#! /bin/sh
set -ex
if [ $# != 1 ] || ! echo "$1" | grep -q '-';then
  echo >&2 "Syntax: $0 branch-list-delimited-by-dashes"
  exit 1
fi
base="origin/master"
gerrit=true
if git branch -D gerrit;then
  git checkout origin/master
  git checkout -b gerrit
else
  gerrit=false
fi
for elem in $(echo "$1"|tr '-' ' ');do
  if [ "$base" = "origin/master" ];then
    next="$elem"
  else
    next="$base-$elem"
  fi
  git checkout "$next"
  git merge "$base"
  if [ -e "$next".patch ];then
    echo -e '/^--- /,$d\nw'|ed "$next".patch || :
  fi
  git diff "$base" "$next"|diffdecvs >>"$next".patch
  if $gerrit;then
    cp "$next".patch dashtopatch.patch
    echo -e '/^--- /,$d\nw'|ed dashtopatch.patch
    git checkout gerrit
    patch -p1 <"$next".patch
    git commit -a -F dashtopatch.patch
    rm -f dashtopatch.patch
  fi
  base="$next"
done
git checkout "$next"
echo OK