From 3fb2f02875bfd0da7097a3fa021c7959bde1811b Mon Sep 17 00:00:00 2001
From: John McLear <john@mclear.co.uk>
Date: Tue, 22 Jan 2013 23:16:49 +0000
Subject: [PATCH] semi working

---
 src/node/db/API.js        |   6 +-
 src/node/utils/padDiff.js | 596 ++++++++++++++++++++++++++++++++++----
 2 files changed, 539 insertions(+), 63 deletions(-)

diff --git a/src/node/db/API.js b/src/node/db/API.js
index 50c4a6c5d..2c8b91abb 100644
--- a/src/node/db/API.js
+++ b/src/node/db/API.js
@@ -611,19 +611,16 @@ exports.createDiff = function(padID, startRev, endRev, callback){
   //get the pad
   getPadSafe(padID, true, function(err, pad)
   {
-console.warn(padID);
     if(err){
       return callback(err);
     }
  
     try {
-console.warn(pad);
       var padDiff = new PadDiff(pad, startRev, endRev);
-console.warn("AFTER");
     } catch(e) {
+      // console.warn(e.stack);
       return callback({stop:e.message});
     }
-/* 
     var html, authors;
  
     async.series([
@@ -650,7 +647,6 @@ console.warn("AFTER");
     ], function(err){
       callback(err, {html: html, authors: authors})
     });
-  */
   });
 }
 
diff --git a/src/node/utils/padDiff.js b/src/node/utils/padDiff.js
index 645c2e2d4..f898cbe16 100644
--- a/src/node/utils/padDiff.js
+++ b/src/node/utils/padDiff.js
@@ -1,74 +1,554 @@
-exports.createDiff = function(padID, startRev, endRev, callback){
-console.warn("WTF");
-
-  //check if rev is a number
-  if(startRev !== undefined && typeof startRev != "number")
+var Changeset = require("../../static/js/Changeset");
+var async = require("async");
+var exportHtml = require('./ExportHtml');
+ 
+function PadDiff (pad, fromRev, toRev){      
+  //check parameters
+  if(!pad || !pad.id || !pad.atext || !pad.pool)
   {
-    //try to parse the number
-    if(!isNaN(parseInt(startRev)))
-    {
-      startRev = parseInt(startRev, 10);
-    }
-    else
-    {
-      callback({stop: "startRev is not a number"});
-      return;
-    }
+    throw new Error('Invalid pad');
   }
  
