iosWebViewFix/lib/src/in_app_webview.dart

import 'dart:io';
import 'dart:async';
import 'dart:collection';
import 'dart:typed_data';
import 'dart:convert';

import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:flutter/widgets.dart';
import 'package:flutter/gestures.dart';

import 'package:html/parser.dart' show parse;

import 'types.dart';
import 'in_app_browser.dart';
import 'webview_options.dart';

const javaScriptHandlerForbiddenNames = [
  "onLoadResource",
  "shouldInterceptAjaxRequest",
  "onAjaxReadyStateChange",
  "onAjaxProgress",
  "shouldInterceptFetchRequest"
];

///InAppWebView Widget class.
///
///Flutter Widget for adding an **inline native WebView** integrated in the flutter widget tree.
class InAppWebView extends StatefulWidget {
  ///Event fired when the [InAppWebView] is created.
  final void Function(InAppWebViewController controller) onWebViewCreated;

  ///Event fired when the [InAppWebView] starts to load an [url].
  final void Function(InAppWebViewController controller, String url)
      onLoadStart;

  ///Event fired when the [InAppWebView] finishes loading an [url].
  final void Function(InAppWebViewController controller, String url) onLoadStop;

  ///Event fired when the [InAppWebView] encounters an error loading an [url].
  final void Function(InAppWebViewController controller, String url, int code,
      String message) onLoadError;

  ///Event fired when the [InAppWebView] main page receives an HTTP error.
  ///
  ///[url] represents the url of the main page that received the HTTP error.
  ///
  ///[statusCode] represents the status code of the response. HTTP errors have status codes >= 400.
  ///
  ///[description] represents the description of the HTTP error. On iOS, it is always an empty string.
  ///
  ///**NOTE**: available on Android 23+.
  final void Function(InAppWebViewController controller, String url,
      int statusCode, String description) onLoadHttpError;

  ///Event fired when the current [progress] of loading a page is changed.
  final void Function(InAppWebViewController controller, int progress)
      onProgressChanged;

  ///Event fired when the [InAppWebView] receives a [ConsoleMessage].
  final void Function(
          InAppWebViewController controller, ConsoleMessage consoleMessage)
      onConsoleMessage;

  ///Give the host application a chance to take control when a URL is about to be loaded in the current WebView.
  ///
  ///**NOTE**: In order to be able to listen this event, you need to set [InAppWebViewOptions.useShouldOverrideUrlLoading] option to `true`.
  final void Function(InAppWebViewController controller, String url)
      shouldOverrideUrlLoading;

  ///Event fired when the [InAppWebView] loads a resource.
  ///
  ///**NOTE**: In order to be able to listen this event, you need to set [InAppWebViewOptions.useOnLoadResource] and [InAppWebViewOptions.javaScriptEnabled] options to `true`.
  final void Function(
          InAppWebViewController controller, LoadedResource resource)
      onLoadResource;

  ///Event fired when the [InAppWebView] scrolls.
  ///
  ///[x] represents the current horizontal scroll origin in pixels.
  ///
  ///[y] represents the current vertical scroll origin in pixels.
  final void Function(InAppWebViewController controller, int x, int y)
      onScrollChanged;

  ///Event fired when [InAppWebView] recognizes and starts a downloadable file.
  ///
  ///[url] represents the url of the file.
  ///
  ///**NOTE**: In order to be able to listen this event, you need to set [InAppWebViewOptions.useOnDownloadStart] option to `true`.
  final void Function(InAppWebViewController controller, String url)
      onDownloadStart;

  ///Event fired when the [InAppWebView] finds the `custom-scheme` while loading a resource. Here you can handle the url request and return a [CustomSchemeResponse] to load a specific resource encoded to `base64`.
  ///
  ///[scheme] represents the scheme of the url.
  ///
  ///[url] represents the url of the request.
  final Future<CustomSchemeResponse> Function(
          InAppWebViewController controller, String scheme, String url)
      onLoadResourceCustomScheme;

  ///Event fired when the [InAppWebView] tries to open a link with `target="_blank"`.
  ///
  ///[url] represents the url of the link.
  ///
  ///**NOTE**: In order to be able to listen this event, you need to set [InAppWebViewOptions.useOnTargetBlank] option to `true`.
  final void Function(InAppWebViewController controller, String url)
      onTargetBlank;

  ///Event that notifies the host application that web content from the specified origin is attempting to use the Geolocation API, but no permission state is currently set for that origin.
  ///Note that for applications targeting Android N and later SDKs (API level > `Build.VERSION_CODES.M`) this method is only called for requests originating from secure origins such as https.
  ///On non-secure origins geolocation requests are automatically denied.
  ///
  ///[origin] represents the origin of the web content attempting to use the Geolocation API.
  ///
  ///**NOTE**: available only on Android.
  final Future<GeolocationPermissionShowPromptResponse> Function(
          InAppWebViewController controller, String origin)
      onGeolocationPermissionsShowPrompt;

  ///Event fired when javascript calls the `alert()` method to display an alert dialog.
  ///If [JsAlertResponse.handledByClient] is `true`, the webview will assume that the client will handle the dialog.
  ///
  ///[message] represents the message to be displayed in the alert dialog.
  final Future<JsAlertResponse> Function(
      InAppWebViewController controller, String message) onJsAlert;

  ///Event fired when javascript calls the `confirm()` method to display a confirm dialog.
  ///If [JsConfirmResponse.handledByClient] is `true`, the webview will assume that the client will handle the dialog.
  ///
  ///[message] represents the message to be displayed in the alert dialog.
  final Future<JsConfirmResponse> Function(
      InAppWebViewController controller, String message) onJsConfirm;

  ///Event fired when javascript calls the `prompt()` method to display a prompt dialog.
  ///If [JsPromptResponse.handledByClient] is `true`, the webview will assume that the client will handle the dialog.
  ///
  ///[message] represents the message to be displayed in the alert dialog.
  ///
  ///[defaultValue] represents the default value displayed in the prompt dialog.
  final Future<JsPromptResponse> Function(InAppWebViewController controller,
      String message, String defaultValue) onJsPrompt;

  ///Event fired when the webview notifies that a loading URL has been flagged by Safe Browsing.
  ///The default behavior is to show an interstitial to the user, with the reporting checkbox visible.
  ///
  ///[url] represents the url of the request.
  ///
  ///[threatType] represents the reason the resource was caught by Safe Browsing, corresponding to a [SafeBrowsingThreat].
  ///
  ///**NOTE**: available only on Android.
  final Future<SafeBrowsingResponse> Function(InAppWebViewController controller,
      String url, SafeBrowsingThreat threatType) onSafeBrowsingHit;

  ///Event fired when the WebView received an HTTP authentication request. The default behavior is to cancel the request.
  ///
  ///[challenge] contains data about host, port, protocol, realm, etc. as specified in the [HttpAuthChallenge].
  final Future<HttpAuthResponse> Function(
          InAppWebViewController controller, HttpAuthChallenge challenge)
      onReceivedHttpAuthRequest;

  ///Event fired when the WebView need to perform server trust authentication (certificate validation).
  ///The host application must return either [ServerTrustAuthResponse] instance with [ServerTrustAuthResponseAction.CANCEL] or [ServerTrustAuthResponseAction.PROCEED].
  ///
  ///[challenge] contains data about host, port, protocol, realm, etc. as specified in the [ServerTrustChallenge].
  final Future<ServerTrustAuthResponse> Function(
          InAppWebViewController controller, ServerTrustChallenge challenge)
      onReceivedServerTrustAuthRequest;

  ///Notify the host application to handle an SSL client certificate request.
  ///Webview stores the response in memory (for the life of the application) if [ClientCertResponseAction.PROCEED] or [ClientCertResponseAction.CANCEL]
  ///is called and does not call [onReceivedClientCertRequest] again for the same host and port pair.
  ///Note that, multiple layers in chromium network stack might be caching the responses.
  ///
  ///[challenge] contains data about host, port, protocol, realm, etc. as specified in the [ClientCertChallenge].
  final Future<ClientCertResponse> Function(
          InAppWebViewController controller, ClientCertChallenge challenge)
      onReceivedClientCertRequest;

  ///Event fired as find-on-page operations progress.
  ///The listener may be notified multiple times while the operation is underway, and the numberOfMatches value should not be considered final unless [isDoneCounting] is true.
  ///
  ///[activeMatchOrdinal] represents the zero-based ordinal of the currently selected match.
  ///
  ///[numberOfMatches] represents how many matches have been found.
  ///
  ///[isDoneCounting] whether the find operation has actually completed.
  final void Function(InAppWebViewController controller, int activeMatchOrdinal,
      int numberOfMatches, bool isDoneCounting) onFindResultReceived;

  ///Event fired when an `XMLHttpRequest` is sent to a server.
  ///It gives the host application a chance to take control over the request before sending it.
  ///
  ///[ajaxRequest] represents the `XMLHttpRequest`.
  ///
  ///**NOTE**: In order to be able to listen this event, you need to set [InAppWebViewOptions.useShouldInterceptAjaxRequest] option to `true`.
  ///Also, unlike iOS that has [WKUserScript](https://developer.apple.com/documentation/webkit/wkuserscript) that
  ///can inject javascript code right after the document element is created but before any other content is loaded, in Android the javascript code
  ///used to intercept ajax requests is loaded as soon as possible so it won't be instantaneous as iOS but just after some milliseconds (< ~100ms).
  ///Inside the `window.addEventListener("flutterInAppWebViewPlatformReady")` event, the ajax requests will be intercept for sure.
  final Future<AjaxRequest> Function(
          InAppWebViewController controller, AjaxRequest ajaxRequest)
      shouldInterceptAjaxRequest;

