git-release

#!/bin/bash

# release

# Prepare a release by bumping the version number and committing the
# CHANGELOG file for the upcoming release.

set -euo pipefail

shopt -s nullglob failglob extglob

[[ ${1-} == -x ]] && set -xv
DEBUG=0; [[ ${1-} == -d ]] && DEBUG=1

if [[ ${1-} == -h ]]; then
  cat <<EOF
[git checkout release/v1.0 &&] ${0##*/} [<version>|point|minor|major]
EOF
exit
fi

changelog=( CHANGELOG.* @(CHANGELOG|changelog)* )
if [[ -z $changelog ]]; then
  changelog='CHANGELOG.md'
fi

cur_branch=$(git rev-parse --abbrev-ref HEAD)
prev_tag=$(git describe --abbrev=0 --tags 2>/dev/null || true)
new_tag=
under_gitflow=0
git config --get gitflow.branch.master &>/dev/null && under_gitflow=1

if [[ ${1-} == v* ]]; then
  new_tag="${1-}"

elif [[ ${1-} == @(bugfix|hotfix|major|minor|patch|point) ]]; then
  _prev_tag="${prev_tag%%-*}"  # Drop any trailing identifiers
  if [[ $1 == @(bugfix|hotfix|patch|point) ]]; then
    # take v1.0.1 -> v1.0.2
    o="${_prev_tag##*.}"
    n=$(( o + 1 ))
    new_tag="${_prev_tag%%$o}$n"
  elif [[ $1 == minor ]]; then
    # take v1.0.1 -> v1.1.0
    t="${_prev_tag%.*}"
    o="${t##*.}"
    n=$(( o + 1 ))
    new_tag="${t%%$o}$n.0"
  elif [[ $1 == major ]]; then
    # take v1.0.1 -> v2.0.0
    t="${_prev_tag%%.*}"
    o="${t##[!0-9]}"
    n=$(( o + 1 ))
    new_tag="${t%%$o}$n.0.0"
  fi

elif [[   $cur_branch == @(bugfix|hotfix|release)@(-|/)* ]]; then
  new_tag="${cur_branch##@(bugfix|hotfix|release)@(-|/)}"

elif [[ $prev_tag ]]; then
  # no args were passed but if current branch has a tag (a la trunk-based-dev,
  # git(hub|lab)flow, etc), let's assume we're making a point release
  exec "$0" point

fi

if (( under_gitflow == 1 )) && [[ $cur_branch != release@(-|/)* ]]; then
  echo "Last identified tag was '$prev_tag', Creating 'release/$new_tag'"
  git flow release start "$new_tag"
fi

if [[ -z $new_tag ]]; then
  echo >&2 "Target tag for release is not specified and could not be determined"
  echo >&2 "Assuming release is the first and so setting tag to v0.1.0"
  new_tag='v0.1.0'
fi

tmpfile=$(mktemp --tmpdir --suffix=md "CHANGELOG.md-$new_tag-XXXXXX")

function cleanup() {
  rm -f "$tmpfile"
}

trap cleanup EXIT INT

content=$(changelog "$prev_tag" HEAD)

if [[ -z $content ]]; then
  echo >&2 "No new changelog content for '$changelog'"
  echo >&2 "  Is the current commit a merge commit?"
  exit 42
fi

{
  title="$new_tag - $(date +%FT%T)"
cat <<EOF
$title
$(echo -n "$title" | tr -c $'\0' '-')

$content

EOF
  [[ -e $changelog ]] && cat "$changelog"
} > "$tmpfile"

if [[ $EDITOR == @(vi*|*/vi*) ]]; then
  args=(-c 4)
fi

"$EDITOR" "$tmpfile" ${args[@]}

if ! diff -qbacs "$tmpfile" "$changelog" &>/dev/null; then
  cp "$tmpfile" "$changelog"
  git add "$changelog"
    { echo "Update $changelog for $new_tag"
      echo
      echo "$changelog updated by '${0##*/} $@' on $cur_branch"
  } | git commit -m "$(</dev/stdin)"

  message=$(sed -n '4p' "$changelog")
  [[ -z $message ]] && message="$new_tag"

  if (( under_gitflow == 1 )); then
    git flow release finish -T "$new_tag" -m "$message"
  else
    git tag -a "$new_tag" -m "$message"
    echo "Tag ($new_tag) not pushed .. when ready, issue"
    echo "   git push --tags"
  fi
else
  echo 'Empty release notes .. aborting'
  exit 3
fi

# vi:ft=bash