diff --git a/rhodecode/lib/vcs/utils/diffs.py b/rhodecode/lib/vcs/utils/diffs.py
new file mode 100644
--- /dev/null
+++ b/rhodecode/lib/vcs/utils/diffs.py
@@ -0,0 +1,460 @@
+# -*- coding: utf-8 -*-
+# original copyright: 2007-2008 by Armin Ronacher
+# licensed under the BSD license.
+
+import re
+import difflib
+import logging
+
+from difflib import unified_diff
+from itertools import tee, imap
+
+from mercurial.match import match
+
+from rhodecode.lib.vcs.exceptions import VCSError
+from rhodecode.lib.vcs.nodes import FileNode, NodeError
+
+
+def get_udiff(filenode_old, filenode_new,show_whitespace=True):
+    """
+    Returns unified diff between given ``filenode_old`` and ``filenode_new``.
+    """
+    try:
+        filenode_old_date = filenode_old.last_changeset.date
+    except NodeError:
+        filenode_old_date = None
+
+    try:
+        filenode_new_date = filenode_new.last_changeset.date
+    except NodeError:
+        filenode_new_date = None
+
+    for filenode in (filenode_old, filenode_new):
+        if not isinstance(filenode, FileNode):
+            raise VCSError("Given object should be FileNode object, not %s"
+                % filenode.__class__)
+
+    if filenode_old_date and filenode_new_date:
+        if not filenode_old_date < filenode_new_date:
+            logging.debug("Generating udiff for filenodes with not increasing "
+                "dates")
+
+    vcs_udiff = unified_diff(filenode_old.content.splitlines(True),
+                               filenode_new.content.splitlines(True),
+                               filenode_old.name,
+                               filenode_new.name,
+                               filenode_old_date,
+                               filenode_old_date)
+    return vcs_udiff
+
+
+def get_gitdiff(filenode_old, filenode_new, ignore_whitespace=True):
+    """
+    Returns git style diff between given ``filenode_old`` and ``filenode_new``.
+
+    :param ignore_whitespace: ignore whitespaces in diff
+    """
+
+    for filenode in (filenode_old, filenode_new):
+        if not isinstance(filenode, FileNode):
+            raise VCSError("Given object should be FileNode object, not %s"
+                % filenode.__class__)
+
+    old_raw_id = getattr(filenode_old.changeset, 'raw_id', '0' * 40)
+    new_raw_id = getattr(filenode_new.changeset, 'raw_id', '0' * 40)
+
+    repo = filenode_new.changeset.repository
+    vcs_gitdiff = repo._get_diff(old_raw_id, new_raw_id, filenode_new.path,
+                                 ignore_whitespace)
+
+    return vcs_gitdiff
+
+
+class DiffProcessor(object):
+    """
+    Give it a unified diff and it returns a list of the files that were
+    mentioned in the diff together with a dict of meta information that
+    can be used to render it in a HTML template.
+    """
+    _chunk_re = re.compile(r'@@ -(\d+)(?:,(\d+))? \+(\d+)(?:,(\d+))? @@(.*)')
+
+    def __init__(self, diff, differ='diff', format='udiff'):
+        """
+        :param diff:   a text in diff format or generator
+        :param format: format of diff passed, `udiff` or `gitdiff`
+        """
+        if isinstance(diff, basestring):
+            diff = [diff]
+
+        self.__udiff = diff
+        self.__format = format
+        self.adds = 0
+        self.removes = 0
+
+        if isinstance(self.__udiff, basestring):
+            self.lines = iter(self.__udiff.splitlines(1))
+
+        elif self.__format == 'gitdiff':
+            udiff_copy = self.copy_iterator()
+            self.lines = imap(self.escaper, self._parse_gitdiff(udiff_copy))
+        else:
+            udiff_copy = self.copy_iterator()
+            self.lines = imap(self.escaper, udiff_copy)
+
+        # Select a differ.
+        if differ == 'difflib':
+            self.differ = self._highlight_line_difflib
+        else:
+            self.differ = self._highlight_line_udiff
+
+    def escaper(self, string):
+        return string.replace('<', '&lt;').replace('>', '&gt;')
+
+    def copy_iterator(self):
+        """
+        make a fresh copy of generator, we should not iterate thru
+        an original as it's needed for repeating operations on
+        this instance of DiffProcessor
+        """
+        self.__udiff, iterator_copy = tee(self.__udiff)
+        return iterator_copy
+
+    def _extract_rev(self, line1, line2):
+        """
+        Extract the filename and revision hint from a line.
