#:  * `--version`, `-v`
#:
#:  Print the version numbers of Homebrew, Homebrew/homebrew-core and Homebrew/homebrew-cask (if tapped) to standard output.

version_string() {
  local repo="$1"
  if ! [ -d "$repo" ]; then
    echo "N/A"
    return
  fi

  local pretty_revision
  pretty_revision="$(git -C "$repo" rev-parse --short --verify --quiet HEAD)"
  if [ -z "$pretty_revision" ]; then
    echo "(no Git repository)"
    return
  fi

  local git_last_commit_date
  git_last_commit_date=$(git -C "$repo" show -s --format='%cd' --date=short HEAD)
  echo "(git revision ${pretty_revision}; last commit ${git_last_commit_date})"
}

homebrew-version() {
  echo "Homebrew $HOMEBREW_VERSION"
  echo "Homebrew/homebrew-core $(version_string "$HOMEBREW_CORE_REPOSITORY")"

  if [ -d "$HOMEBREW_CASK_REPOSITORY" ]; then
    echo "Homebrew/homebrew-cask $(version_string "$HOMEBREW_CASK_REPOSITORY")"
  fi
}