Fix remote document conformance cases.

Author: sblom

src/JsonLD/Core/Context.cs

@@ -180,7 +180,20 @@ public virtual JsonLD.Core.Context Parse(JToken localContext, List<string> remot
 							}
 							remoteContexts.Add(uri);
 							// 3.2.3: Dereference context
-                            RemoteDocument rd = this.options.documentLoader.LoadDocument(uri);
+                            RemoteDocument rd;
+                            try
+                            {
+                                rd = this.options.documentLoader.LoadDocument(uri);
+                            }
+                            catch (JsonLdError err)
+                            {
+                                if (err.Message.StartsWith(JsonLdError.Error.LoadingDocumentFailed.ToString()))
+                                {
+                                    throw new JsonLdError(JsonLdError.Error.LoadingRemoteContextFailed);
+                                }
+                                else
+                                    throw;
+                            }
 							JToken remoteContext = rd.document;
                             if (!(remoteContext is JObject) || !((JObject)remoteContext
 								).ContainsKey("@context"))

src/JsonLD/Core/DocumentLoader.cs

@@ -1,8 +1,11 @@
 using System;
 using System.Collections;
 using System.IO;
+using System.Linq;
 using JsonLD.Core;
 using JsonLD.Util;
+using System.Net;
+using System.Collections.Generic;
 
 namespace JsonLD.Core
 {
@@ -14,18 +17,52 @@ public virtual RemoteDocument LoadDocument(string url)
             RemoteDocument doc = new RemoteDocument(url, null);
             try
             {
-                doc.Document = JSONUtils.FromURL(new Uri(url));
+                HttpWebRequest req = (HttpWebRequest)HttpWebRequest.Create(url);
+                req.Accept = AcceptHeader;
+                WebResponse resp = req.GetResponse();
+                bool isJsonld = resp.Headers[HttpResponseHeader.ContentType] == "application/ld+json";
+                if (!resp.Headers[HttpResponseHeader.ContentType].Contains("json"))
+                {
+                    throw new JsonLdError(JsonLdError.Error.LoadingDocumentFailed, url);
+                }
+
+                string[] linkHeaders = resp.Headers.GetValues("Link");
+                if (!isJsonld && linkHeaders != null)
+                {
+                    linkHeaders = linkHeaders.SelectMany((h) => h.Split(",".ToCharArray()))
+                                             .Select(h => h.Trim()).ToArray();
+                    IEnumerable<string> linkedContexts = linkHeaders.Where(v => v.EndsWith("rel=\"http://www.w3.org/ns/json-ld#context\""));
+                    if (linkedContexts.Count() > 1)
+                    {
+                        throw new JsonLdError(JsonLdError.Error.MultipleContextLinkHeaders);
+                    }
+                    string header = linkedContexts.First();
+                    string linkedUrl = header.Substring(1, header.IndexOf(">") - 1);
+                    string resolvedUrl = URL.Resolve(url, linkedUrl);
+                    var remoteContext = this.LoadDocument(resolvedUrl);
+                    doc.contextUrl = remoteContext.documentUrl;
+                    doc.context = remoteContext.document;
+                }
+
+                Stream stream = resp.GetResponseStream();
+
+                doc.DocumentUrl = req.Address.ToString();
+                doc.Document = JSONUtils.FromInputStream(stream);
+            }
+            catch (JsonLdError)
+            {
+                throw;
             }
             catch (Exception)
             {
-                throw new JsonLdError(JsonLdError.Error.LoadingRemoteContextFailed, url);
+                throw new JsonLdError(JsonLdError.Error.LoadingDocumentFailed, url);
             }
             return doc;
         }
 
-//        /// <summary>An HTTP Accept header that prefers JSONLD.</summary>
-//        /// <remarks>An HTTP Accept header that prefers JSONLD.</remarks>
-//        public const string AcceptHeader = "application/ld+json, application/json;q=0.9, application/javascript;q=0.5, text/javascript;q=0.5, text/plain;q=0.2, */*;q=0.1";
+        /// <summary>An HTTP Accept header that prefers JSONLD.</summary>
+        /// <remarks>An HTTP Accept header that prefers JSONLD.</remarks>
+        public const string AcceptHeader = "application/ld+json, application/json;q=0.9, application/javascript;q=0.5, text/javascript;q=0.5, text/plain;q=0.2, */*;q=0.1";
 
 //        private static volatile IHttpClient httpClient;
 

src/JsonLD/Core/JsonLdProcessor.cs

@@ -71,7 +71,7 @@ public static JArray Expand(JToken input, JsonLdOptions opts)
 			{
 				try
 				{
-                    RemoteDocument tmp = null; // opts.documentLoader.LoadDocument((string)input);
+                    RemoteDocument tmp = opts.documentLoader.LoadDocument((string)input);
 					input = tmp.document;
 				}
 				catch (Exception e)

src/JsonLD/Core/JsonLdUtils.cs

@@ -924,7 +924,7 @@ private static void Resolve(JToken input, JObject cycles)
 				_cycles[url_1] = true;
 				try
 				{
-                    JObject ctx = null; //(IDictionary<string, object>)DocumentLoader.FromURL(new URL(url_1));
+                    JObject ctx = (JObject)new DocumentLoader().LoadDocument(url_1).Document;
 					if (!ctx.ContainsKey("@context"))
 					{
 						ctx = new JObject();

src/JsonLD/Core/RemoteDocument.cs

@@ -12,8 +12,7 @@ public virtual string DocumentUrl
 			}
 			set
 			{
-				string documentUrl = value;
-				this.documentUrl = documentUrl;
+                this.documentUrl = value;
 			}
 		}
 
@@ -25,8 +24,7 @@ public virtual JToken Document
 			}
 			set
 			{
-				JToken document = value;
-				this.document = document;
+                this.document = value;
 			}
 		}
 
@@ -38,17 +36,30 @@ public virtual string ContextUrl
 			}
 			set
 			{
-				string contextUrl = value;
-				this.contextUrl = contextUrl;
+                this.contextUrl = value;
 			}
 		}
 
+        public virtual JToken Context
+        {
+            get
+            {
+                return context;
+            }
+            set
+            {
+                this.context = value;
+            }
+        }
+
 		internal string documentUrl;
 
 		internal JToken document;
 
 		internal string contextUrl;
 
+        internal JToken context;
+
         public RemoteDocument(string url, JToken document)
             : this(url, document, null)
 		{