// 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 System.Net.Http;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.Extensions.Internal;
using Microsoft.Extensions.Logging;

namespace Microsoft.Extensions.Http.Logging
{
    /// <summary>
    /// Handles logging of the lifecycle for an HTTP request within a log scope.
    /// </summary>
    public class LoggingScopeHttpMessageHandler : DelegatingHandler
    {
        private readonly ILogger _logger;
        private readonly HttpClientFactoryOptions? _options;

        /// <summary>
        /// Initializes a new instance of the <see cref="LoggingScopeHttpMessageHandler"/> class with a specified logger.
        /// </summary>
        /// <param name="logger">The <see cref="ILogger"/> to log to.</param>
        /// <exception cref="ArgumentNullException"><paramref name="logger"/> is <see langword="null"/>.</exception>
        public LoggingScopeHttpMessageHandler(ILogger logger)
        {
            ArgumentNullException.ThrowIfNull(logger);

            _logger = logger;
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="LoggingScopeHttpMessageHandler"/> class with a specified logger and options.
        /// </summary>
        /// <param name="logger">The <see cref="ILogger"/> to log to.</param>
        /// <param name="options">The <see cref="HttpClientFactoryOptions"/> used to configure the <see cref="LoggingScopeHttpMessageHandler"/> instance.</param>
        /// <exception cref="ArgumentNullException"><paramref name="logger"/> or <paramref name="options"/> is <see langword="null"/>.</exception>
        public LoggingScopeHttpMessageHandler(ILogger logger, HttpClientFactoryOptions options)
        {
            ArgumentNullException.ThrowIfNull(logger);
            ArgumentNullException.ThrowIfNull(options);

            _logger = logger;
            _options = options;
        }

        private Task<HttpResponseMessage> SendCoreAsync(HttpRequestMessage request, bool useAsync, CancellationToken cancellationToken)
        {
            ArgumentNullException.ThrowIfNull(request);
            return Core(request, useAsync, cancellationToken);

            async Task<HttpResponseMessage> Core(HttpRequestMessage request, bool useAsync, CancellationToken cancellationToken)
            {
                var stopwatch = ValueStopwatch.StartNew();

                Func<string, bool> shouldRedactHeaderValue = _options?.ShouldRedactHeaderValue ?? LogHelper.ShouldRedactHeaderValue;

                using (_logger.BeginRequestPipelineScope(request, out string? formattedUri))
                {
                    _logger.LogRequestPipelineStart(request, formattedUri, shouldRedactHeaderValue);

                    try
                    {
                        HttpResponseMessage response = useAsync
                            ? await base.SendAsync(request, cancellationToken).ConfigureAwait(false)
#if NET
                            : base.Send(request, cancellationToken);
#else
                            : throw new NotImplementedException("Unreachable code");
#endif
                        _logger.LogRequestPipelineEnd(response, stopwatch.GetElapsedTime(), shouldRedactHeaderValue);

                        return response;
                    }
                    catch (HttpRequestException ex)
                    {
                        _logger.LogRequestPipelineFailed(stopwatch.GetElapsedTime(), ex);
                        throw;
                    }
                }
            }
        }

        /// <inheritdoc />
        /// <remarks>Logs the request to and response from the sent <see cref="HttpRequestMessage"/>.</remarks>
        protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
            => SendCoreAsync(request, useAsync: true, cancellationToken);

#if NET
        /// <inheritdoc />
        /// <remarks>Logs the request to and response from the sent <see cref="HttpRequestMessage"/>.</remarks>
        protected override HttpResponseMessage Send(HttpRequestMessage request, CancellationToken cancellationToken)
            => SendCoreAsync(request, useAsync: false, cancellationToken).GetAwaiter().GetResult();
#endif
    }
}