import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import '../../core/providers/insight_provider.dart';

class InsightsScreen extends ConsumerStatefulWidget {
  const InsightsScreen({super.key});

  @override
  ConsumerState<InsightsScreen> createState() => _InsightsScreenState();
}

class _InsightsScreenState extends ConsumerState<InsightsScreen> {
  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addPostFrameCallback((_) {
      ref.read(insightNotifierProvider.notifier).generateInsight();
    });
  }

  void _refresh() {
    ref
        .read(insightNotifierProvider.notifier)
        .generateInsight(forceRefresh: true);
  }

  @override
  Widget build(BuildContext context) {
    final insightAsync = ref.watch(insightNotifierProvider);

    return Scaffold(
      appBar: AppBar(
        title: const Text('Insights'),
        centerTitle: false,
        actions: [
          IconButton(
            icon: const Icon(Icons.refresh),
            tooltip: 'Refresh',
            onPressed: insightAsync is AsyncLoading ? null : _refresh,
          ),
        ],
      ),
      body: insightAsync.when(
        loading: () => const _LoadingView(),
        error: (e, _) => _ErrorView(onRetry: _refresh),
        data: (text) =>
            text == null ? const _EmptyView() : _InsightCard(text: text),
      ),
    );
  }
}

class _LoadingView extends StatelessWidget {
  const _LoadingView();

  @override
  Widget build(BuildContext context) {
    return Center(
      child: Column(
        mainAxisSize: MainAxisSize.min,
        children: [
          const CircularProgressIndicator(),
          const SizedBox(height: 16),
          Text(
            'Analysing your week…',
            style: Theme.of(context).textTheme.bodyMedium?.copyWith(
                  color: Theme.of(context).colorScheme.outline,
                ),
          ),
        ],
      ),
    );
  }
}

class _EmptyView extends StatelessWidget {
  const _EmptyView();

  @override
  Widget build(BuildContext context) {
    return Center(
      child: Padding(
        padding: const EdgeInsets.all(32),
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            Icon(
              Icons.auto_awesome_outlined,
              size: 48,
              color: Theme.of(context).colorScheme.outlineVariant,
            ),
            const SizedBox(height: 16),
            Text(
              'Not enough data yet',
              style: Theme.of(context).textTheme.titleMedium,
            ),
            const SizedBox(height: 8),
            Text(
              'Log a few more entries and check back soon.',
              style: Theme.of(context).textTheme.bodyMedium?.copyWith(
                    color: Theme.of(context).colorScheme.outline,
                  ),
              textAlign: TextAlign.center,
            ),
          ],
        ),
      ),
    );
  }
}

class _ErrorView extends StatelessWidget {
  const _ErrorView({required this.onRetry});

  final VoidCallback onRetry;

  @override
  Widget build(BuildContext context) {
    return Center(
      child: Column(
        mainAxisSize: MainAxisSize.min,
        children: [
          Icon(
            Icons.error_outline,
            size: 48,
            color: Theme.of(context).colorScheme.error,
          ),
          const SizedBox(height: 16),
          Text(
            'Something went wrong',
            style: Theme.of(context).textTheme.titleMedium,
          ),
          const SizedBox(height: 16),
          FilledButton.tonal(
            onPressed: onRetry,
            child: const Text('Try again'),
          ),
        ],
      ),
    );
  }
}

class _InsightCard extends StatelessWidget {
  const _InsightCard({required this.text});

  final String text;

  @override
  Widget build(BuildContext context) {
    return ListView(
      padding: const EdgeInsets.all(16),
      children: [
        Card(
          child: Padding(
            padding: const EdgeInsets.all(20),
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Row(
                  children: [
                    Icon(
                      Icons.auto_awesome,
                      size: 18,
                      color: Theme.of(context).colorScheme.primary,
                    ),
                    const SizedBox(width: 8),
                    Text(
                      'This week',
                      style: Theme.of(context).textTheme.labelLarge?.copyWith(
                            color: Theme.of(context).colorScheme.primary,
                          ),
                    ),
                  ],
                ),
                const SizedBox(height: 12),
                Text(
                  text,
                  style: Theme.of(context).textTheme.bodyMedium?.copyWith(
                        height: 1.5,
                      ),
                ),
              ],
            ),
          ),
        ),
        const SizedBox(height: 8),
        Text(
          'Generated on-device. Your data never leaves your phone.',
          style: Theme.of(context).textTheme.labelSmall?.copyWith(
                color: Theme.of(context).colorScheme.outlineVariant,
              ),
          textAlign: TextAlign.center,
        ),
      ],
    );
  }
}