open git diff/show files in vim

gistfile.zsh

function gitopen() {
  COMMAND=diff
  REV=HEAD
  PATTERN=""

  if [ "$#" -gt 3 ]; then
    echo "Usage: gitopen [command] [revision] [pattern]"
    echo "gitopen -- opens all added files that have changed since HEAD"
    echo "gitopen diff HEAD -- these are the default parameters"
    echo "gitopen diff master -- opens files that have changed from master"
    echo "gitopen show -- opens files that were changed in the last revision (HEAD)"
    echo "gitopen show HEAD -- default param, does the same"
    echo "gitopen show 4b3ca34 -- opens a particular REV"
    echo 'gitopen <command> <rev> ".txt" - use grep to filter filename results'
    return 1
  fi

  if [ "$#" -gt 0 ]; then
    COMMAND=$1
    shift
  fi

  if [ "$#" -gt 0 ]; then
    REV=$1
    shift
  fi

  if [ "$#" -gt 0 ]; then
    PATTERN=$1
    shift
  fi

  if [ "$COMMAND" = "show" ]; then
    PARAMS=(--pretty=format: --name-only --relative)
  else
    PARAMS=(--name-only --relative)
  fi

  if git rev-parse --verify "$REV" >/dev/null 2>&1; then
    CMD=("git" "$COMMAND" "$REV" "${PARAMS[@]}")
    if [ -n "$PATTERN" ]; then
      echo "Running: ${CMD[*]} | grep "$PATTERN" | xargs -o $EDITOR"$'\n'
      "${CMD[@]}" | grep "$PATTERN" | xargs -o $EDITOR
    else
      echo "Running: ${CMD[*]} | xargs -o $EDITOR"$'\n'
      "${CMD[@]}" | xargs -o $EDITOR
    fi
  else
    echo "Error: '$REV' is not a valid revision"
    return 1
  fi
}