// <copyright>

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

// </copyright>



namespace System.Net.Http.Formatting

{

    using System;

    using System.Collections.Specialized;

    using System.Diagnostics.Contracts;

    using System.Net.Http;

    using System.Net.Http.Headers;

    using Microsoft.Server.Common;



    /// <summary>

    /// Class that provides <see cref="MediaTypeHeaderValue"/>s from query strings.

    /// </summary>

    public sealed class QueryStringMapping : MediaTypeMapping

    {

        private static readonly Type queryStringMappingType = typeof(QueryStringMapping);



        /// <summary>

        /// Initializes a new instance of the <see cref="QueryStringMapping"/> class.

        /// </summary>

        /// <param name="queryStringParameterName">The name of the query string parameter to match, if present.</param>

        /// <param name="queryStringParameterValue">The value of the query string parameter specified by <paramref name="queryStringParameterName"/>.</param>

        /// <param name="mediaType">The media type to use if the query parameter specified by <paramref name="queryStringParameterName"/> is present

        /// and assigned the value specified by <paramref name="queryStringParameterValue"/>.</param>

        public QueryStringMapping(string queryStringParameterName, string queryStringParameterValue, string mediaType)

            : base(mediaType)

        {

            this.Initialize(queryStringParameterName, queryStringParameterValue);

        }



        /// <summary>

        /// Initializes a new instance of the <see cref="QueryStringMapping"/> class.

        /// </summary>

        /// <param name="queryStringParameterName">The name of the query string parameter to match, if present.</param>

        /// <param name="queryStringParameterValue">The value of the query string parameter specified by <paramref name="queryStringParameterName"/>.</param>

        /// <param name="mediaType">The <see cref="MediaTypeHeaderValue"/> to use if the query parameter specified by <paramref name="queryStringParameterName"/> is present

        /// and assigned the value specified by <paramref name="queryStringParameterValue"/>.</param>

        public QueryStringMapping(string queryStringParameterName, string queryStringParameterValue, MediaTypeHeaderValue mediaType)

            : base(mediaType)

        {

            this.Initialize(queryStringParameterName, queryStringParameterValue);

        }



        /// <summary>

        /// Gets the query string parameter name.

        /// </summary>

        public string QueryStringParameterName { get; private set; }



        /// <summary>

        /// Gets the query string parameter value.

        /// </summary>

        public string QueryStringParameterValue { get; private set; }



        /// <summary>

        /// Returns a value indicating whether the current <see cref="QueryStringMapping"/>

        /// instance can return a <see cref="MediaTypeHeaderValue"/> from <paramref name="request"/>.

        /// </summary>

        /// <param name="request">The <see cref="HttpRequestMessage"/> to check.</param>

        /// <returns>If this instance can produce a <see cref="MediaTypeHeaderValue"/> from <paramref name="request"/>

        /// it returns <c>1.0</c> otherwise <c>0.0</c>.</returns>

        protected override sealed double OnTryMatchMediaType(HttpRequestMessage request)

        {

            Contract.Assert(request != null, "Base class ensures that the 'request' parameter will never be null.");



            NameValueCollection queryString = GetQueryString(request.RequestUri);

            return this.DoesQueryStringMatch(queryString) ? MediaTypeMatch.Match : MediaTypeMatch.NoMatch;

        }



        /// <summary>

        /// Returns a value indicating whether the current <see cref="QueryStringMapping"/>

        /// instance can return a <see cref="MediaTypeHeaderValue"/> from <paramref name="response"/>.

        /// </summary>

        /// <param name="response">The <see cref="HttpResponseMessage"/> to check.</param>

        /// <returns>If this instance can produce a <see cref="MediaTypeHeaderValue"/> from <paramref name="response"/>

        /// it returns <c>true</c> otherwise <c>false</c>.</returns>

        protected override sealed double OnTryMatchMediaType(HttpResponseMessage response)

        {

            Contract.Assert(response != null, "Base class ensures that the 'response' parameter will never be null.");

            Contract.Assert(response.RequestMessage != null, "Base class ensures that the 'response.RequestMessage' will never be null.");



            NameValueCollection queryString = GetQueryString(response.RequestMessage.RequestUri);

            return this.DoesQueryStringMatch(queryString) ? MediaTypeMatch.Match : MediaTypeMatch.NoMatch;

        }



        private static NameValueCollection GetQueryString(Uri uri)

        {

            if (uri == null)

            {

                throw new InvalidOperationException(SR.NonNullUriRequiredForMediaTypeMapping(queryStringMappingType.Name));

            }



            return UrlUtility.ParseQueryString(uri.Query);

        }



        private void Initialize(string queryStringParameterName, string queryStringParameterValue)

        {

            if (string.IsNullOrWhiteSpace(queryStringParameterName))

            {

                throw new ArgumentNullException("queryStringParameterName");

            }



            if (string.IsNullOrWhiteSpace(queryStringParameterValue))

            {

                throw new ArgumentNullException("queryStringParameterValue");

            }



            this.QueryStringParameterName = queryStringParameterName.Trim();

            this.QueryStringParameterValue = queryStringParameterValue.Trim();

        }



        private bool DoesQueryStringMatch(NameValueCollection queryString)

        {

            if (queryString != null)

            {

                foreach (string queryParameter in queryString.AllKeys)

                {

                    if (string.Equals(queryParameter, this.QueryStringParameterName, StringComparison.Ordinal))

                    {

                        string queryValue = queryString[queryParameter];

                        if (string.Equals(queryValue, this.QueryStringParameterValue, StringComparison.Ordinal))

                        {

                            return true;

                        }

                    }

                }

            }



            return false;

        }

    }

}