#!/bin/bash

set -e -o pipefail
shopt -s dotglob extglob nullglob
cd -- "$(git -C "${0%/*}" rev-parse --show-toplevel)"

if [[ $@ != +([0-9])*(.+([0-9])) ]]; then
  echo "Usage: ${0##*/} UPSTREAM-VERSION"
  echo "Update upstream branch then merge changes into master."
  echo "This maintainer script does not attempt to be portable."
  exit 64
elif ! git diff --exit-code --quiet; then
  echo "Uncommitted changes in the working directory"
  exit 1
elif ! git diff --cached --exit-code --quiet; then
  echo "Uncommitted changes in the index"
  exit 1
fi >&2

TMP=$(mktemp -d tmp-XXXXXX)
trap 'rm -r $TMP' EXIT

echo "Downloading upstream files for version $1:"
URL=https://sourceware.org/elfutils/ftp/$1/elfutils-$1.tar.bz2
COLUMNS=64 curl -L -# "$URL" | tar -x -f - -C $TMP --strip-components=1

git checkout upstream
git rm -q -r include src
mkdir -p include src

for FILE in $TMP/libelf/*.[ch] $TMP/lib/{crc32,eu-search,next_prime}.c \
    $TMP/lib/{eu-config,eu-search,fixedsizehash,locks,system}.h; do
  sed ':a;s/[ \t]*$//;/^\n*$/{$d;N;ba}' "$FILE" >"src/${FILE##*/}"
  git add "src/${FILE##*/}"
done

git mv src/gelf.h src/libelf.h src/nlist.h include

cp $TMP/COPYING-GPLV2 $TMP/COPYING-LGPLV3 .
git add COPYING-GPLV2 COPYING-LGPLV3

if git diff --cached --exit-code --quiet; then
  echo "No upstream changes to merge"
  git checkout master
else
  git commit -m "Update upstream files from elfutils $1"
  git checkout master
  git merge --no-commit upstream

  sed -i "s/^MINOR *=.*/MINOR = $1/" Makefile
  git add Makefile
  git commit -m "Merge from upstream libelf $1"

  echo "Merged libelf ready to review, build and test"
  echo "Sign: git tag -m v$1 -s v$1"
  echo "Push: git push --tags origin upstream master"
fi