  ///Event fired whenever the `readyState` attribute of an `XMLHttpRequest` changes.
  ///It gives the host application a chance to abort the request.
  ///
  ///[ajaxRequest] represents the [XMLHttpRequest].
  ///
  ///**NOTE**: In order to be able to listen this event, you need to set [InAppWebViewOptions.useShouldInterceptAjaxRequest] option to `true`.
  ///Also, unlike iOS that has [WKUserScript](https://developer.apple.com/documentation/webkit/wkuserscript) that
  ///can inject javascript code right after the document element is created but before any other content is loaded, in Android the javascript code
  ///used to intercept ajax requests is loaded as soon as possible so it won't be instantaneous as iOS but just after some milliseconds (< ~100ms).
  ///Inside the `window.addEventListener("flutterInAppWebViewPlatformReady")` event, the ajax requests will be intercept for sure.
  final Future<AjaxRequestAction> Function(
          InAppWebViewController controller, AjaxRequest ajaxRequest)
      onAjaxReadyStateChange;

  ///Event fired as an `XMLHttpRequest` progress.
  ///It gives the host application a chance to abort the request.
  ///
  ///[ajaxRequest] represents the [XMLHttpRequest].
  ///
  ///**NOTE**: In order to be able to listen this event, you need to set [InAppWebViewOptions.useShouldInterceptAjaxRequest] option to `true`.
  ///Also, unlike iOS that has [WKUserScript](https://developer.apple.com/documentation/webkit/wkuserscript) that
  ///can inject javascript code right after the document element is created but before any other content is loaded, in Android the javascript code
  ///used to intercept ajax requests is loaded as soon as possible so it won't be instantaneous as iOS but just after some milliseconds (< ~100ms).
  ///Inside the `window.addEventListener("flutterInAppWebViewPlatformReady")` event, the ajax requests will be intercept for sure.
  final Future<AjaxRequestAction> Function(
          InAppWebViewController controller, AjaxRequest ajaxRequest)
      onAjaxProgress;

  ///Event fired when a request is sent to a server through [Fetch API](https://developer.mozilla.org/it/docs/Web/API/Fetch_API).
  ///It gives the host application a chance to take control over the request before sending it.
  ///
  ///[fetchRequest] represents a resource request.
  ///
  ///**NOTE**: In order to be able to listen this event, you need to set [InAppWebViewOptions.useShouldInterceptFetchRequest] option to `true`.
  ///Also, unlike iOS that has [WKUserScript](https://developer.apple.com/documentation/webkit/wkuserscript) that
  ///can inject javascript code right after the document element is created but before any other content is loaded, in Android the javascript code
  ///used to intercept fetch requests is loaded as soon as possible so it won't be instantaneous as iOS but just after some milliseconds (< ~100ms).
  ///Inside the `window.addEventListener("flutterInAppWebViewPlatformReady")` event, the fetch requests will be intercept for sure.
  final Future<FetchRequest> Function(
          InAppWebViewController controller, FetchRequest fetchRequest)
      shouldInterceptFetchRequest;

  ///Event fired when the navigation state of the [InAppWebView] changes throught the usage of
  ///javascript **[History API](https://developer.mozilla.org/en-US/docs/Web/API/History_API)** functions (`pushState()`, `replaceState()`) and `onpopstate` event.
  ///
  ///Also, the event is fired when the javascript `window.location` changes without reloading the webview (for example appending or modifying an hash to the url).
  ///
  ///[url] represents the new url.
  final void Function(InAppWebViewController controller, String url)
      onNavigationStateChange;

  ///Event fired when the WebView is requesting permission to access the specified resources and the permission currently isn't granted or denied.
  ///
  ///[origin] represents the origin of the web page which is trying to access the restricted resources.
  ///
  ///[resources] represents the array of resources the web content wants to access.
  ///
  ///**NOTE**: available only on Android 23+.
  final Future<PermissionRequestResponse> Function(
      InAppWebViewController controller,
      String origin,
      List<String> resources) onPermissionRequest;

  ///Initial url that will be loaded.
  final String initialUrl;

  ///Initial asset file that will be loaded. See [InAppWebView.loadFile()] for explanation.
  final String initialFile;

  ///Initial [InAppWebViewInitialData] that will be loaded.
  final InAppWebViewInitialData initialData;

  ///Initial headers that will be used.
  final Map<String, String> initialHeaders;

  ///Initial options that will be used.
  final InAppWebViewWidgetOptions initialOptions;

  /// `gestureRecognizers` specifies which gestures should be consumed by the web view.
  /// It is possible for other gesture recognizers to be competing with the web view on pointer
  /// events, e.g if the web view is inside a [ListView] the [ListView] will want to handle
  /// vertical drags. The web view will claim gestures that are recognized by any of the
  /// recognizers on this list.
  /// When `gestureRecognizers` is empty or null, the web view will only handle pointer events for gestures that
  /// were not claimed by any other gesture recognizer.
  final Set<Factory<OneSequenceGestureRecognizer>> gestureRecognizers;

  const InAppWebView({
    Key key,
    this.initialUrl = "about:blank",
    this.initialFile,
    this.initialData,
    this.initialHeaders = const {},
    @required this.initialOptions,
    this.onWebViewCreated,
    this.onLoadStart,
    this.onLoadStop,
    this.onLoadError,
    this.onLoadHttpError,
    this.onConsoleMessage,
    this.onProgressChanged,
    this.shouldOverrideUrlLoading,
    this.onLoadResource,
    this.onScrollChanged,
    this.onDownloadStart,
    this.onLoadResourceCustomScheme,
    this.onTargetBlank,
    this.onGeolocationPermissionsShowPrompt,
    this.onJsAlert,
    this.onJsConfirm,
    this.onJsPrompt,
    this.onSafeBrowsingHit,
    this.onReceivedHttpAuthRequest,
    this.onReceivedServerTrustAuthRequest,
    this.onReceivedClientCertRequest,
    this.onFindResultReceived,
    this.shouldInterceptAjaxRequest,
    this.onAjaxReadyStateChange,
    this.onAjaxProgress,
    this.shouldInterceptFetchRequest,
    this.onNavigationStateChange,
    this.onPermissionRequest,
    this.gestureRecognizers,
  }) : super(key: key);

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

class _InAppWebViewState extends State<InAppWebView> {
  InAppWebViewController _controller;

  @override
  Widget build(BuildContext context) {
    Map<String, dynamic> initialOptions = {};
    initialOptions
        .addAll(widget.initialOptions.inAppWebViewOptions?.toMap() ?? {});
    if (Platform.isAndroid)
      initialOptions.addAll(
          widget.initialOptions.androidInAppWebViewOptions?.toMap() ?? {});
    else if (Platform.isIOS)
      initialOptions
          .addAll(widget.initialOptions.iosInAppWebViewOptions?.toMap() ?? {});

    if (defaultTargetPlatform == TargetPlatform.android) {
      return AndroidView(
        viewType: 'com.pichillilorenzo/flutter_inappwebview',
        onPlatformViewCreated: _onPlatformViewCreated,
        gestureRecognizers: widget.gestureRecognizers,
        layoutDirection: TextDirection.rtl,
        creationParams: <String, dynamic>{
          'initialUrl': widget.initialUrl,
          'initialFile': widget.initialFile,
          'initialData': widget.initialData?.toMap(),
          'initialHeaders': widget.initialHeaders,
          'initialOptions': initialOptions
        },
        creationParamsCodec: const StandardMessageCodec(),
      );
      // onLongPress issue: https://github.com/flutter/plugins/blob/f31d16a6ca0c4bd6849cff925a00b6823973696b/packages/webview_flutter/lib/src/webview_android.dart#L31
      /*return GestureDetector(
        onLongPress: () {},
        excludeFromSemantics: true,
        child: AndroidView(
          viewType: 'com.pichillilorenzo/flutter_inappwebview',
          onPlatformViewCreated: _onPlatformViewCreated,
          gestureRecognizers: widget.gestureRecognizers,
          layoutDirection: TextDirection.rtl,
          creationParams: <String, dynamic>{
            'initialUrl': widget.initialUrl,
            'initialFile': widget.initialFile,
            'initialData': widget.initialData?.toMap(),
            'initialHeaders': widget.initialHeaders,
            'initialOptions': initialOptions
          },
          creationParamsCodec: const StandardMessageCodec(),
        ),
      );*/
    } else if (defaultTargetPlatform == TargetPlatform.iOS) {
      return UiKitView(
        viewType: 'com.pichillilorenzo/flutter_inappwebview',
        onPlatformViewCreated: _onPlatformViewCreated,
        gestureRecognizers: widget.gestureRecognizers,
        creationParams: <String, dynamic>{
          'initialUrl': widget.initialUrl,
          'initialFile': widget.initialFile,
          'initialData': widget.initialData?.toMap(),
          'initialHeaders': widget.initialHeaders,
          'initialOptions': initialOptions
        },
        creationParamsCodec: const StandardMessageCodec(),
      );
    }
    return Text(
        '$defaultTargetPlatform is not yet supported by the flutter_inappwebview plugin');
  }

