1 files changed, 37 insertions, 3 deletions

diff --git a/lib/render-msg.js b/lib/render-msg.js
index 68ea4d7..3a55a3b 100644
--- a/lib/render-msg.js
+++ b/lib/render-msg.js
@@ -19,13 +19,17 @@ function RenderMsg(render, app, msg, opts) {
   this.isMissing = !content
   this.hasFullLink =
     this.c.type === 'chess_move' ||
-    this.c.type === 'ssb_chess_move'
+    this.c.type === 'ssb_chess_move' ||
+    (this.c.type === 'about' && this.c.about == this.value.author
+      && typeof this.c.description === 'string')
 
   if (typeof opts === 'boolean') opts = {raw: opts}
   this.opts = opts || {}
   this.shouldWrap = this.opts.wrap !== false
   var ts = this.value.timestamp
   this.date = ts ? new Date(ts) : null
+  this.thread = opts.links || []
+  this.single = opts.single
 }
 
 RenderMsg.prototype.getMsg = function (id, cb) {
@@ -645,6 +649,7 @@ var knownAboutProps = {
 }
 
 RenderMsg.prototype.about = function (cb) {
+  var self = this
   var keys = Object.keys(this.c).filter(function (k) {
     return k !== 'about' && k !== 'type' && k !== 'recps'
   }).sort().join()
@@ -702,6 +707,15 @@ RenderMsg.prototype.about = function (cb) {
   var target = this.c.about
   var pwh = this.c.publicWebHosting
 
+  function descriptionOrDiff(cb) {
+    // show diff for self-description and gathering thread.
+    // otherwise it might require a more expensive query
+    var prevMsg = !self.opts.full && self.getPreviousAboutInThreadSync()
+    cb()
+    if (prevMsg) return self.render.textEditDiffTable(prevMsg, self.msg)
+    return h('div', {innerHTML: self.render.markdown(self.c.description)})
+  }
+
   this.wrap([
     this.c.root && this.c.root !== target ? h('div',
       h('small', '→ ', this.link1(this.c.root, done()))
@@ -731,8 +745,7 @@ RenderMsg.prototype.about = function (cb) {
     ]) : '',
     this.c.genre ? h('div', ['genre: ', h('u', u.toString(this.c.genre))]) : '',
     this.c.shelve ? h('div', ['shelf: ', h('u', u.toString(this.c.shelve))]) : '',
-    this.c.description ? h('div',
-      {innerHTML: this.render.markdown(this.c.description)}) : '',
+    this.c.description ? descriptionOrDiff(done()) : '',
     this.c.review ? h('blockquote',
       {innerHTML: this.render.markdown(this.c.review)}) : '',
     this.c.attendee ? h('div',
@@ -763,6 +776,27 @@ RenderMsg.prototype.about = function (cb) {
   done(cb)
 }
 
+RenderMsg.prototype.getPreviousAboutInThreadSync = function () {
+  var self = this
+  var root = this.thread[0]
+  if (!root) return
+  if (this.c.about !== root.key) {
+    // probably won't work
+    return
+  }
+  var i = this.thread.indexOf(this.msg)
+  var target = this.c.about
+  if (i === -1) return
+  for (var j = i-1; j >= 0; j--) {
+    var msg = this.thread[j]
+    var c = msg && msg.value && msg.value.content
+    if (c && c.type === 'about' && c.about === target
+          && typeof c.description === 'string') {
+      return msg
+    }
+  }
+}
+
 RenderMsg.prototype.aboutRating = function (cb) {
   var rating = Number(this.c.rating)
   var max = Number(this.c.ratingMax)