#!/usr/bin/env bash

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

if [[ "$#" = "0" || "$1" = "-h" || "$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 (a ".[^.]*" argument, possibly with
	(quoted) globs), then only files of these extension will be
	grepped.  (Use "./.foo" for a path that begins with a a ".".)
	If named as something with "egrep" or "fgrep", will use these
	for searching.
EOF
  exit
fi

grep_opts=($GREP_OPTIONS)
pattern=""
find_opts=()

unset GREP_OPTIONS

while getopts "VEFGPe:f:ivwxycLlm:oqsbHhnTuZA:B:C:aD:d:IrRUz" name; do
  if [[ "$name" = "e" ]]; then         pattern="$OPTARG"
  elif [[ "${OPTARG+x}" = "x" ]]; then grep_opts+=( "-$name" "$OPTARG" )
  else                                 grep_opts+=( "-$name" )
  fi
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

fst_sfx="Y"
while [[ "x$1" = "x."* && ! -e "$1" ]]; do
  if [[ "$fst_sfx" = "Y" ]]; then find_opts+=( "(" );
  else find_opts+=( "-o" ); fi
  find_opts+=( "-name" "*$1" ); shift; fst_sfx="N"
done
if [[ "$fst_sfx" = "N" ]]; then find_opts+=( ")" ); fi

# If there is a single null argument from an emacs `grep', drop it
if [[ "$#" = "1" && "$TERM" = "emacs-grep" ]]; then
  case "$1__$(uname -s)" in
    /dev/null__* | NUL_CYGWIN* ) shift ;;
  esac
fi

# use "." if there are no arguments
if [[ "$#" = "0" ]]; then set "."; fi

# check that all of the rest are existing paths
for i; do
  if [[ ! -e "$i" ]]; then echo "$0: missing path: $i" 1>&2; exit 1; fi
done

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

# print paths with NUL separators, drop "./" if the only place is "."
if [[ "x$*" = "x." ]]; then find_opts+=( "-printf" '%P\0' )
else                        find_opts+=( "-print0" )
fi

# See also the values of emacs vars:
#   grep-find-ignored-directories, grep-find-ignored-files
find "$@" "(" -name .svn -o -name .git -o -name CVS ")" -prune -o \
     -type f "${find_opts[@]}" \
  | sort -z \
  | xargs -0 "$grep" "${grep_opts[@]}" -e "$pattern" -- \
  | sed 's/\(.\{1999\}\).*/\1.../'