url_launcher_platform_interface.dart

// Copyright 2017 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:meta/meta.dart' show required, visibleForTesting;

import 'method_channel_url_launcher.dart';

class MustExtend<T> {
  MustExtend<T> verifyExtends() => this;
}

/// Provides default implementations of interface methods.
///
/// Can be mocked for testing. However, production implementations
/// should extend [UrlLauncherPlatform] instead.
@visibleForTesting
abstract class UrlLauncherPlatformInterface with MustExtend<UrlLauncherPlatformInterface> {
  /// Returns `true` if this platform is able to launch [url].
  Future<bool> canLaunch(String url) {
    throw UnimplementedError('canLaunch() has not been implemented.');
  }

  /// Returns `true` if the given [url] was successfully launched.
  ///
  /// For documentation on the other arguments, see the `launch` documentation
  /// in `package:url_launcher/url_launcher.dart`.
  Future<bool> launch(
    String url, {
    @required bool useSafariVC,
    @required bool useWebView,
    @required bool enableJavaScript,
    @required bool enableDomStorage,
    @required bool universalLinksOnly,
    @required Map<String, String> headers,
  }) {
    throw UnimplementedError('launch() has not been implemented.');
  }

  /// Closes the WebView, if one was opened earlier by [launch].
  Future<void> closeWebView() {
    throw UnimplementedError('closeWebView() has not been implemented.');
  }
}

/// The interface that implementations of url_launcher must implement.
///
/// Platform implementations should extend this class rather than
/// `UrlLauncherPlatformInterface`.
abstract class UrlLauncherPlatform extends UrlLauncherPlatformInterface {
  /// The default instance of [UrlLauncherPlatform] to use.
  ///
  /// Platform-specific plugins should override this with their own
  /// platform-specific class that extends [UrlLauncherPlatform] when they
  /// register themselves.
  ///
  /// Defaults to [MethodChannelUrlLauncher].
  static UrlLauncherPlatform get instance => _instance;
  static UrlLauncherPlatform _instance = MethodChannelUrlLauncher();
  // TODO(amirh): Extract common platform interface logic.
  // https://github.com/flutter/flutter/issues/43368
  static set instance(UrlLauncherPlatform instance) {
    _instance = instance.verifyExtends<UrlLauncherPlatformInterface>();
  }
}