import 'dart:async';
import 'dart:math';

import 'package:dio/dio.dart';
import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';

void main() {
  runApp(
    ProviderScope(child: const MainApp()),
  );
}

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

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      home: PostScreen(),
    );
  }
}

final baseUrlProvider = StateProvider<String>((ref) {
  return 'https://mybackend.com';
});

final perPageProvider = StateProvider<int>((ref) {
  return 1;
});

final dioProvider = Provider.family<Dio, String>((ref, url) {
  final dio = Dio(
    BaseOptions(
      baseUrl: url,
    ),
  );

  return dio;
});

final postRepoProvider =
    Provider.autoDispose.family<PostRepository, String>((ref, baseUrl) {
  final dio = ref.watch(dioProvider(baseUrl));

  return PostRepository(dio: dio);
});

class PostRepository {
  PostRepository({required this.dio});
  final Dio dio;
  final Random random = Random();

  Future<List<String>> fetchPosts({required int perPage}) async {
    await Future.delayed(const Duration(milliseconds: 500));
    return List.generate(
        perPage,
        (index) =>
            'Post $perPage - ${random.nextInt(perPage)}, ${dio.options.baseUrl}');
  }
}

final postsProvider = AsyncNotifierProvider.autoDispose
    .family<PostNotifier, List<String>, String>(PostNotifier.new);

class PostNotifier
    extends AutoDisposeFamilyAsyncNotifier<List<String>, String> {
  @override
  FutureOr<List<String>> build(String arg) {
    final perPage = ref.watch(perPageProvider);
    return ref.watch(postRepoProvider(arg)).fetchPosts(
          perPage: perPage,
        );
  }
}

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

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    return const Scaffold(
      body: SafeArea(
        child: Column(
          children: [
            Row(
              children: [
                UpdateUrlButton(),
                UpdatePerPageButton(),
              ],
            ),
            PerPageText(),
            UrlDisplayText(),
            Expanded(child: PostList()),
          ],
        ),
      ),
    );
  }
}

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

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final rnd = Random();

    return FilledButton(
      onPressed: () {
        ref.read(baseUrlProvider.notifier).state =
            'https://example.com/${rnd.nextInt(100)}';
      },
      child: const Text('Update URL'),
    );
  }
}

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

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

    return FilledButton(
      onPressed: () {
        ref.read(perPageProvider.notifier).state = perPage + 1;
      },
      child: const Text('Update Per Page'),
    );
  }
}

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

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

    return ref.watch(postsProvider(baseUrl)).when(
          data: (posts) {
            return ListView.builder(
              itemCount: posts.length,
              itemBuilder: (context, index) {
                final data = posts[index].split(', ');

                return ListTile(
                  title: Text(data[0]),
                  subtitle: Text(data[1]),
                );
              },
            );
          },
          loading: () => const Center(
            child: CircularProgressIndicator(),
          ),
          error: (error, stackTrace) => Center(
            child: Text('Error: $error'),
          ),
        );
  }
}

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

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

    return Text('Per page: $count');
  }
}

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

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

    return Text('URL: $url');
  }
}