cleanup-pr-branch

#!/bin/bash
set -e
set -o pipefail

MASTER_BRANCH="master"

if [[ ! -z "$TOKEN" ]]; then
	GITHUB_TOKEN=$TOKEN
fi

if [[ ! -z "$BRANCH" ]]; then
	MASTER_BRANCH=$BRANCH
fi

if [[ -z "$GITHUB_TOKEN" ]]; then
	echo "Set the GITHUB_TOKEN env variable."
	exit 1
fi

if [[ -z "$GITHUB_REPOSITORY" ]]; then
	echo "Set the GITHUB_REPOSITORY env variable."
	exit 1
fi

URI=https://api.github.com
API_VERSION=v3
API_HEADER="Accept: application/vnd.github.${API_VERSION}+json"
AUTH_HEADER="Authorization: token ${GITHUB_TOKEN}"

main(){
	action=$(jq --raw-output .action "$GITHUB_EVENT_PATH")
	merged=$(jq --raw-output .pull_request.merged "$GITHUB_EVENT_PATH")
	target_branch=$(jq --raw-output .pull_request.base.ref "$GITHUB_EVENT_PATH")

	echo "DEBUG -> action: $action merged: $merged"

	if [[ "$action" == "closed" ]] && [[ "$merged" == "true" ]] && [[ "$target_branch" == "$MASTER_BRANCH" ]]; then
		# delete the branch.
		ref=$(jq --raw-output .pull_request.head.ref "$GITHUB_EVENT_PATH")
		owner=$(jq --raw-output .pull_request.head.repo.owner.login "$GITHUB_EVENT_PATH")
		repo=$(jq --raw-output .pull_request.head.repo.name "$GITHUB_EVENT_PATH")
		default_branch=$(
 			curl -XGET -sSL \
				-H "${AUTH_HEADER}" \
 				-H "${API_HEADER}" \
				"${URI}/repos/${owner}/${repo}" | jq .default_branch
		)

		if [[ "$ref" == "$default_branch" ]]; then
			# Never delete the default branch.
			echo "Will not delete default branch (${default_branch}) for ${owner}/${repo}, exiting."
			exit 0
		fi

		echo "Deleting branch ref $ref for owner ${owner}/${repo}..."
		curl -XDELETE -sSL \
			-H "${AUTH_HEADER}" \
			-H "${API_HEADER}" \
			"${URI}/repos/${owner}/${repo}/git/refs/heads/${ref}"

		echo "Branch delete success!"
	fi
}

main "$@"