FloatingActionButton(  onPressed: () async {    final url = await _showUrlDialog(context);    if (url == null) return;    final collection = FirebaseFirestore.instance.collection('urls');    collection.add({'url': url});    ScaffoldMessenger.of(context).showSnackBar(      SnackBar(        content: Text('URL added successfully!'),      ),    );  },  child: Icon(Icons.add),)

Future<String?> _showUrlDialog(BuildContext context) async {  String url = '';  final result = await showDialog<String>(    context: context,    barrierDismissible: false,    builder: (BuildContext context) {      return AlertDialog(        title: Text('Add URL'),        content: SizedBox(          width: double.maxFinite,          child: TextField(            onChanged: (value) {              url = value;            },            decoration: InputDecoration(              hintText: 'https://www.flutter.dev',              border: OutlineInputBorder(),            ),          ),        ),        actions: <Widget>[          TextButton(            child: Text(              'Cancel',            ),            onPressed: () {              Navigator.of(context).pop();            },          ),          ElevatedButton(            child: Text(              'Add',            ),            onPressed: () {              Navigator.of(context).pop(url);            },          ),        ],      );    },  );  return result;}

npm install got cheerio

// packages to make api request and parse responseconst got = require('got');const cheerio = require('cheerio');const functions = require('firebase-functions');const admin = require('firebase-admin'); // Cloud Firestore accessconst db = admin.initializeApp().firestore();exports.addUrlPreview = functions.firestore  .document('urls/{urlId}')  .onCreate(async (snapshot) => {    var querySnapshot = await snapshot.ref.get();    var data = querySnapshot.data();    var url = data.url;    if (url.trim() === '') {      console.log('Empty string... Skipping...');      return;    }    const ogData = await getOGData(url);    console.log(ogData);    const publicationRef = db.collection('previews');    await publicationRef.add(ogData);  });/** * Get the og details from the URL * * @param {String} url * @return {Promise} of object containing site's title, description, siteName, and image. */async function getOGData(url) {  if (!url || url.length === 0) return;  const response = await got(url);  const $ = cheerio.load(response.body);  const titleAttr = $('meta[property="og:title"]').attr();  const descriptionAttr = $('meta[property="og:description"]').attr();  const siteNameAttr = $('meta[property="og:site_name"]').attr();  const imageAttr = $('meta[property="og:image"]').attr();  return {    title: titleAttr ? titleAttr.content : '',    description: descriptionAttr ? descriptionAttr.content : '',    siteName: siteNameAttr ? siteNameAttr.content : '',    image: imageAttr ? imageAttr.content : '',    url: url,  };}

StreamBuilder(  stream: FirebaseFirestore.instance.collection('urls').snapshots(),  builder: (context, AsyncSnapshot<QuerySnapshot> snapshot) {    if (!snapshot.hasData) return Text('Loading..');    final docs = snapshot.data!.docs;    if (docs.isEmpty) return Text('Add urls to load their previews');    final previews =        docs.map((doc) => doc.data() as Map<String, dynamic>).toList();    return ListView.separated(      padding: const EdgeInsets.all(0),      itemCount: previews.length,      separatorBuilder: (context, index) => const Divider(),      itemBuilder: (context, index) {        final preview = previews[index];        return ListTile(          contentPadding: const EdgeInsets.all(0),          leading: preview['image'].isEmpty              ? Container(                  height: 100,                  width: 100,                  color: Colors.grey,                )              : Image.network(                  preview['image'],                  height: 100,                  width: 100,                ),          title: Text(preview['title']),          subtitle: Column(            crossAxisAlignment: CrossAxisAlignment.start,            children: [              SizedBox(height: 4),              Text(preview['description']),              SizedBox(height: 2),              Text(                preview['siteName'],                style: TextStyle(                  fontWeight: FontWeight.bold,                ),              ),            ],          ),        );      },    );  },)