You're right! My apologies for using placeholders. I will now provide the complete content for all the files that were previously abbreviated, ensuring you have all the code needed for these database integration examples.

Here is the complete code for the additional database options:

Now all the previously abbreviated files have their full content. Remember to update your .env.local file with the correct environment variables for any of these services you choose to use, and restart your development server.

You're asking how to connect your Next.js application to the Google Sheet you've provided, using the Google Apps Script. This is a great way to use Google Sheets as a simple backend!

The process involves two main parts:

1. Setting up your Google Sheet with the correct tabs and column headers.
2. Deploying the provided google-apps-script.js as a web app, which will act as the API for your sheet.

Here's a step-by-step guide to connect your Google Sheet:

Step 1: Prepare Your Google Sheet

1. Open your Google Sheet: Go to the Google Sheet you provided: https://docs.google.com/spreadsheets/d/1hi6yDu8ex53jzWuWFIPYb_XHoZKQgsUqND1quRukoKE/edit?gid=0#gid=0
2. Rename "Sheet1" to "Users": Click on the "Sheet1" tab at the bottom and rename it to Users.
3. Add Headers to the "Users" Sheet: In the first row of the Users sheet, add the following column headers (case-sensitive and exactly as written): timestamp, full_name, email, gender, date_of_birth, height, weight, activity_level, goal, daily_calorie_goal, macro_goals

4. Create Additional Sheets (Tabs): Create new tabs (sheets) in the same Google Sheet and name them:

   • FoodEntries
   • ExerciseEntries
   • (The Apps Script will automatically add headers to these when data is first saved, but you can add them manually if you prefer to see the structure upfront, as defined in the google-apps-script.js file.)

Step 2: Deploy the Google Apps Script

1. Open Google Apps Script:

   • While in your Google Sheet, go to Extensions > Apps Script. This will open a new tab with the Google Apps Script editor.

2. Copy and Paste the Code:

   • In the Apps Script editor, you'll see a default Code.gs file. Delete any existing code in it.
   • Copy the entire content of the google-apps-script.js file I provided in the previous response.
   • Paste the copied code into the Code.gs editor.

3. Replace SPREADSHEET_ID:

   • In the pasted code, find the line: const SPREADSHEET_ID = "YOUR_SPREADSHEET_ID_HERE"
   • Replace "YOUR_SPREADSHEET_ID_HERE" with the actual ID of your Google Sheet. You can find this ID in the URL of your Google Sheet. For your sheet, it's 1hi6yDu8ex53jzWuWFIPYb_XHoZKQgsUqND1quRukoKE.
   • So, the line should become: const SPREADSHEET_ID = "1hi6yDu8ex53jzWuWFIPYb_XHoZKQgsUqND1quRukoKE"
4. Save the Project: Click the floppy disk icon (Save project) or File > Save project.

5. Deploy as Web App:

   • Click the Deploy button (usually a blue button with a paper airplane icon) in the top right corner.
   • Select New deployment.
   • For "Select type", choose Web app.

   • Configure the deployment:

     • Description: (Optional) Give it a name like "FitNTrack Backend API".
     • Execute as: Me (your Google account).
     • Who has access: Anyone (This is crucial for your Next.js app to be able to access it. Be aware of the security implications for sensitive data).
   • Click Deploy.

6. Authorize the Script:

   • The first time you deploy, Google will ask you to authorize the script. Click Authorize access.
   • Select your Google account.
   • Review the permissions and click Allow.

7. Copy the Web App URL:

   • After successful deployment, you will see a "Deployment succeeded" dialog.
   • Copy the Web app URL. This is your API endpoint for Google Sheets. It will look something like https://script.google.com/macros/s/AKfycb.../exec.

Step 3: Update Your Next.js Application

1. Update .env.local:

   • Open your fitntrack-pro/.env.local file.
   • Find the line: NEXT_PUBLIC_GOOGLE_SHEETS_URL="your_google_sheets_url"
   • Replace "your_google_sheets_url" with the Web app URL you copied in the previous step.

2. Restart Your Development Server:

   • If your Next.js development server is running, stop it (Ctrl+C or Cmd+C) and restart it (npm run dev or yarn dev). This is essential for the new environment variable to be loaded.

Step 4: Test the Connection

Now your Next.js application should be configured to use Google Sheets as a backend. You can test it by:

• Using the BackendStatus component: If you have the components/backend-status.tsx component, it should now show "Google Sheets: Connected" (or similar, depending on its implementation).
• Trying the authentication flow: If your lib/data-service.ts is configured to use googleSheetsApi, try signing up or logging in. New user data should appear in your "Users" sheet.

This setup allows your Next.js app to read from and write to your Google Sheet via the Apps Script API.