using System;

using System.Reactive.Disposables;

using System.Reactive.Linq;

using Android.App;

using Android.Content;

using Android.Hardware.Usb;

namespace ReactiveUI

{

public static class UsbManagerExtensions

{

const string ACTION_USB_PERMISSION = "com.reactiveui.USB_PERMISSION";

/// <summary>

/// Requests temporary permission for the given package to access the device.

/// This may result in a system dialog being displayed to the user if permission had not already been granted.

/// </summary>

/// <returns>The observable sequence of permission values.</returns>

/// <param name="manager">The UsbManager system service.</param>

/// <param name="context">The Context to request the permission from.</param>

/// <param name="device">The UsbDevice to request permission for.</param>

public static IObservable<bool> PermissionRequested(this UsbManager manager, Context context, UsbDevice device)

{

return Observable.Create<bool> (observer => {

var usbPermissionReceiver = new UsbDevicePermissionReceiver (observer, device);

context.RegisterReceiver (usbPermissionReceiver, new IntentFilter (ACTION_USB_PERMISSION));

var intent = PendingIntent.GetBroadcast (context, 0, new Intent (ACTION_USB_PERMISSION), 0);

manager.RequestPermission (device, intent);

return Disposable.Create (() => context.UnregisterReceiver (usbPermissionReceiver));

});

}

/// <summary>

/// Requests temporary permission for the given package to access the accessory.

/// This may result in a system dialog being displayed to the user if permission had not already been granted.

/// </summary>

/// <returns>The observable sequence of permission values.</returns>

/// <param name="manager">The UsbManager system service.</param>

/// <param name="context">The Context to request the permission from.</param>

/// <param name="accessory">The UsbAccessory to request permission for.</param>

public static IObservable<bool> PermissionRequested(this UsbManager manager, Context context, UsbAccessory accessory)

{

return Observable.Create<bool> (observer => {

var usbPermissionReceiver = new UsbAccessoryPermissionReceiver (observer, accessory);

context.RegisterReceiver (usbPermissionReceiver, new IntentFilter (ACTION_USB_PERMISSION));

var intent = PendingIntent.GetBroadcast (context, 0, new Intent (ACTION_USB_PERMISSION), 0);

manager.RequestPermission (accessory, intent);

return Disposable.Create (() => context.UnregisterReceiver (usbPermissionReceiver));

});

}

/// <summary>

/// Private implementation of BroadcastReceiver to handle device permission requests.

/// </summary>

class UsbDevicePermissionReceiver

: BroadcastReceiver

{

readonly IObserver<bool> observer;

readonly UsbDevice device;

public UsbDevicePermissionReceiver (IObserver<bool> observer, UsbDevice device)

{

this.observer = observer;

this.device = device;

}

public override void OnReceive (Context context, Intent intent)

{

var extraDevice = intent.GetParcelableExtra(UsbManager.ExtraDevice) as UsbDevice;

if (device.DeviceName != extraDevice.DeviceName)

return;

var permissionGranted = intent.GetBooleanExtra (UsbManager.ExtraPermissionGranted, false);

observer.OnNext (permissionGranted);

observer.OnCompleted ();

}

}

/// <summary>

/// Private implementation of BroadcastReceiver to handle accessory permission requests.

/// </summary>

class UsbAccessoryPermissionReceiver

: BroadcastReceiver

{

readonly IObserver<bool> observer;

readonly UsbAccessory accessory;

public UsbAccessoryPermissionReceiver (IObserver<bool> observer, UsbAccessory accessory)

{

this.observer = observer;

this.accessory = accessory;

}

public override void OnReceive (Context context, Intent intent)

{

var extraAccessory = intent.GetParcelableExtra(UsbManager.ExtraAccessory) as UsbAccessory;

if (accessory.Manufacturer != extraAccessory.Manufacturer || accessory.Model != extraAccessory.Model)

return;

var permissionGranted = intent.GetBooleanExtra (UsbManager.ExtraPermissionGranted, false);

observer.OnNext (permissionGranted);

observer.OnCompleted ();

}

}

}

}