  @override
  void didUpdateWidget(InAppWebView oldWidget) {
    super.didUpdateWidget(oldWidget);
  }

  @override
  void dispose() {
    super.dispose();
  }

  void _onPlatformViewCreated(int id) {
    _controller = InAppWebViewController(id, widget);
    if (widget.onWebViewCreated != null) {
      widget.onWebViewCreated(_controller);
    }
  }
}

/// Controls an [InAppWebView] widget instance.
///
/// An [InAppWebViewController] instance can be obtained by setting the [InAppWebView.onWebViewCreated]
/// callback for an [InAppWebView] widget.
class InAppWebViewController {
  InAppWebView _widget;
  MethodChannel _channel;
  Map<String, JavaScriptHandlerCallback> javaScriptHandlersMap =
      HashMap<String, JavaScriptHandlerCallback>();
  // ignore: unused_field
  bool _isOpened = false;
  // ignore: unused_field
  int _id;
  String _inAppBrowserUuid;
  InAppBrowser _inAppBrowser;

  InAppWebViewController(int id, InAppWebView widget) {
    this._id = id;
    this._channel =
        MethodChannel('com.pichillilorenzo/flutter_inappwebview_$id');
    this._channel.setMethodCallHandler(handleMethod);
    this._widget = widget;
  }

  InAppWebViewController.fromInAppBrowser(
      String uuid, MethodChannel channel, InAppBrowser inAppBrowser) {
    this._inAppBrowserUuid = uuid;
    this._channel = channel;
    this._inAppBrowser = inAppBrowser;
  }

  Future<dynamic> handleMethod(MethodCall call) async {
    switch (call.method) {
      case "onLoadStart":
        String url = call.arguments["url"];
        if (_widget != null && _widget.onLoadStart != null)
          _widget.onLoadStart(this, url);
        else if (_inAppBrowser != null) _inAppBrowser.onLoadStart(url);
        break;
      case "onLoadStop":
        String url = call.arguments["url"];
        if (_widget != null && _widget.onLoadStop != null)
          _widget.onLoadStop(this, url);
        else if (_inAppBrowser != null) _inAppBrowser.onLoadStop(url);
        break;
      case "onLoadError":
        String url = call.arguments["url"];
        int code = call.arguments["code"];
        String message = call.arguments["message"];
        if (_widget != null && _widget.onLoadError != null)
          _widget.onLoadError(this, url, code, message);
        else if (_inAppBrowser != null)
          _inAppBrowser.onLoadError(url, code, message);
        break;
      case "onLoadHttpError":
        String url = call.arguments["url"];
        int statusCode = call.arguments["statusCode"];
        String description = call.arguments["description"];
        if (_widget != null && _widget.onLoadHttpError != null)
          _widget.onLoadHttpError(this, url, statusCode, description);
        else if (_inAppBrowser != null)
          _inAppBrowser.onLoadHttpError(url, statusCode, description);
        break;
      case "onProgressChanged":
        int progress = call.arguments["progress"];
        if (_widget != null && _widget.onProgressChanged != null)
          _widget.onProgressChanged(this, progress);
        else if (_inAppBrowser != null)
          _inAppBrowser.onProgressChanged(progress);
        break;
      case "shouldOverrideUrlLoading":
        String url = call.arguments["url"];
        if (_widget != null && _widget.shouldOverrideUrlLoading != null)
          _widget.shouldOverrideUrlLoading(this, url);
        else if (_inAppBrowser != null)
          _inAppBrowser.shouldOverrideUrlLoading(url);
        break;
      case "onConsoleMessage":
        String message = call.arguments["message"];
        ConsoleMessageLevel messageLevel =
            ConsoleMessageLevel.fromValue(call.arguments["messageLevel"]);
        ConsoleMessage consoleMessage =
            ConsoleMessage(message: message, messageLevel: messageLevel);
        if (_widget != null && _widget.onConsoleMessage != null)
          _widget.onConsoleMessage(this, consoleMessage);
        else if (_inAppBrowser != null)
          _inAppBrowser.onConsoleMessage(consoleMessage);
        break;
      case "onScrollChanged":
        int x = call.arguments["x"];
        int y = call.arguments["y"];
        if (_widget != null && _widget.onScrollChanged != null)
          _widget.onScrollChanged(this, x, y);
        else if (_inAppBrowser != null) _inAppBrowser.onScrollChanged(x, y);
        break;
      case "onDownloadStart":
        String url = call.arguments["url"];
        if (_widget != null && _widget.onDownloadStart != null)
          _widget.onDownloadStart(this, url);
        else if (_inAppBrowser != null) _inAppBrowser.onDownloadStart(url);
        break;
      case "onLoadResourceCustomScheme":
        String scheme = call.arguments["scheme"];
        String url = call.arguments["url"];
        if (_widget != null && _widget.onLoadResourceCustomScheme != null) {
          try {
            var response =
                await _widget.onLoadResourceCustomScheme(this, scheme, url);
            return (response != null) ? response.toJson() : null;
          } catch (error) {
            print(error);
            return null;
          }
        } else if (_inAppBrowser != null) {
          try {
            var response =
                await _inAppBrowser.onLoadResourceCustomScheme(scheme, url);
            return (response != null) ? response.toJson() : null;
          } catch (error) {
            print(error);
            return null;
          }
        }
        break;
      case "onTargetBlank":
        String url = call.arguments["url"];
        if (_widget != null && _widget.onTargetBlank != null)
          _widget.onTargetBlank(this, url);
        else if (_inAppBrowser != null) _inAppBrowser.onTargetBlank(url);
        break;
      case "onGeolocationPermissionsShowPrompt":
        String origin = call.arguments["origin"];
        if (_widget != null &&
            _widget.onGeolocationPermissionsShowPrompt != null)
          return (await _widget.onGeolocationPermissionsShowPrompt(
                  this, origin))
              ?.toMap();
        else if (_inAppBrowser != null)
          return (await _inAppBrowser
                  .onGeolocationPermissionsShowPrompt(origin))
              ?.toMap();
        break;
      case "onJsAlert":
        String message = call.arguments["message"];
        if (_widget != null && _widget.onJsAlert != null)
          return (await _widget.onJsAlert(this, message))?.toMap();
        else if (_inAppBrowser != null)
          return (await _inAppBrowser.onJsAlert(message))?.toMap();
        break;
      case "onJsConfirm":
        String message = call.arguments["message"];
        if (_widget != null && _widget.onJsConfirm != null)
          return (await _widget.onJsConfirm(this, message))?.toMap();
        else if (_inAppBrowser != null)
          return (await _inAppBrowser.onJsConfirm(message))?.toMap();
        break;
      case "onJsPrompt":
        String message = call.arguments["message"];
        String defaultValue = call.arguments["defaultValue"];
        if (_widget != null && _widget.onJsPrompt != null)
          return (await _widget.onJsPrompt(this, message, defaultValue))
              ?.toMap();
        else if (_inAppBrowser != null)
          return (await _inAppBrowser.onJsPrompt(message, defaultValue))
              ?.toMap();
        break;
      case "onSafeBrowsingHit":
        String url = call.arguments["url"];
        SafeBrowsingThreat threatType =
            SafeBrowsingThreat.fromValue(call.arguments["threatType"]);
        if (_widget != null && _widget.onSafeBrowsingHit != null)
          return (await _widget.onSafeBrowsingHit(this, url, threatType))
              ?.toMap();
        else if (_inAppBrowser != null)
          return (await _inAppBrowser.onSafeBrowsingHit(url, threatType))
              ?.toMap();
        break;
      case "onReceivedHttpAuthRequest":
        String host = call.arguments["host"];
        String protocol = call.arguments["protocol"];
        String realm = call.arguments["realm"];
        int port = call.arguments["port"];
        int previousFailureCount = call.arguments["previousFailureCount"];
        var protectionSpace = ProtectionSpace(
            host: host, protocol: protocol, realm: realm, port: port);
        var challenge = HttpAuthChallenge(
            previousFailureCount: previousFailureCount,
            protectionSpace: protectionSpace);
        if (_widget != null && _widget.onReceivedHttpAuthRequest != null)
          return (await _widget.onReceivedHttpAuthRequest(this, challenge))
              ?.toMap();
        else if (_inAppBrowser != null)
          return (await _inAppBrowser.onReceivedHttpAuthRequest(challenge))
              ?.toMap();
        break;
      case "onReceivedServerTrustAuthRequest":
        String host = call.arguments["host"];
        String protocol = call.arguments["protocol"];
        String realm = call.arguments["realm"];
        int port = call.arguments["port"];
        int error = call.arguments["error"];
        String message = call.arguments["message"];
        Uint8List serverCertificate = call.arguments["serverCertificate"];
        var protectionSpace = ProtectionSpace(
            host: host, protocol: protocol, realm: realm, port: port);
        var challenge = ServerTrustChallenge(
            protectionSpace: protectionSpace,
            error: error,
            message: message,
            serverCertificate: serverCertificate);
        if (_widget != null && _widget.onReceivedServerTrustAuthRequest != null)
          return (await _widget.onReceivedServerTrustAuthRequest(
                  this, challenge))
              ?.toMap();
        else if (_inAppBrowser != null)
          return (await _inAppBrowser
                  .onReceivedServerTrustAuthRequest(challenge))
              ?.toMap();
        break;
      case "onReceivedClientCertRequest":
        String host = call.arguments["host"];
        String protocol = call.arguments["protocol"];
        String realm = call.arguments["realm"];
        int port = call.arguments["port"];
        var protectionSpace = ProtectionSpace(
            host: host, protocol: protocol, realm: realm, port: port);
        var challenge = ClientCertChallenge(protectionSpace: protectionSpace);
        if (_widget != null && _widget.onReceivedClientCertRequest != null)
          return (await _widget.onReceivedClientCertRequest(this, challenge))
              ?.toMap();
        else if (_inAppBrowser != null)
          return (await _inAppBrowser.onReceivedClientCertRequest(challenge))
              ?.toMap();
        break;
      case "onFindResultReceived":
        int activeMatchOrdinal = call.arguments["activeMatchOrdinal"];
        int numberOfMatches = call.arguments["numberOfMatches"];
        bool isDoneCounting = call.arguments["isDoneCounting"];
        if (_widget != null && _widget.onFindResultReceived != null)
          _widget.onFindResultReceived(
              this, activeMatchOrdinal, numberOfMatches, isDoneCounting);
        else if (_inAppBrowser != null)
          _inAppBrowser.onFindResultReceived(
              activeMatchOrdinal, numberOfMatches, isDoneCounting);
        break;
      case "onNavigationStateChange":
        String url = call.arguments["url"];
        if (_widget != null && _widget.onNavigationStateChange != null)
          _widget.onNavigationStateChange(this, url);
        else if (_inAppBrowser != null)
          _inAppBrowser.onNavigationStateChange(url);
        break;
      case "onPermissionRequest":
        String origin = call.arguments["origin"];
        List<String> resources = call.arguments["resources"].cast<String>();
        if (_widget != null && _widget.onPermissionRequest != null)
          return (await _widget.onPermissionRequest(this, origin, resources))
              ?.toMap();
        else if (_inAppBrowser != null)
          return (await _inAppBrowser.onPermissionRequest(origin, resources))
              ?.toMap();
        break;
      case "onCallJsHandler":
        String handlerName = call.arguments["handlerName"];
        // decode args to json
        List<dynamic> args = jsonDecode(call.arguments["args"]);

