Platform.android.cs

using System;
using System.Collections.Concurrent;
using System.Threading;
using System.Threading.Tasks;
using Android.App;
using Android.Content;
using Android.Content.PM;
using Android.Hardware;
using Android.Hardware.Camera2;
using Android.Locations;
using Android.Net;
using Android.Net.Wifi;
using Android.OS;
using Android.Views;
using AndroidIntent = Android.Content.Intent;
using AndroidUri = Android.Net.Uri;

namespace Xamarin.Essentials
{
    public static partial class Platform
    {
        static ActivityLifecycleContextListener lifecycleListener;

        public static Context AppContext => Application.Context;

        public static Activity CurrentActivity => lifecycleListener?.Activity;

        public static event EventHandler<ActivityStateChangedEventArgs> ActivityStateChanged;

        internal const int requestCodeFilePicker = 11001;
        internal const int requestCodeMediaPicker = 11002;
        internal const int requestCodeMediaCapture = 11003;
        internal const int requestCodePickContact = 11004;

        internal const int requestCodeStart = 12000;

        static int requestCode = requestCodeStart;

        internal static int NextRequestCode()
        {
            if (++requestCode >= 12999)
                requestCode = requestCodeStart;

            return requestCode;
        }

        internal static void OnActivityStateChanged(Activity activity, ActivityState ev)
            => ActivityStateChanged?.Invoke(null, new ActivityStateChangedEventArgs(activity, ev));

        public static async Task<Activity> WaitForActivityAsync(CancellationToken cancelToken = default)
        {
            if (CurrentActivity != null)
                return CurrentActivity;

            var tcs = new TaskCompletionSource<Activity>();
            var handler = new EventHandler<ActivityStateChangedEventArgs>((sender, args) =>
            {
                if (args.State == ActivityState.Created || args.State == ActivityState.Resumed)
                    tcs.TrySetResult(args.Activity);
            });

            try
            {
                using (cancelToken.Register(() => tcs.TrySetCanceled()))
                {
                    ActivityStateChanged += handler;
                    return await tcs.Task.ConfigureAwait(false);
                }
            }
            finally
            {
                ActivityStateChanged -= handler;
            }
        }

        internal static Activity GetCurrentActivity(bool throwOnNull)
        {
            var activity = lifecycleListener?.Activity;
            if (throwOnNull && activity == null)
                throw new NullReferenceException("The current Activity can not be detected. Ensure that you have called Init in your Activity or Application class.");

            return activity;
        }

        public static void Init(Application application)
        {
            lifecycleListener = new ActivityLifecycleContextListener();
            application.RegisterActivityLifecycleCallbacks(lifecycleListener);
        }

        public static void Init(Activity activity, Bundle bundle)
        {
            Init(activity.Application);
            lifecycleListener.Activity = activity;
        }

        public static void OnRequestPermissionsResult(int requestCode, string[] permissions, Permission[] grantResults) =>
            Permissions.OnRequestPermissionsResult(requestCode, permissions, grantResults);

        public static void OnNewIntent(AndroidIntent intent)
            => CheckAppActions(intent);

        public static void OnResume(Activity activity = null)
        {
            if (activity != null)
                CheckAppActions(activity.Intent);
        }

        static void CheckAppActions(AndroidIntent intent)
        {
            if (intent?.Action == Intent.ActionAppAction)
            {
                var appAction = intent.ToAppAction();

                if (!string.IsNullOrEmpty(appAction?.Id))
                    AppActions.InvokeOnAppAction(Platform.CurrentActivity, appAction);
            }
        }

        internal static bool HasSystemFeature(string systemFeature)
        {
            var packageManager = AppContext.PackageManager;
            foreach (var feature in packageManager.GetSystemAvailableFeatures())
            {
                if (feature?.Name?.Equals(systemFeature, StringComparison.OrdinalIgnoreCase) ?? false)
                    return true;
            }
            return false;
        }

        internal static bool IsIntentSupported(AndroidIntent intent) =>
            intent.ResolveActivity(AppContext.PackageManager) != null;

        internal static bool IsIntentSupported(AndroidIntent intent, string expectedPackageName) =>
            intent.ResolveActivity(AppContext.PackageManager) is ComponentName c && c.PackageName == expectedPackageName;

        internal static AndroidUri GetShareableFileUri(FileBase file)
        {
            Java.IO.File sharedFile;
            if (FileProvider.IsFileInPublicLocation(file.FullPath))
            {
                // we are sharing a file in a "shared/public" location
                sharedFile = new Java.IO.File(file.FullPath);
            }
            else
            {
                var root = FileProvider.GetTemporaryRootDirectory();

                var tmpFile = FileSystem.GetEssentialsTemporaryFile(root, file.FileName);

                System.IO.File.Copy(file.FullPath, tmpFile.CanonicalPath);

                sharedFile = tmpFile;
            }

            // create the uri, if N use file provider
            if (HasApiLevelN)
            {
                return FileProvider.GetUriForFile(sharedFile);
            }

