// 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 Microsoft.Extensions.Logging;
using Microsoft.Extensions.Logging.Abstractions;
using Microsoft.Shared.Diagnostics;
 
namespace Microsoft.Extensions.AI;
 
/// <summary>Provides extensions for configuring <see cref="LoggingEmbeddingGenerator{TInput, TEmbedding}"/> instances.</summary>
public static class LoggingEmbeddingGeneratorBuilderExtensions
{
    /// <summary>Adds logging to the embedding generator pipeline.</summary>
    /// <typeparam name="TInput">Specifies the type of the input passed to the generator.</typeparam>
    /// <typeparam name="TEmbedding">Specifies the type of the embedding instance produced by the generator.</typeparam>
    /// <param name="builder">The <see cref="EmbeddingGeneratorBuilder{TInput, TEmbedding}"/>.</param>
    /// <param name="loggerFactory">
    /// An optional <see cref="ILoggerFactory"/> used to create a logger with which logging should be performed.
    /// If not supplied, a required instance will be resolved from the service provider.
    /// </param>
    /// <param name="configure">An optional callback that can be used to configure the <see cref="LoggingEmbeddingGenerator{TInput, TEmbedding}"/> instance.</param>
    /// <returns>The <paramref name="builder"/>.</returns>
    /// <exception cref="ArgumentNullException"><paramref name="builder"/> is <see langword="null"/>.</exception>
    /// <remarks>
    /// <para>
    /// When the employed <see cref="ILogger"/> enables <see cref="Logging.LogLevel.Trace"/>, the contents of
    /// values and options are logged. These values and options may contain sensitive application data.
    /// <see cref="Logging.LogLevel.Trace"/> is disabled by default and should never be enabled in a production environment.
    /// Messages and options are not logged at other logging levels.
    /// </para>
    /// </remarks>
    public static EmbeddingGeneratorBuilder<TInput, TEmbedding> UseLogging<TInput, TEmbedding>(
        this EmbeddingGeneratorBuilder<TInput, TEmbedding> builder,
        ILoggerFactory? loggerFactory = null,
        Action<LoggingEmbeddingGenerator<TInput, TEmbedding>>? configure = null)
        where TEmbedding : Embedding
    {
        _ = Throw.IfNull(builder);
 
        return builder.Use((innerGenerator, services) =>
        {
            loggerFactory ??= services.GetRequiredService<ILoggerFactory>();
 
            // If the factory we resolve is for the null logger, the LoggingEmbeddingGenerator will end up
            // being an expensive nop, so skip adding it and just return the inner generator.
            if (loggerFactory == NullLoggerFactory.Instance)
            {
                return innerGenerator;
            }
 
            var generator = new LoggingEmbeddingGenerator<TInput, TEmbedding>(innerGenerator, loggerFactory.CreateLogger(typeof(LoggingEmbeddingGenerator<TInput, TEmbedding>)));
            configure?.Invoke(generator);
            return generator;
        });
    }
}