using System;
using System.Collections.Generic;
using System.Net;
using System.Net.Http;
using Amazon.Runtime.Internal.Util;
using Amazon.XRay.Recorder.Core;
using Amazon.XRay.Recorder.Core.Exceptions;
using Amazon.XRay.Recorder.Core.Internal.Entities;

namespace Amazon.XRay.Recorder.Handlers.System.Net.Utils
{
    public static class RequestUtil
    {
        private static readonly Logger _logger = Runtime.Internal.Util.Logger.GetLogger(typeof(RequestUtil));

        /// <summary>
        /// Collects information from and adds a tracing header to the request.
        /// Depending on the flag sanitizeHttpRequestTracing the query string on http request is stripped before tracing is submitted.
        /// </summary>
        /// <param name="request">An instance of <see cref="WebRequest"/></param>
        /// <param name="sanitizeHttpRequestTracing"><see cref="Boolean"/> value</param>
        internal static void ProcessRequest(WebRequest request, bool sanitizeHttpRequestTracing = false)
        {
            ProcessRequest(request.RequestUri, request.Method, header => request.Headers.Add(TraceHeader.HeaderKey, header), sanitizeHttpRequestTracing);
        }

        /// <summary>
        /// Collects information from and adds a tracing header to the request.
        /// Depending on the flag sanitizeHttpRequestTracing the query string on http request is stripped before tracing is submitted.
        /// </summary>
        /// <param name="request">An instance of <see cref="HttpRequestMessage"/></param>
        /// <param name="sanitizeHttpRequestTracing"><see cref="Boolean"/> value</param>
        internal static void ProcessRequest(HttpRequestMessage request, bool sanitizeHttpRequestTracing = false)
        {
            ProcessRequest(request.RequestUri, request.Method.Method, AddOrReplaceHeader, sanitizeHttpRequestTracing);

            void AddOrReplaceHeader(string header)
            {
                request.Headers.Remove(TraceHeader.HeaderKey);
                request.Headers.Add(TraceHeader.HeaderKey, header);
            }
        }

        /// <summary>
        /// Collects information from the response and adds to <see cref="AWSXRayRecorder"/> instance.
        /// </summary>
        /// <param name="response">An instance of <see cref="HttpWebResponse"/></param>
        internal static void ProcessResponse(HttpWebResponse response)
        {
            ProcessResponse(response.StatusCode, response.ContentLength);
        }

        /// <summary>
        /// Collects information from the response and adds to <see cref="AWSXRayRecorder"/> instance.
        /// </summary>
        /// <param name="response">An instance of <see cref="HttpResponseMessage"/></param>
        internal static void ProcessResponse(HttpResponseMessage response)
        {
            ProcessResponse(response.StatusCode, response.Content.Headers.ContentLength);
        }

        private static void ProcessRequest(Uri uri, string method, Action<string> addHeaderAction, bool sanitizeHttpRequestTracing)
        {
            if (AWSXRayRecorder.Instance.IsTracingDisabled())
            {
                _logger.DebugFormat("Tracing is disabled. Not starting a subsegment on HTTP request.");
                return;
            }

            var recorder = AWSXRayRecorder.Instance;
            recorder.BeginSubsegment(uri.Host);
            recorder.SetNamespace("remote");

            var requestInformation = new Dictionary<string, object>
            {
                ["url"] = sanitizeHttpRequestTracing ? uri.AbsoluteUri.Split(new[] { '?' })[0] : uri.AbsoluteUri,
                ["method"] = method
            };
            recorder.AddHttpInformation("request", requestInformation);

            try
            {
                if (TraceHeader.TryParse(recorder.GetEntity(), out var header))
                {
                    addHeaderAction(header.ToString());
                }
            }
            catch (EntityNotAvailableException e)
            {
               recorder.TraceContext.HandleEntityMissing(recorder,e, "Failed to get entity since it is not available in trace context while processing http request.");
            }
        }

        private static void ProcessResponse(HttpStatusCode httpStatusCode, long? contentLength)
        {
            if (AWSXRayRecorder.Instance.IsTracingDisabled())
            {
                _logger.DebugFormat("Tracing is disabled. Not ending a subsegment on HTTP response.");
                return;
            }

            var statusCode = (int)httpStatusCode;

            var responseInformation = new Dictionary<string, object> { ["status"] = statusCode };
            if (statusCode >= 400 && statusCode <= 499)
            {
                AWSXRayRecorder.Instance.MarkError();

                if (statusCode == 429)
                {
                    AWSXRayRecorder.Instance.MarkThrottle();
                }
            }
            else if (statusCode >= 500 && statusCode <= 599)
            {
                AWSXRayRecorder.Instance.MarkFault();
            }

            responseInformation["content_length"] = contentLength;
            AWSXRayRecorder.Instance.AddHttpInformation("response", responseInformation);
        }
    }
}