future_stream.dart

// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

// Future -> Stream
// FutureBuilder -> StreamBuilder

import 'dart:convert';
import 'dart:math';

import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;

void main() => runApp(MyApp());

/*
 {
"userId": 1,
"id": 1,
"title": "sunt aut facere repellat provident occaecati excepturi optio reprehenderit",
"body": "quia et suscipit\nsuscipit recusandae consequuntur expedita et cum\nreprehenderit 
molestiae ut ut quas totam\nnostrum rerum est autem sunt rem eveniet architecto"
}
 
 */

class Post {
  final int userId;
  final int id;
  final String title;
  final String body;

  const Post({
    required this.userId,
    required this.id,
    required this.title,
    required this.body,
  });

  factory Post.fromJson(Map json) {
    return Post(
      userId: json['userId'],
      id: json['id'],
      title: json['title'],
      body: json['body'],
    );
  }
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
        colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
        useMaterial3: true,
      ),
      home: const MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  final String title;

  const MyHomePage({
    Key? key,
    required this.title,
  }) : super(key: key);

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  Stream<List<Post>> _getPosts() async* {
    final posts = <Post>[];

    for (int i = 10; i < 21; i++) {
      final url = "https://jsonplaceholder.typicode.com/posts/$i";

      final response = await http.get(Uri.parse(url));

      await Future.delayed(Duration(seconds: Random().nextInt(4)));

      if (response.statusCode == 200) {
        posts.add(Post.fromJson(jsonDecode(response.body)));
        yield posts;
      }
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        backgroundColor: Theme.of(context).colorScheme.inversePrimary,
        title: Text(widget.title),
      ),
      body: Column(
        children: [
          Text(
            'Posts',
            style: Theme.of(context).textTheme.headlineMedium,
          ),
          Expanded(
            child: StreamBuilder(
              stream: _getPosts(),
              builder: (context, snapshot) {
                if (snapshot.hasData) {
                  final posts = snapshot.data!;

                  return ListView(
                    children: [
                      for (final post in posts)
                        Card(
                          child: ListTile(
                            title: Text(post.title),
                            subtitle: Text(post.body),
                          ),
                        ),
                    ],
                  );
                } else if (snapshot.hasError) {
                  return Text(snapshot.error.toString());
                } else {
                  return const Center(child: CircularProgressIndicator());
                }
              },
            ),
          ),
        ],
      ),
      floatingActionButton: const FloatingActionButton(
        onPressed: null,
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ),
    );
  }
}