// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// ignore_for_file: public_member_api_docs

import 'dart:async';
import 'dart:convert';
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:webview_flutter_platform_interface/webview_flutter_platform_interface.dart';

import 'navigation_decision.dart';
import 'navigation_request.dart';
import 'web_view.dart';

void main() {
  runApp(MaterialApp(home: _WebViewExample()));
}

const String kNavigationExamplePage = '''
<!DOCTYPE html><html>
<head><title>Navigation Delegate Example</title></head>
<body>
<p>
The navigation delegate is set to block navigation to the youtube website.
</p>
<ul>
<ul><a href="https://www.youtube.com/">https://www.youtube.com/</a></ul>
<ul><a href="https://www.google.com/">https://www.google.com/</a></ul>
</ul>
</body>
</html>
''';

class _WebViewExample extends StatefulWidget {
  const _WebViewExample({Key? key}) : super(key: key);

  @override
  _WebViewExampleState createState() => _WebViewExampleState();
}

class _WebViewExampleState extends State<_WebViewExample> {
  final Completer<WebViewController> _controller =
      Completer<WebViewController>();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Flutter WebView example'),
        // This drop down menu demonstrates that Flutter widgets can be shown over the web view.
        actions: <Widget>[
          _NavigationControls(_controller.future),
          _SampleMenu(_controller.future),
        ],
      ),
      // We're using a Builder here so we have a context that is below the Scaffold
      // to allow calling Scaffold.of(context) so we can show a snackbar.
      body: Builder(builder: (context) {
        return WebView(
          initialUrl: 'https://flutter.dev',
          onWebViewCreated: (WebViewController controller) {
            _controller.complete(controller);
          },
          javascriptChannels: _createJavascriptChannels(context),
          javascriptMode: JavascriptMode.unrestricted,
          navigationDelegate: (NavigationRequest request) {
            if (request.url.startsWith('https://www.youtube.com/')) {
              print('blocking navigation to $request}');
              return NavigationDecision.prevent;
            }
            print('allowing navigation to $request');
            return NavigationDecision.navigate;
          },
        );
      }),
      floatingActionButton: favoriteButton(),
    );
  }

  Widget favoriteButton() {
    return FutureBuilder<WebViewController>(
        future: _controller.future,
        builder: (BuildContext context,
            AsyncSnapshot<WebViewController> controller) {
          if (controller.hasData) {
            return FloatingActionButton(
              onPressed: () async {
                final String url = (await controller.data!.currentUrl())!;
                // ignore: deprecated_member_use
                Scaffold.of(context).showSnackBar(
                  SnackBar(content: Text('Favorited $url')),
                );
              },
              child: const Icon(Icons.favorite),
            );
          }
          return Container();
        });
  }
}

Set<JavascriptChannel> _createJavascriptChannels(BuildContext context) {
  return {
    JavascriptChannel(
        name: 'Snackbar',
        onMessageReceived: (JavascriptMessage message) {
          ScaffoldMessenger.of(context)
              .showSnackBar(SnackBar(content: Text(message.message)));
        }),
  };
}

enum _MenuOptions {
  showUserAgent,
  listCookies,
  clearCookies,
  addToCache,
  listCache,
  clearCache,
  navigationDelegate,
}

class _SampleMenu extends StatelessWidget {
  _SampleMenu(this.controller);

  final Future<WebViewController> controller;

  @override
  Widget build(BuildContext context) {
    return FutureBuilder<WebViewController>(
      future: controller,
      builder:
          (BuildContext context, AsyncSnapshot<WebViewController> controller) {
        return PopupMenuButton<_MenuOptions>(
          onSelected: (_MenuOptions value) {
            switch (value) {
              case _MenuOptions.showUserAgent:
                _onShowUserAgent(controller.data!, context);
                break;
              case _MenuOptions.listCookies:
                _onListCookies(controller.data!, context);
                break;
              case _MenuOptions.clearCookies:
                _onClearCookies(controller.data!, context);
                break;
              case _MenuOptions.addToCache:
                _onAddToCache(controller.data!, context);
                break;
              case _MenuOptions.listCache:
                _onListCache(controller.data!, context);
                break;
              case _MenuOptions.clearCache:
                _onClearCache(controller.data!, context);
                break;
              case _MenuOptions.navigationDelegate:
                _onNavigationDelegateExample(controller.data!, context);
                break;
            }
          },
          itemBuilder: (BuildContext context) => <PopupMenuItem<_MenuOptions>>[
            PopupMenuItem<_MenuOptions>(
              value: _MenuOptions.showUserAgent,
              child: const Text('Show user agent'),
              enabled: controller.hasData,
            ),
            const PopupMenuItem<_MenuOptions>(
              value: _MenuOptions.listCookies,
              child: Text('List cookies'),
            ),
            const PopupMenuItem<_MenuOptions>(
              value: _MenuOptions.clearCookies,
              child: Text('Clear cookies'),
            ),
            const PopupMenuItem<_MenuOptions>(
              value: _MenuOptions.addToCache,
              child: Text('Add to cache'),
            ),
            const PopupMenuItem<_MenuOptions>(
              value: _MenuOptions.listCache,
              child: Text('List cache'),
            ),
            const PopupMenuItem<_MenuOptions>(
              value: _MenuOptions.clearCache,
              child: Text('Clear cache'),
            ),
            const PopupMenuItem<_MenuOptions>(
              value: _MenuOptions.navigationDelegate,
              child: Text('Navigation Delegate example'),
            ),
          ],
        );
      },
    );
  }