+        """
+
+        try:
+            if line1.startswith('--- ') and line2.startswith('+++ '):
+                l1 = line1[4:].split(None, 1)
+                old_filename = l1[0].lstrip('a/') if len(l1) >= 1 else None
+                old_rev = l1[1] if len(l1) == 2 else 'old'
+
+                l2 = line2[4:].split(None, 1)
+                new_filename = l2[0].lstrip('b/') if len(l1) >= 1 else None
+                new_rev = l2[1] if len(l2) == 2 else 'new'
+
+                filename = old_filename if (old_filename !=
+                                            'dev/null') else new_filename
+
+                return filename, new_rev, old_rev
+        except (ValueError, IndexError):
+            pass
+
+        return None, None, None
+
+    def _parse_gitdiff(self, diffiterator):
+        def line_decoder(l):
+            if l.startswith('+') and not l.startswith('+++'):
+                self.adds += 1
+            elif l.startswith('-') and not l.startswith('---'):
+                self.removes += 1
+            return l.decode('utf8', 'replace')
+
+        output = list(diffiterator)
+        size = len(output)
+
+        if size == 2:
+            l = []
+            l.extend([output[0]])
+            l.extend(output[1].splitlines(1))
+            return map(line_decoder, l)
+        elif size == 1:
+            return  map(line_decoder, output[0].splitlines(1))
+        elif size == 0:
+            return []
+
+        raise Exception('wrong size of diff %s' % size)
+
+    def _highlight_line_difflib(self, line, next):
+        """
+        Highlight inline changes in both lines.
+        """
+
+        if line['action'] == 'del':
+            old, new = line, next
+        else:
+            old, new = next, line
+
+        oldwords = re.split(r'(\W)', old['line'])
+        newwords = re.split(r'(\W)', new['line'])
+
+        sequence = difflib.SequenceMatcher(None, oldwords, newwords)
+
+        oldfragments, newfragments = [], []
+        for tag, i1, i2, j1, j2 in sequence.get_opcodes():
+            oldfrag = ''.join(oldwords[i1:i2])
+            newfrag = ''.join(newwords[j1:j2])
+            if tag != 'equal':
+                if oldfrag:
+                    oldfrag = '<del>%s</del>' % oldfrag
+                if newfrag:
+                    newfrag = '<ins>%s</ins>' % newfrag
+            oldfragments.append(oldfrag)
+            newfragments.append(newfrag)
+
+        old['line'] = "".join(oldfragments)
+        new['line'] = "".join(newfragments)
+
+    def _highlight_line_udiff(self, line, next):
+        """
+        Highlight inline changes in both lines.
+        """
+        start = 0
+        limit = min(len(line['line']), len(next['line']))
+        while start < limit and line['line'][start] == next['line'][start]:
+            start += 1
+        end = -1
+        limit -= start
+        while -end <= limit and line['line'][end] == next['line'][end]:
+            end -= 1
+        end += 1
+        if start or end:
+            def do(l):
+                last = end + len(l['line'])
+                if l['action'] == 'add':
+                    tag = 'ins'
+                else:
+                    tag = 'del'
+                l['line'] = '%s<%s>%s</%s>%s' % (
+                    l['line'][:start],
+                    tag,
+                    l['line'][start:last],
+                    tag,
+                    l['line'][last:]
+                )
+            do(line)
+            do(next)
+
+    def _parse_udiff(self):
+        """
+        Parse the diff an return data for the template.
+        """
+        lineiter = self.lines
+        files = []
+        try:
+            line = lineiter.next()
+            # skip first context
+            skipfirst = True
+            while 1:
+                # continue until we found the old file
+                if not line.startswith('--- '):
+                    line = lineiter.next()
+                    continue
+
+                chunks = []
+                filename, old_rev, new_rev = \
+                    self._extract_rev(line, lineiter.next())
+                files.append({
+                    'filename':         filename,
+                    'old_revision':     old_rev,
+                    'new_revision':     new_rev,
+                    'chunks':           chunks
+                })
+
+                line = lineiter.next()
+                while line:
+                    match = self._chunk_re.match(line)
+                    if not match:
+                        break
+
+                    lines = []
+                    chunks.append(lines)
+
+                    old_line, old_end, new_line, new_end = \
+                        [int(x or 1) for x in match.groups()[:-1]]
+                    old_line -= 1
+                    new_line -= 1
+                    context = len(match.groups()) == 5
+                    old_end += old_line
+                    new_end += new_line
+
+                    if context:
+                        if not skipfirst:
+                            lines.append({
+                                'old_lineno': '...',
+                                'new_lineno': '...',
+                                'action': 'context',
+                                'line': line,
+                            })
+                        else:
+                            skipfirst = False
+
+                    line = lineiter.next()
+                    while old_line < old_end or new_line < new_end:
+                        if line:
+                            command, line = line[0], line[1:]
+                        else:
+                            command = ' '
+                        affects_old = affects_new = False
+
+                        # ignore those if we don't expect them
+                        if command in '#@':
+                            continue
+                        elif command == '+':
+                            affects_new = True
+                            action = 'add'
+                        elif command == '-':
+                            affects_old = True
+                            action = 'del'
+                        else:
+                            affects_old = affects_new = True
+                            action = 'unmod'
+
+                        old_line += affects_old
+                        new_line += affects_new
+                        lines.append({
+                            'old_lineno':   affects_old and old_line or '',
+                            'new_lineno':   affects_new and new_line or '',
+                            'action':       action,
+                            'line':         line
+                        })
+                        line = lineiter.next()
+
+        except StopIteration:
+            pass
+
+        # highlight inline changes
+        for file in files:
+            for chunk in chunks:
+                lineiter = iter(chunk)
+                #first = True
+                try:
+                    while 1:
+                        line = lineiter.next()
+                        if line['action'] != 'unmod':
+                            nextline = lineiter.next()
+                            if nextline['action'] == 'unmod' or \
+                               nextline['action'] == line['action']:
+                                continue
+                            self.differ(line, nextline)
+                except StopIteration:
+                    pass
+
+        return files
+
+    def prepare(self):
+        """
+        Prepare the passed udiff for HTML rendering. It'l return a list
+        of dicts
+        """
+        return self._parse_udiff()
+
+    def _safe_id(self, idstring):
+        """Make a string safe for including in an id attribute.
