recover-hard-rebase.sh

#!/bin/bash
BRANCH="$1"
ORIGINAL_BRANCH="develop"

if [[ -z "${BRANCH}" ]]; then
    echo "You must provide a branch as first argument"
    echo ""
    echo " $0 features/develop/new-sidebars"
    exit 1;
fi

EXISTING_BRANCH=$(git branch -a |grep $BRANCH |wc -l)
if [[ $EXISTING_BRANCH == 0 ]] ; then
  echo "Unknown branch $BRANCH"
  exit 1
fi

FORMAT="--pretty=format:%h%x09%an%x09%s"
TMP_BRANCH="${BRANCH}-tmp"
FINAL_COMMIT=$(git log $FORMAT $BRANCH |head -n1|cut -f1)


find_ancestor_commit() {
    OLDEST_ANCESTOR=$(git merge-base $BRANCH $ORIGINAL_BRANCH)
    ORIGIN_COMMIT=""
    while read line ; do
        if [[ -n "${ORIGIN_COMMIT}" ]]; then
            continue;
        fi
        HASH=$(echo "$line" | cut -f1)
        SUBJECT=$(echo "$line"|cut -f3)

        # check if subject exists in $ORIGINAL_BRANCH
        echo $line
        SUBJECT_EXISTS=$(git log $FORMAT $ORIGINAL_BRANCH|head -n50|grep "$SUBJECT"|wc -l)
        if [[ $SUBJECT_EXISTS -gt 0 ]]; then
            ORIGIN_COMMIT="$HASH"
        fi
    done <<< "$(git log $FORMAT "${OLDEST_ANCESTOR}".."${BRANCH}")"
    if [[ -z "$ORIGIN_COMMIT" ]]; then
        ORIGIN_COMMIT=$OLDEST_ANCESTOR
        echo "Fallback to merge point"
    fi
    echo "Common ancestor: $ORIGIN_COMMIT" #$(git show --oneline $ORIGIN_COMMIT)"
}

init_cherry_pick() {
    EXISTING_TMP_BRANCH=$(git branch |grep $TMP_BRANCH |wc -l)
    if [[ $EXISTING_TMP_BRANCH == 0 ]] ; then
        echo "create tmp branch ${TMP_BRANCH}"
        git checkout develop
        git checkout -b $TMP_BRANCH
        git cherry-pick ${ORIGIN_COMMIT}..${FINAL_COMMIT}
    fi
}

exit_if_conflict() {
    CONFLICT_STATE=$(git ls-files -u |wc -l)
    if [[ $CONFLICT_STATE -gt 0 ]] ; then
        echo "###########################################"
        echo ""
        echo "     You must resolve conflicts first"
        echo ""
        echo "###########################################"
        git status
        exit 1;
    fi
}

continue_if_clean_state() {
    UNMERGED_STATE=$(git status --porcelain | grep -v '^??' |wc -l)
    if [[ $UNMERGED_STATE -gt 0 ]] ; then
        git cherry-pick --continue
    fi
    UNMERGED_STATE=$(git status --porcelain | grep -v '^??' |wc -l)
    if [[ $UNMERGED_STATE -gt 0 ]] ; then
        # cherry-pick finished in a non clean state
        echo "###########################################"
        echo ""
        echo "      Something went wrong with commit."
        echo "        Fix it then relanch script."
        echo ""
        echo "###########################################"
        exit 1;
    fi
}

delete_tmp_branch() {
    EXISTING_TMP_BRANCH=$(git branch |grep $TMP_BRANCH |wc -l)
    if [[ $EXISTING_TMP_BRANCH -gt 0  ]] ; then
        echo "replace branch"
        git branch -D $BRANCH
        git checkout -b $BRANCH
        git branch -D $TMP_BRANCH
        echo "###########################################"
        echo ""
        echo "     Rebase is done."
        echo "  Launch your stack to check it went well"
        echo ""
        echo "###########################################"
    fi
}

find_ancestor_commit
init_cherry_pick
exit_if_conflict
continue_if_clean_state
exit_if_conflict
delete_tmp_branch