#!/bin/bash

case "$0" in
  ( *egrep* ) grep="egrep" ;;
  ( *fgrep* ) grep="fgrep" ;;
  ( * )       grep="grep"  ;;
esac

if [ "$#" = "0" -o "$1" = "-h" -o "$1" = "--help" ]; then
  cat <<-EOF
	usage:
	  $0 [grep-args] <pattern> [<.ext>] [<file-or-dir> ...]
	Will use "grep" to search recursively through the given files or
	directories, which defaults to ".".  ".svn" and ".git" directories
	are omitted.

	If an extension is given (an argument that begins with a "." and
	something other than a ".", can contain shell patterns), then only
	files of that extension will be grepped.
	If named as something with "egrep" or "fgrep", will use these for
	searching.
EOF
  exit
fi

grep_opts=()
pattern=""
find_opts=()

while getopts "e:m:nwxivqsolhHE" name; do
  case "$name" in
    ( e )               pattern="$OPTARG" ;;
    ( [nwxivqsolhHEc] ) grep_opts=( "${grep_opts[@]}" "-$name" ) ;;
    ( m )               grep_opts=( "${grep_opts[@]}" "-$name" "$OPTARG" ) ;;
    ( * )               echo "$0: internal error" 1>&2; exit 1 ;;
  esac
done

shift $(( OPTIND - 1 ))

if [ "x$pattern" = "x" ]; then
  if [ "$#" = "0" ]; then echo "$0: missing pattern" 1>&2; exit 1
  else pattern="$1"; shift
  fi
fi

case "$1" in
  ( .[^.]* ) if [ ! -e "$1" ]; then
               find_opts=( "${find_opts[@]}" "-name" "*$1" ); shift
             fi ;;
esac

if [ "$#" = "0" ]; then set ".";
# Emacs automatically appends a /dev/null, so if this is the only one, use "."
elif [ "$#" = "1" -a "$1" = "/dev/null" ]; then set "."
fi

# if not a single file or if a directory, add -H to show file names
# (before other flags so it can be can ovverriden)
if [ "$#" != "1" -o -d "$1" ]; then grep_opts=( "-H" "${grep_opts[@]}" ); fi

find "$@" -name ".svn" -prune -o -name ".git" -prune -o -type f \
          "${find_opts[@]}" -print0 \
| sort -z \
| xargs -0 "$grep" "${grep_opts[@]}" -e "$pattern"