Replay commits from submodule in main git repository

git-submodule-replay

#!/bin/sh

#Replay commits from submodule in main git repository
#For each commit in the submodule in range, create a commit in the
#main repository that adds the commit of the submodule with the same
#commit message as the submodule

SUBMODULE=$1
RANGE=$2

function is_submodule() {
    true #TODO: Can we implement this?
}

if [ -z $SUBMODULE ] || [ -z $RANGE ]; then
    echo "usage: $0 SUBMODULE RANGE" >&2
    exit 1
fi

if [ ! -d "$SUBMODULE" ]; then
    echo "$SUBMODULE: No such directory" >&2
    exit 2
fi

if [ $( cd $SUBMODULE && is_submodule )]; then
    echo "$SUBMODULE: Not a submodule" >&2
    exit 2
fi

if [ -n "$( git status --untracked-files=no --ignore-submodules --porcelain )" ]; then
    echo "Working directory or index is not clean, aborting!" >&2
    exit 3
fi

if [ -n "$( cd $SUBMODULE && git status --untracked-files=no --ignore-submodules --porcelain )" ]; then
    echo "Working directory or index of submodule is not clean, aborting!" >&2
    exit 3
fi

SUBMODULE_HEAD=$( cd "${SUBMODULE}" && git rev-parse --abbrev-ref --verify HEAD)
SUBMODULE_COMMITS=$( cd "${SUBMODULE}" && git rev-list "${RANGE}")
#reverse list of commits
REVERSED_SUBMODULE_COMMITS=$( echo "$SUBMODULE_COMMITS" | awk '{a[i++]=$0} END {for (j=i-1; j>=0;) print a[j--] }' - )

echo "Replaying commits of submodule ${SUBMODULE} ${RANGE}..."
echo

for COMMIT in $REVERSED_SUBMODULE_COMMITS ; do
    SUBMODULE_COMMIT_MSG=$( cd "$SUBMODULE" && git show -s --format=%B $COMMIT )
    SUBMODULE_COMMIT_SUBJECT=$( cd "$SUBMODULE" && git show -s --format=%s $COMMIT )
    echo "[${COMMIT}] ${SUBMODULE_COMMIT_SUBJECT}"
    $( cd "$SUBMODULE" && git checkout -q $COMMIT ) && \
    git add "${SUBMODULE}" && ( echo "$SUBMODULE_COMMIT_MSG" | git commit -q --file - )
done

echo

echo "Resetting HEAD of submodule to previous value '$SUBMODULE_HEAD'"
( cd "$SUBMODULE" && git checkout -q "$SUBMODULE_HEAD" )