+
+        The HTML spec says that id attributes 'must begin with
+        a letter ([A-Za-z]) and may be followed by any number
+        of letters, digits ([0-9]), hyphens ("-"), underscores
+        ("_"), colons (":"), and periods (".")'. These regexps
+        are slightly over-zealous, in that they remove colons
+        and periods unnecessarily.
+
+        Whitespace is transformed into underscores, and then
+        anything which is not a hyphen or a character that
+        matches \w (alphanumerics and underscore) is removed.
+
+        """
+        # Transform all whitespace to underscore
+        idstring = re.sub(r'\s', "_", '%s' % idstring)
+        # Remove everything that is not a hyphen or a member of \w
+        idstring = re.sub(r'(?!-)\W', "", idstring).lower()
+        return idstring
+
+    def raw_diff(self):
+        """
+        Returns raw string as udiff
+        """
+        udiff_copy = self.copy_iterator()
+        if self.__format == 'gitdiff':
+            udiff_copy = self._parse_gitdiff(udiff_copy)
+        return u''.join(udiff_copy)
+
+    def as_html(self, table_class='code-difftable', line_class='line',
+                new_lineno_class='lineno old', old_lineno_class='lineno new',
+                code_class='code'):
+        """
+        Return udiff as html table with customized css classes
+        """
+        def _link_to_if(condition, label, url):
+            """
+            Generates a link if condition is meet or just the label if not.
+            """
+
+            if condition:
+                return '''<a href="%(url)s">%(label)s</a>''' % {'url': url,
+                                                                'label': label}
+            else:
+                return label
+        diff_lines = self.prepare()
+        _html_empty = True
+        _html = []
+        _html.append('''<table class="%(table_class)s">\n''' \
+                                            % {'table_class': table_class})
+        for diff in diff_lines:
+            for line in diff['chunks']:
+                _html_empty = False
+                for change in line:
+                    _html.append('''<tr class="%(line_class)s %(action)s">\n''' \
+                        % {'line_class': line_class,
+                           'action': change['action']})
+                    anchor_old_id = ''
+                    anchor_new_id = ''
+                    anchor_old = "%(filename)s_o%(oldline_no)s" % \
+                                {'filename': self._safe_id(diff['filename']),
+                                 'oldline_no': change['old_lineno']}
+                    anchor_new = "%(filename)s_n%(oldline_no)s" % \
+                                {'filename': self._safe_id(diff['filename']),
+                                 'oldline_no': change['new_lineno']}
+                    cond_old = change['old_lineno'] != '...' and \
+                                                        change['old_lineno']
+                    cond_new = change['new_lineno'] != '...' and \
+                                                        change['new_lineno']
+                    if cond_old:
+                        anchor_old_id = 'id="%s"' % anchor_old
+                    if cond_new:
+                        anchor_new_id = 'id="%s"' % anchor_new
+                    ###########################################################
+                    # OLD LINE NUMBER
+                    ###########################################################
+                    _html.append('''\t<td %(a_id)s class="%(old_lineno_cls)s">''' \
+                                    % {'a_id': anchor_old_id,
+                                       'old_lineno_cls': old_lineno_class})
+
+                    _html.append('''<pre>%(link)s</pre>''' \
+                        % {'link':
+                        _link_to_if(cond_old, change['old_lineno'], '#%s' \
+                                                                % anchor_old)})
+                    _html.append('''</td>\n''')
+                    ###########################################################
+                    # NEW LINE NUMBER
+                    ###########################################################
+
+                    _html.append('''\t<td %(a_id)s class="%(new_lineno_cls)s">''' \
+                                    % {'a_id': anchor_new_id,
+                                       'new_lineno_cls': new_lineno_class})
+
+                    _html.append('''<pre>%(link)s</pre>''' \
+                        % {'link':
+                        _link_to_if(cond_new, change['new_lineno'], '#%s' \
+                                                                % anchor_new)})
+                    _html.append('''</td>\n''')
+                    ###########################################################
+                    # CODE
+                    ###########################################################
+                    _html.append('''\t<td class="%(code_class)s">''' \
+                                                % {'code_class': code_class})
+                    _html.append('''\n\t\t<pre>%(code)s</pre>\n''' \
+                                                % {'code': change['line']})
+                    _html.append('''\t</td>''')
+                    _html.append('''\n</tr>\n''')
+        _html.append('''</table>''')
+        if _html_empty:
+            return None
+        return ''.join(_html)
+
+    def stat(self):
+        """
+        Returns tuple of adde,and removed lines for this instance
+        """
+        return self.adds, self.removes