I'll create a simple web SMS viewer app using Next.js with function-based components. We'll use a SQLite database for storing the messages, and implement a dashboard with filtering capabilities. Let's break this down into steps:

Let's start by setting up the project structure and implementing the necessary components:

This implementation creates a simple web SMS viewer app with the following features:

1. An API route (/api/sms) that handles POST requests from the Android app to store SMS data in the database.
2. A dashboard page that displays all messages sorted by time.
3. A date filter to choose messages from a specific day or period.
4. Mobile responsiveness using Tailwind CSS.

To use this app:

1. Set up a Vercel Postgres database and configure the environment variables for the database connection.
2. Deploy the app to Vercel or run it locally using npm run dev.
3. The Android app can send POST requests to https://your-domain.com/api/sms with the SMS data.
4. Users can view the dashboard at https://your-domain.com and use the date filter to narrow down the displayed messages.

The app uses Server Components for data fetching and Client Components for interactivity, providing a good balance between performance and user experience. The design is responsive and will work well on both desktop and mobile devices.

I understand that you're encountering an error related to a missing connection string for Vercel Postgres. Let's address this issue by properly setting up the database connection.

To resolve this error, we need to properly set up the Vercel Postgres connection string. Here's how we can modify our code:

These changes should address the connection string error and improve error handling throughout the application. Here's a summary of what we've done:

1. Updated the db.ts file to use the postgres() function, which automatically uses the connection string from environment variables.
2. Improved error handling in the API routes to catch and return specific Vercel Postgres errors.
3. Updated the useMessages hook to handle and display error messages more effectively.

To complete the setup, you need to add the Vercel Postgres connection string to your environment variables. You can do this in your Vercel project settings or by adding a .env.local file to your project root with the following content:

Make sure to replace "your_connection_string_here" with the actual connection string provided by Vercel for your Postgres database.

If you're running the app locally, you'll need to set up this environment variable. When deploying to Vercel, make sure to add this environment variable in your project settings.

These changes should resolve the connection string error and allow your application to connect to the Vercel Postgres database successfully.