From e47dd9286f20438dceb48dd5e9b4707fd2aae8d5 Mon Sep 17 00:00:00 2001
From: Will Murphy <william@datatitian.com>
Date: Wed, 25 Sep 2019 17:15:39 -0500
Subject: [PATCH] add Undo support to unfollow

---
 pub/activity.js   | 28 ++++++++++++++++++++++------
 pub/federation.js |  2 +-
 routes/inbox.js   | 30 ++++++++++++++++++++++--------
 store/stream.js   |  6 ++++++
 4 files changed, 51 insertions(+), 15 deletions(-)

diff --git a/pub/activity.js b/pub/activity.js
index df53542..c49efa8 100644
--- a/pub/activity.js
+++ b/pub/activity.js
@@ -7,7 +7,8 @@ const pubFederation = require('./federation')
 module.exports = {
   address,
   addToOutbox,
-  build
+  build,
+  undo
 }
 
 function build (type, actorId, object, to, cc, etc) {
@@ -61,11 +62,26 @@ async function address (activity) {
 }
 
 function addToOutbox (actor, activity) {
-  return Promise.all([
-    // ensure object is cached, but don't alter representation in activity
-    // so activities can be sent with objects as links
-    //pubObject.resolve(activity.object),
+  const tasks = [
     store.stream.save(activity),
     address(activity).then(addresses => pubFederation.deliver(actor, activity, addresses))
-  ])
+  ]
+  // ensure activity object is cached if local, but do not try to resolve links
+  // because Mastodon won't resolve activity IRIs
+  if (pubUtils.validateObject(activity.object)) {
+    tasks.push(pubObject.resolve(activity.object))
+  }
+  return Promise.all(tasks)
+}
+
+function undo (activity, undoActor) {
+  if (!pubUtils.validateActivity(activity)) {
+    if (!activity || Object.prototype.toString.call(activity) !== '[object String]') {
+      throw new Error('Invalid undo target')
+    }
+    activity = { id: activity }
+  }
+  // matches the target activity with the actor from the undo
+  // so actors can only undo their own activities
+  return store.stream.remove(activity, undoActor)
 }
diff --git a/pub/federation.js b/pub/federation.js
index 0c671cd..13441c4 100644
--- a/pub/federation.js
+++ b/pub/federation.js
@@ -24,7 +24,7 @@ function deliver (actor, activity, addresses) {
     delete activity.bcc
   }
   const requests = addresses.map(addr => {
-    console.log(`delivering to${addr}`) 
+    console.log(`delivering to ${addr}`)
     return request({
       method: 'POST',
       url: addr,
diff --git a/routes/inbox.js b/routes/inbox.js
index f4de2b5..6fe8c89 100644
--- a/routes/inbox.js
+++ b/routes/inbox.js
@@ -6,14 +6,19 @@ const store = require('../store')
 
 router.post('/', net.validators.activity, net.security.verifySignature, function (req, res) {
   req.body._meta = { _target: pub.utils.usernameToIRI(req.user) }
-  console.log(req.body);
+  console.log(req.body)
+  const toDo = {
+    saveActivity: true,
+    saveObject: false
+  }
   // side effects
   switch (req.body.type) {
     case 'Accept':
       // TODO - side effect necessary for following collection?
       break
     case 'Follow':
-      //req.body._meta._target = req.body.object.id
+      // TODO resolve object and ensure specified target matches inbox user
+      // req.body._meta._target = req.body.object.id
       // send acceptance reply
       pub.actor.getOrCreateActor(req.user, true)
         .then(user => {
@@ -24,6 +29,7 @@ router.post('/', net.validators.activity, net.security.verifySignature, function
         .catch(e => console.log(e))
       break
     case 'Create':
+      toDo.saveObject = true
       pub.actor.getOrCreateActor(req.user, true)
         .then(user => {
           const to = [user.followers]
@@ -31,15 +37,23 @@ router.post('/', net.validators.activity, net.security.verifySignature, function
             pub.utils.actorFromActivity(req.body),
             'https://www.w3.org/ns/activitystreams#Public'
           ]
-          const accept = pub.activity.build('Announce', user.id, req.body.object.id, to, cc)
-          return pub.activity.addToOutbox(user, accept)
+          const announce = pub.activity.build('Announce', user.id, req.body.object.id, to, cc)
+          return pub.activity.addToOutbox(user, announce)
         }).catch(e => console.log(e))
       break
+    case 'Undo':
+      pub.activity.undo(req.body.object, req.body.actor)
+        .catch(err => console.log(err))
+      break
   }
-  Promise.all([
-    pub.object.resolve(req.body.object),
-    store.stream.save(req.body)
-  ]).then(() => res.status(200).send())
+  const tasks = []
+  if (toDo.saveObject) {
+    tasks.push(pub.object.resolve(req.body.object))
+  }
+  if (toDo.saveActivity) {
+    tasks.push(store.stream.save(req.body))
+  }
+  Promise.all(tasks).then(() => res.status(200).send())
     .catch(err => {
       console.log(err)
       res.status(500).send()
diff --git a/store/stream.js b/store/stream.js
index c603544..c153299 100644
--- a/store/stream.js
+++ b/store/stream.js
@@ -2,6 +2,7 @@
 const connection = require('./connection')
 module.exports = {
   get,
+  remove,
   save
 }
 
@@ -34,3 +35,8 @@ async function save (activity) {
     // server object ID avoids mutating local copy of document
     .insertOne(activity, { forceServerObjectId: true })
 }
+
+function remove (activity, actor) {
+  return connection.getDb().collection('streams')
+    .deleteMany({ id: activity.id, actor: actor })
+}