#!/bin/sh

if [ $# != 1 ]; then
  echo "Usage: $(basename "$0") <pr-number>" >&2
  exit 1
fi

pr="$1"
rebasing="$(git status | grep -q rebase && echo yes)"
branch="$(git rev-parse --abbrev-ref HEAD)"
inrollup="$(echo $branch | grep -q '^tmp/rollup/' && echo yes)"
if [ -n "$inrollup" ]; then
  branch="$(echo $branch | sed 's#^tmp/rollup/##g')"
fi
rollupbranch="tmp/rollup/$branch"
rolledup="$(git branch | grep -q " $rollupbranch" && echo yes)"

if [ -n "$rebasing" ]; then
  echo "please continue rebase in progress first" >&2
  exit 1
fi

set -ex
if [ -z "$rolledup" ]; then
  gh pr checkout "$pr" --branch "$rollupbranch"
  git rebase "$branch"
fi
if git rev-parse --abbrev-ref HEAD | grep -q '^tmp/rollup/'; then
  git checkout "$branch"
fi
git merge --ff-only "$rollupbranch"
git branch -D "$rollupbranch"