pr-merge

#!/bin/bash
#
# This script expects:
#
# 0. jq commandline JSON processor, see https://stedolan.github.io/jq
#
# 1. .netrc with configuration as follows:
#    machine	api.github.com
#    login	UID
#    password	ACCESS_TOKEN
#
# 2. Remote URLs in your jboss-eap clone using git protocol instead of https, ie. something like:
#    origin	git@github.com:istudens/jboss-eap7.git (fetch)
#    origin	git@github.com:istudens/jboss-eap7.git (push)
#    upstream	git@github.com:jbossas/jboss-eap7.git (fetch)
#    upstream	git@github.com:jbossas/jboss-eap7.git (push)
#
# 3. In case of remotes like above, the first parameter should be 'upstream' and the second parameter should be a number of PR being merged.
#

usage() {
    local script_name=$(basename "${0}")
    echo 1>&2 "Usage: ${script_name} <remote> <pr>"
    echo 1>&2 'Ex:'
    echo 1>&2 "${script_name} upstream 3"
}

isNetrcPresent() {
  local netrc_file=${1:-"${HOME}/.netrc"}

  if [ ! -e "${netrc_file}" -o ! -r "${netrc_file}" ] ; then
    echo "Missing configuration file ${netrc_file} - required by CuRL to authentificate against Github."
    exit 4
  fi
}

isJqInstalled() {
  local jq_url='https://stedolan.github.io/jq'
  which jq > /dev/null
  if [  "${?}" != 0 ]; then
    echo "No jq commandline install - please install JQ before using this script: ${jq_url}"
  fi
}

isHubInstalled() {
  which hub &> /dev/null
  if [  "${?}" != 0 ]; then
    echo "The hub commandline tool is not installed. Using curl."
    false
  fi
}

apiCommand() {
  if [ isHubInstalled ]; then
    hub api "${1}"
  else
    curl -L -s -n "${1}"
  fi
}

sanity_check() {
  isJqInstalled
  if [ ! isHubInstalled ]; then
    isNetrcPresent
  fi
}

sanity_check
set -eo pipefail

if [ ${#} != 2 ]; then
    echo 1>&2 "Usage: $0 <remote> <pr>"
    exit 1
fi

readonly BRANCH=$(git rev-parse --abbrev-ref HEAD)
readonly REMOTE=${1}
readonly PR_ID=${2}

if [ -z "${REMOTE}" ]; then
  echo "No REMOTE provided."
  usage
  exit 2
fi

if [ -z "${PR_ID}" ]; then
  echo "No PR provided."
  usage
  exit 3
fi

echo "Merging ${PR_ID} from ${REMOTE} onto ${BRANCH}"
readonly FETCH_URL=$(git remote -v | grep "^${REMOTE}[ ]*" | grep 'fetch' | cut -f2 | cut -d" " -f1)
if [ -z "${FETCH_URL}" ]; then
  usage
  echo "Unable to retrieve remote fetch URL from ${REMOTE}."
  echo ''
  echo 'Available remotes in your repository are:'
  git remote -v
  exit 4
fi

# replace all slashes with colons to keep delimiter consistent
readonly URL_PARSE=$(echo "${FETCH_URL}" | sed "s/\//:/g")
readonly REPO_PART="${URL_PARSE##*:}"
readonly REPO=$(echo "${REPO_PART}" | sed "s/.git//")
readonly URL_LEFT="${URL_PARSE:0:$((${#URL_PARSE} - ${#REPO_PART} - 1))}"
readonly OWNER="${URL_LEFT##*:}"

if [ -z "${OWNER}" -o -z "${REPO}" ]; then
  echo "Unable to parse owner and repo from ${FETCH_URL}"
  exit 4
fi
readonly PR_GITHUB_API_URL="https://api.github.com/repos/${OWNER}/${REPO}/pulls/${PR_ID}"
readonly PULL=$(apiCommand "${PR_GITHUB_API_URL}")
set -e
echo -n "Retrieving PR information from ${PR_GITHUB_API_URL}... "
if [ $(echo ${PULL} | jq .status) == '"404"' ]; then
  echo "Failed."
  echo "GitHub response:"
  echo "${PULL}"
  exit 2
fi
echo 'Done.'
set +e

readonly MSG="Merge pull request #${PR_ID} from $(echo ${PULL} | jq -r .head.label) $(echo $PULL | jq -r .title)"
echo "Git commit message will be: ${MSG}"
if [ -z "${NO_STOP_BEFORE_MERGE}" ] ; then
  echo -n "Continue..." && read _
fi
set -ex
git fetch "${REMOTE}" "pull/${PR_ID}/head"
git merge --no-ff -m "${MSG}" 'FETCH_HEAD'