-  //check if rev is a number
-  if(endRev !== undefined && typeof endRev != "number")
-  {
-    //try to parse the number
-    if(!isNaN(parseInt(endRev)))
-    {
-      endRev = parseInt(endRev, 10);
-    }
-    else
-    {
-      callback({stop: "endRev is not a number"});
-      return;
-    }
+  var range = pad.getValidRevisionRange(fromRev, toRev);
+  if(!range) { throw new Error('Invalid revision range.' + 
+      ' startRev: ' + fromRev +
+      ' endRev: ' + toRev); }
+  
+  this._pad = pad;
+  this._fromRev = range.startRev;
+  this._toRev = range.endRev;
+  this._html = null;
+  this._authors = [];
+}
+ 
+PadDiff.prototype._isClearAuthorship = function(changeset){
+  //unpack
+  var unpacked = Changeset.unpack(changeset);
+  
+  //check if there is nothing in the charBank
+  if(unpacked.charBank !== "")
+    return false;
+  
+  //check if oldLength == newLength
+  if(unpacked.oldLen !== unpacked.newLen)
+    return false;
+ 
+  //lets iterator over the operators
+  var iterator = Changeset.opIterator(unpacked.ops);
+  
+  //get the first operator, this should be a clear operator
+  var clearOperator = iterator.next();
+  
+  //check if there is only one operator
+  if(iterator.hasNext() === true)
+    return false;
+    
+  //check if this operator doesn't change text
+  if(clearOperator.opcode !== "=")
+    return false;
+    
+  //check that this operator applys to the complete text
+  //if the text ends with a new line, its exactly one character less, else it has the same length
+  if(clearOperator.chars !== unpacked.oldLen-1 && clearOperator.chars !== unpacked.oldLen)
+    return false;
+  
+  var attributes = [];
+  Changeset.eachAttribNumber(changeset, function(attrNum){
+    attributes.push(attrNum);
+  });
+    
+  //check that this changeset uses only one attribute
+  if(attributes.length !== 1)
+    return false;
+    
+  var appliedAttribute = this._pad.pool.getAttrib(attributes[0]);
+  
+  //check if the applied attribute is an anonymous author attribute
+  if(appliedAttribute[0] !== "author" || appliedAttribute[1] !== "")
+    return false;
+    
+  return true;
+}
+ 
+PadDiff.prototype._createClearAuthorship = function(rev, callback){
+  var self = this;
+  this._pad.getInternalRevisionAText(rev, function(err, atext){
+   if(err){
+     return callback(err);
+   }
+   
+   //build clearAuthorship changeset
+   var builder = Changeset.builder(atext.text.length);
+   builder.keepText(atext.text, [['author','']], self._pad.pool);
+   var changeset = builder.toString();
+   
+   callback(null, changeset);
+  });
+}
+ 
+PadDiff.prototype._createClearStartAtext = function(rev, callback){
+  var self = this;
+  
+  //get the atext of this revision
+  this._pad.getInternalRevisionAText(rev, function(err, atext){
+   if(err){
+     return callback(err);
+   }
+   
+   //create the clearAuthorship changeset
+   self._createClearAuthorship(rev, function(err, changeset){
+     if(err){
+       return callback(err);
+     }
+   
+     //apply the clearAuthorship changeset
+     var newAText = Changeset.applyToAText(changeset, atext, self._pad.pool);
+     
+     callback(null, newAText);
+   });
+  });
+}
+ 
+PadDiff.prototype._getChangesetsInBulk = function(startRev, count, callback) {
+  var self = this;
+  
+  //find out which revisions we need
+  var revisions = [];
+  for(var i=startRev;i<(startRev+count) && i<=this._pad.head;i++){
+    revisions.push(i);
   }
+  
+  var changesets = [], authors = [];
+  
+  //get all needed revisions
+  async.forEach(revisions, function(rev, callback){
+    self._pad.getRevision(rev, function(err, revision){
+      if(err){
+        return callback(err)
+      }
+      
+      var arrayNum = rev-startRev;
+      
+      changesets[arrayNum] = revision.changeset;
+      authors[arrayNum] = revision.meta.author;
+  
+      callback();
+    });
+  }, function(err){
+    callback(err, changesets, authors);
+  });
+}
  
-  //get the pad
-  getPadSafe(padID, true, function(err, pad)
-  {
-    if(err){
-      return callback(err);
+PadDiff.prototype._addAuthors = function(authors) {
+  var self = this;
+  //add to array if not in the array
+  authors.forEach(function(author){
+    if(self._authors.indexOf(author) == -1){
+      self._authors.push(author);
     }
+  });
+}
  
-    try {
-      var padDiff = new PadDiff(pad, startRev, endRev);
-    } catch(e) {
-      return callback({stop:e.message});
-    }
+PadDiff.prototype._createDiffAtext = function(callback) {
+  var self = this;
+  var bulkSize = 100;
+  
+  //get the cleaned startAText
+  self._createClearStartAtext(self._fromRev, function(err, atext){
+    if(err) { return callback(err); }
+    
+    var superChangeset = null;
+    
+    var rev = self._fromRev + 1;
  
