Improve ActivityStream objects

- Add optional fields
- Parse json correctly
- Add print helper

source/ap/util.d

@@ -0,0 +1,78 @@
+module ap.util;
+
+import std.format;
+import std.json;
+
+import requests;
+import slf4d;
+
+import singletons;
+import net.request_pool;
+import webfinger;
+import ap.errors;
+import ap.actor;
+import ap.activity_stream;
+
+enum {
+  ActivityJson = "application/activity+json",
+  ActivityJsonLd = `application/ld+json; profile="https://www.w3.org/ns/activitystreams"`,
+}
+
+/++ 
+ + Fetches remote actor based on WebFinger link
+ + Params:
+ +   wf = WebFinger link to user
+ + Returns: User Actor JSON representation
+ +/
+JSONValue apFetchRemoteUser(JSONValue wf) {
+  PRequest rq = PRequest();
+  rq.url = wf["href"].str;
+  rq.headers["Accept"] = wf["type"].str;
+
+  Response rs = Rp.request(rq, true);
+  return parseJSON(cast(string) rs.responseBody);
+}
+
+/++ 
+ + Fetches remote ActivityStream object by its id
+ + Params:
+ +   id = the id of ActivityStream object
+ + Returns: ActivityStream object
+ +/
+ASObject apFetchASObject(string id, string contentType = ActivityJson) {
+  PRequest rq = PRequest();
+  rq.url = id;
+  rq.headers["Accept"] = contentType;
+
+  Response rs = Rp.request(rq, true);
+  return new ASObject(parseJSON(cast(string) rs.responseBody));
+}
+
+/++ 
+ + Resolves remote user to Actor based on username handle
+ + Params:
+ +   username = Account username
+ + Returns: ActivityPub Actor
+ +/
+ASObject apResolveRemoteUsername(string username) {
+  JSONValue resource = wfRequestAccount(username);
+  JSONValue accountLink;
+
+  foreach (link; resource["links"].array)
+    if (
+      link["type"].str == ActivityJsonLd ||
+      link["type"].str == ActivityJson
+      ) {
+      accountLink = link;
+      break;
+    }
+
+  if (accountLink == JSONValue())
+    throw new Exception("No valid activity streams href found for " ~ username);
+
+  string id = accountLink["href"].str;
+  string contentType = accountLink["type"].str;
+
+  // return new Actor(apFetchASObject(id, contentType));
+  return apFetchASObject(id, contentType);
+}