  void _onShowUserAgent(
      WebViewController controller, BuildContext context) async {
    // Send a message with the user agent string to the Snackbar JavaScript channel we registered
    // with the WebView.
    await controller.evaluateJavascript(
        'Snackbar.postMessage("User Agent: " + navigator.userAgent);');
  }

  void _onListCookies(
      WebViewController controller, BuildContext context) async {
    final String cookies =
        await controller.evaluateJavascript('document.cookie');
    ScaffoldMessenger.of(context).showSnackBar(SnackBar(
      content: Column(
        mainAxisAlignment: MainAxisAlignment.end,
        mainAxisSize: MainAxisSize.min,
        children: <Widget>[
          const Text('Cookies:'),
          _getCookieList(cookies),
        ],
      ),
    ));
  }

  void _onAddToCache(WebViewController controller, BuildContext context) async {
    await controller.evaluateJavascript(
        'caches.open("test_caches_entry"); localStorage["test_localStorage"] = "dummy_entry";');
    ScaffoldMessenger.of(context).showSnackBar(const SnackBar(
      content: Text('Added a test entry to cache.'),
    ));
  }

  void _onListCache(WebViewController controller, BuildContext context) async {
    await controller.evaluateJavascript('caches.keys()'
        '.then((cacheKeys) => JSON.stringify({"cacheKeys" : cacheKeys, "localStorage" : localStorage}))'
        '.then((caches) => Snackbar.postMessage(caches))');
  }

  void _onClearCache(WebViewController controller, BuildContext context) async {
    await controller.clearCache();
    ScaffoldMessenger.of(context).showSnackBar(const SnackBar(
      content: Text("Cache cleared."),
    ));
  }

  void _onClearCookies(
      WebViewController controller, BuildContext context) async {
    final bool hadCookies = await WebView.platform.clearCookies();
    String message = 'There were cookies. Now, they are gone!';
    if (!hadCookies) {
      message = 'There are no cookies.';
    }
    ScaffoldMessenger.of(context).showSnackBar(SnackBar(
      content: Text(message),
    ));
  }

  void _onNavigationDelegateExample(
      WebViewController controller, BuildContext context) async {
    final String contentBase64 =
        base64Encode(const Utf8Encoder().convert(kNavigationExamplePage));
    await controller.loadUrl('data:text/html;base64,$contentBase64');
  }

  Widget _getCookieList(String cookies) {
    if (cookies == null || cookies == '""') {
      return Container();
    }
    final List<String> cookieList = cookies.split(';');
    final Iterable<Text> cookieWidgets =
        cookieList.map((String cookie) => Text(cookie));
    return Column(
      mainAxisAlignment: MainAxisAlignment.end,
      mainAxisSize: MainAxisSize.min,
      children: cookieWidgets.toList(),
    );
  }
}

class _NavigationControls extends StatelessWidget {
  const _NavigationControls(this._webViewControllerFuture)
      : assert(_webViewControllerFuture != null);

  final Future<WebViewController> _webViewControllerFuture;

  @override
  Widget build(BuildContext context) {
    return FutureBuilder<WebViewController>(
      future: _webViewControllerFuture,
      builder:
          (BuildContext context, AsyncSnapshot<WebViewController> snapshot) {
        final bool webViewReady =
            snapshot.connectionState == ConnectionState.done;
        final WebViewController? controller = snapshot.data;

        return Row(
          children: <Widget>[
            IconButton(
              icon: const Icon(Icons.arrow_back_ios),
              onPressed: !webViewReady
                  ? null
                  : () async {
                      if (await controller!.canGoBack()) {
                        await controller.goBack();
                      } else {
                        // ignore: deprecated_member_use
                        Scaffold.of(context).showSnackBar(
                          const SnackBar(content: Text("No back history item")),
                        );
                        return;
                      }
                    },
            ),
            IconButton(
              icon: const Icon(Icons.arrow_forward_ios),
              onPressed: !webViewReady
                  ? null
                  : () async {
                      if (await controller!.canGoForward()) {
                        await controller.goForward();
                      } else {
                        // ignore: deprecated_member_use
                        Scaffold.of(context).showSnackBar(
                          const SnackBar(
                              content: Text("No forward history item")),
                        );
                        return;
                      }
                    },
            ),
            IconButton(
              icon: const Icon(Icons.replay),
              onPressed: !webViewReady
                  ? null
                  : () {
                      controller!.reload();
                    },
            ),
          ],
        );
      },
    );
  }
}

/// Callback type for handling messages sent from Javascript running in a web view.
typedef void JavascriptMessageHandler(JavascriptMessage message);