git-review-diff-old-version.sh

#!/bin/bash
REVIEW=$1
GERRIT_USER=$(git config --get gitreview.username)

WHEREAMI=$(git rev-parse --abbrev-ref HEAD)

[[ -z ${WHEREAMI} ]] && {
    echo "Cannot detect the current branch"
    exit 1
}

[[ -z ${GERRIT_USER} ]] && {
    echo "you need to configure your gerrit user"
    exit 1
}

[[ -z ${REVIEW} ]] && {
    echo "i need a review"; exit 1;
}

REF=$(ssh -n -x -p 29418 ${GERRIT_USER}@review.openstack.org gerrit query --format=JSON --current-patch-set change:${REVIEW} | sed -n '/"number"/ { s/.*ref.:.//;s/".*//;p;}')

[[ -z ${REF} || ${REF} != refs/changes/* ]] && {
    echo "cannot find your branch reference."
    exit 1;
}

CURRENT=${REF##*/}
if [[ ${CURRENT} -le 1 ]];then
    echo "This is revision 1"
    exit 1;
fi

LAST=$(($CURRENT-1))
REF_OLD=${REF%/*}
REF_OLD="${REF_OLD}/${LAST}"

BRANCH_CURRENT=${REF//\/}
BRANCH_OLD=${REF_OLD//\/}

git fetch gerrit ${REF}
if $(git branch -l >/dev/null 2>/dev/null|grep -q ${BRANCH_CURRENT});then
    git checkout ${BRANCH_CURRENT} FETCH_HEAD
    git reset --hard FETCH_HEAD
else
    git checkout -b ${BRANCH_CURRENT} FETCH_HEAD
fi

git fetch gerrit ${REF_OLD}
if $(git branch -l >/dev/null 2>/dev/null|grep -q ${BRANCH_OLD});then
    git checkout ${BRANCH_OLD} FETCH_HEAD
    git reset --hard FETCH_HEAD
else
    git checkout -b ${BRANCH_OLD} FETCH_HEAD
fi

git diff --color ${BRANCH_OLD}..${BRANCH_CURRENT}

git checkout ${WHEREAMI}

git branch -D ${BRANCH_CURRENT}
git branch -D ${BRANCH_OLD}