        switch (handlerName) {
          case "onLoadResource":
            Map<dynamic, dynamic> argMap = args[0];
            String initiatorType = argMap["initiatorType"];
            String url = argMap["name"];
            double startTime = argMap["startTime"] is int
                ? argMap["startTime"].toDouble()
                : argMap["startTime"];
            double duration = argMap["duration"] is int
                ? argMap["duration"].toDouble()
                : argMap["duration"];

            var response = new LoadedResource(
                initiatorType: initiatorType,
                url: url,
                startTime: startTime,
                duration: duration);

            if (_widget != null && _widget.onLoadResource != null)
              _widget.onLoadResource(this, response);
            else if (_inAppBrowser != null)
              _inAppBrowser.onLoadResource(response);
            return null;
          case "shouldInterceptAjaxRequest":
            Map<dynamic, dynamic> argMap = args[0];
            dynamic data = argMap["data"];
            String method = argMap["method"];
            String url = argMap["url"];
            bool isAsync = argMap["isAsync"];
            String user = argMap["user"];
            String password = argMap["password"];
            bool withCredentials = argMap["withCredentials"];
            AjaxRequestHeaders headers = AjaxRequestHeaders(argMap["headers"]);
            String responseType = argMap["responseType"];

            var request = new AjaxRequest(
                data: data,
                method: method,
                url: url,
                isAsync: isAsync,
                user: user,
                password: password,
                withCredentials: withCredentials,
                headers: headers,
                responseType: responseType);

            if (_widget != null && _widget.shouldInterceptAjaxRequest != null)
              return jsonEncode(
                  await _widget.shouldInterceptAjaxRequest(this, request));
            else if (_inAppBrowser != null)
              return jsonEncode(
                  await _inAppBrowser.shouldInterceptAjaxRequest(request));
            return null;
          case "onAjaxReadyStateChange":
            Map<dynamic, dynamic> argMap = args[0];
            dynamic data = argMap["data"];
            String method = argMap["method"];
            String url = argMap["url"];
            bool isAsync = argMap["isAsync"];
            String user = argMap["user"];
            String password = argMap["password"];
            bool withCredentials = argMap["withCredentials"];
            AjaxRequestHeaders headers = AjaxRequestHeaders(argMap["headers"]);
            int readyState = argMap["readyState"];
            int status = argMap["status"];
            String responseURL = argMap["responseURL"];
            String responseType = argMap["responseType"];
            dynamic response = argMap["response"];
            String responseText = argMap["responseText"];
            String responseXML = argMap["responseXML"];
            String statusText = argMap["statusText"];
            Map<dynamic, dynamic> responseHeaders = argMap["responseHeaders"];

            var request = new AjaxRequest(
                data: data,
                method: method,
                url: url,
                isAsync: isAsync,
                user: user,
                password: password,
                withCredentials: withCredentials,
                headers: headers,
                readyState: AjaxRequestReadyState.fromValue(readyState),
                status: status,
                responseURL: responseURL,
                responseType: responseType,
                response: response,
                responseText: responseText,
                responseXML: responseXML,
                statusText: statusText,
                responseHeaders: responseHeaders);

            if (_widget != null && _widget.onAjaxReadyStateChange != null)
              return jsonEncode(
                  await _widget.onAjaxReadyStateChange(this, request));
            else if (_inAppBrowser != null)
              return jsonEncode(
                  await _inAppBrowser.onAjaxReadyStateChange(request));
            return null;
          case "onAjaxProgress":
            Map<dynamic, dynamic> argMap = args[0];
            dynamic data = argMap["data"];
            String method = argMap["method"];
            String url = argMap["url"];
            bool isAsync = argMap["isAsync"];
            String user = argMap["user"];
            String password = argMap["password"];
            bool withCredentials = argMap["withCredentials"];
            AjaxRequestHeaders headers = AjaxRequestHeaders(argMap["headers"]);
            int readyState = argMap["readyState"];
            int status = argMap["status"];
            String responseURL = argMap["responseURL"];
            String responseType = argMap["responseType"];
            dynamic response = argMap["response"];
            String responseText = argMap["responseText"];
            String responseXML = argMap["responseXML"];
            String statusText = argMap["statusText"];
            Map<dynamic, dynamic> responseHeaders = argMap["responseHeaders"];
            Map<dynamic, dynamic> eventMap = argMap["event"];

            AjaxRequestEvent event = AjaxRequestEvent(
                lengthComputable: eventMap["lengthComputable"],
                loaded: eventMap["loaded"],
                total: eventMap["total"],
                type: AjaxRequestEventType.fromValue(eventMap["type"]));

            var request = new AjaxRequest(
                data: data,
                method: method,
                url: url,
                isAsync: isAsync,
                user: user,
                password: password,
                withCredentials: withCredentials,
                headers: headers,
                readyState: AjaxRequestReadyState.fromValue(readyState),
                status: status,
                responseURL: responseURL,
                responseType: responseType,
                response: response,
                responseText: responseText,
                responseXML: responseXML,
                statusText: statusText,
                responseHeaders: responseHeaders,
                event: event);

            if (_widget != null && _widget.onAjaxProgress != null)
              return jsonEncode(await _widget.onAjaxProgress(this, request));
            else if (_inAppBrowser != null)
              return jsonEncode(await _inAppBrowser.onAjaxProgress(request));
            return null;
          case "shouldInterceptFetchRequest":
            Map<dynamic, dynamic> argMap = args[0];
            String url = argMap["url"];
            String method = argMap["method"];
            Map<dynamic, dynamic> headers = argMap["headers"];
            Uint8List body = Uint8List.fromList(argMap["body"].cast<int>());
            String mode = argMap["mode"];
            FetchRequestCredential credentials =
                FetchRequest.createFetchRequestCredentialFromMap(
                    argMap["credentials"]);
            String cache = argMap["cache"];
            String redirect = argMap["redirect"];
            String referrer = argMap["referrer"];
            String referrerPolicy = argMap["referrerPolicy"];
            String integrity = argMap["integrity"];
            bool keepalive = argMap["keepalive"];

            var request = new FetchRequest(
                url: url,
                method: method,
                headers: headers,
                body: body,
                mode: mode,
                credentials: credentials,
                cache: cache,
                redirect: redirect,
                referrer: referrer,
                referrerPolicy: referrerPolicy,
                integrity: integrity,
                keepalive: keepalive);

            if (_widget != null && _widget.shouldInterceptFetchRequest != null)
              return jsonEncode(
                  await _widget.shouldInterceptFetchRequest(this, request));
            else if (_inAppBrowser != null)
              return jsonEncode(
                  await _inAppBrowser.shouldInterceptFetchRequest(request));
            return null;
        }

        if (javaScriptHandlersMap.containsKey(handlerName)) {
          // convert result to json
          try {
            return jsonEncode(await javaScriptHandlersMap[handlerName](args));
          } catch (error) {
            print(error);
            return null;
          }
        }
        break;
      default:
        throw UnimplementedError("Unimplemented ${call.method} method");
    }
  }

