Added option to turn device children on as in EP40.

Kasa/Data/Child.cs

@@ -0,0 +1,21 @@
+using System;
+using Newtonsoft.Json;
+
+namespace Kasa;
+
+    /// <summary>
+    /// Child element for outlet device with more than one plug
+    /// </summary>
+    public struct Child {
+        [JsonProperty("id")] public string id { get; set; }  //  "800671BEB946D3C691ECBD2940991375202E165600",
+        [JsonProperty("state")] public string state { get; set; }  //  1,
+        [JsonProperty("alias")] public string alias { get; set; }  //  "Outside Plug 1",
+        [JsonProperty("on_time")] public string on_time { get; set; }  //  1882,
+
+        /// <exception cref="ArgumentOutOfRangeException"></exception>
+        public static Feature FromJsonString(string jsonString) => jsonString.ToUpperInvariant() switch {
+            "TIM" => Feature.Timer,
+            "ENE" => Feature.EnergyMeter,
+            _     => throw new ArgumentOutOfRangeException(nameof(jsonString), jsonString, "Unknown feature")
+        };
+    }

Kasa/Data/SystemInfo.cs

@@ -93,4 +93,8 @@ public struct SystemInfo {
     /// </summary>
     [JsonProperty("feature")] public ISet<Feature> Features { get; internal set; }
 
+    /// <summary>
+    /// Children switches in a single device
+    /// </summary>
+    [JsonProperty("children")] public ISet<Child> Children { get; internal set; }
 }

Kasa/Data/Timer.cs

@@ -62,6 +62,7 @@ public Timer(TimeSpan duration, bool willSetOutletOn): this() {
         IsEnabled       = true;
         TotalDuration   = duration;
         WillSetOutletOn = willSetOutletOn;
+        RemainingDuration = duration;  // Necissary to build.        
     }
 
 }

Kasa/IKasaClient.cs

@@ -17,6 +17,6 @@ internal interface IKasaClient: IDisposable {
     /// <exception cref="FeatureUnavailable">If the device is missing a feature that is required to run the given method, such as running <c>EnergyMeter.GetInstantaneousPowerUsage()</c> on an EP10, which does not have the EnergyMeter Feature.</exception>
     /// <exception cref="NetworkException">if the TCP connection to the outlet failed and could not automatically reconnect</exception>
     /// <exception cref="ResponseParsingException">if the JSON received from the outlet contained unexpected data</exception>
-    Task<T> Send<T>(CommandFamily commandFamily, string methodName, object? parameters = null);
+    Task<T> Send<T>(CommandFamily commandFamily, string methodName, object? parameters = null, string[]? childIds = null);
 
 }

Kasa/IKasaOutlet.cs

@@ -98,6 +98,18 @@ public interface ISystemCommands {
         /// <exception cref="ResponseParsingException">if the JSON received from the outlet contained unexpected data</exception>
         Task SetOutletOn(bool turnOn);
 
+        /// <summary>
+        /// <para>Turn on or off the device's children outlets so it can supply power to any connected electrical consumers or not.</para>
+        /// <para>You can also toggle the outlet by pressing the physical button on the device.</para>
+        /// <para>This call is idempotent: if you try to turn the outlet on and it's already on, the call will have no effect.</para>
+        /// <para>The state is persisted across restarts. If the device loses power, it will restore the previous outlet power state when it turns on again.</para>
+        /// <para>This call is unrelated to turning the entire Kasa device on or off. To reboot the device, use <see cref="Reboot"/>.</para>
+        /// </summary>
+        /// <param name="turnOnChild"><c>true</c> to supply power to the outlet, or <c>false</c> to switch if off.</param>
+        /// <exception cref="NetworkException">if the TCP connection to the outlet failed and could not automatically reconnect</exception>
+        /// <exception cref="ResponseParsingException">if the JSON received from the outlet contained unexpected data</exception>
+        Task SetAllChildOutletOn(bool turnOn);
+
         /// <summary>
         /// <para>Get data about the device, including hardware, software, configuration, and current state.</para>
         /// </summary>

