Add plugin isolation IPC scaffolding and host phase one docs (#5)

LanMountainDesktop.PluginIsolation.Ipc/PluginIpcClient.cs

@@ -0,0 +1,90 @@
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+namespace LanMountainDesktop.PluginIsolation.Ipc;
+
+public sealed class PluginIpcClient
+{
+    public PluginIpcClient(PluginIpcClientOptions options)
+    {
+        Options = options ?? throw new ArgumentNullException(nameof(options));
+        SerializerContext = options.SerializerContext ?? throw new ArgumentNullException(nameof(options.SerializerContext));
+        SerializerOptions = SerializerContext.Options;
+    }
+
+    public PluginIpcClientOptions Options { get; }
+
+    public JsonSerializerContext SerializerContext { get; }
+
+    public JsonSerializerOptions SerializerOptions { get; }
+
+    public PluginIpcRequestDispatcher? RequestDispatcher { get; set; }
+
+    public PluginIpcNotificationDispatcher? NotificationDispatcher { get; set; }
+
+    public Task<TResponse?> RequestAsync<TRequest, TResponse>(
+        string route,
+        TRequest payload,
+        CancellationToken cancellationToken = default)
+    {
+        ArgumentException.ThrowIfNullOrWhiteSpace(route);
+        return RequestCoreAsync<TRequest, TResponse>(route, payload, cancellationToken);
+    }
+
+    public Task NotifyAsync<TPayload>(
+        string route,
+        TPayload payload,
+        CancellationToken cancellationToken = default)
+    {
+        ArgumentException.ThrowIfNullOrWhiteSpace(route);
+        return NotifyCoreAsync(route, Serialize(payload), cancellationToken);
+    }
+
+    private async Task<TResponse?> RequestCoreAsync<TRequest, TResponse>(
+        string route,
+        TRequest payload,
+        CancellationToken cancellationToken)
+    {
+        if (RequestDispatcher is null)
+        {
+            throw new NotSupportedException(
+                "PluginIpcClient is not yet bound to a dotnetCampus.Ipc transport dispatcher. " +
+                "Wire RequestDispatcher during host/worker transport integration.");
+        }
+
+        var response = await RequestDispatcher(route, Serialize(payload), cancellationToken).ConfigureAwait(false);
+        if (response is null)
+        {
+            return default;
+        }
+
+        return Deserialize<TResponse>(response);
+    }
+
+    private async Task NotifyCoreAsync(string route, JsonElement? payload, CancellationToken cancellationToken)
+    {
+        if (NotificationDispatcher is null)
+        {
+            throw new NotSupportedException(
+                "PluginIpcClient is not yet bound to a dotnetCampus.Ipc transport dispatcher. " +
+                "Wire NotificationDispatcher during host/worker transport integration.");
+        }
+
+        await NotificationDispatcher(route, payload, cancellationToken).ConfigureAwait(false);
+    }
+
+    private JsonElement Serialize<T>(T payload)
+    {
+        return JsonSerializer.SerializeToElement(payload, SerializerOptions);
+    }
+
+    private T? Deserialize<T>(JsonElement? payload)
+    {
+        if (payload is null)
+        {
+            return default;
+        }
+
+        return payload.Value.Deserialize<T>(SerializerOptions);
+    }
+}