/// <summary>
 /// Creates a new <see cref="HelpPageSampleKey"/> based on media type, <see cref="SampleDirection"/>, controller name, action name and parameter names.
 /// </summary>
 /// <param name="mediaType">The media type.</param>
 /// <param name="sampleDirection">The <see cref="SampleDirection"/>.</param>
 /// <param name="controllerName">Name of the controller.</param>
 /// <param name="actionName">Name of the action.</param>
 /// <param name="parameterNames">The parameter names.</param>
 public HelpPageSampleKey(MediaTypeHeaderValue mediaType, SampleDirection sampleDirection, string controllerName, string actionName, IEnumerable<string> parameterNames)
 {
     if (mediaType == null)
     {
         throw new ArgumentNullException("mediaType");
     }
     if (!Enum.IsDefined(typeof(SampleDirection), sampleDirection))
     {
         throw new InvalidEnumArgumentException("sampleDirection", (int)sampleDirection, typeof(SampleDirection));
     }
     if (controllerName == null)
     {
         throw new ArgumentNullException("controllerName");
     }
     if (actionName == null)
     {
         throw new ArgumentNullException("actionName");
     }
     if (parameterNames == null)
     {
         throw new ArgumentNullException("parameterNames");
     }
     ControllerName = controllerName;
     ActionName = actionName;
     MediaType = mediaType;
     ParameterNames = new HashSet<string>(parameterNames, StringComparer.OrdinalIgnoreCase);
     SampleDirection = sampleDirection;
 }

        /// <summary>
        /// Creates a new <see cref="HelpPageSampleKey"/> based on media type, <see cref="SampleDirection"/>, controller name, action name and parameter names.
        /// </summary>
        /// <param name="mediaType">The media type.</param>
        /// <param name="sampleDirection">The <see cref="SampleDirection"/>.</param>
        /// <param name="controllerName">Name of the controller.</param>
        /// <param name="actionName">Name of the action.</param>
        /// <param name="parameterNames">The parameter names.</param>
        public HelpPageSampleKey(MediaTypeHeaderValue mediaType, SampleDirection sampleDirection, string controllerName, string actionName, IEnumerable<string> parameterNames)
            : this(sampleDirection, controllerName, actionName, parameterNames) {
            if (mediaType == null) {
                throw new ArgumentNullException("mediaType");
            }

            MediaType = mediaType;
        }

        public virtual object GetActionSample(string controllerName, string actionName, IEnumerable<string> parameterNames, Type type, MediaTypeFormatter formatter, MediaTypeHeaderValue mediaType, SampleDirection sampleDirection)
        {
            object sample;
               if (ActionSamples.TryGetValue(new HelpPageSampleKey(mediaType, sampleDirection, controllerName, actionName, parameterNames), out sample) ||
                ActionSamples.TryGetValue(new HelpPageSampleKey(mediaType, sampleDirection, controllerName, actionName, new[] { "*" }), out sample) ||
                ActionSamples.TryGetValue(new HelpPageSampleKey(mediaType, type), out sample))
            {
                return sample;
            }

            return null;
        }

        /// <summary>
        /// Search for samples that are provided directly through <see cref="ActionSamples"/>.
        /// </summary>
        /// <param name="controllerName">Name of the controller.</param>
        /// <param name="actionName">Name of the action.</param>
        /// <param name="parameterNames">The parameter names.</param>
        /// <param name="type">The CLR type.</param>
        /// <param name="formatter">The formatter.</param>
        /// <param name="mediaType">The media type.</param>
        /// <param name="sampleDirection">The value indicating whether the sample is for a request or for a response.</param>
        /// <returns>The sample that matches the parameters.</returns>
        public virtual object GetActionSample(string controllerName, string actionName, IEnumerable<string> parameterNames, Type type, MediaTypeFormatter formatter, MediaTypeHeaderValue mediaType, SampleDirection sampleDirection)
        {
            object sample;