Kasa/KasaClient.cs

@@ -108,10 +108,11 @@ public async Task Connect() {
 
     /// <inheritdoc />
     // ExceptionAdjustment: M:System.Threading.SemaphoreSlim.Release -T:System.Threading.SemaphoreFullException
-    public async Task<T> Send<T>(CommandFamily commandFamily, string methodName, object? parameters = null) {
+    public async Task<T> Send<T>(CommandFamily commandFamily, string methodName, object? parameters = null, string[]? childIds = null)
+    {
         await TcpMutex.WaitAsync().ConfigureAwait(false); //only one TCP write operation may occur in parallel, which is a requirement of TcpClient
         try {
-            Task<T> Attempt() => SendWithoutRetry<T>(commandFamily, methodName, parameters);
+            Task<T> Attempt() => SendWithoutRetry<T>(commandFamily, methodName, parameters, childIds);
 
 #pragma warning disable Ex0100 // Member may throw undocumented exception
             return await Retrier.InvokeWithRetry(Attempt, Options.MaxAttempts, _ => Options.RetryDelay, IsRetryAllowed).ConfigureAwait(false);
@@ -132,15 +133,16 @@ public async Task<T> Send<T>(CommandFamily commandFamily, string methodName, obj
     // ExceptionAdjustment: M:System.Threading.Interlocked.Increment(System.Int64@) -T:System.NullReferenceException
     // ExceptionAdjustment: M:System.IO.Stream.WriteAsync(System.Byte[],System.Int32,System.Int32,System.Threading.CancellationToken) -T:System.NotSupportedException
     // ExceptionAdjustment: M:System.IO.Stream.ReadAsync(System.Byte[],System.Int32,System.Int32,System.Threading.CancellationToken) -T:System.NotSupportedException
-    private async Task<T> SendWithoutRetry<T>(CommandFamily commandFamily, string methodName, object? parameters) {
+    private async Task<T> SendWithoutRetry<T>(CommandFamily commandFamily, string methodName, object? parameters, string[]? childIds = null)
+    {
         /*
          * Send request
          */
 
         Stream tcpStream = await GetNetworkStream().ConfigureAwait(false);
-        long   requestId = Interlocked.Increment(ref _requestId);
-        JObject request = new(new JProperty(commandFamily.ToJsonString(), new JObject(
-            new JProperty(methodName, parameters is null ? null : JObject.FromObject(parameters, JsonSerializer)))));
+        long requestId = Interlocked.Increment(ref _requestId);
+        JObject request = BuildRequest(commandFamily, methodName, parameters, childIds);
+
         byte[] requestBytes = Serialize(request, requestId);
         byte[] headerBuffer = BitConverter.GetBytes(IPAddress.HostToNetworkOrder(requestBytes.Length));
 
@@ -170,6 +172,71 @@ private async Task<T> SendWithoutRetry<T>(CommandFamily commandFamily, string me
         return Deserialize<T>(payloadBuffer, requestId, request, commandFamily, methodName);
     }
 
+    private static JObject BuildRequest(CommandFamily commandFamily, string methodName, object? parameters, string[]? childIds = null)
+    {
+        JObject request = new JObject();
+
+        try
+        {
+            if (childIds is null)
+            {
+                request = new
+                (
+                    new JProperty(
+                        commandFamily.ToJsonString(),
+                        new JObject
+                        (
+                            new JProperty(methodName, parameters is null ? null : JObject.FromObject(parameters, JsonSerializer))
+                        )
+                    )
+                );
+            }
+            else
+            {
+                request = new
+                (
+                    new JProperty
+                    (
+                        "context", new JObject
+                        (
+                            new JProperty
+                            (
+                                "child_ids", JToken.FromObject(childIds, JsonSerializer)
+                            )
+                        )
+                    ),
+                    new JProperty(
+                        commandFamily.ToJsonString(),
+                        new JObject
+                        (
+                            new JProperty(methodName, parameters is null ? null : JObject.FromObject(parameters, JsonSerializer))
+                        )
+                    )
+                );
+            }
+            // request.Add(
+            //     new JProperty
+            //     (
+            //         "context", new JObject
+            //         (
+            //             new JProperty
+            //             (
+            //                 "child_ids", JToken.FromObject(childIds, JsonSerializer)
+            //             )
+            //         )
+            //     )
+            // );
+        }
+        catch (Exception ex)
+        {
+            var serializedObject1 = Newtonsoft.Json.JsonConvert.SerializeObject(request);
+        }
+
+        var serializedObject = Newtonsoft.Json.JsonConvert.SerializeObject(request);
+
+        return request;
+    }
+
     /// <exception cref="SocketException">The TCP socket failed to connect.</exception>
     internal virtual async Task<Stream> GetNetworkStream() {
         await EnsureConnected().ConfigureAwait(false);