  ///Gets the URL for the current page.
  ///This is not always the same as the URL passed to [InAppWebView.onLoadStarted] because although the load for that URL has begun, the current page may not have changed.
  Future<String> getUrl() async {
    Map<String, dynamic> args = <String, dynamic>{};
    if (_inAppBrowserUuid != null && _inAppBrowser != null) {
      _inAppBrowser.throwIsNotOpened();
      args.putIfAbsent('uuid', () => _inAppBrowserUuid);
    }
    return await _channel.invokeMethod('getUrl', args);
  }

  ///Gets the title for the current page.
  Future<String> getTitle() async {
    Map<String, dynamic> args = <String, dynamic>{};
    if (_inAppBrowserUuid != null && _inAppBrowser != null) {
      _inAppBrowser.throwIsNotOpened();
      args.putIfAbsent('uuid', () => _inAppBrowserUuid);
    }
    return await _channel.invokeMethod('getTitle', args);
  }

  ///Gets the progress for the current page. The progress value is between 0 and 100.
  Future<int> getProgress() async {
    Map<String, dynamic> args = <String, dynamic>{};
    if (_inAppBrowserUuid != null && _inAppBrowser != null) {
      _inAppBrowser.throwIsNotOpened();
      args.putIfAbsent('uuid', () => _inAppBrowserUuid);
    }
    return await _channel.invokeMethod('getProgress', args);
  }

  ///Gets the content html of the page. It first tries to get the content through javascript.
  ///If this doesn't work, it tries to get the content reading the file:
  ///- checking if it is an asset (`file:///`) or
  ///- downloading it using an `HttpClient` through the WebView's current url.
  Future<String> getHtml() async {
    var html = "";
    InAppWebViewWidgetOptions options = await getOptions();
    if (options != null &&
        options.inAppWebViewOptions.javaScriptEnabled == true) {
      html = await evaluateJavascript(
          source: "window.document.getElementsByTagName('html')[0].outerHTML;");
      if (html != null && html.isNotEmpty) return html;
    }

    var webviewUrl = await getUrl();
    if (webviewUrl.startsWith("file:///")) {
      var assetPathSplitted = webviewUrl.split("/flutter_assets/");
      var assetPath = assetPathSplitted[assetPathSplitted.length - 1];
      var bytes = await rootBundle.load(assetPath);
      html = utf8.decode(bytes.buffer.asUint8List());
    } else {
      HttpClient client = new HttpClient();
      var url = Uri.parse(webviewUrl);
      try {
        var htmlRequest = await client.getUrl(url);
        html =
            await (await htmlRequest.close()).transform(Utf8Decoder()).join();
      } catch (e) {
        print(e);
      }
    }
    return html;
  }

  ///Gets the list of all favicons for the current page.
  Future<List<Favicon>> getFavicons() async {
    List<Favicon> favicons = [];

    HttpClient client = new HttpClient();
    var webviewUrl = await getUrl();
    var url = (webviewUrl.startsWith("file:///"))
        ? Uri.file(webviewUrl)
        : Uri.parse(webviewUrl);
    String manifestUrl;

    var html = await getHtml();
    if (html.isEmpty) {
      return favicons;
    }

    var assetPathBase;

    if (webviewUrl.startsWith("file:///")) {
      var assetPathSplitted = webviewUrl.split("/flutter_assets/");
      assetPathBase = assetPathSplitted[0] + "/flutter_assets/";
    }

    // get all link html elements
    var document = parse(html);
    var links = document.getElementsByTagName('link');
    for (var link in links) {
      var attributes = link.attributes;
      if (attributes["rel"] == "manifest") {
        manifestUrl = attributes["href"];
        if (!_isUrlAbsolute(manifestUrl)) {
          if (manifestUrl.startsWith("/")) {
            manifestUrl = manifestUrl.substring(1);
          }
          manifestUrl = ((assetPathBase == null)
                  ? url.scheme + "://" + url.host + "/"
                  : assetPathBase) +
              manifestUrl;
        }
        continue;
      }
      if (!attributes["rel"].contains("icon")) {
        continue;
      }
      favicons.addAll(_createFavicons(url, assetPathBase, attributes["href"],
          attributes["rel"], attributes["sizes"], false));
    }

    // try to get /favicon.ico
    try {
      var faviconUrl = url.scheme + "://" + url.host + "/favicon.ico";
      await client.headUrl(Uri.parse(faviconUrl));
      favicons.add(Favicon(url: faviconUrl, rel: "shortcut icon"));
    } catch (e) {
      print("/favicon.ico file not found: " + e.toString());
    }

    // try to get the manifest file
    HttpClientRequest manifestRequest;
    HttpClientResponse manifestResponse;
    bool manifestFound = false;
    if (manifestUrl == null) {
      manifestUrl = url.scheme + "://" + url.host + "/manifest.json";
    }
    try {
      manifestRequest = await client.getUrl(Uri.parse(manifestUrl));
      manifestResponse = await manifestRequest.close();
      manifestFound = manifestResponse.statusCode == 200 &&
          manifestResponse.headers.contentType?.mimeType == "application/json";
    } catch (e) {
      print("Manifest file not found: " + e.toString());
    }

    if (manifestFound) {
      Map<String, dynamic> manifest =
          json.decode(await manifestResponse.transform(Utf8Decoder()).join());
      if (manifest.containsKey("icons")) {
        for (Map<String, dynamic> icon in manifest["icons"]) {
          favicons.addAll(_createFavicons(url, assetPathBase, icon["src"],
              icon["rel"], icon["sizes"], true));
        }
      }
    }

    return favicons;
  }

  bool _isUrlAbsolute(String url) {
    return url.startsWith("http://") || url.startsWith("https://");
  }

  List<Favicon> _createFavicons(Uri url, String assetPathBase, String urlIcon,
      String rel, String sizes, bool isManifest) {
    List<Favicon> favicons = [];

    List<String> urlSplitted = urlIcon.split("/");
    if (!_isUrlAbsolute(urlIcon)) {
      if (urlIcon.startsWith("/")) {
        urlIcon = urlIcon.substring(1);
      }
      urlIcon = ((assetPathBase == null)
              ? url.scheme + "://" + url.host + "/"
              : assetPathBase) +
          urlIcon;
    }
    if (isManifest) {
      rel = (sizes != null)
          ? urlSplitted[urlSplitted.length - 1]
              .replaceFirst("-" + sizes, "")
              .split(" ")[0]
              .split(".")[0]
          : null;
    }
    if (sizes != null && sizes.isNotEmpty && sizes != "any") {
      List<String> sizesSplitted = sizes.split(" ");
      for (String size in sizesSplitted) {
        int width = int.parse(size.split("x")[0]);
        int height = int.parse(size.split("x")[1]);
        favicons
            .add(Favicon(url: urlIcon, rel: rel, width: width, height: height));
      }
    } else {
      favicons.add(Favicon(url: urlIcon, rel: rel, width: null, height: null));
    }

    return favicons;
  }

  ///Loads the given [url] with optional [headers] specified as a map from name to value.
  Future<void> loadUrl(
      {@required String url, Map<String, String> headers = const {}}) async {
    assert(url != null && url.isNotEmpty);
    Map<String, dynamic> args = <String, dynamic>{};
    if (_inAppBrowserUuid != null && _inAppBrowser != null) {
      _inAppBrowser.throwIsNotOpened(message: 'Cannot laod $url!');
      args.putIfAbsent('uuid', () => _inAppBrowserUuid);
    }
    args.putIfAbsent('url', () => url);
    args.putIfAbsent('headers', () => headers);
    await _channel.invokeMethod('loadUrl', args);
  }

  ///Loads the given [url] with [postData] using `POST` method into this WebView.
  Future<void> postUrl(
      {@required String url, @required Uint8List postData}) async {
    assert(url != null && url.isNotEmpty);
    assert(postData != null);
    Map<String, dynamic> args = <String, dynamic>{};
    if (_inAppBrowserUuid != null && _inAppBrowser != null) {
      _inAppBrowser.throwIsNotOpened(message: 'Cannot laod $url!');
      args.putIfAbsent('uuid', () => _inAppBrowserUuid);
    }
    args.putIfAbsent('url', () => url);
    args.putIfAbsent('postData', () => postData);
    await _channel.invokeMethod('postUrl', args);
  }

