chore: Add script to squash commits in PRs ready to merge

bin/git/squash-commits.sh

@@ -0,0 +1,114 @@
+#!/bin/bash
+
+if [[ $# -ne 3 || "$1" == "--help" || "$1" = "-h" ]]
+then
+  name=$( basename $0 )
+  cat <<- USAGE
+  Usage: $name pr "title" "description"
+
+  * All commits in the specified PR will be squashed and a new commit prepared
+    with the provided title and description as commit message.
+  * This script will not push the new commit. You will need to do so yourself
+    by force-pushing, since you will be rewriting history. You must be the
+    author of the PR or a maintainer of the repository in order to perform this
+    operation.
+  * The 'gh' CLI tool must be installed and authenticated.
+  * To write a multiline description, you can use "\$(cat <<EOF
+line 1
+line 2
+EOF
+)" to pass it as a single argument.
+  * If you get a '[rejected]' error when updating the target branch and then
+    locally merging the changes into the source branch, it is likely because the
+    source branch already exists on your machine (e.g. you ran this script
+    multiple times). In that case, you can delete the local source branch
+    (e.g. 'git branch -D [source]') and try again.
+
+USAGE
+exit 0
+fi
+
+pr="$1"
+shift
+
+title=$1
+shift
+
+description=$1
+shift
+
+set -e
+
+echo "Checking workspace."
+diff=$(git status --porcelain)
+if [ -n "${diff}" ]; then
+  echo "Error: Workspace is not clean. Please commit or stash your changes."
+  exit 1
+fi
+
+echo "Checking out PR ${pr}."
+gh pr checkout "${pr}"
+
+echo "Getting the target branch of the PR."
+target=$(gh pr view --json "baseRefName" --jq '.baseRefName')
+if [ -z "${target}" ]; then
+  echo "Error: Could not determine target branch of PR ${pr}."
+  exit 1
+fi
+
+echo "Getting the source branch of the PR."
+source=$(git branch --show-current)
+
+echo "Ensuring the PR source branch '${source}' is up to date with the target branch '${target}'."
+git checkout ${target}
+git pull --rebase
+gh pr checkout "${pr}"
+git merge ${target} --no-edit
+
+# TODO: check for conflicts and abort if there are any.
+
+echo "Squashing commits in the PR."
+git reset --soft $(git merge-base ${target} HEAD)
+git commit -S -m "${title}" -m "${description}"
+
+# We assume that external contributors will create a fork in their personal
+# repository, i.e. the repo owner matches the currently logged in user. In that
+# case they can push directly to their branch. If the owner is 'XRPLF', we also
+# push directly to the branch, as we assume that the user running this script
+# will be a maintainer.
+echo "Gathering user details."
+owner=$(gh pr view --json "headRepositoryOwner" --jq '.headRepositoryOwner.login')
+user=$(gh api user --jq '.login')
+echo "The PR is owned by '${owner}'. The current user is '${user}'."
+if [ "${owner}" = 'XRPLF' ] || [ "${owner}" = "${user}" ]; then
+  remote="origin"
+else
+  remote="${owner}"
+fi
+
+if [ "${remote}" = "origin" ]; then
+  cat << EOF
+----------------------------------------------------------------------
+This script will not push. Verify everything is correct, then force
+push to the source branch using the following command:
+
+git push --force-with-lease origin ${source}
+
+Remember to navigate back to your previous branch after pushing.
+----------------------------------------------------------------------
+EOF
+else
+  cat << EOF
+----------------------------------------------------------------------
+This script will not push. Verify everything is correct, then force
+push to the fork using the following command:
+
+git remote add ${remote} git@github.com:${remote}/rippled.git
+git fetch ${remote}
+git push --force-with-lease ${remote} ${source}
+git remote remove ${remote}
+
+Remember to navigate back to your previous branch after pushing.
+----------------------------------------------------------------------
+EOF
+fi