Kasa/KasaOutlet.System.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Linq;
 using System.Threading.Tasks;
 using Newtonsoft.Json.Linq;
 
@@ -20,6 +21,29 @@ Task IKasaOutlet.ISystemCommands.SetOutletOn(bool turnOn) {
         return _client.Send<JObject>(CommandFamily.System, "set_relay_state", new { state = Convert.ToInt32(turnOn) });
     }
 
+    /// <inheritdoc />
+    Task IKasaOutlet.ISystemCommands.SetAllChildOutletOn(bool turnOn)
+    {
+        var systemInfo = System.GetInfo().Result;
+
+        if (systemInfo.Children == null)
+        {
+            // No children are found, return.
+            return Task.FromResult(false);
+        }
+
+        // In order to support multiple outlets, a 'context' node must be added:
+        // {"system":{"set_relay_state":{"state":0}},"context":{"child_ids":["etc00", "etc01]}}
+        // https://community.home-assistant.io/t/tp-link-kasa-kp400-2-outlet-support/113135/9
+
+        string[] children = systemInfo.Children.Select(child => child.id).ToArray();
+        var commandParameters = new { state = Convert.ToInt32(turnOn) };
+
+        //var serializedObject = Newtonsoft.Json.JsonConvert.SerializeObject(commandParameters); // Debug
+        // Include array of children IDs to Send<JObject>().
+        return _client.Send<JObject>(CommandFamily.System, "set_relay_state", commandParameters, children);
+    }
+
     /// <inheritdoc />
     Task<SystemInfo> IKasaOutlet.ISystemCommands.GetInfo() {
         return _client.Send<SystemInfo>(CommandFamily.System, "get_sysinfo");

