destructuring_json.dart

import 'dart:convert';
import 'dart:io';

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

parseJSON() async {
  final json = JsonCodec.withReviver((key, value) {
    // print('  -- reviver -- key: $key, value: $value');
    return switch (value) {
      /* Address */ {
        'street': String street,
        'suite': String suite,
        'city': String city,
        'zipcode': String zipcode,
        'geo': Geo geo,
      } => Address(street, suite, city, zipcode, geo),

      /* Geo */ {
        'lat': String lat,
        'lng': String lng,
      } => Geo(lat, lng),

      /* Company */ {
        'name': String name,
        'catchPhrase': String catchPhrase,
        'bs': String bs,
      } => Company(name, catchPhrase, bs),

      /* Login */ {
        'uuid': String uuid,
        'username': String username,
        'password': String password,
        'md5': String md5,
        'sha1': String sha1,
        'registered': String registered,
      } => Login(uuid, username, password, md5, sha1, registered),

      /* User */ {
        'id': int id,
        'firstname': String firstname,
        'lastname': String lastname,
        'email': String email,
        'birthDate': String birthDate,
        'login': Login login,
        'address': Address address,
        'phone': String phone,
        'website': String website,
        'company': Company company,
      } => User(id, firstname, lastname, email, birthDate, login, address, phone, website, company),

      // final List<User> array (optional?)
      List allUsers => allUsers.cast<User>(),

      // all other go unchanged
      _ => value
    };
  });

  final request = http.Request('get', Uri.parse('https://jsonplaceholder.org/users'));
  // final request = http.Request('get', Uri.parse('http://0.0.0.0/flutter/users.json'));
  // final request = http.Request('get', Uri.parse('http://0.0.0.0/flutter/users.json.gz'));

  final response = await request.send();
  assert (response.statusCode == 200);

  debugPrint('start ------------------------------------------');
  final t1 = DateTime.now();

  Stream<List<int>> stream = response.stream;
  if (response.headers['content-type'] == 'application/gzip') {
    debugPrint('📢 activated gzip transformed stream 📢');
    stream = stream.transform(gzip.decoder);
  }
  final users = await stream.transform(json.fuse(utf8).decoder).single as List<User>;

  final t2 = DateTime.now();
  debugPrint('end --------------------------------------------');
  debugPrint('✅ parsing took ${t2.millisecondsSinceEpoch - t1.millisecondsSinceEpoch} ms');
  debugPrint('users.runtimeType: ${users.runtimeType}');
  debugPrint('users.length: ${users.length}');
  // users.forEach(print);
  debugPrint(users.first.address.city);
  debugPrint(users.last.company.name);
  debugPrint('------------------------------------------------');
}

//
// automagically created with https://app.quicktype.io
//
class User {
  User(this.id, this.firstname, this.lastname, this.email, this.birthDate, this.login, this.address, this.phone, this.website, this.company);

  final int id;
  final String firstname;
  final String lastname;
  final String email;
  final String birthDate;
  final Login login;
  final Address address;
  final String phone;
  final String website;
  final Company company;

  @override
  String toString() {
    return 'User(id: $id, firstname: $firstname, lastname: $lastname, email: $email, birthDate: $birthDate, login: $login, address: $address, phone: $phone, website: $website, company: $company)';
  }
}

class Address {
  Address(this.street, this.suite, this.city, this.zipcode, this.geo);

  final String street;
  final String suite;
  final String city;
  final String zipcode;
  final Geo geo;

  @override
  String toString() {
    return 'Address(street: $street, suite: $suite, city: $city, zipcode: $zipcode, geo: $geo)';
  }
}

class Geo {
  Geo(this.lat, this.lng);

  final String lat;
  final String lng;

  @override
  String toString() => 'Geo(lat: $lat, lng: $lng)';
}

class Company {
  Company(this.name, this.catchPhrase, this.bs);

  final String name;
  final String catchPhrase;
  final String bs;

  @override
  String toString() => 'Company(name: $name, catchPhrase: $catchPhrase, bs: $bs)';
}

class Login {
  Login(this.uuid, this.username, this.password, this.md5, this.sha1, this.registered);

  final String uuid;
  final String username;
  final String password;
  final String md5;
  final String sha1;
  final String registered;

  @override
  String toString() {
    return 'Login(uuid: $uuid, username: $username, password: $password, md5: $md5, sha1: $sha1, registered: $registered)';
  }
}