#!/bin/sh
# create versioned tarballs from git trees
# by ponce <matteo.bernardini@gmail.com>

# This program is free software. It comes without any warranty, to
# the extent permitted by applicable law. You can redistribute it
# and/or modify it under the terms of the WTFPL, Version 2, as
# published by Sam Hocevar. For more details, see
# http://sam.zoy.org/wtfpl/COPYING

# This shell script uses the following binaries:
# git, head, cut, awk, sed, xz, md5sum

# are we in a git tree?
if [ "$( git log 2>&1 | head -1 | cut -d: -f1 )" = "fatal" ]; then
  echo "this is not a git repository."
  exit 1
fi

# OUTPUT is set to /tmp if not else specified
OUTPUT=${OUTPUT:-/tmp}

# the name of the tarball is desumed by the remote
# repository name.
# you can override also this specifying SRCNAM
REMOTEGIT=$( git remote -v | grep fetch | cut -d\  -f1 | awk -F/ '{print $NF}' )
SRCNAM=${SRCNAM:-"$REMOTEGIT"}

# form a string usable for versioning a tarball.
# run it in a git tree and it will output a string
# composed by the date, an underscore, and the first 
# 7 digit of the commit id of the active branch.
COMMIT=$( git log -1 | head -1 | cut -c 8-14 )
TODAY=$( git log -1 --format=format:%ci | awk '{print $1}' | sed 's/-//g' )
#TODAY=$( git log -1 --format=format:%ci | sed -e 's/-//g' -e 's/\ .*//' )

# the branch is extracted from git branch
BRANCH=$( git branch | grep ^\* | cut -d\  -f2 )

# some output
echo "creating tarball from $SRCNAM sources, with version ${TODAY}_${COMMIT}"
echo "${OUTPUT}/${SRCNAM}-${TODAY}_${COMMIT}.tar.xz"

# create the tarball xz compressed
git archive --prefix=${SRCNAM}-${TODAY}_${COMMIT}/ $BRANCH | xz -c -z \
  > ${OUTPUT}/${SRCNAM}-${TODAY}_${COMMIT}.tar.xz

# calculate the md5
( cd $OUTPUT
  md5sum ${SRCNAM}-${TODAY}_${COMMIT}.tar.xz \
  > ${SRCNAM}-${TODAY}_${COMMIT}.tar.xz.md5 )