/WCFWebApi/src/Microsoft.Net.Http.Formatting/System/Net/Http/FormattingUtilities.cs

// <copyright>

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

// </copyright>



namespace System.Net.Http

{

    using System.Collections.Generic;

    using System.Collections.ObjectModel;

    using System.Json;

    using System.Linq;

    using System.Net.Http.Formatting;

    using System.Net.Http.Headers;

    using System.Text;



    /// <summary>

    /// Provides various internal utility functions

    /// </summary>

    internal static class FormattingUtilities

    {

        /// <summary>

        /// A <see cref="Type"/> representing <see cref="UTF8Encoding"/>.

        /// </summary>

        public static readonly Type Utf8EncodingType = typeof(UTF8Encoding);



        /// <summary>

        /// A <see cref="Type"/> representing <see cref="UnicodeEncoding"/>.

        /// </summary>

        public static readonly Type Utf16EncodingType = typeof(UnicodeEncoding);



        /// <summary>

        /// A <see cref="Type"/> representing <see cref="HttpRequestMessage"/>.

        /// </summary>

        public static readonly Type HttpRequestMessageType = typeof(HttpRequestMessage);



        /// <summary>

        /// A <see cref="Type"/> representing <see cref="HttpResponseMessage"/>.

        /// </summary>

        public static readonly Type HttpResponseMessageType = typeof(HttpResponseMessage);



        /// <summary>

        /// A <see cref="Type"/> representing <see cref="HttpContent"/>.

        /// </summary>

        public static readonly Type HttpContentType = typeof(HttpContent);



        /// <summary>

        /// A <see cref="Type"/> representing <see cref="DelegatingEnumerable{T}"/>.

        /// </summary>

        public static readonly Type DelegatingEnumerableGenericType = typeof(DelegatingEnumerable<>);



        /// <summary>

        /// A <see cref="Type"/> representing <see cref="IEnumerable{T}"/>.

        /// </summary>

        public static readonly Type EnumerableInterfaceGenericType = typeof(IEnumerable<>);



        /// <summary>

        /// A <see cref="Type"/> representing <see cref="IQueryable{T}"/>.

        /// </summary>

        public static readonly Type QueryableInterfaceGenericType = typeof(IQueryable<>);



        /// <summary>

        /// A <see cref="Type"/> representing <see cref="JsonValue"/>.

        /// </summary>

        public static readonly Type JsonValueType = typeof(JsonValue);



        /// <summary>

        /// HTTP X-Requested-With header field name

        /// </summary>

        public const string HttpRequestedWithHeader = @"x-requested-with";



        /// <summary>

        /// HTTP X-Requested-With header field value

        /// </summary>

        public const string HttpRequestedWithHeaderValue = @"xmlhttprequest";



        /// <summary>

        /// JSON literal for 'null'

        /// </summary>

        public const string JsonNullLiteral = "null";



        /// <summary>

        /// HTTP Host header field name

        /// </summary>

        public const string HttpHostHeader = "Host";



        /// <summary>

        /// HTTP Version token

        /// </summary>

        public const string HttpVersionToken = "HTTP";



        // This list should be kept in sync with the list of headers supported by HttpContentHeaders

        // TODO: CSDMAIN 231195 -- Change hard-coded list of HttpContentHeaders to dynamic list provided by DCR #225156

        private static readonly HashSet<string> httpContentHeaders = new HashSet<string>()

        {

            "Allow", 

            "Content-Disposition", 

            "Content-Encoding", 

            "Content-Language", 

            "Content-Length",

            "Content-Location", 

            "Content-MD5",

            "Content-Range", 

            "Content-Type", 

            "Expires", 

            "Last-Modified", 

        };



        /// <summary>

        /// Gets the HTTP headers that are associated with <see cref="HttpContentHeaders"/>.

        /// </summary>

        public static HashSet<string> HttpContentHeaders

        {

            get

            {

                return FormattingUtilities.httpContentHeaders;

            }

        }



        /// <summary>

        /// Determines whether <paramref name="type"/> is a <see cref="JsonValue"/> type.

        /// </summary>

        /// <param name="type">The type to test.</param>

        /// <returns>

        ///   <c>true</c> if <paramref name="type"/> is a <see cref="JsonValue"/> type; otherwise, <c>false</c>.

        /// </returns>

        public static bool IsJsonValueType(Type type)

        {

            return JsonValueType.IsAssignableFrom(type);

        }



        /// <summary>

        /// Creates an empty <see cref="HttpContentHeaders"/> instance. The only way is to get it from a dummy 

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

        /// </summary>

        /// <returns>The created instance.</returns>

        public static HttpContentHeaders CreateEmptyContentHeaders()

        {

            HttpContent tempContent = null;

            HttpContentHeaders contentHeaders = null;

            try

            {

                tempContent = new StringContent(string.Empty);

                contentHeaders = tempContent.Headers;

                contentHeaders.Clear();

            }

            finally

            {

                // We can dispose the content without touching the headers

                if (tempContent != null)

                {

                    tempContent.Dispose();

                }

            }



            return contentHeaders;

        }



        /// <summary>

        /// Ensure the actual collection is identical to the expected one

        /// </summary>

        /// <param name="actual">The actual collection of the instance</param>

        /// <param name="expected">The expected collection of the instance</param>

        /// <returns>Returns true if they are identical</returns>

        public static bool ValidateCollection(Collection<MediaTypeHeaderValue> actual, MediaTypeHeaderValue[] expected)

        {

            if (actual.Count != expected.Length)

            {

                return false;

            }



            foreach (MediaTypeHeaderValue value in expected)

            {

                if (!actual.Contains(value))

                {

                    return false;

                }

            }



            return true;

        }



        /// <summary>

        /// Remove bounding quotes on a token if present

        /// </summary>

        /// <param name="token">Token to unquote.</param>

        /// <returns>Unquoted token.</returns>

        public static string UnquoteToken(string token)

        {

            if (string.IsNullOrWhiteSpace(token))

            {

                return token;

            }



            if (token.StartsWith("\"", StringComparison.Ordinal) && token.EndsWith("\"", StringComparison.Ordinal) && token.Length > 1)

            {

                return token.Substring(1, token.Length - 2);

            }



            return token;

        }

    }

}