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

class ModelDownloadScreen extends ConsumerWidget {
  const ModelDownloadScreen({super.key});

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final downloadState = ref.watch(modelDownloadNotifierProvider);

    return Scaffold(
      body: SafeArea(
        child: Padding(
          padding: const EdgeInsets.all(32),
          child: downloadState.when(
            data: (progress) => progress == 0.0
                ? _IdleView(
                    onDownload: () => ref
                        .read(modelDownloadNotifierProvider.notifier)
                        .startDownload(),
                  )
                : _DownloadingView(progress: progress),
            loading: () => const Center(child: CircularProgressIndicator()),
            error: (e, _) => _ErrorView(
              error: e.toString(),
              onRetry: () {
                ref.read(modelDownloadNotifierProvider.notifier).reset();
              },
            ),
          ),
        ),
      ),
    );
  }
}

class _IdleView extends StatelessWidget {
  const _IdleView({required this.onDownload});

  final VoidCallback onDownload;

  @override
  Widget build(BuildContext context) {
    return Column(
      mainAxisAlignment: MainAxisAlignment.center,
      crossAxisAlignment: CrossAxisAlignment.stretch,
      children: [
        Icon(
          Icons.auto_awesome,
          size: 64,
          color: Theme.of(context).colorScheme.primary,
        ),
        const SizedBox(height: 24),
        Text(
          'On-device AI',
          style: Theme.of(context).textTheme.headlineSmall,
          textAlign: TextAlign.center,
        ),
        const SizedBox(height: 12),
        Text(
          'DailyYou uses an on-device AI model to spot patterns in your moods '
          'and behaviour. Your data never leaves your phone.',
          style: Theme.of(context).textTheme.bodyMedium?.copyWith(
                color: Theme.of(context).colorScheme.onSurfaceVariant,
              ),
          textAlign: TextAlign.center,
        ),
        const SizedBox(height: 8),
        Text(
          'The model is ~1.1 GB and only needs to be downloaded once.',
          style: Theme.of(context).textTheme.bodySmall?.copyWith(
                color: Theme.of(context).colorScheme.outline,
              ),
          textAlign: TextAlign.center,
        ),
        const SizedBox(height: 40),
        FilledButton.icon(
          onPressed: onDownload,
          icon: const Icon(Icons.download),
          label: const Text('Download model'),
        ),
      ],
    );
  }
}

class _DownloadingView extends StatelessWidget {
  const _DownloadingView({required this.progress});

  final double progress;

  @override
  Widget build(BuildContext context) {
    final pct = (progress * 100).toStringAsFixed(0);
    final done = progress >= 1.0;

    return Column(
      mainAxisAlignment: MainAxisAlignment.center,
      crossAxisAlignment: CrossAxisAlignment.stretch,
      children: [
        Icon(
          done ? Icons.check_circle : Icons.downloading,
          size: 64,
          color: done
              ? Theme.of(context).colorScheme.primary
              : Theme.of(context).colorScheme.secondary,
        ),
        const SizedBox(height: 24),
        Text(
          done ? 'Ready!' : 'Downloading…',
          style: Theme.of(context).textTheme.headlineSmall,
          textAlign: TextAlign.center,
        ),
        const SizedBox(height: 24),
        LinearProgressIndicator(value: progress),
        const SizedBox(height: 8),
        Text(
          done ? 'Model downloaded successfully.' : '$pct% — keep the app open',
          style: Theme.of(context).textTheme.bodySmall?.copyWith(
                color: Theme.of(context).colorScheme.outline,
              ),
          textAlign: TextAlign.center,
        ),
      ],
    );
  }
}

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

  final String error;
  final VoidCallback onRetry;

  @override
  Widget build(BuildContext context) {
    return Column(
      mainAxisAlignment: MainAxisAlignment.center,
      crossAxisAlignment: CrossAxisAlignment.stretch,
      children: [
        Icon(Icons.error_outline,
            size: 64, color: Theme.of(context).colorScheme.error),
        const SizedBox(height: 24),
        Text(
          'Download failed',
          style: Theme.of(context).textTheme.headlineSmall,
          textAlign: TextAlign.center,
        ),
        const SizedBox(height: 8),
        Text(
          'Check your connection and try again.',
          style: Theme.of(context).textTheme.bodyMedium?.copyWith(
                color: Theme.of(context).colorScheme.onSurfaceVariant,
              ),
          textAlign: TextAlign.center,
        ),
        const SizedBox(height: 40),
        FilledButton.icon(
          onPressed: onRetry,
          icon: const Icon(Icons.refresh),
          label: const Text('Try again'),
        ),
      ],
    );
  }
}