server: ActivityStreams reply/link/unlink API

1 files changed, 83 insertions, 28 deletions

diff --git a/server/main.ts b/server/main.ts
index 02d5933..7cb21a0 100644
--- a/server/main.ts
+++ b/server/main.ts
@@ -23,19 +23,47 @@ if (DEBUG) {
 app.use(express.json());
 app.use(cookieParser());
 
+type LinkOr<T> = string | T;
+
+type Person = {
+  id: string;
+  type: 'Person',
+  name: string;
+};
+
 type Note = {
   type: 'Note';
   published: string;
-  attributedTo: string | {
-    id: string;
-    type: 'Person',
-    name: string;
-  };
+  attributedTo: LinkOr<Person>;
   inReplyTo: string[];
   replies: string[];
   content: string;
 };
 
+type Relationship<S, O> = {
+  type: 'Relationship';
+  relationship: string;
+  subject: S;
+  object: O;
+};
+
+type Create<O> = {
+  type: 'Create';
+  actor: LinkOr<Person>;
+  object: O;
+};
+
+type Delete<O> = {
+  type: 'Create';
+  actor: LinkOr<Person>;
+  object: O;
+};
+
+const iri2id = (iri: string) => {
+  const parts = iri.split('/');
+  return parts[parts.length - 1];
+};
+
 const discdag = express()
   .post('/login', wrap(async ($req, $res) => {
     const { username, password } = $req.body;
@@ -189,7 +217,6 @@ const discdag = express()
         {
           items: {
             '@id': 'as:items',
-            '@type': '@id',
             '@container': '@id'
           },
         },
@@ -202,30 +229,51 @@ const discdag = express()
     });
   }))
 
-  .put('/disc/:discussion', wrap(async ($req, $res) => {
-    const { inReplyTo, content } = $req.body as { inReplyTo: string[], content: string };
+  .post('/disc/:discussion', wrap(async ($req, $res) => {
     const { discussion } = $req.params;
     const { digest } = $req.cookies;
 
     if (!digest || !digest.length)
       return $res.status(401).end();
 
-    if (!inReplyTo.length || !content.length)
-      return $res.status(400).end();
+    type Activity =
+      | Create<Note>
+      | Create<Relationship<string, string>>
+      | Delete<Relationship<string, string>>
+    ;
+    const activity = $req.body as Activity;
+
+    let selection: string[];
+    let body: string;
+    let method = 'GET';
+    if (activity.type === 'Create' && activity.object?.type === 'Note') {
+      method = 'POST';
+      selection = activity.object.inReplyTo.map(iri2id);
+      body = new URLSearchParams({ Action: 'SendReply', ReplyText: activity.object.content }).toString();
+    } else if (activity.object?.type === 'Relationship' && activity.object.relationship === 'as:inReplyTo') {
+      const frm = iri2id(activity.object.object);
+      const to = iri2id(activity.object.subject);
+      selection = [frm, to];
+      body = new URLSearchParams({
+        Action: activity.type === 'Create' ? 'CreateLink' : 'RemoveLink',
+        N0: frm,
+        N1: to,
+      }).toString();
+    } else {
+      return $res.status(501).end();
+    }
 
-    const parents = inReplyTo.map(id => {
-      const parts = id.split('/');
-      return parts[parts.length - 1];
-    }).join(',');
+    const headers = {
+      'Content-Type': 'application/x-www-form-urlencoded',
+      'Cookie': `DiscussionID=${discussion}; digest=${digest}; SelectedNodes=${selection.join(',')}`,
+    };
 
-    const res = await fetch(DISCDAG_URL, {
-      method: 'POST',
-      headers: {
-        'Content-Type': 'application/x-www-form-urlencoded',
-        'Cookie': `DiscussionID=${discussion}; digest=${digest}; SelectedNodes=${parents}`,
-      },
-      body: new URLSearchParams({ Action: 'SendReply', ReplyText: content }).toString(),
-    });
+    let res;
+    if (method === 'POST') {
+      res = await fetch(DISCDAG_URL, { method, headers, body });
+    } else {
+      res = await fetch(DISCDAG_URL + `?${body}`, { method, headers });
+    }
 
     if (res.status !== 200)
       throw new Error("bad response");
@@ -271,11 +319,18 @@ const discdag = express()
       items[to]?.inReplyTo.push(frm);
     }
 
-    return $res
-      .json({
-        '@context': 'https://www.w3.org/ns/activitystreams',
-        items,
-      });
+    return $res.json({
+      '@context': [
+        'https://www.w3.org/ns/activitystreams',
+        {
+          items: {
+            '@id': 'as:items',
+            '@container': '@id'
+          },
+        },
+      ],
+      items,
+    });
   }))
 ;
 
@@ -318,7 +373,7 @@ app.get(/\/remote\/.*/, wrap(async ($req, $res) => {
 
 try {
   app.listen(PORT, (): void => {
-  console.log(`Connected successfully on port ${PORT}`);
+    console.log(`Connected successfully on port ${PORT}`);
   });
 } catch (error) {
   console.error(`Error occured: ${error}`);