  ///Loads the given [data] into this WebView, using [baseUrl] as the base URL for the content.
  ///
  ///The [mimeType] parameter specifies the format of the data. The default value is `"text/html"`.
  ///
  ///The [encoding] parameter specifies the encoding of the data. The default value is `"utf8"`.
  ///
  ///The [historyUrl] parameter is the URL to use as the history entry. The default value is `about:blank`. If non-null, this must be a valid URL. This parameter is used only on Android.
  Future<void> loadData(
      {@required String data,
      String mimeType = "text/html",
      String encoding = "utf8",
      String baseUrl = "about:blank",
      String historyUrl = "about:blank"}) async {
    assert(data != null);
    Map<String, dynamic> args = <String, dynamic>{};
    if (_inAppBrowserUuid != null && _inAppBrowser != null) {
      _inAppBrowser.throwIsNotOpened();
      args.putIfAbsent('uuid', () => _inAppBrowserUuid);
    }
    args.putIfAbsent('data', () => data);
    args.putIfAbsent('mimeType', () => mimeType);
    args.putIfAbsent('encoding', () => encoding);
    args.putIfAbsent('baseUrl', () => baseUrl);
    args.putIfAbsent('historyUrl', () => historyUrl);
    await _channel.invokeMethod('loadData', args);
  }

  ///Loads the given [assetFilePath] with optional [headers] specified as a map from name to value.
  ///
  ///To be able to load your local files (assets, js, css, etc.), you need to add them in the `assets` section of the `pubspec.yaml` file, otherwise they cannot be found!
  ///
  ///Example of a `pubspec.yaml` file:
  ///```yaml
  ///...
  ///
  ///# The following section is specific to Flutter.
  ///flutter:
  ///
  ///  # The following line ensures that the Material Icons font is
  ///  # included with your application, so that you can use the icons in
  ///  # the material Icons class.
  ///  uses-material-design: true
  ///
  ///  assets:
  ///    - assets/index.html
  ///    - assets/css/
  ///    - assets/images/
  ///
  ///...
  ///```
  ///Example of a `main.dart` file:
  ///```dart
  ///...
  ///inAppBrowser.loadFile("assets/index.html");
  ///...
  ///```
  Future<void> loadFile(
      {@required String assetFilePath,
      Map<String, String> headers = const {}}) async {
    assert(assetFilePath != null && assetFilePath.isNotEmpty);
    Map<String, dynamic> args = <String, dynamic>{};
    if (_inAppBrowserUuid != null && _inAppBrowser != null) {
      _inAppBrowser.throwIsNotOpened(message: 'Cannot laod $assetFilePath!');
      args.putIfAbsent('uuid', () => _inAppBrowserUuid);
    }
    args.putIfAbsent('url', () => assetFilePath);
    args.putIfAbsent('headers', () => headers);
    await _channel.invokeMethod('loadFile', args);
  }

  ///Reloads the WebView.
  Future<void> reload() async {
    Map<String, dynamic> args = <String, dynamic>{};
    if (_inAppBrowserUuid != null && _inAppBrowser != null) {
      _inAppBrowser.throwIsNotOpened();
      args.putIfAbsent('uuid', () => _inAppBrowserUuid);
    }
    await _channel.invokeMethod('reload', args);
  }

  ///Goes back in the history of the WebView.
  Future<void> goBack() async {
    Map<String, dynamic> args = <String, dynamic>{};
    if (_inAppBrowserUuid != null && _inAppBrowser != null) {
      _inAppBrowser.throwIsNotOpened();
      args.putIfAbsent('uuid', () => _inAppBrowserUuid);
    }
    await _channel.invokeMethod('goBack', args);
  }

  ///Returns a boolean value indicating whether the WebView can move backward.
  Future<bool> canGoBack() async {
    Map<String, dynamic> args = <String, dynamic>{};
    if (_inAppBrowserUuid != null && _inAppBrowser != null) {
      _inAppBrowser.throwIsNotOpened();
      args.putIfAbsent('uuid', () => _inAppBrowserUuid);
    }
    return await _channel.invokeMethod('canGoBack', args);
  }

  ///Goes forward in the history of the WebView.
  Future<void> goForward() async {
    Map<String, dynamic> args = <String, dynamic>{};
    if (_inAppBrowserUuid != null && _inAppBrowser != null) {
      _inAppBrowser.throwIsNotOpened();
      args.putIfAbsent('uuid', () => _inAppBrowserUuid);
    }
    await _channel.invokeMethod('goForward', args);
  }

  ///Returns a boolean value indicating whether the WebView can move forward.
  Future<bool> canGoForward() async {
    Map<String, dynamic> args = <String, dynamic>{};
    if (_inAppBrowserUuid != null && _inAppBrowser != null) {
      _inAppBrowser.throwIsNotOpened();
      args.putIfAbsent('uuid', () => _inAppBrowserUuid);
    }
    return await _channel.invokeMethod('canGoForward', args);
  }

  ///Goes to the history item that is the number of steps away from the current item. Steps is negative if backward and positive if forward.
  Future<void> goBackOrForward({@required int steps}) async {
    assert(steps != null);

    Map<String, dynamic> args = <String, dynamic>{};
    if (_inAppBrowserUuid != null && _inAppBrowser != null) {
      _inAppBrowser.throwIsNotOpened();
      args.putIfAbsent('uuid', () => _inAppBrowserUuid);
    }
    args.putIfAbsent('steps', () => steps);
    await _channel.invokeMethod('goBackOrForward', args);
  }

  ///Returns a boolean value indicating whether the WebView can go back or forward the given number of steps. Steps is negative if backward and positive if forward.
  Future<bool> canGoBackOrForward({@required int steps}) async {
    assert(steps != null);

    Map<String, dynamic> args = <String, dynamic>{};
    if (_inAppBrowserUuid != null && _inAppBrowser != null) {
      _inAppBrowser.throwIsNotOpened();
      args.putIfAbsent('uuid', () => _inAppBrowserUuid);
    }
    args.putIfAbsent('steps', () => steps);
    return await _channel.invokeMethod('canGoBackOrForward', args);
  }

  ///Navigates to a [WebHistoryItem] from the back-forward [WebHistory.list] and sets it as the current item.
  Future<void> goTo({@required WebHistoryItem historyItem}) async {
    await goBackOrForward(steps: historyItem.offset);
  }

  ///Check if the WebView instance is in a loading state.
  Future<bool> isLoading() async {
    Map<String, dynamic> args = <String, dynamic>{};
    if (_inAppBrowserUuid != null && _inAppBrowser != null) {
      _inAppBrowser.throwIsNotOpened();
      args.putIfAbsent('uuid', () => _inAppBrowserUuid);
    }
    return await _channel.invokeMethod('isLoading', args);
  }

  ///Stops the WebView from loading.
  Future<void> stopLoading() async {
    Map<String, dynamic> args = <String, dynamic>{};
    if (_inAppBrowserUuid != null && _inAppBrowser != null) {
      _inAppBrowser.throwIsNotOpened();
      args.putIfAbsent('uuid', () => _inAppBrowserUuid);
    }
    await _channel.invokeMethod('stopLoading', args);
  }

  ///Evaluates JavaScript code into the WebView and returns the result of the evaluation.
  Future<dynamic> evaluateJavascript({@required String source}) async {
    Map<String, dynamic> args = <String, dynamic>{};
    if (_inAppBrowserUuid != null && _inAppBrowser != null) {
      _inAppBrowser.throwIsNotOpened();
      args.putIfAbsent('uuid', () => _inAppBrowserUuid);
    }
    args.putIfAbsent('source', () => source);
    var data = await _channel.invokeMethod('evaluateJavascript', args);
    if (data != null && Platform.isAndroid) data = json.decode(data);
    return data;
  }

  ///Injects an external JavaScript file into the WebView from a defined url.
  Future<void> injectJavascriptFileFromUrl({@required String urlFile}) async {
    Map<String, dynamic> args = <String, dynamic>{};
    if (_inAppBrowserUuid != null && _inAppBrowser != null) {
      _inAppBrowser.throwIsNotOpened();
      args.putIfAbsent('uuid', () => _inAppBrowserUuid);
    }
    args.putIfAbsent('urlFile', () => urlFile);
    await _channel.invokeMethod('injectJavascriptFileFromUrl', args);
  }

  ///Injects a JavaScript file into the WebView from the flutter assets directory.
  Future<void> injectJavascriptFileFromAsset(
      {@required String assetFilePath}) async {
    String source = await rootBundle.loadString(assetFilePath);
    await evaluateJavascript(source: source);
  }

  ///Injects CSS into the WebView.
  Future<void> injectCSSCode({@required String source}) async {
    Map<String, dynamic> args = <String, dynamic>{};
    if (_inAppBrowserUuid != null && _inAppBrowser != null) {
      _inAppBrowser.throwIsNotOpened();
      args.putIfAbsent('uuid', () => _inAppBrowserUuid);
    }
    args.putIfAbsent('source', () => source);
    await _channel.invokeMethod('injectCSSCode', args);
  }

  ///Injects an external CSS file into the WebView from a defined url.
  Future<void> injectCSSFileFromUrl({@required String urlFile}) async {
    Map<String, dynamic> args = <String, dynamic>{};
    if (_inAppBrowserUuid != null && _inAppBrowser != null) {
      _inAppBrowser.throwIsNotOpened();
      args.putIfAbsent('uuid', () => _inAppBrowserUuid);
    }
    args.putIfAbsent('urlFile', () => urlFile);
    await _channel.invokeMethod('injectStyleFile', args);
  }

  ///Injects a CSS file into the WebView from the flutter assets directory.
  Future<void> injectCSSFileFromAsset({@required String assetFilePath}) async {
    String source = await rootBundle.loadString(assetFilePath);
    await injectCSSCode(source: source);
  }

