// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System;
using Microsoft.Extensions.DependencyInjection;
using Xunit;
 
namespace Microsoft.Extensions.AI;
 
public class DependencyInjectionPatterns
{
    private IServiceCollection ServiceCollection { get; } = new ServiceCollection();
 
    [Fact]
    public void CanRegisterSingletonUsingFactory()
    {
        // Arrange/Act
        ServiceCollection.AddChatClient(services => new TestChatClient { Services = services })
            .UseSingletonMiddleware();
 
        // Assert
        var services = ServiceCollection.BuildServiceProvider();
        using var scope1 = services.CreateScope();
        using var scope2 = services.CreateScope();
 
        var instance1 = scope1.ServiceProvider.GetRequiredService<IChatClient>();
        var instance1Copy = scope1.ServiceProvider.GetRequiredService<IChatClient>();
        var instance2 = scope2.ServiceProvider.GetRequiredService<IChatClient>();
 
        // Each scope gets the same instance, because it's singleton
        var instance = Assert.IsType<SingletonMiddleware>(instance1);
        Assert.Same(instance, instance1Copy);
        Assert.Same(instance, instance2);
        Assert.IsType<TestChatClient>(instance.InnerClient);
    }
 
    [Fact]
    public void CanRegisterSingletonUsingSharedInstance()
    {
        // Arrange/Act
        using var singleton = new TestChatClient();
        ServiceCollection.AddChatClient(singleton)
            .UseSingletonMiddleware();
 
        // Assert
        var services = ServiceCollection.BuildServiceProvider();
        using var scope1 = services.CreateScope();
        using var scope2 = services.CreateScope();
 
        var instance1 = scope1.ServiceProvider.GetRequiredService<IChatClient>();
        var instance1Copy = scope1.ServiceProvider.GetRequiredService<IChatClient>();
        var instance2 = scope2.ServiceProvider.GetRequiredService<IChatClient>();
 
        // Each scope gets the same instance, because it's singleton
        var instance = Assert.IsType<SingletonMiddleware>(instance1);
        Assert.Same(instance, instance1Copy);
        Assert.Same(instance, instance2);
        Assert.IsType<TestChatClient>(instance.InnerClient);
    }
 
    [Fact]
    public void CanRegisterKeyedSingletonUsingFactory()
    {
        // Arrange/Act
        ServiceCollection.AddKeyedChatClient("mykey", services => new TestChatClient { Services = services })
            .UseSingletonMiddleware();
 
        // Assert
        var services = ServiceCollection.BuildServiceProvider();
        using var scope1 = services.CreateScope();
        using var scope2 = services.CreateScope();
 
        Assert.Null(services.GetService<IChatClient>());
 
        var instance1 = scope1.ServiceProvider.GetRequiredKeyedService<IChatClient>("mykey");
        var instance1Copy = scope1.ServiceProvider.GetRequiredKeyedService<IChatClient>("mykey");
        var instance2 = scope2.ServiceProvider.GetRequiredKeyedService<IChatClient>("mykey");
 
        // Each scope gets the same instance, because it's singleton
        var instance = Assert.IsType<SingletonMiddleware>(instance1);
        Assert.Same(instance, instance1Copy);
        Assert.Same(instance, instance2);
        Assert.IsType<TestChatClient>(instance.InnerClient);
    }
 
    [Fact]
    public void CanRegisterKeyedSingletonUsingSharedInstance()
    {
        // Arrange/Act
        using var singleton = new TestChatClient();
        ServiceCollection.AddKeyedChatClient("mykey", singleton)
            .UseSingletonMiddleware();
 
        // Assert
        var services = ServiceCollection.BuildServiceProvider();
        using var scope1 = services.CreateScope();
        using var scope2 = services.CreateScope();
 
        Assert.Null(services.GetService<IChatClient>());
 
        var instance1 = scope1.ServiceProvider.GetRequiredKeyedService<IChatClient>("mykey");
        var instance1Copy = scope1.ServiceProvider.GetRequiredKeyedService<IChatClient>("mykey");
        var instance2 = scope2.ServiceProvider.GetRequiredKeyedService<IChatClient>("mykey");
 
        // Each scope gets the same instance, because it's singleton
        var instance = Assert.IsType<SingletonMiddleware>(instance1);
        Assert.Same(instance, instance1Copy);
        Assert.Same(instance, instance2);
        Assert.IsType<TestChatClient>(instance.InnerClient);
    }
 
    public class SingletonMiddleware(IChatClient inner, IServiceProvider services) : DelegatingChatClient(inner)
    {
        public new IChatClient InnerClient => base.InnerClient;
        public IServiceProvider Services => services;
    }
}