Voice Assistant

import 'dart:math';
import 'package:flutter/material.dart';

class VoiceAssistant extends StatefulWidget {
  const VoiceAssistant({super.key});

  @override
  State<VoiceAssistant> createState() => _VoiceAssistantState();
}

class _VoiceAssistantState extends State<VoiceAssistant>
    with SingleTickerProviderStateMixin {
  late final AnimationController _c =
      AnimationController(vsync: this, duration: const Duration(milliseconds: 700))
        ..repeat(reverse: true);
  bool _listening = true;

  @override
  void dispose() {
    _c.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final scheme = theme.colorScheme;

    return Scaffold(
      appBar: AppBar(title: const Text('Voice Assistant')),
      body: Padding(
        padding: const EdgeInsets.all(28),
        child: Column(
          children: [
            const Spacer(),
            Text(_listening ? 'Listening…' : 'Tap the mic to speak',
                style: theme.textTheme.titleMedium),
            const SizedBox(height: 32),
            SizedBox(
              height: 80,
              child: AnimatedBuilder(
                animation: _c,
                builder: (context, _) {
                  return Row(
                    mainAxisAlignment: MainAxisAlignment.center,
                    crossAxisAlignment: CrossAxisAlignment.center,
                    children: List.generate(24, (i) {
                      final base = sin((i / 24) * pi);
                      final h = _listening
                          ? 12 + base * 50 * (0.4 + 0.6 * _c.value)
                          : 8.0;
                      return Container(
                        width: 5,
                        height: h,
                        margin: const EdgeInsets.symmetric(horizontal: 2),
                        decoration: BoxDecoration(
                          color: scheme.primary,
                          borderRadius: BorderRadius.circular(3),
                        ),
                      );
                    }),
                  );
                },
              ),
            ),
            const SizedBox(height: 40),
            Container(
              padding: const EdgeInsets.all(16),
              decoration: BoxDecoration(
                color: scheme.surfaceContainerHighest,
                borderRadius: BorderRadius.circular(16),
              ),
              child: Text(
                '"What\'s the weather like this weekend?"',
                style: theme.textTheme.bodyLarge,
                textAlign: TextAlign.center,
              ),
            ),
            const Spacer(),
            GestureDetector(
              onTap: () => setState(() => _listening = !_listening),
              child: Container(
                width: 84,
                height: 84,
                decoration: BoxDecoration(
                  shape: BoxShape.circle,
                  color: _listening ? scheme.primary : scheme.surfaceContainerHighest,
                ),
                child: Icon(
                  _listening ? Icons.mic : Icons.mic_off,
                  size: 40,
                  color: _listening ? scheme.onPrimary : scheme.onSurface,
                ),
              ),
            ),
            const SizedBox(height: 24),
          ],
        ),
      ),
    );
  }
}