/WCFWebApi/src/Microsoft.ApplicationServer.Http/Microsoft/ApplicationServer/Http/Description/HttpOperationDescriptionExtensionMethods.cs

// <copyright>

//   Copyright (c) Microsoft Corporation.  All rights reserved.

// </copyright>



namespace Microsoft.ApplicationServer.Http.Description

{

    using System;

    using System.ComponentModel;

    using System.Net.Http;

    using System.ServiceModel.Description;

    using System.ServiceModel.Web;

    using System.Text;

    using System.Xml;

    using Microsoft.Server.Common;



    /// <summary>

    /// Provides extension methods for <see cref="OperationDescription"/> instances.

    /// </summary>

    public static class HttpOperationDescriptionExtensionMethods

    {

        private static readonly Type webGetAttributeType = typeof(WebGetAttribute);

        private static readonly Type webInvokeAttributeType = typeof(WebInvokeAttribute);

        private static readonly Type descriptionAttributeType = typeof(DescriptionAttribute);



        /// <summary>

        /// Creates an <see cref="HttpOperationDescription"/> instance based on the given

        /// <see cref="OperationDescription"/> instance.

        /// </summary>

        /// <param name="operation">The <see cref="OperationDescription"/> instance.</param>

        /// <returns>A new <see cref="HttpOperationDescription"/> instance.</returns>

        public static HttpOperationDescription ToHttpOperationDescription(this OperationDescription operation)

        {

            if (operation == null)

            {

                throw Fx.Exception.ArgumentNull("operation");

            }



            return new HttpOperationDescription(operation);

        }



        /// <summary>

        /// Gets the <see cref="HttpMethod"/> for the given <paramref name="operation"/>.

        /// </summary>

        /// <param name="operation">The <see cref="HttpOperationDescription"/> instance.</param>

        /// <returns>The <see cref="HttpMethod"/>.</returns>

        public static HttpMethod GetHttpMethod(this HttpOperationDescription operation)

        {

            if (operation == null)

            {

                throw Fx.Exception.ArgumentNull("operation");

            }



            return new HttpMethod(GetWebMethod(operation));

        }



        /// <summary>

        /// Gets the <see cref="UriTemplate"/> associated with the given <paramref name="operation"/>.

        /// </summary>

        /// <param name="operation">The <see cref="HttpOperationDescription"/> instance.</param>

        /// <returns>The <see cref="UriTemplate"/>.</returns>

        public static UriTemplate GetUriTemplate(this HttpOperationDescription operation)

        {

            // AutoRedirect is default TrailingSlashMode

            return GetUriTemplate(operation, TrailingSlashMode.AutoRedirect);

        }



        /// <summary>

        /// Gets the <see cref="UriTemplate"/> associated with the given <paramref name="operation"/>.

        /// </summary>

        /// <param name="operation">The <see cref="HttpOperationDescription"/> instance.</param>

        /// <param name="trailingSlashMode">The <see cref="TrailingSlashMode"/> option to use for the <see cref="UriTemplate"/>.</param>

        /// <returns>The <see cref="UriTemplate"/>.</returns>

        public static UriTemplate GetUriTemplate(this HttpOperationDescription operation, TrailingSlashMode trailingSlashMode)

        {

            if (operation == null)

            {

                throw Fx.Exception.ArgumentNull("operation");

            }



            TrailingSlashModeHelper.Validate(trailingSlashMode, "trailingSlashMode");



            return new UriTemplate(operation.GetUriTemplateStringOrDefault(), trailingSlashMode == TrailingSlashMode.Ignore);

        }



        internal static string GetDescription(this HttpOperationDescription operation)

        {

            Fx.Assert(operation != null, "The 'operation' parameter should not be null.");



            OperationDescription operationDescription = operation.ToOperationDescription();



            object[] attributes = null;

            if (operationDescription.SyncMethod != null)

            {

                attributes = operationDescription.SyncMethod.GetCustomAttributes(descriptionAttributeType, true);

            }

            else if (operationDescription.BeginMethod != null)

            {

                attributes = operationDescription.BeginMethod.GetCustomAttributes(descriptionAttributeType, true);

            }



            if (attributes != null && attributes.Length > 0)

            {

                return ((DescriptionAttribute)attributes[0]).Description;

            }

            else

            {

                return String.Empty;

            }

        }



        private static string GetWebMethod(this HttpOperationDescription operation)

        {

            Fx.Assert(operation != null, "The 'operation' parameter should not be null.");



            WebGetAttribute webGet = operation.Behaviors.Find<WebGetAttribute>();

            WebInvokeAttribute webInvoke = operation.Behaviors.Find<WebInvokeAttribute>();

            EnsureOneOneWebAttribute(webGet, webInvoke, operation);

            if (webGet != null)

            {

                return HttpMethod.Get.ToString();

            }



            if (webInvoke == null)

            {

                return HttpMethod.Post.ToString();

            }



            return webInvoke.Method ?? HttpMethod.Post.ToString();

        }



        private static string GetWebUriTemplate(this HttpOperationDescription operation)

        {

            Fx.Assert(operation != null, "The 'operation' parameter should not be null.");



            WebGetAttribute webGet = operation.Behaviors.Find<WebGetAttribute>();

            WebInvokeAttribute webInvoke = operation.Behaviors.Find<WebInvokeAttribute>();

            EnsureOneOneWebAttribute(webGet, webInvoke, operation);

            if (webGet != null)

            {

                return webGet.UriTemplate;

            }



            if (webInvoke != null)

            {

                return webInvoke.UriTemplate;

            }



            return null;

        }



        private static string GetUriTemplateStringOrDefault(this HttpOperationDescription operation)

        {

            Fx.Assert(operation != null, "The 'operation' parameter should not be null.");



            string webUriTemplate = GetWebUriTemplate(operation);

            if ((webUriTemplate == null) && (GetWebMethod(operation) == HttpMethod.Get.ToString()))

            {

                webUriTemplate = MakeDefaultGetUriTemplateString(operation);

            }



            if (webUriTemplate == null)

            {

                webUriTemplate = operation.Name;

            }



            return webUriTemplate;

        }



        private static string MakeDefaultGetUriTemplateString(this HttpOperationDescription operation)

        {

            Fx.Assert(operation != null, "The 'operation' parameter should not be null.");



            StringBuilder builder = new StringBuilder(XmlConvert.DecodeName(operation.Name));

            builder.Append("?");



            foreach (HttpParameter parameterDescription in operation.InputParameters)

            {

                string decodedName = XmlConvert.DecodeName(parameterDescription.Name);



                builder.Append(decodedName);

                builder.Append("={");

                builder.Append(decodedName);

                builder.Append("}&");

            }



            builder.Remove(builder.Length - 1, 1);

            return builder.ToString();

        }



        private static void EnsureOneOneWebAttribute(WebGetAttribute webGet, WebInvokeAttribute webInvoke, HttpOperationDescription operation)

        {

            if (webGet != null && webInvoke != null)

            {

                throw Fx.Exception.AsError(

                    new InvalidOperationException(

                        Http.SR.MultipleWebAttributes(

                            operation.Name,

                            operation.DeclaringContract.Name,

                            webGetAttributeType.Name,

                            webInvokeAttributeType.Name)));

            }

        }

    }

}