            // First, try get sample provided for a specific mediaType, controllerName, actionName and parameterNames.
            // If not found, try get the sample provided for a specific mediaType, controllerName and actionName regardless of the parameterNames
            // If still not found, try get the sample provided for a specific type and mediaType
            if (ActionSamples.TryGetValue(new HelpPageSampleKey(mediaType, sampleDirection, controllerName, actionName, parameterNames), out sample) ||
                ActionSamples.TryGetValue(new HelpPageSampleKey(mediaType, sampleDirection, controllerName, actionName, new[] { "*" }), out sample) ||
                ActionSamples.TryGetValue(new HelpPageSampleKey(mediaType, type), out sample))
                return sample;

            return null;
        }

        /// <summary>
        ///     Gets the request or response body samples.
        /// </summary>
        /// <param name="api">The <see cref="ApiDescription" />.</param>
        /// <param name="sampleDirection">The value indicating whether the sample is for a request or for a response.</param>
        /// <returns>The samples keyed by media type.</returns>
        public virtual IDictionary<MediaTypeHeaderValue, object> GetSample(ApiDescription api,
            SampleDirection sampleDirection)
        {
            if (api == null)
            {
                throw new ArgumentNullException("api");
            }
            string controllerName = api.ActionDescriptor.ControllerDescriptor.ControllerName;
            string actionName = api.ActionDescriptor.ActionName;
            IEnumerable<string> parameterNames = api.ParameterDescriptions.Select(p => p.Name);
            Collection<MediaTypeFormatter> formatters;
            Type type = ResolveType(api, controllerName, actionName, parameterNames, sampleDirection, out formatters);
            var samples = new Dictionary<MediaTypeHeaderValue, object>();

            // Use the samples provided directly for actions
            var actionSamples = GetAllActionSamples(controllerName, actionName, parameterNames, sampleDirection);
            foreach (var actionSample in actionSamples)
            {
                samples.Add(actionSample.Key.MediaType, WrapSampleIfString(actionSample.Value));
            }

            // Do the sample generation based on formatters only if an action doesn't return an HttpResponseMessage.
            // Here we cannot rely on formatters because we don't know what's in the HttpResponseMessage, it might not even use formatters.
            if (type != null && !typeof (HttpResponseMessage).IsAssignableFrom(type))
            {
                object sampleObject = GetSampleObject(type);
                foreach (var formatter in formatters)
                {
                    foreach (MediaTypeHeaderValue mediaType in formatter.SupportedMediaTypes)
                    {
                        if (!samples.ContainsKey(mediaType))
                        {
                            object sample = GetActionSample(controllerName, actionName, parameterNames, type, formatter,
                                mediaType, sampleDirection);

                            // If no sample found, try generate sample using formatter and sample object
                            if (sample == null && sampleObject != null)
                            {
                                sample = WriteSampleObjectUsingFormatter(formatter, sampleObject, type, mediaType);
                            }

                            samples.Add(mediaType, WrapSampleIfString(sample));
                        }
                    }
                }
            }

            return samples;
        }

        public virtual IDictionary<MediaTypeHeaderValue, object> GetSample(ApiDescription api, SampleDirection sampleDirection)
        {
            if (api == null)
            {
                throw new ArgumentNullException("api");
            }

            var controllerName = api.ActionDescriptor.ControllerDescriptor.ControllerName;
            var actionName = api.ActionDescriptor.ActionName;
            var parameterNames = api.ParameterDescriptions.Select(p => p.Name);
            Collection<MediaTypeFormatter> formatters;
            var type = ResolveType(api, controllerName, actionName, parameterNames, sampleDirection, out formatters);
            var samples = new Dictionary<MediaTypeHeaderValue, object>();

