Added option to restore revisions #1791

src/node/db/API.js

@@ -576,6 +576,104 @@ exports.deletePad = function(padID, callback)
   });
 }
 
+exports.restoreRevision = function(padID, rev, callback)
+{
+    var Changeset = require("ep_etherpad-lite/static/js/Changeset");
+    
+    //check if rev is a number
+    if(rev !== undefined && typeof rev != "number")
+    {
+        //try to parse the number
+        if(!isNaN(parseInt(rev)))
+        {
+            rev = parseInt(rev);
+        }
+        else
+        {
+            callback(new customError("rev is not a number", "apierror"));
+            return;
+        }
+    }
+
+    //ensure this is not a negativ number
+    if(rev !== undefined && rev < 0)
+    {
+        callback(new customError("rev is a negativ number","apierror"));
+        return;
+    }
+
+    //ensure this is not a float value
+    if(rev !== undefined && !is_int(rev))
+    {
+        callback(new customError("rev is a float value","apierror"));
+        return;
+    }
+
+    //get the pad
+    getPadSafe(padID, true, function(err, pad)
+    {
+        if(ERR(err, callback)) return;
+
+
+            //check if this is a valid revision
+            if(rev > pad.getHeadRevisionNumber())
+            {
+                callback(new customError("rev is higher than the head revision of the pad","apierror"));
+                return;
+            }
+
+        pad.getInternalRevisionAText(rev, function(err, atext)
+        {
+            if(ERR(err, callback)) return;
+
+            var oldText = pad.text();
+            atext.text += "\n";
+            function eachAttribRun(attribs, func)
+            {
+                var attribsIter = Changeset.opIterator(attribs);
+                var textIndex = 0;
+                var newTextStart = 0;
+                var newTextEnd = atext.text.length;
+                while (attribsIter.hasNext())
+                {
+                    var op = attribsIter.next();
+                    var nextIndex = textIndex + op.chars;
+                    if (!(nextIndex <= newTextStart || textIndex >= newTextEnd))
+                    {
+                        func(Math.max(newTextStart, textIndex), Math.min(newTextEnd, nextIndex), op.attribs);
+                    }
+                    textIndex = nextIndex;
+                }
+            }
+
+            // create a new changeset with a helper builder object
+            var builder = Changeset.builder(oldText.length);
+
+            // assemble each line into the builder
+            eachAttribRun(atext.attribs, function(start, end, attribs)
+            {
+                builder.insert(atext.text.substring(start, end), attribs);
+            });
+
+            var lastNewlinePos = oldText.lastIndexOf('\n');
+            if (lastNewlinePos < 0) {
+                builder.remove(oldText.length-1,0);
+            } else {
+                builder.remove(lastNewlinePos, oldText.match(/\n/g).length-1);
+                builder.remove(oldText.length - lastNewlinePos-1,0);
+            }
+
+            var changeset = builder.toString();
+
+            //append the changeset
+            pad.appendRevision(changeset);
+            //
+            callback(null, changeset);
+        });
+
+    });
+};
+
 /**
 copyPad(sourceID, destinationID[, force=false]) copies a pad. If force is true, 
   the destination will be overwritten if it exists.