app/lib/screens/welcome_screen.dart

import 'package:flutter/material.dart';
import '../theme.dart';
import 'baseline_screen.dart';

class WelcomeScreen extends StatelessWidget {
  const WelcomeScreen({super.key});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: SafeArea(
        child: Padding(
          padding: const EdgeInsets.symmetric(horizontal: 32),
          child: Column(
            children: [
              const Spacer(flex: 2),
              // Icon or logo area
              Container(
                width: 80,
                height: 80,
                decoration: BoxDecoration(
                  color: AppColors.surfaceVariant,
                  borderRadius: BorderRadius.circular(20),
                ),
                child: const Icon(
                  Icons.timeline,
                  size: 40,
                  color: AppColors.primary,
                ),
              ),
              const SizedBox(height: 32),
              // Title
              Text(
                'Add Months',
                style: Theme.of(context).textTheme.headlineLarge,
                textAlign: TextAlign.center,
              ),
              const SizedBox(height: 16),
              // Description
              Text(
                'Identify the single change most likely to extend your lifespan.',
                style: Theme.of(context).textTheme.bodyLarge?.copyWith(
                      color: AppColors.textSecondary,
                    ),
                textAlign: TextAlign.center,
              ),
              const SizedBox(height: 48),
              // Features list
              _buildFeatureItem(
                context,
                Icons.shield_outlined,
                'Private',
                'All data stays on your device',
              ),
              const SizedBox(height: 16),
              _buildFeatureItem(
                context,
                Icons.science_outlined,
                'Evidence-based',
                'Hazard ratios from meta-analyses',
              ),
              const SizedBox(height: 16),
              _buildFeatureItem(
                context,
                Icons.trending_up_outlined,
                'Actionable',
                'Focus on what matters most',
              ),
              const Spacer(flex: 3),
              // Start button
              SizedBox(
                width: double.infinity,
                child: ElevatedButton(
                  onPressed: () => _navigateToBaseline(context),
                  child: const Text('Start'),
                ),
              ),
              const SizedBox(height: 32),
            ],
          ),
        ),
      ),
    );
  }

  Widget _buildFeatureItem(
    BuildContext context,
    IconData icon,
    String title,
    String description,
  ) {
    return Row(
      children: [
        Container(
          width: 44,
          height: 44,
          decoration: BoxDecoration(
            color: AppColors.surfaceVariant,
            borderRadius: BorderRadius.circular(12),
          ),
          child: Icon(icon, color: AppColors.primary, size: 22),
        ),
        const SizedBox(width: 16),
        Expanded(
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Text(
                title,
                style: Theme.of(context).textTheme.labelLarge,
              ),
              Text(
                description,
                style: Theme.of(context).textTheme.bodySmall,
              ),
            ],
          ),
        ),
      ],
    );
  }

  void _navigateToBaseline(BuildContext context) {
    Navigator.of(context).push(
      MaterialPageRoute(builder: (_) => const BaselineScreen()),
    );
  }
}