From b41373339e18d78782eb044b692a81fd6e50d7c0 Mon Sep 17 00:00:00 2001
From: Developer 02 <developer02@didaloghe.onmicrosoft.com>
Date: Mon, 28 Apr 2025 14:56:25 +0200
Subject: [PATCH] =?UTF-8?q?feat(core):=20DeferredServiceProvider=20f=C3=BC?=
 =?UTF-8?q?r=20verz=C3=B6gerte=20IServiceProvider-Initialisierung=20hinzug?=
 =?UTF-8?q?ef=C3=BCgt?=
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---
 .../LazyServiceProvider.cs                    | 40 +++++++++++++++++++
 1 file changed, 40 insertions(+)
 create mode 100644 DigitalData.Core.Abstractions/LazyServiceProvider.cs

diff --git a/DigitalData.Core.Abstractions/LazyServiceProvider.cs b/DigitalData.Core.Abstractions/LazyServiceProvider.cs
new file mode 100644
index 0000000..99a6fdd
--- /dev/null
+++ b/DigitalData.Core.Abstractions/LazyServiceProvider.cs
@@ -0,0 +1,40 @@
+namespace DigitalData.Core.Abstractions;
+
+/// <summary>
+/// A deferred implementation of <see cref="IServiceProvider"/> that allows the <see cref="IServiceProvider"/> instance 
+/// to be provided at a later time via a factory callback.
+/// </summary>
+/// <remarks>
+/// This is particularly useful when service registration requires an <see cref="IServiceProvider"/> instance,
+/// but the service provider is not yet available at registration time. 
+/// By using <see cref="DeferredServiceProvider"/>, a service can safely resolve dependencies once
+/// the application's service provider has been built, ensuring a single consistent scope.
+/// </remarks>
+public class DeferredServiceProvider : IServiceProvider
+{
+    private Lazy<IServiceProvider>? _serviceProvider;
+
+    /// <summary>
+    /// Sets the factory that will be used to lazily initialize the <see cref="IServiceProvider"/> instance.
+    /// </summary>
+    public Func<IServiceProvider> Factory
+    {
+        set => _serviceProvider = new(value);
+    }
+
+    /// <summary>
+    /// Retrieves the requested service object from the deferred <see cref="IServiceProvider"/>.
+    /// </summary>
+    /// <param name="serviceType">The type of service object to retrieve.</param>
+    /// <returns>The requested service object, or <c>null</c> if the service is not available.</returns>
+    /// <exception cref="InvalidOperationException">
+    /// Thrown if the service provider factory has not been set before calling <see cref="GetService"/>.
+    /// </exception>
+    public object? GetService(Type serviceType)
+    {
+        if (_serviceProvider is null)
+            throw new InvalidOperationException("The service provider has not been initialized. Make sure 'Factory' is set before calling 'GetService'.");
+
+        return _serviceProvider.Value.GetService(serviceType);
+    }
+}