version

#!/bin/bash

# Automagically calculate project version number and copyright date from git

# Usage: version [version | year | flags]
#   Options:
#     version - (default) output version info
#     year    - output copyright year
#     flags   - output compiler flags to set VERSION and YEAR

# Archive hash, refs and date set by git-archive via export-subst in .gitattributes

# Note: the refs (%d) are truncated to only show the version tag, thus avoiding
# variability caused by moving branch references (like master). This makes archives
# build from tags stable for downstream package distribution. However, versons tags
# are limited to a maximum 9 chars (i.e. v00.00.00) and must start with "v".

ARCHIVED='$Format:archived$'
HASH='$Format:%h$'
REFS='$Format:%<(13,ltrunc)%d$'
DATE='$Format:%aI$'

# Examples expansions:
#ARCHIVED='archived'
#HASH='09f863b'
#REFS='..g: v1.2.3)'
#DATE='1988-01-01...'

VERSION='unknown'
YEAR='????'

case $ARCHIVED in

# When archiving is detected, extract year from date and version from refs, or fall back to hash.
archived)
	if [[ $REFS =~ (v[^\)]+)\)$ ]]
	then
		VERSION=${BASH_REMATCH[1]}
	else
		VERSION=$HASH
	fi
	YEAR=${DATE:0:4}
	;;		

# Default to using git to generate version number and year in working tree
*)
	if [[ $(git rev-parse --is-inside-work-tree) == 'true' ]]
	then
		VERSION=$(git describe --always --tags --dirty)
		YEAR=$(git log -1 --date=format:%Y --pretty=format:%ad)
	fi
	;;
	
esac

# Strip leading 'v' if found
if [[ ${VERSION:0:1} == 'v' ]]
then
	VERSION=${VERSION:1}
fi

# Send output based on option
case ${1:-version} in
version)
	echo $VERSION
	;;
year)
	echo $YEAR
	;;
flags)
	echo -DVERSION=$VERSION -DYEAR=$YEAR
	;;
esac