using System;
using System.Collections.Generic;
using System.IO;
using System.Net;
using System.Xml.Linq;
using DotNetOpenAuth.Messaging;
using DotNetOpenAuth.OAuth;
using DotNetOpenAuth.OAuth.ChannelElements;
using DotNetOpenAuth.OAuth.Messages;

namespace DotNetOpenAuth.Web.Clients
{
    /// <summary>
    /// Represents LinkedIn authentication client.
    /// </summary>
    internal sealed class LinkedInClient : OAuthClient
    {
        public static readonly ServiceProviderDescription LinkedInServiceDescription = new ServiceProviderDescription
        {
            RequestTokenEndpoint = new MessageReceivingEndpoint("https://api.linkedin.com/uas/oauth/requestToken", HttpDeliveryMethods.GetRequest | HttpDeliveryMethods.AuthorizationHeaderRequest),
            UserAuthorizationEndpoint = new MessageReceivingEndpoint("https://www.linkedin.com/uas/oauth/authenticate", HttpDeliveryMethods.GetRequest | HttpDeliveryMethods.AuthorizationHeaderRequest),
            AccessTokenEndpoint = new MessageReceivingEndpoint("https://api.linkedin.com/uas/oauth/accessToken", HttpDeliveryMethods.GetRequest | HttpDeliveryMethods.AuthorizationHeaderRequest),
            TamperProtectionElements = new ITamperProtectionChannelBindingElement[] { new HmacSha1SigningBindingElement() },
        };

        /// <summary>
        /// Initializes a new instance of the <see cref="LinkedInClient"/> class.
        /// </summary>
        /// <param name="consumerKey">The LinkedIn app's consumer key.</param>
        /// <param name="consumerSecret">The LinkedIn app's consumer secret.</param>
        [System.Diagnostics.CodeAnalysis.SuppressMessage(
            "Microsoft.Reliability",
            "CA2000:Dispose objects before losing scope",
            Justification = "We can't dispose the object because we still need it through the app lifetime.")]
        public LinkedInClient(string consumerKey, string consumerSecret) :
            base("linkedIn", LinkedInServiceDescription, consumerKey, consumerSecret)
        {
        }

        /// <summary>
        /// Check if authentication succeeded after user is redirected back from the service provider.
        /// </summary>
        /// <param name="response">The response token returned from service provider</param>
        /// <returns>
        /// Authentication result.
        /// </returns>
        [System.Diagnostics.CodeAnalysis.SuppressMessage(
            "Microsoft.Design",
            "CA1031:DoNotCatchGeneralExceptionTypes",
            Justification = "We don't care if the request fails.")]
        protected override AuthenticationResult VerifyAuthenticationCore(AuthorizedTokenResponse response)
        {
            // See here for Field Selectors API http://developer.linkedin.com/docs/DOC-1014
            const string profileRequestUrl = "http://api.linkedin.com/v1/people/~:(id,first-name,last-name,headline,industry,summary)";

            string accessToken = response.AccessToken;

            var profileEndpoint = new MessageReceivingEndpoint(profileRequestUrl, HttpDeliveryMethods.GetRequest);
            HttpWebRequest request = WebWorker.PrepareAuthorizedRequest(profileEndpoint, accessToken);

            try
            {
                using (WebResponse profileResponse = request.GetResponse())
                {
                    using (Stream responseStream = profileResponse.GetResponseStream())
                    {
                        XDocument document = XDocument.Load(responseStream);
                        string userId = document.Root.Element("id").Value;

                        string firstName = document.Root.Element("first-name").Value;
                        string lastName = document.Root.Element("last-name").Value;
                        string userName = firstName + " " + lastName;

                        var extraData = new Dictionary<string, string>();
                        extraData.Add("name", userName);
                        extraData.AddDataIfNotEmpty(document, "headline");
                        extraData.AddDataIfNotEmpty(document, "summary");
                        extraData.AddDataIfNotEmpty(document, "industry");

                        return new AuthenticationResult(
                            isSuccessful: true,
                            provider: ProviderName,
                            providerUserId: userId,
                            userName: userName,
                            extraData: extraData);
                    }
                }
            }
            catch (Exception exception)
            {
                return new AuthenticationResult(exception);
            }
        }
    }
}