// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using Aspire.OpenAI;
using Microsoft.Extensions.AI;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using OpenAI;
 
namespace Microsoft.Extensions.Hosting;
 
/// <summary>
/// Provides extension methods for registering <see cref="IEmbeddingGenerator{TInput, TEmbedding}"/> as a singleton in the services provided by the <see cref="IHostApplicationBuilder"/>.
/// </summary>
public static class AspireOpenAIClientBuilderEmbeddingGeneratorExtensions
{
    /// <summary>
    /// Registers a singleton <see cref="IEmbeddingGenerator{TInput, TEmbedding}"/> in the services provided by the <paramref name="builder"/>.
    /// </summary>
    /// <param name="builder">An <see cref="AspireOpenAIClientBuilder" />.</param>
    /// <param name="deploymentName">Optionally specifies which model deployment to use. If not specified, a value will be taken from the connection string.</param>
    /// <returns>A <see cref="EmbeddingGeneratorBuilder{TInput, TEmbedding}"/> that can be used to build a pipeline around the inner <see cref="IEmbeddingGenerator{TInput, TEmbedding}"/>.</returns>
    public static EmbeddingGeneratorBuilder<string, Embedding<float>> AddEmbeddingGenerator(
        this AspireOpenAIClientBuilder builder,
        string? deploymentName = null)
    {
        ArgumentNullException.ThrowIfNull(builder);
 
        return builder.HostBuilder.Services.AddEmbeddingGenerator(
            services => CreateInnerEmbeddingGenerator(services, builder, deploymentName));
    }
 
    /// <summary>
    /// Registers a keyed singleton <see cref="IEmbeddingGenerator{TInput, TEmbedding}"/> in the services provided by the <paramref name="builder"/>.
    /// </summary>
    /// <param name="builder">An <see cref="AspireOpenAIClientBuilder" />.</param>
    /// <param name="serviceKey">The service key with which the <see cref="IEmbeddingGenerator{TInput, TEmbedding}"/> will be registered.</param>
    /// <param name="deploymentName">Optionally specifies which model deployment to use. If not specified, a value will be taken from the connection string.</param>
    /// <returns>A <see cref="EmbeddingGeneratorBuilder{TInput, TEmbedding}"/> that can be used to build a pipeline around the inner <see cref="IEmbeddingGenerator{TInput, TEmbedding}"/>.</returns>
    public static EmbeddingGeneratorBuilder<string, Embedding<float>> AddKeyedEmbeddingGenerator(
        this AspireOpenAIClientBuilder builder,
        string serviceKey,
        string? deploymentName = null)
    {
        ArgumentNullException.ThrowIfNull(builder);
        ArgumentException.ThrowIfNullOrEmpty(serviceKey);
 
        return builder.HostBuilder.Services.AddKeyedEmbeddingGenerator(
            serviceKey,
            services => CreateInnerEmbeddingGenerator(services, builder, deploymentName));
    }
 
    /// <summary>
    /// Wrap the <see cref="OpenAIClient"/> in a telemetry client if tracing is enabled.
    /// Note that this doesn't use ".UseOpenTelemetry()" because the order of the clients would be incorrect.
    /// We want the telemetry client to be the innermost client, right next to the inner <see cref="OpenAIClient"/>.
    /// </summary>
    private static IEmbeddingGenerator<string, Embedding<float>> CreateInnerEmbeddingGenerator(
        IServiceProvider services,
        AspireOpenAIClientBuilder builder,
        string? deploymentName)
    {
        var openAiClient = builder.ServiceKey is null
            ? services.GetRequiredService<OpenAIClient>()
            : services.GetRequiredKeyedService<OpenAIClient>(builder.ServiceKey);
 
        deploymentName ??= builder.GetRequiredDeploymentName();
        var result = openAiClient.AsEmbeddingGenerator(deploymentName);
 
        if (builder.DisableTracing)
        {
            return result;
        }
 
        var loggerFactory = services.GetService<ILoggerFactory>();
        return new OpenTelemetryEmbeddingGenerator<string, Embedding<float>>(
            result,
            loggerFactory?.CreateLogger(typeof(OpenTelemetryEmbeddingGenerator<string, Embedding<float>>)));
    }
}