            // use the shared file path created
            return AndroidUri.FromFile(sharedFile);
        }

        internal static bool HasApiLevelKitKat => HasApiLevel(BuildVersionCodes.Kitkat);

        internal static bool HasApiLevelN => HasApiLevel(24);

        internal static bool HasApiLevelNMr1 => HasApiLevel(25);

        internal static bool HasApiLevelO => HasApiLevel(26);

        internal static bool HasApiLevelQ => HasApiLevel(29);

        static int? sdkInt;

        internal static int SdkInt
            => sdkInt ??= (int)Build.VERSION.SdkInt;

        internal static bool HasApiLevel(BuildVersionCodes versionCode) =>
            SdkInt >= (int)versionCode;

        internal static bool HasApiLevel(int apiLevel) =>
            SdkInt >= apiLevel;

        internal static CameraManager CameraManager =>
            AppContext.GetSystemService(Context.CameraService) as CameraManager;

        internal static ConnectivityManager ConnectivityManager =>
            AppContext.GetSystemService(Context.ConnectivityService) as ConnectivityManager;

        internal static Vibrator Vibrator =>
            AppContext.GetSystemService(Context.VibratorService) as Vibrator;

        internal static WifiManager WifiManager =>
            AppContext.GetSystemService(Context.WifiService) as WifiManager;

        internal static SensorManager SensorManager =>
            AppContext.GetSystemService(Context.SensorService) as SensorManager;

        internal static ClipboardManager ClipboardManager =>
            AppContext.GetSystemService(Context.ClipboardService) as ClipboardManager;

        internal static LocationManager LocationManager =>
            AppContext.GetSystemService(Context.LocationService) as LocationManager;

        internal static PowerManager PowerManager =>
            AppContext.GetSystemService(Context.PowerService) as PowerManager;

#if __ANDROID_25__
        internal static ShortcutManager ShortcutManager =>
            AppContext.GetSystemService(Context.ShortcutService) as ShortcutManager;
#endif

        internal static IWindowManager WindowManager =>
            AppContext.GetSystemService(Context.WindowService) as IWindowManager;

        internal static ContentResolver ContentResolver =>
            AppContext.ContentResolver;

        internal static Java.Util.Locale GetLocale()
        {
            var resources = AppContext.Resources;
            var config = resources.Configuration;
#if __ANDROID_24__
            if (HasApiLevelN)
                return config.Locales.Get(0);
#endif

#pragma warning disable CS0618 // Type or member is obsolete
            return config.Locale;
#pragma warning restore CS0618 // Type or member is obsolete
        }

        internal static void SetLocale(Java.Util.Locale locale)
        {
            Java.Util.Locale.Default = locale;
            var resources = AppContext.Resources;
            var config = resources.Configuration;

#if __ANDROID_24__
            if (HasApiLevelN)
                config.SetLocale(locale);
            else
#endif
#pragma warning disable CS0618 // Type or member is obsolete
                config.Locale = locale;
#pragma warning restore CS0618 // Type or member is obsolete

#pragma warning disable CS0618 // Type or member is obsolete
            resources.UpdateConfiguration(config, resources.DisplayMetrics);
#pragma warning restore CS0618 // Type or member is obsolete
        }

        public static class Intent
        {
            public const string ActionAppAction = "ACTION_XE_APP_ACTION";
        }
    }

    public enum ActivityState
    {
        Created,
        Resumed,
        Paused,
        Destroyed,
        SaveInstanceState,
        Started,
        Stopped
    }

    public class ActivityStateChangedEventArgs : EventArgs
    {
        internal ActivityStateChangedEventArgs(Activity activity, ActivityState ev)
        {
            State = ev;
            Activity = activity;
        }

        public ActivityState State { get; }

        public Activity Activity { get; }
    }

    class ActivityLifecycleContextListener : Java.Lang.Object, Application.IActivityLifecycleCallbacks
    {
        WeakReference<Activity> currentActivity = new WeakReference<Activity>(null);

        internal Context Context =>
            Activity ?? Application.Context;

        internal Activity Activity
        {
            get => currentActivity.TryGetTarget(out var a) ? a : null;
            set => currentActivity.SetTarget(value);
        }

        void Application.IActivityLifecycleCallbacks.OnActivityCreated(Activity activity, Bundle savedInstanceState)
        {
            Activity = activity;
            Platform.OnActivityStateChanged(activity, ActivityState.Created);
        }

        void Application.IActivityLifecycleCallbacks.OnActivityDestroyed(Activity activity) =>
            Platform.OnActivityStateChanged(activity, ActivityState.Destroyed);

        void Application.IActivityLifecycleCallbacks.OnActivityPaused(Activity activity)
        {
            Activity = activity;
            Platform.OnActivityStateChanged(activity, ActivityState.Paused);
        }

