// <auto-generated /> (Turns off StyleCop analysis in this file.)
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

/*
 Note: This class was copied from
 https://github.com/dotnet/runtime/blob/e13e7388dedc6672381e61592c2e74385fe781a5/src/libraries/Microsoft.Extensions.Options/src/OptionsFactory.cs
 and then modified to have delegate features needed by the SDK. In the future if
 we take a dependency on Microsoft.Extensions.Options v5.0.0 (or greater), much
 of this can be removed in favor of the "CreateInstance" API added in 5:
 https://learn.microsoft.com/dotnet/api/microsoft.extensions.options.optionsfactory-1.createinstance?view=dotnet-plat-ext-5.0.
 See https://github.com/open-telemetry/opentelemetry-dotnet/pull/4093 for an
 example of how that works.
*/

#nullable enable

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Diagnostics.CodeAnalysis;
using Microsoft.Extensions.Configuration;

namespace Microsoft.Extensions.Options
{
    /// <summary>
    /// Implementation of <see cref="IOptionsFactory{TOptions}"/>.
    /// </summary>
    /// <typeparam name="TOptions">The type of options being requested.</typeparam>
    internal sealed class DelegatingOptionsFactory<TOptions> :
        IOptionsFactory<TOptions>
        where TOptions : class, new()
    {
        private readonly Func<IConfiguration, string, TOptions> optionsFactoryFunc;
        private readonly IConfiguration configuration;
        private readonly IConfigureOptions<TOptions>[] _setups;
        private readonly IPostConfigureOptions<TOptions>[] _postConfigures;
        private readonly IValidateOptions<TOptions>[] _validations;

        /// <summary>
        /// Initializes a new instance with the specified options configurations.
        /// </summary>
        /// <param name="setups">The configuration actions to run.</param>
        /// <param name="postConfigures">The initialization actions to run.</param>
        /// <param name="validations">The validations to run.</param>
        public DelegatingOptionsFactory(
            Func<IConfiguration, string, TOptions> optionsFactoryFunc,
            IConfiguration configuration,
            IEnumerable<IConfigureOptions<TOptions>> setups,
            IEnumerable<IPostConfigureOptions<TOptions>> postConfigures,
            IEnumerable<IValidateOptions<TOptions>> validations)
        {
            // The default DI container uses arrays under the covers. Take advantage of this knowledge
            // by checking for an array and enumerate over that, so we don't need to allocate an enumerator.
            // When it isn't already an array, convert it to one, but don't use System.Linq to avoid pulling Linq in to
            // small trimmed applications.

            Debug.Assert(optionsFactoryFunc != null, "optionsFactoryFunc was null");
            Debug.Assert(configuration != null, "configuration was null");

            this.optionsFactoryFunc = optionsFactoryFunc!;
            this.configuration = configuration!;
            _setups = setups as IConfigureOptions<TOptions>[] ?? new List<IConfigureOptions<TOptions>>(setups).ToArray();
            _postConfigures = postConfigures as IPostConfigureOptions<TOptions>[] ?? new List<IPostConfigureOptions<TOptions>>(postConfigures).ToArray();
            _validations = validations as IValidateOptions<TOptions>[] ?? new List<IValidateOptions<TOptions>>(validations).ToArray();
        }

        /// <summary>
        /// Returns a configured <typeparamref name="TOptions"/> instance with the given <paramref name="name"/>.
        /// </summary>
        /// <param name="name">The name of the <typeparamref name="TOptions"/> instance to create.</param>
        /// <returns>The created <typeparamref name="TOptions"/> instance with the given <paramref name="name"/>.</returns>
        /// <exception cref="OptionsValidationException">One or more <see cref="IValidateOptions{TOptions}"/> return failed <see cref="ValidateOptionsResult"/> when validating the <typeparamref name="TOptions"/> instance been created.</exception>
        /// <exception cref="MissingMethodException">The <typeparamref name="TOptions"/> does not have a public parameterless constructor or <typeparamref name="TOptions"/> is <see langword="abstract"/>.</exception>
        public TOptions Create(string name)
        {
            TOptions options = this.optionsFactoryFunc(this.configuration, name);
            foreach (IConfigureOptions<TOptions> setup in _setups)
            {
                if (setup is IConfigureNamedOptions<TOptions> namedSetup)
                {
                    namedSetup.Configure(name, options);
                }
                else if (name == Options.DefaultName)
                {
                    setup.Configure(options);
                }
            }
            foreach (IPostConfigureOptions<TOptions> post in _postConfigures)
            {
                post.PostConfigure(name, options);
            }

            if (_validations.Length > 0)
            {
                var failures = new List<string>();
                foreach (IValidateOptions<TOptions> validate in _validations)
                {
                    ValidateOptionsResult result = validate.Validate(name, options);
                    if (result is not null && result.Failed)
                    {
                        failures.AddRange(result.Failures);
                    }
                }
                if (failures.Count > 0)
                {
                    throw new OptionsValidationException(name, typeof(TOptions), failures);
                }
            }

            return options;
        }
    }
}
