unixorn/git-extra-commands

#!/usr/bin/env bash
# Author: Mislav Marohnić  <mislav.marohnic@gmail.com>
# https://github.com/mislav/dotfiles
#
# Usage: merge [<BRANCH>]
#
# Sophisticated git merge with integrated CI check and automatic cleanup upon
# completion.
#
# - Fast-forwards BRANCH to latest version (if applicable)
# - Checks if BRANCH passed CI
# - Fast-forwards master to latest version
# - Merges BRANCH into master
# - Pushes master upstream
# - Deletes BRANCH both locally and on its remote.
#
# Depends on: hub v1.10.6

set -e

branch="$1"
upstream_name=origin
upstream_branch=""

if [ -z "$branch" ]; then
  branch="$(git symbolic-ref -q HEAD)"
  branch="${branch#refs/heads/}"
fi

symbolic_full_name() {
  local output
  if output="$(git rev-parse --symbolic-full-name "$@" 2>/dev/null)"; then
    echo "${output#refs/remotes/}"
  else
    return 1
  fi
}

checkout_latest() {
  git checkout -q "$1" && git pull --ff-only
}

if master_name="$(symbolic_full_name "$upstream_name")"; then
  master_name="${master_name#*/}"
else
  master_name=master
fi

if [ "$branch" = "$master_name" ]; then
  echo "Won't merge master branch into itself!" >&2
  exit 1
fi

if upstream="$(symbolic_full_name "${branch}@{u}")"; then
  upstream_remote="${upstream%%/*}"
  upstream_branch="${upstream#*/}"
fi

if [ -n "$upstream_branch" ]; then
  checkout_latest "$branch"
fi

if ! output="$(hub ci-status "$branch" 2>&1)"; then
  echo "hub ci-status: $output" >&2
  exit 1
fi

checkout_latest "$master_name"
git merge --no-ff "$branch" -m "Merge branch '${upstream_branch:-$branch}'"
git push "$upstream_name" "$master_name"

git branch -d "$branch"

if [ -n "$upstream_branch" ]; then
  git branch -dr "${upstream_remote}/${upstream_branch}"
  git push "$upstream_remote" --delete "$upstream_branch"
fi