Test/KasaOutletEnergyMeterTest.cs

@@ -10,7 +10,7 @@ public class KasaOutletEnergyMeterTest: AbstractKasaOutletTest {
     [Fact]
     public async Task GetInstantaneousPowerUsage() {
         PowerUsage expected = new() { Current = 18, Voltage = 121995, Power = 967, CumulativeEnergySinceBoot = 0 };
-        A.CallTo(() => Client.Send<PowerUsage>(CommandFamily.EnergyMeter, "get_realtime", null)).Returns(expected);
+        A.CallTo(() => Client.Send<PowerUsage>(CommandFamily.EnergyMeter, "get_realtime", null, null)).Returns(expected);
         PowerUsage actual = await Outlet.EnergyMeter.GetInstantaneousPowerUsage();
         actual.Current.Should().Be(18);
         actual.Voltage.Should().Be(121995);
@@ -21,7 +21,7 @@ public async Task GetInstantaneousPowerUsage() {
     [Fact]
     public async Task GetDailyEnergyUsageOneDay() {
         JObject json = JObject.Parse(@"{""day_list"": [{""year"": 2022, ""month"": 5, ""day"": 31, ""energy_wh"": 6}]}");
-        A.CallTo(() => Client.Send<JObject>(CommandFamily.EnergyMeter, "get_daystat", An<object>.That.Matches(o => o.Should().BeEquivalentTo(new { year = 2022, month = 5 }, "")))).Returns(json);
+        A.CallTo(() => Client.Send<JObject>(CommandFamily.EnergyMeter, "get_daystat", An<object>.That.Matches(o => o.Should().BeEquivalentTo(new { year = 2022, month = 5 }, "")), null)).Returns(json);
         IList<int>? actual = await Outlet.EnergyMeter.GetDailyEnergyUsage(2022, 5);
         actual.Should().HaveCount(31);
         actual.Should().BeEquivalentTo(new List<int> { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 6 });
@@ -30,7 +30,7 @@ public async Task GetDailyEnergyUsageOneDay() {
     [Fact]
     public async Task GetDailyEnergyUsageTwoDays() {
         JObject json = JObject.Parse(@"{""day_list"": [{""year"": 2022, ""month"": 6, ""day"": 1, ""energy_wh"": 22}, {""year"": 2022, ""month"": 6, ""day"": 2, ""energy_wh"": 1}]}");
-        A.CallTo(() => Client.Send<JObject>(CommandFamily.EnergyMeter, "get_daystat", An<object>.That.Matches(o => o.Should().BeEquivalentTo(new { year = 2022, month = 6 }, "")))).Returns(json);
+        A.CallTo(() => Client.Send<JObject>(CommandFamily.EnergyMeter, "get_daystat", An<object>.That.Matches(o => o.Should().BeEquivalentTo(new { year = 2022, month = 6 }, "")), null)).Returns(json);
         IList<int>? actual = await Outlet.EnergyMeter.GetDailyEnergyUsage(2022, 6);
         actual.Should().HaveCount(30);
         actual.Should().BeEquivalentTo(new List<int> { 22, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 });
@@ -39,31 +39,31 @@ public async Task GetDailyEnergyUsageTwoDays() {
     [Fact]
     public async Task GetDailyEnergyUsageNotFound() {
         JObject json = JObject.Parse(@"{""day_list"": []}");
-        A.CallTo(() => Client.Send<JObject>(CommandFamily.EnergyMeter, "get_daystat", An<object>.That.Matches(o => o.Should().BeEquivalentTo(new { year = 2022, month = 4 }, "")))).Returns(json);
+        A.CallTo(() => Client.Send<JObject>(CommandFamily.EnergyMeter, "get_daystat", An<object>.That.Matches(o => o.Should().BeEquivalentTo(new { year = 2022, month = 4 }, "")), null)).Returns(json);
         IList<int>? actual = await Outlet.EnergyMeter.GetDailyEnergyUsage(2022, 4);
         actual.Should().BeNull();
     }
 
     [Fact]
     public async Task GetMonthlyEnergyUsage() {
         JObject json = JObject.Parse(@"{""month_list"": [{""year"": 2022, ""month"": 5, ""energy_wh"": 6}, {""year"": 2022, ""month"": 6, ""energy_wh"": 18}]}");
-        A.CallTo(() => Client.Send<JObject>(CommandFamily.EnergyMeter, "get_monthstat", An<object>.That.HasProperty("year", 2022))).Returns(json);
+        A.CallTo(() => Client.Send<JObject>(CommandFamily.EnergyMeter, "get_monthstat", An<object>.That.HasProperty("year", 2022), null)).Returns(json);
         IList<int>? actual = await Outlet.EnergyMeter.GetMonthlyEnergyUsage(2022);
         actual.Should().BeEquivalentTo(new List<int> { 0, 0, 0, 0, 6, 18, 0, 0, 0, 0, 0, 0 });
     }
 
     [Fact]
     public async Task GetMonthlyEnergyUsageNotFound() {
         JObject json = JObject.Parse(@"{""month_list"": []}");
-        A.CallTo(() => Client.Send<JObject>(CommandFamily.EnergyMeter, "get_monthstat", An<object>.That.HasProperty("year", 2021))).Returns(json);
+        A.CallTo(() => Client.Send<JObject>(CommandFamily.EnergyMeter, "get_monthstat", An<object>.That.HasProperty("year", 2021), null)).Returns(json);
         IList<int>? actual = await Outlet.EnergyMeter.GetMonthlyEnergyUsage(2021);
         actual.Should().BeNull();
     }
 
     [Fact]
     public async Task ClearHistoricalUsage() {
         await Outlet.EnergyMeter.DeleteHistoricalUsage();
-        A.CallTo(() => Client.Send<JObject>(CommandFamily.EnergyMeter, "erase_emeter_stat", null)).MustHaveHappened();
+        A.CallTo(() => Client.Send<JObject>(CommandFamily.EnergyMeter, "erase_emeter_stat", null, null)).MustHaveHappened();
     }
 
 }