#!/bin/sh

set -eu

usage()

{

cat << EOF >&2

Usage:

  -h            show this HELP message

  -s  SRCDIR    set source directory

  -o  OUTPUT    set output header

  -p  PREFIX    set macro prefix

EOF

exit 1

}

# one

workdir=$(pwd -P)

srcdir=

output=

prefix=

while getopts "hs:o:p:" opt; do

	case $opt in

	h)

  		usage

  		;;

	s)

    		srcdir="$OPTARG"

    		;;

	o)

    		output="$OPTARG"

    		;;

	p)

    		prefix="$OPTARG"

    		;;

	\?)

		printf 'Invalid option: -%s' "$OPTARG" >&2

    		usage

    		;;

	esac

done

# two

if [ -z "$srcdir" ] || [ -z "$output" ] || [ -z "$prefix" ]; then

	usage

fi

cd -- "$srcdir"

gitver=$(git rev-parse --verify HEAD      2>/dev/null) || gitver="unknown"

cvdate=$(git show -s --format=%ci $gitver 2>/dev/null) || cvdate=$(date)

vmacro=$(printf '%s' "$prefix"'_GIT_VERSION' | tr '[:lower:]' '[:upper:]')

dmacro=$(printf '%s' "$prefix"'_GIT_DATE   ' | tr '[:lower:]' '[:upper:]')

cd -- "$workdir"

# three

printf '#define %s "%s"\n#define %s "%s"\n' \

		"$vmacro" "$gitver" \

		"$dmacro" "$cvdate" \

	> "$output"

# all done

exit 0