-    var html, authors;
- 
-    async.series([
-      function(callback){
-        padDiff.getHtml(function(err, _html){
-          if(err){
-            return callback(err);
+    //async while loop
+    async.whilst(
+      //loop condition
+      function () { return rev <= self._toRev; },
+      
+      //loop body
+      function (callback) {
+        //get the bulk
+        self._getChangesetsInBulk(rev,bulkSize,function(err, changesets, authors){
+          var addedAuthors = [];
+          
+          //run trough all changesets
+          for(var i=0;i<changesets.length && (rev+i)<=self._toRev;i++){
+            var changeset = changesets[i];
+            
+            //skip clearAuthorship Changesets
+            if(self._isClearAuthorship(changeset)){
+              continue;
+            }
+            
+            changeset = self._extendChangesetWithAuthor(changeset, authors[i], self._pad.pool);
+            
+            //add this author to the authorarray
+            addedAuthors.push(authors[i]);
+            
+            //compose it with the superChangset            
+            if(superChangeset === null){
+              superChangeset = changeset;
+            } else {           
+              superChangeset = Changeset.composeWithDeletions(superChangeset, changeset, self._pad.pool);
+            }
           }
- 
-          html = _html;
+          
+          //add the authors to the PadDiff authorArray
+          self._addAuthors(addedAuthors);
+        
+          //lets continue with the next bulk 
+          rev += bulkSize;
           callback();
         });
       },
-      function(callback){
-        padDiff.getAuthors(function(err, _authors){
-          if(err){
-            return callback(err);
-          }
+      
+      //after the loop has ended
+      function (err) {
+        //if there are only clearAuthorship changesets, we don't get a superChangeset, so we can skip this step
+        if(superChangeset){
+          var deletionChangeset = self._createDeletionChangeset(superChangeset,atext,self._pad.pool);
+        
+          //apply the superChangeset, which includes all addings
+          atext = Changeset.applyToAText(superChangeset,atext,self._pad.pool);
+          //apply the deletionChangeset, which adds a deletions
+          atext = Changeset.applyToAText(deletionChangeset,atext,self._pad.pool);
+        }      
  
