rebase-using-merge.sh

# very VERY crappy version of `git rebase` that assumes that there are no merge conflicts.
# the goal is to try to show the relationship between "rebase" and "merge" by 
# showing how you can implement `git rebase` using repeated `git merge`s into a copy of the target branch

set -euo pipefail

TARGET=$1
CURRENT=$(git rev-parse --abbrev-ref HEAD)

# Make a copy of the target branch to work in
git checkout -b temp-rebase-branch $TARGET

# Cherry pick commits onto the target branch, one at a time
for COMMIT in $(git rev-list --reverse --topo-order $TARGET..$CURRENT); do
    git merge --no-commit --no-ff $COMMIT
    git reset HEAD
    git commit -a -C $COMMIT
done

# Force the branch we're rebasing to point at our temp rebase branch
git branch -f $CURRENT temp-rebase-branch

# Go back to the current branch
git checkout $CURRENT

# Delete the temporary branch
git branch -d temp-rebase-branch