git-vimdiff

#!/bin/bash

NOBLOB=0000000000000000000000000000000000000000

root=$(git rev-parse --show-toplevel) || exit

revs=()
for arg; do
  if [[ $arg == *...* ]] ; then
    revs+=($(git name-rev --name-only --always ${arg%...*})
        $(git name-rev --name-only --always ${arg#*...}))
  elif [[ $arg == *..* ]] ; then
    revs+=($(git name-rev --name-only --always ${arg%..*})
        $(git name-rev --name-only --always ${arg#*..}))
  elif git rev-parse --verify $arg >/dev/null 2>&1; then
    revs+=($(git name-rev --name-only --always $arg))
  fi
done

: ${EDITOR:=gvim}
[[ "${EDITOR}" == vim && "${DISPLAY}" ]] && EDITOR=gvim
"$EDITOR" -s <(
  echo ":let &columns+=&columns + 5"
git --no-pager diff --raw --abbrev=40 --find-renames=1% "$@" \
  | cut -c2- \
  | while read oldmode newmode oldblob newblob status oldname newname; do
  : ${newname:=$oldname}

  echo ":cd $root"
  echo ":tabnew"
  echo ":setlocal noswapfile"
  if [[ $newblob == $NOBLOB ]]; then
    echo ":e $oldname"
  else
    if diff -q <(git --no-pager show $newblob) "$newname" >/dev/null 2>/dev/null; then
      echo ":e $newname"
    else
      echo ":0read ++edit !git --no-pager show $newblob"
      echo ":normal Gdd"
    fi
    if [[ "${revs[1]}" && "$newname" ]]; then
      echo ":set buftype=nofile"
      echo ":file ${revs[1]}:$newname"
    elif [[ "${revs[1]}" ]]; then
      echo ":set buftype=nofile"
      echo ":file ${revs[1]}:$oldname"
    elif [[ "$newname" ]]; then
      echo ":file $newname"
    else
      echo ":file $oldname"
    fi
    echo ":filetype detect"
  fi

  echo ":vert diffsplit"
  echo ":enew"
  echo ":setlocal noswapfile"
  echo ":set buftype=nofile"
  if [[ $oldblob != $NOBLOB ]]; then
    echo ":0read ++edit !git --no-pager show $oldblob"
    echo ":normal Gdd"
  fi
  if [[ "${revs[0]}" ]]; then
    echo ":file ${revs[0]}:$oldname"
  else
    echo ":file $oldname"
  fi
  echo ":filetype detect"

  echo ":diffthis"
  echo ":diffup"
  echo ":wincmd l"
  echo ":0"
done
[[ ${PIPESTATUS[0]} == 0 ]] || echo ":q"
echo ":tabfirst"
echo ":tabclose"
)