// Copyright 2018 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import 'dart:async';
import 'package:flutter/material.dart';
import 'package:webview_flutter/webview_flutter.dart';

void main() => runApp(MaterialApp(home: WebViewExample()));

class WebViewExample extends StatelessWidget {
  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: (BuildContext context) {
        return WebView(
          initialUrl: 'https://flutter.io',
          javascriptMode: JavascriptMode.unrestricted,
          onWebViewCreated: (WebViewController webViewController) {
            _controller.complete(webViewController);
          },
          javascriptChannels: <JavascriptChannel>[
            _toasterJavascriptChannel(context),
          ].toSet(),
        );
      }),
      floatingActionButton: favoriteButton(),
    );
  }

  JavascriptChannel _toasterJavascriptChannel(BuildContext context) {
    return JavascriptChannel(
        name: 'Toaster',
        onMessageReceived: (JavascriptMessage message) {
          Scaffold.of(context).showSnackBar(
            SnackBar(content: Text(message.message)),
          );
        });
  }

  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();
                Scaffold.of(context).showSnackBar(
                  SnackBar(content: Text('Favorited $url')),
                );
              },
              child: const Icon(Icons.favorite),
            );
          }
          return Container();
        });
  }
}

enum MenuOptions {
  showUserAgent,
  toast,
  listCookies,
  clearCookies,
}

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

  final Future<WebViewController> controller;
  final CookieManager cookieManager = CookieManager();

  @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.toast:
                Scaffold.of(context).showSnackBar(
                  SnackBar(
                    content: Text('You selected: $value'),
                  ),
                );
                break;
              case MenuOptions.listCookies:
                _onListCookies(controller.data, context);
                break;
              case MenuOptions.clearCookies:
                _onClearCookies(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.toast,
                  child: Text('Make a toast'),
                ),
                const PopupMenuItem<MenuOptions>(
                  value: MenuOptions.listCookies,
                  child: Text('List cookies'),
                ),
                const PopupMenuItem<MenuOptions>(
                  value: MenuOptions.clearCookies,
                  child: Text('Clear cookies'),
                ),
              ],
        );
      },
    );
  }

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

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

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

  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()) {
                        controller.goBack();
                      } else {
                        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()) {
                        controller.goForward();
                      } else {
                        Scaffold.of(context).showSnackBar(
                          const SnackBar(
                              content: Text("No forward history item")),
                        );
                        return;
                      }
                    },
            ),
            IconButton(
              icon: const Icon(Icons.replay),
              onPressed: !webViewReady
                  ? null
                  : () {
                      controller.reload();
                    },
            ),
          ],
        );
      },
    );
  }
}