            // Use the samples provided directly for actions
            var actionSamples = GetAllActionSamples(controllerName, actionName, parameterNames, sampleDirection);
            foreach (var actionSample in actionSamples)
            {
                samples.Add(actionSample.Key.MediaType, WrapSampleIfString(actionSample.Value));
            }

            if (type != null && !typeof(HttpResponseMessage).IsAssignableFrom(type))
            {
                var sampleObject = GetSampleObject(type);
                foreach (var formatter in formatters)
                {
                    foreach (var mediaType in formatter.SupportedMediaTypes)
                    {
                        if (!samples.ContainsKey(mediaType))
                        {
                            var sample = GetActionSample(controllerName, actionName, parameterNames, type, formatter, mediaType, sampleDirection);

                            // If no sample found, try generate sample using formatter and sample object
                            if (sample == null && sampleObject != null)
                            {
                                sample = WriteSampleObjectUsingFormatter(formatter, sampleObject, type, mediaType);
                            }

                            samples.Add(mediaType, WrapSampleIfString(sample));
                        }
                    }
                }
            }

            return samples;
        }

        /// <summary>
        /// Creates a new <see cref="HelpPageSampleKey"/> based on <see cref="SampleDirection"/>, controller name, action name and parameter names.
        /// </summary>
        /// <param name="sampleDirection">The <see cref="SampleDirection"/>.</param>
        /// <param name="controllerName">Name of the controller.</param>
        /// <param name="actionName">Name of the action.</param>
        /// <param name="parameterNames">The parameter names.</param>
        public HelpPageSampleKey(SampleDirection sampleDirection, string controllerName, string actionName, IEnumerable<string> parameterNames)
        {
            if (!Enum.IsDefined(typeof(SampleDirection), sampleDirection))
            {
                throw new InvalidEnumArgumentException(nameof(sampleDirection), (int)sampleDirection, typeof(SampleDirection));
            }
            if (controllerName == null)
            {
                throw new ArgumentNullException(nameof(controllerName));
            }
            if (actionName == null)
            {
                throw new ArgumentNullException(nameof(actionName));
            }
            if (parameterNames == null)
            {
                throw new ArgumentNullException(nameof(parameterNames));
            }

            ControllerName = controllerName;
            ActionName = actionName;
            ParameterNames = new HashSet<string>(parameterNames, StringComparer.OrdinalIgnoreCase);
            SampleDirection = sampleDirection;
        }

 private IEnumerable<KeyValuePair<HelpPageSampleKey, object>> GetAllActionSamples(string controllerName, string actionName, IEnumerable<string> parameterNames, SampleDirection sampleDirection)
 {
     HashSet<string> parameterNamesSet = new HashSet<string>(parameterNames, StringComparer.OrdinalIgnoreCase);
     foreach (var sample in ActionSamples)
     {
         HelpPageSampleKey sampleKey = sample.Key;
         if (String.Equals(controllerName, sampleKey.ControllerName, StringComparison.OrdinalIgnoreCase) &&
             String.Equals(actionName, sampleKey.ActionName, StringComparison.OrdinalIgnoreCase) &&
             (sampleKey.ParameterNames.SetEquals(new[] { "*" }) || parameterNamesSet.SetEquals(sampleKey.ParameterNames)) &&
             sampleDirection == sampleKey.SampleDirection)
         {
             yield return sample;
         }
     }
 }

 private static bool IsFormatSupported(SampleDirection sampleDirection, MediaTypeFormatter formatter, Type type)
 {
     switch (sampleDirection)
     {
         case SampleDirection.Request:
             return formatter.CanReadType(type);
         case SampleDirection.Response:
             return formatter.CanWriteType(type);
     }
     return false;
 }