  ///Adds a JavaScript message handler [callback] ([JavaScriptHandlerCallback]) that listen to post messages sent from JavaScript by the handler with name [handlerName].
  ///
  ///The Android implementation uses [addJavascriptInterface](https://developer.android.com/reference/android/webkit/WebView#addJavascriptInterface(java.lang.Object,%20java.lang.String)).
  ///The iOS implementation uses [addScriptMessageHandler](https://developer.apple.com/documentation/webkit/wkusercontentcontroller/1537172-addscriptmessagehandler?language=objc)
  ///
  ///The JavaScript function that can be used to call the handler is `window.flutter_inappwebview.callHandler(handlerName <String>, ...args)`, where `args` are [rest parameters](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/rest_parameters).
  ///The `args` will be stringified automatically using `JSON.stringify(args)` method and then they will be decoded on the Dart side.
  ///
  ///In order to call `window.flutter_inappwebview.callHandler(handlerName <String>, ...args)` properly, you need to wait and listen the JavaScript event `flutterInAppWebViewPlatformReady`.
  ///This event will be dispatched as soon as the platform (Android or iOS) is ready to handle the `callHandler` method.
  ///```javascript
  ///   window.addEventListener("flutterInAppWebViewPlatformReady", function(event) {
  ///     console.log("ready");
  ///   });
  ///```
  ///
  ///`window.flutter_inappwebview.callHandler` returns a JavaScript [Promise](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise)
  ///that can be used to get the json result returned by [JavaScriptHandlerCallback].
  ///In this case, simply return data that you want to send and it will be automatically json encoded using [jsonEncode] from the `dart:convert` library.
  ///
  ///So, on the JavaScript side, to get data coming from the Dart side, you will use:
  ///```html
  ///<script>
  ///   window.addEventListener("flutterInAppWebViewPlatformReady", function(event) {
  ///     window.flutter_inappwebview.callHandler('handlerFoo').then(function(result) {
  ///       console.log(result);
  ///     });
  ///
  ///     window.flutter_inappwebview.callHandler('handlerFooWithArgs', 1, true, ['bar', 5], {foo: 'baz'}).then(function(result) {
  ///       console.log(result);
  ///     });
  ///   });
  ///</script>
  ///```
  ///
  ///Instead, on the `onLoadStop` WebView event, you can use `callHandler` directly:
  ///```dart
  ///  // Inject JavaScript that will receive data back from Flutter
  ///  inAppWebViewController.evaluateJavascript(source: """
  ///    window.flutter_inappwebview.callHandler('test', 'Text from Javascript').then(function(result) {
  ///      console.log(result);
  ///    });
  ///  """);
  ///```
  void addJavaScriptHandler(
      {@required String handlerName,
      @required JavaScriptHandlerCallback callback}) {
    assert(!javaScriptHandlerForbiddenNames.contains(handlerName));
    this.javaScriptHandlersMap[handlerName] = (callback);
  }

  ///Removes a JavaScript message handler previously added with the [addJavaScriptHandler()] associated to [handlerName] key.
  ///Returns the value associated with [handlerName] before it was removed.
  ///Returns `null` if [handlerName] was not found.
  JavaScriptHandlerCallback removeJavaScriptHandler(
      {@required String handlerName}) {
    return this.javaScriptHandlersMap.remove(handlerName);
  }

  ///Takes a screenshot (in PNG format) of the WebView's visible viewport and returns a `Uint8List`. Returns `null` if it wasn't be able to take it.
  ///
  ///**NOTE for iOS**: available from iOS 11.0+.
  Future<Uint8List> takeScreenshot() async {
    Map<String, dynamic> args = <String, dynamic>{};
    if (_inAppBrowserUuid != null && _inAppBrowser != null) {
      _inAppBrowser.throwIsNotOpened();
      args.putIfAbsent('uuid', () => _inAppBrowserUuid);
    }
    return await _channel.invokeMethod('takeScreenshot', args);
  }

  ///Sets the WebView options with the new [options] and evaluates them.
  Future<void> setOptions({@required InAppWebViewWidgetOptions options}) async {
    Map<String, dynamic> args = <String, dynamic>{};
    if (_inAppBrowserUuid != null && _inAppBrowser != null) {
      _inAppBrowser.throwIsNotOpened();
      args.putIfAbsent('uuid', () => _inAppBrowserUuid);
    }

    Map<String, dynamic> optionsMap = {};
    optionsMap.addAll(options.inAppWebViewOptions?.toMap() ?? {});
    if (Platform.isAndroid)
      optionsMap.addAll(options.androidInAppWebViewOptions?.toMap() ?? {});
    else if (Platform.isIOS)
      optionsMap.addAll(options.iosInAppWebViewOptions?.toMap() ?? {});

    args.putIfAbsent('options', () => optionsMap);
    await _channel.invokeMethod('setOptions', args);
  }

  ///Gets the current WebView options. Returns the options with `null` value if they are not set yet.
  Future<InAppWebViewWidgetOptions> getOptions() async {
    Map<String, dynamic> args = <String, dynamic>{};
    if (_inAppBrowserUuid != null && _inAppBrowser != null) {
      _inAppBrowser.throwIsNotOpened();
      args.putIfAbsent('uuid', () => _inAppBrowserUuid);
    }

    InAppWebViewWidgetOptions inAppWebViewWidgetOptions =
        InAppWebViewWidgetOptions();
    Map<dynamic, dynamic> options =
        await _channel.invokeMethod('getOptions', args);
    if (options != null) {
      options = options.cast<String, dynamic>();
      inAppWebViewWidgetOptions.inAppWebViewOptions =
          InAppWebViewOptions.fromMap(options);
      if (Platform.isAndroid)
        inAppWebViewWidgetOptions.androidInAppWebViewOptions =
            AndroidInAppWebViewOptions.fromMap(options);
      else if (Platform.isIOS)
        inAppWebViewWidgetOptions.iosInAppWebViewOptions =
            IosInAppWebViewOptions.fromMap(options);
    }

    return inAppWebViewWidgetOptions;
  }

  ///Gets the WebHistory for this WebView. This contains the back/forward list for use in querying each item in the history stack.
  ///This contains only a snapshot of the current state.
  ///Multiple calls to this method may return different objects.
  ///The object returned from this method will not be updated to reflect any new state.
  Future<WebHistory> getCopyBackForwardList() async {
    Map<String, dynamic> args = <String, dynamic>{};
    if (_inAppBrowserUuid != null && _inAppBrowser != null) {
      _inAppBrowser.throwIsNotOpened();
      args.putIfAbsent('uuid', () => _inAppBrowserUuid);
    }
    Map<dynamic, dynamic> result =
        await _channel.invokeMethod('getCopyBackForwardList', args);
    result = result.cast<String, dynamic>();

    List<dynamic> historyListMap = result["history"];
    historyListMap = historyListMap.cast<LinkedHashMap<dynamic, dynamic>>();

    int currentIndex = result["currentIndex"];

    List<WebHistoryItem> historyList = List();
    for (var i = 0; i < historyListMap.length; i++) {
      LinkedHashMap<dynamic, dynamic> historyItem = historyListMap[i];
      historyList.add(WebHistoryItem(
          originalUrl: historyItem["originalUrl"],
          title: historyItem["title"],
          url: historyItem["url"],
          index: i,
          offset: i - currentIndex));
    }
    return WebHistory(list: historyList, currentIndex: currentIndex);
  }

  ///Starts Safe Browsing initialization.
  ///
  ///URL loads are not guaranteed to be protected by Safe Browsing until after the this method returns true.
  ///Safe Browsing is not fully supported on all devices. For those devices this method will returns false.
  ///
  ///This should not be called if Safe Browsing has been disabled by manifest tag
  ///or [AndroidInAppWebViewOptions.safeBrowsingEnabled]. This prepares resources used for Safe Browsing.
  ///
  ///**NOTE**: available only on Android 27+.
  Future<bool> startSafeBrowsing() async {
    Map<String, dynamic> args = <String, dynamic>{};
    if (_inAppBrowserUuid != null && _inAppBrowser != null) {
      _inAppBrowser.throwIsNotOpened();
      args.putIfAbsent('uuid', () => _inAppBrowserUuid);
    }
    return await _channel.invokeMethod('startSafeBrowsing', args);
  }

  ///Sets the list of hosts (domain names/IP addresses) that are exempt from SafeBrowsing checks. The list is global for all the WebViews.
  ///
  /// Each rule should take one of these:
  ///| Rule | Example | Matches Subdomain |
  ///| -- | -- | -- |
  ///| HOSTNAME | example.com | Yes |
  ///| .HOSTNAME | .example.com | No |
  ///| IPV4_LITERAL | 192.168.1.1 | No |
  ///| IPV6_LITERAL_WITH_BRACKETS | [10:20:30:40:50:60:70:80] | No |
  ///
  ///All other rules, including wildcards, are invalid. The correct syntax for hosts is defined by [RFC 3986](https://tools.ietf.org/html/rfc3986#section-3.2.2).
  ///
  ///[hosts] represents the list of hosts. This value must never be null.
  ///
  ///**NOTE**: available only on Android 27+.
  Future<bool> setSafeBrowsingWhitelist({@required List<String> hosts}) async {
    assert(hosts != null);
    Map<String, dynamic> args = <String, dynamic>{};
    if (_inAppBrowserUuid != null && _inAppBrowser != null) {
      _inAppBrowser.throwIsNotOpened();
      args.putIfAbsent('uuid', () => _inAppBrowserUuid);
    }
    args.putIfAbsent('hosts', () => hosts);
    return await _channel.invokeMethod('setSafeBrowsingWhitelist', args);
  }

