git-vd

#!/usr/bin/env python
import os
import subprocess
import os.path
import shutil
import sys
import tempfile

def exec_stdout(cmd):
  return os.popen(cmd).read()


def grab_revision(repo_topdir, git_path, rev, dest_topdir):
  dest_path = os.path.join(dest_topdir, git_path)
  dest_dirname = os.path.dirname(dest_path)
  if not os.path.exists(dest_dirname):
    os.makedirs(dest_dirname)
  if rev == '':
    src_path = os.path.join(repo_topdir, git_path)
    shutil.copyfile(src_path, dest_path)
  else:
    with open(dest_path, 'w') as f:
      subprocess.call(['git', 'cat-file', 'blob', rev + ':' + git_path], stdout=f)


class DirDiff:
  def __init__(self, left_rev, right_rev):
    """"empty rev means work tree"""
    self.repo_topdir = exec_stdout('git rev-parse --show-cdup').rstrip("\n")
    self.left_rev = left_rev
    self.right_rev = right_rev

  def prepare_dirs(self):
    self.left_dir = tempfile.mkdtemp()
    self.right_dir = tempfile.mkdtemp()
    if not self.right_rev:
      diff_cmd = 'git diff-index -z --diff-filter=ADM --no-renames ' + self.left_rev
    else:
      diff_cmd = 'git diff-tree -z -r --diff-filter=ADM --no-renames %s %s' % (self.left_rev, self.right_rev)
    diff = exec_stdout(diff_cmd)
    entries = diff.split("\0")
    i = 0
    while i < len(entries) - 1:
      status, path = entries[i], entries[i+1]
      i += 2
      mode = status[97]
      if mode == 'D':
        self.process_deleted(path)
      elif mode == 'A':
        self.process_added(path)
      elif mode == 'M':
        self.process_modified(path)

  def delete_dirs(self):
    shutil.rmtree(self.left_dir)
    shutil.rmtree(self.right_dir)

  def _grab_left_version(self, path):
    grab_revision(self.repo_topdir, path, self.left_rev, self.left_dir)

  def _grab_right_version(self, path):
    grab_revision(self.repo_topdir, path, self.right_rev, self.right_dir)

  def process_deleted(self, path):
    self._grab_left_version(path)

  def process_added(self, path):
    self._grab_right_version(path)

  def process_modified(self, path):
    self._grab_right_version(path)
    self._grab_left_version(path)

  def kdiff3(self):
    try:
      self.prepare_dirs()
      print self.left_dir, self.right_dir
      os.system('kdiff3 %s %s' % (self.left_dir, self.right_dir))
    finally:
      self.delete_dirs()

if __name__ == "__main__":
  if exec_stdout('git rev-parse --is-inside-work-tree').rstrip("\n") != "true":
    print "Not inside a work tree."
  else:
    left = "HEAD"
    right = ""
    if len(sys.argv) >= 2:
      left = sys.argv[1]
    if len(sys.argv) >= 3:
      right = sys.argv[2]
    DirDiff(left, right).kdiff3()