-          authors = _authors;
-          callback();
-        });
+        callback(err, atext);
       }
-    ], function(err){
-      callback(err, {html: html, authors: authors})
-    });
+    );
   });
 }
+ 
+PadDiff.prototype.getHtml = function(callback){
+  //cache the html
+  if(this._html != null){
+    return callback(null, this._html);
+  }
+  
+  var self = this;
+  var atext, html, authorColors;
+  
+  async.series([
+    //get the diff atext
+    function(callback){
+      self._createDiffAtext(function(err, _atext){
+        if(err){
+          return callback(err);
+        }
+        
+        atext = _atext;
+        callback();
+      });
+    },
+    //get the authorColor table
+    function(callback){
+      self._pad.getAllAuthorColors(function(err, _authorColors){
+        if(err){
+          return callback(err);
+        }
+        
+        authorColors = _authorColors;
+        callback();
+      });
+    },
+    //convert the atext to html
+    function(callback){
+      html = exportHtml.getHTMLFromAtext(self._pad, atext, authorColors);
+      self._html = html;
+      callback();
+    }
+  ], function(err){
+    callback(err, html);
+  });
+}
+ 
+PadDiff.prototype.getAuthors = function(callback){
+  var self = this;
+  
+  //check if html was already produced, if not produce it, this generates the author array at the same time
+  if(self._html == null){
+    self.getHtml(function(err){
+      if(err){
+        return callback(err);
+      }
+      
+      callback(null, self._authors);
+    });
+  } else {
+    callback(null, self._authors);
+  }
+}
+ 
+PadDiff.prototype._extendChangesetWithAuthor = function(changeset, author, apool) {  
+  //unpack
+  var unpacked = Changeset.unpack(changeset);  
+  
+  var iterator = Changeset.opIterator(unpacked.ops);
+  var assem = Changeset.opAssembler();
+  
+  //create deleted attribs
+  var authorAttrib = apool.putAttrib(["author", author || ""]);
+  var deletedAttrib = apool.putAttrib(["removed", true]);
+  var attribs = "*" + Changeset.numToString(authorAttrib) + "*" + Changeset.numToString(deletedAttrib);
+  
+  //iteratore over the operators of the changeset
+  while(iterator.hasNext()){
+    var operator = iterator.next();
+    
+    //this is a delete operator, extend it with the author
+    if(operator.opcode === "-"){
+      operator.attribs = attribs;
+    } 
+    //this is operator changes only attributes, let's mark which author did that
+    else if(operator.opcode === "=" && operator.attribs){
+      operator.attribs+="*"+Changeset.numToString(authorAttrib);
+    }
+    
+    //append the new operator to our assembler
+    assem.append(operator);
+  }
+  
+  //return the modified changeset
+  return Changeset.pack(unpacked.oldLen, unpacked.newLen, assem.toString(), unpacked.charBank);
+}
+ 
+//this method is 80% like Changeset.inverse. I just changed so instead of reverting, it adds deletions and attribute changes to to the atext.
+PadDiff.prototype._createDeletionChangeset = function(cs, startAText, apool) {
+  var lines = Changeset.splitTextLines(startAText.text);
+  var alines = Changeset.splitAttributionLines(startAText.attribs, startAText.text);
+  
+  // lines and alines are what the exports is meant to apply to.
+  // They may be arrays or objects with .get(i) and .length methods.
+  // They include final newlines on lines.
+ 
+  function lines_get(idx) {
+    if (lines.get) {
+      return lines.get(idx);
+    } else {
+      return lines[idx];
+    }
+  }
+ 
+  function lines_length() {
+    if ((typeof lines.length) == "number") {
+      return lines.length;
+    } else {
+      return lines.length();
+    }
+  }
+ 
+  function alines_get(idx) {
+    if (alines.get) {
+      return alines.get(idx);
+    } else {
+      return alines[idx];
+    }
+  }
+ 
+  function alines_length() {
+    if ((typeof alines.length) == "number") {
+      return alines.length;
+    } else {
+      return alines.length();
+    }
+  }
+ 
+  var curLine = 0;
+  var curChar = 0;
+  var curLineOpIter = null;
+  var curLineOpIterLine;
+  var curLineNextOp = Changeset.newOp('+');
+ 
+  var unpacked = Changeset.unpack(cs);
+  var csIter = Changeset.opIterator(unpacked.ops);
+  var builder = Changeset.builder(unpacked.newLen);
+ 
+  function consumeAttribRuns(numChars, func /*(len, attribs, endsLine)*/ ) {
+ 
+    if ((!curLineOpIter) || (curLineOpIterLine != curLine)) {
+      // create curLineOpIter and advance it to curChar
+      curLineOpIter = Changeset.opIterator(alines_get(curLine));
+      curLineOpIterLine = curLine;
+      var indexIntoLine = 0;
+      var done = false;
+      while (!done) {
+        curLineOpIter.next(curLineNextOp);
+        if (indexIntoLine + curLineNextOp.chars >= curChar) {
+          curLineNextOp.chars -= (curChar - indexIntoLine);
+          done = true;
+        } else {
+          indexIntoLine += curLineNextOp.chars;
+        }
+      }
+    }
+ 
+    while (numChars > 0) {
+      if ((!curLineNextOp.chars) && (!curLineOpIter.hasNext())) {
+        curLine++;
+        curChar = 0;
+        curLineOpIterLine = curLine;
+        curLineNextOp.chars = 0;
+        curLineOpIter = Changeset.opIterator(alines_get(curLine));
+      }
+      if (!curLineNextOp.chars) {
+        curLineOpIter.next(curLineNextOp);