  ///Returns a URL pointing to the privacy policy for Safe Browsing reporting. This value will never be `null`.
  ///
  ///**NOTE**: available only on Android 27+.
  Future<String> getSafeBrowsingPrivacyPolicyUrl() async {
    Map<String, dynamic> args = <String, dynamic>{};
    if (_inAppBrowserUuid != null && _inAppBrowser != null) {
      _inAppBrowser.throwIsNotOpened();
      args.putIfAbsent('uuid', () => _inAppBrowserUuid);
    }
    return await _channel.invokeMethod('getSafeBrowsingPrivacyPolicyUrl', args);
  }

  ///Clears all the webview's cache.
  Future<void> clearCache() async {
    Map<String, dynamic> args = <String, dynamic>{};
    if (_inAppBrowserUuid != null && _inAppBrowser != null) {
      _inAppBrowser.throwIsNotOpened();
      args.putIfAbsent('uuid', () => _inAppBrowserUuid);
    }
    await _channel.invokeMethod('clearCache', args);
  }

  ///Clears the SSL preferences table stored in response to proceeding with SSL certificate errors.
  ///
  ///**NOTE**: available only on Android.
  Future<void> clearSslPreferences() async {
    Map<String, dynamic> args = <String, dynamic>{};
    if (_inAppBrowserUuid != null && _inAppBrowser != null) {
      _inAppBrowser.throwIsNotOpened();
      args.putIfAbsent('uuid', () => _inAppBrowserUuid);
    }
    await _channel.invokeMethod('clearSslPreferences', args);
  }

  ///Clears the client certificate preferences stored in response to proceeding/cancelling client cert requests.
  ///Note that WebView automatically clears these preferences when the system keychain is updated.
  ///The preferences are shared by all the WebViews that are created by the embedder application.
  ///
  ///**NOTE**: On iOS certificate-based credentials are never stored permanently.
  ///
  ///**NOTE**: available on Android 21+.
  Future<void> clearClientCertPreferences() async {
    Map<String, dynamic> args = <String, dynamic>{};
    if (_inAppBrowserUuid != null && _inAppBrowser != null) {
      _inAppBrowser.throwIsNotOpened();
      args.putIfAbsent('uuid', () => _inAppBrowserUuid);
    }
    await _channel.invokeMethod('clearClientCertPreferences', args);
  }

  ///Finds all instances of find on the page and highlights them. Notifies [onFindResultReceived] listener.
  ///
  ///[find] represents the string to find.
  ///
  ///**NOTE**: on Android, it finds all instances asynchronously. Successive calls to this will cancel any pending searches.
  ///
  ///**NOTE**: on iOS, this is implemented using CSS and Javascript.
  Future<void> findAllAsync({@required String find}) async {
    assert(find != null);
    Map<String, dynamic> args = <String, dynamic>{};
    if (_inAppBrowserUuid != null && _inAppBrowser != null) {
      _inAppBrowser.throwIsNotOpened();
      args.putIfAbsent('uuid', () => _inAppBrowserUuid);
    }
    args.putIfAbsent('find', () => find);
    await _channel.invokeMethod('findAllAsync', args);
  }

  ///Highlights and scrolls to the next match found by [findAllAsync()]. Notifies [onFindResultReceived] listener.
  ///
  ///[forward] represents the direction to search.
  ///
  ///**NOTE**: on iOS, this is implemented using CSS and Javascript.
  Future<void> findNext({@required bool forward}) async {
    assert(forward != null);
    Map<String, dynamic> args = <String, dynamic>{};
    if (_inAppBrowserUuid != null && _inAppBrowser != null) {
      _inAppBrowser.throwIsNotOpened();
      args.putIfAbsent('uuid', () => _inAppBrowserUuid);
    }
    args.putIfAbsent('forward', () => forward);
    await _channel.invokeMethod('findNext', args);
  }

  ///Clears the highlighting surrounding text matches created by [findAllAsync()].
  ///
  ///**NOTE**: on iOS, this is implemented using CSS and Javascript.
  Future<void> clearMatches() async {
    Map<String, dynamic> args = <String, dynamic>{};
    if (_inAppBrowserUuid != null && _inAppBrowser != null) {
      _inAppBrowser.throwIsNotOpened();
      args.putIfAbsent('uuid', () => _inAppBrowserUuid);
    }
    await _channel.invokeMethod('clearMatches', args);
  }

  ///Gets the html (with javascript) of the Chromium's t-rex runner game. Used in combination with [getTRexRunnerCss()].
  Future<String> getTRexRunnerHtml() async {
    return await rootBundle
        .loadString("packages/flutter_inappwebview/t_rex_runner/t-rex.html");
  }

  ///Gets the css of the Chromium's t-rex runner game. Used in combination with [getTRexRunnerHtml()].
  Future<String> getTRexRunnerCss() async {
    return await rootBundle
        .loadString("packages/flutter_inappwebview/t_rex_runner/t-rex.css");
  }

  ///Scrolls the WebView to the position.
  ///
  ///[x] represents the x position to scroll to.
  ///
  ///[y] represents the y position to scroll to.
  Future<void> scrollTo({@required int x, @required int y}) async {
    assert(x != null && y != null);
    Map<String, dynamic> args = <String, dynamic>{};
    if (_inAppBrowserUuid != null && _inAppBrowser != null) {
      _inAppBrowser.throwIsNotOpened();
      args.putIfAbsent('uuid', () => _inAppBrowserUuid);
    }
    args.putIfAbsent('x', () => x);
    args.putIfAbsent('y', () => y);
    await _channel.invokeMethod('scrollTo', args);
  }

  ///Moves the scrolled position of the WebView.
  ///
  ///[x] represents the amount of pixels to scroll by horizontally.
  ///
  ///[y] represents the amount of pixels to scroll by vertically.
  Future<void> scrollBy({@required int x, @required int y}) async {
    assert(x != null && y != null);
    Map<String, dynamic> args = <String, dynamic>{};
    if (_inAppBrowserUuid != null && _inAppBrowser != null) {
      _inAppBrowser.throwIsNotOpened();
      args.putIfAbsent('uuid', () => _inAppBrowserUuid);
    }
    args.putIfAbsent('x', () => x);
    args.putIfAbsent('y', () => y);
    await _channel.invokeMethod('scrollBy', args);
  }

  ///Does a best-effort attempt to pause any processing that can be paused safely, such as animations and geolocation. Note that this call does not pause JavaScript.
  ///To pause JavaScript globally, use [pauseTimers()]. To resume WebView, call [resume()].
  ///
  ///**NOTE**: available only on Android.
  Future<void> pause() async {
    Map<String, dynamic> args = <String, dynamic>{};
    if (_inAppBrowserUuid != null && _inAppBrowser != null) {
      _inAppBrowser.throwIsNotOpened();
      args.putIfAbsent('uuid', () => _inAppBrowserUuid);
    }
    await _channel.invokeMethod('pause', args);
  }

  ///Resumes a WebView after a previous call to [pause()].
  ///
  ///**NOTE**: available only on Android.
  Future<void> resume() async {
    Map<String, dynamic> args = <String, dynamic>{};
    if (_inAppBrowserUuid != null && _inAppBrowser != null) {
      _inAppBrowser.throwIsNotOpened();
      args.putIfAbsent('uuid', () => _inAppBrowserUuid);
    }
    await _channel.invokeMethod('resume', args);
  }

  ///On Android, it pauses all layout, parsing, and JavaScript timers for all WebViews.
  ///This is a global requests, not restricted to just this WebView. This can be useful if the application has been paused.
  ///
  ///On iOS, it is restricted to just this WebView.
  Future<void> pauseTimers() async {
    Map<String, dynamic> args = <String, dynamic>{};
    if (_inAppBrowserUuid != null && _inAppBrowser != null) {
      _inAppBrowser.throwIsNotOpened();
      args.putIfAbsent('uuid', () => _inAppBrowserUuid);
    }
    await _channel.invokeMethod('pauseTimers', args);
  }

  ///On Android, it resumes all layout, parsing, and JavaScript timers for all WebViews. This will resume dispatching all timers.
  ///
  ///On iOS, it resumes all layout, parsing, and JavaScript timers to just this WebView.
  Future<void> resumeTimers() async {
    Map<String, dynamic> args = <String, dynamic>{};
    if (_inAppBrowserUuid != null && _inAppBrowser != null) {
      _inAppBrowser.throwIsNotOpened();
      args.putIfAbsent('uuid', () => _inAppBrowserUuid);
    }
    await _channel.invokeMethod('resumeTimers', args);
  }

  /*Future<void> dispose() async {
    Map<String, dynamic> args = <String, dynamic>{};
    if (Platform.isIOS)
      await _channel.invokeMethod('removeFromSuperview', args);
  }*/
}