Intro

import 'package:flutter/material.dart';

// ===== The model =====
// - Dart language (statically typed, JIT in dev, AOT in prod)
// - Flutter draws every pixel via Skia / Impeller (no native widgets)
// - Composable widgets; UI = f(state)
// - Hot reload is genuinely instant
// - One codebase, six platforms (iOS, Android, web, Windows, macOS, Linux)

// ===== Hello, Flutter =====
void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(useMaterial3: true),
      home: const Counter(),
    );
  }
}

class Counter extends StatefulWidget {
  const Counter({super.key});
  @override
  State<Counter> createState() => _CounterState();
}

class _CounterState extends State<Counter> {
  int _n = 0;
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Counter')),
      body: Center(child: Text('Clicks: $_n', style: const TextStyle(fontSize: 24))),
      floatingActionButton: FloatingActionButton(
        onPressed: () => setState(() => _n++),
        child: const Icon(Icons.add),
      ),
    );
  }
}

// ===== State management options =====
// Provider, Riverpod, Bloc, GetX, Zustand-like
// Choose one; mixing them across a codebase causes pain

// ===== When Flutter wins =====
// - Pixel-perfect UIs across iOS + Android
// - Teams that want one stack for mobile + desktop + web
// - Apps with custom UIs that should look identical everywhere
// - Material/Cupertino designs out of the box

// ===== When Flutter hurts =====
// - You need native look-and-feel that adopts OS updates instantly
// - SEO-critical web (Flutter web is canvas-based; not for blogs)
// - Heavy native-API needs (FFI is great but extra work)

// ===== Patterns to internalise =====
// - Compose small widgets; const constructors for free perf
// - setState locally; lift state when shared
// - Use ListView.builder for lazy lists
// - Use 'flutter analyze' + 'dart format' in CI

// ===== Pitfalls =====
// - StatefulWidget for everything -> hard to test; prefer StatelessWidget + a state lib
// - Overlong build() methods -> extract widgets
// - Forgetting const constructors -> avoidable rebuilds
// - Treating BuildContext like a global -> careful with async + context

// Flutter: Google's SDK, single codebase → iOS, Android, web, desktop.
// UI is composed of Widgets; layout is reactive and declarative.