+      }
+      var charsToUse = Math.min(numChars, curLineNextOp.chars);
+      func(charsToUse, curLineNextOp.attribs, charsToUse == curLineNextOp.chars && curLineNextOp.lines > 0);
+      numChars -= charsToUse;
+      curLineNextOp.chars -= charsToUse;
+      curChar += charsToUse;
+    }
+ 
+    if ((!curLineNextOp.chars) && (!curLineOpIter.hasNext())) {
+      curLine++;
+      curChar = 0;
+    }
+  }
+ 
+  function skip(N, L) {
+    if (L) {
+      curLine += L;
+      curChar = 0;
+    } else {
+      if (curLineOpIter && curLineOpIterLine == curLine) {
+        consumeAttribRuns(N, function () {});
+      } else {
+        curChar += N;
+      }
+    }
+  }
+ 
+  function nextText(numChars) {
+    var len = 0;
+    var assem = Changeset.stringAssembler();
+    var firstString = lines_get(curLine).substring(curChar);
+    len += firstString.length;
+    assem.append(firstString);
+ 
+    var lineNum = curLine + 1;
+    while (len < numChars) {
+      var nextString = lines_get(lineNum);
+      len += nextString.length;
+      assem.append(nextString);
+      lineNum++;
+    }
+ 
+    return assem.toString().substring(0, numChars);
+  }
+ 
+  function cachedStrFunc(func) {
+    var cache = {};
+    return function (s) {
+      if (!cache[s]) {
+        cache[s] = func(s);
+      }
+      return cache[s];
+    };
+  }
+ 
+  var attribKeys = [];
+  var attribValues = [];
+ 
+  //iterate over all operators of this changeset
+  while (csIter.hasNext()) {
+    var csOp = csIter.next();
+ 
+    if (csOp.opcode == '=') {      
+      var textBank = nextText(csOp.chars);
+ 
+      // decide if this equal operator is an attribution change or not. We can see this by checkinf if attribs is set.
+      // If the text this operator applies to is only a star, than this is a false positive and should be ignored
+      if (csOp.attribs && textBank != "*") {
+        var deletedAttrib = apool.putAttrib(["removed", true]);
+        var authorAttrib = apool.putAttrib(["author", ""]);;
+ 
+        attribKeys.length = 0;
+        attribValues.length = 0;
+        Changeset.eachAttribNumber(csOp.attribs, function (n) {
+          attribKeys.push(apool.getAttribKey(n));
+          attribValues.push(apool.getAttribValue(n));
+ 
+          if(apool.getAttribKey(n) === "author"){
+            authorAttrib = n;
+          };
+        });
+ 
+        var undoBackToAttribs = cachedStrFunc(function (attribs) {
+          var backAttribs = [];
+          for (var i = 0; i < attribKeys.length; i++) {
+            var appliedKey = attribKeys[i];
+            var appliedValue = attribValues[i];
+            var oldValue = Changeset.attribsAttributeValue(attribs, appliedKey, apool);
+            if (appliedValue != oldValue) {
+              backAttribs.push([appliedKey, oldValue]);
+            }
+          }
+          return Changeset.makeAttribsString('=', backAttribs, apool);
+        });
+ 
+        var oldAttribsAddition = "*" + Changeset.numToString(deletedAttrib) + "*" + Changeset.numToString(authorAttrib);
+ 
+        var textLeftToProcess = textBank;
+ 
+        while(textLeftToProcess.length > 0){
+          //process till the next line break or process only one line break
+          var lengthToProcess = textLeftToProcess.indexOf("\n");
+          var lineBreak = false;
+          switch(lengthToProcess){
+            case -1: 
+              lengthToProcess=textLeftToProcess.length;
+              break;
+            case 0:
+              lineBreak = true;
+              lengthToProcess=1;
+              break;
+          }
+ 
+          //get the text we want to procceed in this step
+          var processText = textLeftToProcess.substr(0, lengthToProcess);
+          textLeftToProcess = textLeftToProcess.substr(lengthToProcess);
+ 
+          if(lineBreak){
+            builder.keep(1, 1); //just skip linebreaks, don't do a insert + keep for a linebreak
+ 
+            //consume the attributes of this linebreak
+            consumeAttribRuns(1, function(){});
+          } else {
+            //add the old text via an insert, but add a deletion attribute + the author attribute of the author who deleted it
+            var textBankIndex = 0;
+            consumeAttribRuns(lengthToProcess, function (len, attribs, endsLine) {
+              //get the old attributes back
+              var attribs = (undoBackToAttribs(attribs) || "") + oldAttribsAddition;
+ 
+              builder.insert(processText.substr(textBankIndex, len), attribs);
+              textBankIndex += len;
+            });
+ 
+            builder.keep(lengthToProcess, 0);
+          }
+        }
+      } else {
+        skip(csOp.chars, csOp.lines);
+        builder.keep(csOp.chars, csOp.lines);
+      }
+    } else if (csOp.opcode == '+') {
+      builder.keep(csOp.chars, csOp.lines);
+    } else if (csOp.opcode == '-') {
+      var textBank = nextText(csOp.chars);
+      var textBankIndex = 0;
+      
+      consumeAttribRuns(csOp.chars, function (len, attribs, endsLine) {
+        builder.insert(textBank.substr(textBankIndex, len), attribs + csOp.attribs);
+        textBankIndex += len;
+      });
+    }
+  }
+ 
+  return Changeset.checkRep(builder.toString());
+};
+ 
+//export the constructor
+module.exports = PadDiff;