// <copyright>

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

// </copyright>



namespace Microsoft.ApplicationServer.Http.Dispatcher

{

    using System;

    using System.Net.Http;

    using System.ServiceModel.Channels;

    using System.ServiceModel.Dispatcher;

    using Microsoft.ApplicationServer.Http.Channels;

    using Microsoft.Server.Common;



    /// <summary>

    /// Defines the contract that associates incoming messages with a local operation 

    /// to customize service execution behavior using

    /// <see cref="HttpBinding">HttpBinding</see>.

    /// </summary>

    public abstract class HttpOperationSelector : IDispatchOperationSelector

    {

        /// <summary>

        /// The name of the message property that will store the name of the selected operation.

        /// </summary>

        public const string SelectedOperationPropertyName = "HttpOperationName";



        /// <summary>

        /// Associates a local operation with the incoming method.

        /// </summary>

        /// <param name="message">The incoming <see cref="HttpRequestMessage"/>.</param>

        /// <returns>The name of the operation to be associated with the message.</returns>

        public string SelectOperation(HttpRequestMessage message)

        {

            if (message == null)

            {

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

            }



            return this.OnSelectOperation(message);

        }



        /// <summary>

        /// Associates a local operation with the incoming method.

        /// </summary>

        /// <param name="message">The incoming <see cref="Message"/> to be associated with an operation.</param>

        /// <returns>The name of the operation to be associated with the message.</returns>

        string IDispatchOperationSelector.SelectOperation(ref Message message)

        {

            if (message == null)

            {

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

            }



            HttpRequestMessage requestMessage = message.ToHttpRequestMessage();

            if (requestMessage == null)

            {

                throw Fx.Exception.AsError(

                    new InvalidOperationException(

                        Http.SR.HttpOperationSelectorNullRequest(

                            this.GetType().Name, 

                            typeof(HttpRequestMessage).Name, 

                            "SelectOperation")));

            }



            string operation = this.SelectOperation(requestMessage);

            if (operation == null)

            {

                throw Fx.Exception.AsError(

                    new InvalidOperationException(

                        Http.SR.HttpOperationSelectorNullOperation(this.GetType().Name)));

            }

            

            message.Properties[SelectedOperationPropertyName] = operation;



            ////TODO, CSDMain 205175, need to decide what to do with the tracing

            ////if (operation != null)

            ////{

            ////    if (TD2.WebRequestMatchesOperationIsEnabled())

            ////    {

            ////        TD2.WebRequestMatchesOperation(

            ////            requestMessage.RequestUri != null ? requestMessage.RequestUri.ToString() : string.Empty, 

            ////            operation,

            ////            typeof(HttpOperationSelector).Name);

            ////    }

            ////}



            return operation;

        }



        /// <summary>

        /// Abstract method called by <see cref="SelectOperation(HttpRequestMessage)"/>

        /// to determine the associated operation.   Derived classes must implement this.

        /// </summary>

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

        /// <returns>The name of the operation to be associated with the message.</returns>

        protected abstract string OnSelectOperation(HttpRequestMessage request);

    }

}