        void Application.IActivityLifecycleCallbacks.OnActivityResumed(Activity activity)
        {
            Activity = activity;
            Platform.OnActivityStateChanged(activity, ActivityState.Resumed);
        }

        void Application.IActivityLifecycleCallbacks.OnActivitySaveInstanceState(Activity activity, Bundle outState) =>
            Platform.OnActivityStateChanged(activity, ActivityState.SaveInstanceState);

        void Application.IActivityLifecycleCallbacks.OnActivityStarted(Activity activity) =>
            Platform.OnActivityStateChanged(activity, ActivityState.Started);

        void Application.IActivityLifecycleCallbacks.OnActivityStopped(Activity activity) =>
            Platform.OnActivityStateChanged(activity, ActivityState.Stopped);
    }

    [Activity(ConfigurationChanges = ConfigChanges.Orientation | ConfigChanges.ScreenSize)]
    class IntermediateActivity : Activity
    {
        const string launchedExtra = "launched";
        const string actualIntentExtra = "actual_intent";
        const string guidExtra = "guid";
        const string requestCodeExtra = "request_code";

        static readonly ConcurrentDictionary<string, IntermediateTask> pendingTasks =
            new ConcurrentDictionary<string, IntermediateTask>();

        bool launched;
        Intent actualIntent;
        string guid;
        int requestCode;

        protected override void OnCreate(Bundle savedInstanceState)
        {
            base.OnCreate(savedInstanceState);

            var extras = savedInstanceState ?? Intent.Extras;

            // read the values
            launched = extras.GetBoolean(launchedExtra, false);
            actualIntent = extras.GetParcelable(actualIntentExtra) as Intent;
            guid = extras.GetString(guidExtra);
            requestCode = extras.GetInt(requestCodeExtra, -1);

            if (GetIntermediateTask(guid) is IntermediateTask task)
            {
                task.OnCreate?.Invoke(actualIntent);
            }

            // if this is the first time, lauch the real activity
            if (!launched)
                StartActivityForResult(actualIntent, requestCode);
        }

        protected override void OnSaveInstanceState(Bundle outState)
        {
            // make sure we mark this activity as launched
            outState.PutBoolean(launchedExtra, true);

            // save the values
            outState.PutParcelable(actualIntentExtra, actualIntent);
            outState.PutString(guidExtra, guid);
            outState.PutInt(requestCodeExtra, requestCode);

            base.OnSaveInstanceState(outState);
        }

        protected override void OnActivityResult(int requestCode, Result resultCode, Intent data)
        {
            base.OnActivityResult(requestCode, resultCode, data);

            // we have a valid GUID, so handle the task
            if (GetIntermediateTask(guid, true) is IntermediateTask task)
            {
                if (resultCode == Result.Canceled)
                {
                    task.TaskCompletionSource.TrySetCanceled();
                }
                else
                {
                    try
                    {
                        data ??= new AndroidIntent();

                        task.OnResult?.Invoke(data);

                        task.TaskCompletionSource.TrySetResult(data);
                    }
                    catch (Exception ex)
                    {
                        task.TaskCompletionSource.TrySetException(ex);
                    }
                }
            }

            // close the intermediate activity
            Finish();
        }

        public static Task<Intent> StartAsync(Intent intent, int requestCode, Action<Intent> onCreate = null, Action<Intent> onResult = null)
        {
            // make sure we have the activity
            var activity = Platform.GetCurrentActivity(true);

            // create a new task
            var data = new IntermediateTask(onCreate, onResult);
            pendingTasks[data.Id] = data;

            // create the intermediate intent, and add the real intent to it
            var intermediateIntent = new Intent(activity, typeof(IntermediateActivity));
            intermediateIntent.PutExtra(actualIntentExtra, intent);
            intermediateIntent.PutExtra(guidExtra, data.Id);
            intermediateIntent.PutExtra(requestCodeExtra, requestCode);

            // start the intermediate activity
            activity.StartActivityForResult(intermediateIntent, requestCode);

            return data.TaskCompletionSource.Task;
        }

        static IntermediateTask GetIntermediateTask(string guid, bool remove = false)
        {
            if (string.IsNullOrEmpty(guid))
                return null;

            if (remove)
            {
                pendingTasks.TryRemove(guid, out var removedTask);
                return removedTask;
            }

            pendingTasks.TryGetValue(guid, out var task);
            return task;
        }

        class IntermediateTask
        {
            public IntermediateTask(Action<Intent> onCreate, Action<AndroidIntent> onResult)
            {
                Id = Guid.NewGuid().ToString();
                TaskCompletionSource = new TaskCompletionSource<Intent>();

                OnCreate = onCreate;
                OnResult = onResult;
            }

            public string Id { get; }

            public TaskCompletionSource<Intent> TaskCompletionSource { get; }

            public Action<Intent> OnCreate { get; }

            public Action<AndroidIntent> OnResult { get; }
        }
    }
}