = await supabase
      .from('subscriptions')
      .insert([
        { user_id: userId, plan: plan, status: 'active', valid_until: new Date(new Date().setMonth(new Date().getMonth() + 1)) }
      ]);
  
    if (error) throw error;
    return data;
  }

  
  

7. Manage Subscription Status

• To manage subscription status, update the subscription based on certain criteria:

  async function updateSubscriptionStatus(userId, status) {
    const { data, error } = await supabase
      .from('subscriptions')
      .update({ status: status })
      .eq('user\_id', userId);
  
    if (error) throw error;
    return data;
  }

  
  

8. Implement Middleware for Protected Routes

• To protect certain routes, create middleware to check user authentication:

  function requireAuth(req, res, next) {
    const session = supabase.auth.session();
    if (!session) {
      return res.status(401).send('Unauthorized');
    }
    req.user = session.user;
    next();
  }

9. Frontend (Optional)

• Implement the frontend to let users select subscription plans and manage their subscriptions:

  // Example code to display subscription plans
  const plans = ['Basic', 'Premium', 'Pro'];
  
  plans.forEach(plan => {
    const button = document.createElement('button');
    button.innerText = plan;
    button.onclick = async () => {
      const user = supabase.auth.user();
      if (user) {
        await createSubscription(user.id, plan);
        alert('Subscription created successfully!');
      } else {
        alert('You need to be logged in to subscribe.');
      }
    };
    document.body.appendChild(button);
  });

  
  

10. Maintain Subscription

• Implement a background job or cron job to check subscription validity and update status accordingly:
• Example: Node.js with node-cron

  const cron = require('node-cron');
  
  cron.schedule('_ _ _ _ *', async () => {
    const { data: subscriptions } = await supabase
      .from('subscriptions')
      .select('*')
      .eq('status', 'active');
    subscriptions.forEach(async subscription => {
      if (new Date(subscription.valid_until) < new Date()) {
        await updateSubscriptionStatus(subscription.user_id, 'expired');
      }
    });
  });