        public virtual Type ResolveType(ApiDescription api, string controllerName, string actionName, IEnumerable<string> parameterNames, SampleDirection sampleDirection, out Collection<MediaTypeFormatter> formatters)
        {
            if (!Enum.IsDefined(typeof(SampleDirection), sampleDirection))
            {
                throw new InvalidEnumArgumentException("sampleDirection", (int)sampleDirection, typeof(SampleDirection));
            }
            if (api == null)
            {
                throw new ArgumentNullException("api");
            }
            Type type;
            if (ActualHttpMessageTypes.TryGetValue(new HelpPageSampleKey(sampleDirection, controllerName, actionName, parameterNames), out type) ||
                ActualHttpMessageTypes.TryGetValue(new HelpPageSampleKey(sampleDirection, controllerName, actionName, new[] { "*" }), out type))
            {
                // Re-compute the supported formatters based on type
                Collection<MediaTypeFormatter> newFormatters = new Collection<MediaTypeFormatter>();
                foreach (var formatter in api.ActionDescriptor.Configuration.Formatters)
                {
                    if (IsFormatSupported(sampleDirection, formatter, type))
                    {
                        newFormatters.Add(formatter);
                    }
                }
                formatters = newFormatters;
            }
            else
            {
                switch (sampleDirection)
                {
                    case SampleDirection.Request:
                        ApiParameterDescription requestBodyParameter = api.ParameterDescriptions.FirstOrDefault(p => p.Source == ApiParameterSource.FromBody);
                        type = requestBodyParameter == null ? null : requestBodyParameter.ParameterDescriptor.ParameterType;
                        formatters = api.SupportedRequestBodyFormatters;
                        break;
                    case SampleDirection.Response:
                    default:
                        type = api.ActionDescriptor.ReturnType;
                        formatters = api.SupportedResponseFormatters;
                        break;
                }
            }

            return type;
        }

        /// <summary>
        /// Search for samples that are provided directly through <see cref="ActionSamples"/>.
        /// </summary>
        /// <param name="controllerName">Name of the controller.</param>
        /// <param name="actionName">Name of the action.</param>
        /// <param name="parameterNames">The parameter names.</param>
        /// <param name="type">The CLR type.</param>
        /// <param name="formatter">The formatter.</param>
        /// <param name="mediaType">The media type.</param>
        /// <param name="sampleDirection">
        /// The value indicating whether the sample is for a request or for a response.
        /// </param>
        /// <returns>The sample that matches the parameters.</returns>
        public virtual object GetActionSample(string controllerName, string actionName, IEnumerable<string> parameterNames, Type type, MediaTypeFormatter formatter, MediaTypeHeaderValue mediaType, SampleDirection sampleDirection)
        {
            object sample;

            // First, try to get the sample provided for the specified mediaType, sampleDirection,
            // controllerName, actionName and parameterNames. If not found, try to get the sample
            // provided for the specified mediaType, sampleDirection, controllerName and actionName
            // regardless of the parameterNames. If still not found, try to get the sample provided
            // for the specified mediaType and type. Finally, try to get the sample provided for the
            // specified mediaType.
            if (ActionSamples.TryGetValue(new HelpPageSampleKey(mediaType, sampleDirection, controllerName, actionName, parameterNames), out sample) ||
                ActionSamples.TryGetValue(new HelpPageSampleKey(mediaType, sampleDirection, controllerName, actionName, new[] { "*" }), out sample) ||
                ActionSamples.TryGetValue(new HelpPageSampleKey(mediaType, type), out sample) ||
                ActionSamples.TryGetValue(new HelpPageSampleKey(mediaType), out sample))
            {
                return sample;
            }

            return null;
        }

 private IEnumerable<KeyValuePair<HelpPageSampleKey, object>> GetAllActionSamples(string controllerName, string actionName, 
     IEnumerable<string> parameterNames, SampleDirection sampleDirection)
 {
     var parameterNamesSet = new HashSet<string>(parameterNames, StringComparer.OrdinalIgnoreCase);
     return from sample in ActionSamples
         let sampleKey
             = sample.Key
         where string.Equals(controllerName, sampleKey.ControllerName, StringComparison.OrdinalIgnoreCase) &&
               string.Equals(actionName, sampleKey.ActionName, StringComparison.OrdinalIgnoreCase) &&
               (sampleKey.ParameterNames.SetEquals(new[] {"*"}) ||
                parameterNamesSet.SetEquals(sampleKey.ParameterNames)) &&
               sampleDirection == sampleKey.SampleDirection
         select sample;
 }