feat(battery_plus): Added power source type of how the device is powered.

packages/battery_plus/battery_plus/android/src/main/kotlin/dev/fluttercommunity/plus/battery/BatteryPlusPlugin.kt

@@ -58,6 +58,9 @@ class BatteryPlusPlugin : MethodCallHandler, EventChannel.StreamHandler, Flutter
                     result.error("UNAVAILABLE", "Battery level not available.", null)
                 }
             }
+            "getPowerSourceType" -> {
+                result.success(getPowerSourceType())
+            }
 
             "getBatteryState" -> {
                 val currentBatteryStatus = getBatteryStatus()
@@ -109,6 +112,20 @@ class BatteryPlusPlugin : MethodCallHandler, EventChannel.StreamHandler, Flutter
         return convertBatteryStatus(status)
     }
 
+    private fun getPowerSourceType(): String? {
+            val intent = ContextWrapper(applicationContext).registerReceiver(null, IntentFilter(Intent.ACTION_BATTERY_CHANGED))
+            val source = intent!!.getIntExtra(BatteryManager.EXTRA_PLUGGED, -1)
+           return when (source) {
+                -1 -> "unknown"
+                0 -> "battery"
+                BatteryManager.BATTERY_PLUGGED_AC -> "ac"
+                BatteryManager.BATTERY_PLUGGED_DOCK -> "dock"
+                BatteryManager.BATTERY_PLUGGED_USB -> "usb"
+                BatteryManager.BATTERY_PLUGGED_WIRELESS -> "wireless"
+                else -> null
+            }
+    } 
+
     private fun getBatteryLevel(): Int {
         return if (VERSION.SDK_INT >= VERSION_CODES.LOLLIPOP) {
             getBatteryProperty(BatteryManager.BATTERY_PROPERTY_CAPACITY)

packages/battery_plus/battery_plus/lib/battery_plus.dart

@@ -7,7 +7,7 @@ import 'dart:async';
 import 'package:battery_plus_platform_interface/battery_plus_platform_interface.dart';
 
 export 'package:battery_plus_platform_interface/battery_plus_platform_interface.dart'
-    show BatteryState;
+    show BatteryState, PowerSourceType;
 
 export 'src/battery_plus_linux.dart';
 
@@ -44,6 +44,20 @@ class Battery {
     return _platform.isInBatterySaveMode;
   }
 
+  /// get the current power source type.
+  ///
+  /// When the [BatteryState] is in a state of
+  /// [BatteryState.connectedNotCharging],[BatteryState.charging]
+  /// or [BatteryState.full], the [PowerSourceType] can be determined
+  /// and see how the device gets it's power.
+  ///
+  /// when the device is mobile and has the [BatteryState] of
+  /// [BatteryState.discharging] or [BatteryState.unknown] the power source can
+  /// not be determined
+  Future<PowerSourceType> get powerSourceType {
+    return _platform.powerSourceType;
+  }
+
   /// Get battery state
   Future<BatteryState> get batteryState {
     return _platform.batteryState;

packages/battery_plus/battery_plus_platform_interface/lib/battery_plus_platform_interface.dart

@@ -52,6 +52,10 @@ abstract class BatteryPlatform extends PlatformInterface {
     throw UnimplementedError('batteryState() has not been implemented.');
   }
 
+  Future<PowerSourceType> get powerSourceType {
+    throw UnimplementedError('powerSourceType() has not been implemented.');
+  }
+
   /// Returns a Stream of BatteryState changes.
   Stream<BatteryState> get onBatteryStateChanged {
     throw UnimplementedError(

packages/battery_plus/battery_plus_platform_interface/lib/method_channel_battery_plus.dart

@@ -42,6 +42,13 @@ class MethodChannelBattery extends BatteryPlatform {
       .invokeMethod<String>('getBatteryState')
       .then<BatteryState>((dynamic result) => parseBatteryState(result));
 
+  @override
+  Future<PowerSourceType> get powerSourceType => methodChannel
+      .invokeMethod<String>('getPowerSourceType')
+      .then<PowerSourceType>(
+        (dynamic result) => PowerSourceType.parsePowerSource(result),
+      );
+
   /// Fires whenever the battery state changes.
   @override
   Stream<BatteryState> get onBatteryStateChanged {

packages/battery_plus/battery_plus_platform_interface/lib/src/enums.dart

@@ -20,3 +20,42 @@ enum BatteryState {
   /// The state of the battery is unknown.
   unknown;
 }
+
+/// Indicates the current power source type.
+///
+/// When the [BatteryState] is in a state of
+///  [connectedNotCharging],[charging] or [full].
+///
+/// We can get some extra info battery info on how it is powered.
+enum PowerSourceType {
+  /// Power source is an AC charger.
+  ac('ac'),
+
+  /// Power source is dock.
+  dock('dock'),
+
+  /// Power source is a USB port.
+  usb('usb'),
+
+  /// Power source is wireless.
+  wireless('wireless'),
+
+  /// Power source is battery
+  battery('battery'),
+
+  /// Power source could not be determined.
+  unknown('unknown');
+
+  /// The known string value communicated from the channel.
+  final String _state;
+
+  const PowerSourceType(this._state);
+
+  /// Parse the power source string value to the given power source type.
+  static PowerSourceType parsePowerSource(String? value) {
+    return PowerSourceType.values.firstWhere(
+      (sourceType) => sourceType._state == value,
+      orElse: () => PowerSourceType.unknown,
+    );
+  }
+}