#!/bin/bash
set -o nounset -o errexit -o pipefail
SCRIPT_DIR="$( cd "$( dirname "$0" )" && pwd )"
COMMITISH=${1:-HEAD}
DIRTY_TAG=""

# Figure out if the worktree is dirty, we run update-index first
# as we've seen cases in Travis where not doing so causes git to
# treat the worktree as dirty when it is not.
git update-index -q --refresh
if ! git diff-files --quiet; then
    DIRTY_TAG="-dirty"
fi

# If we have an exact tag, and it is not a -dev tag, just use it.
if git describe --tags --exact-match "${COMMITISH}" >/dev/null 2>&1; then
    TAG="$(git describe --tags --exact-match "${COMMITISH}")"
    if [[ ! "${TAG}" =~ -dev$ ]]; then
        echo "$(git describe --tags --exact-match "${COMMITISH}")${DIRTY_TAG}"
        exit 0
    fi
fi

# Otherwise we want to include some additional information. To the
# base tag we add a timestamp and commit hash. We use the timestamp of
# the commit itself, not the date it was authored (so it will change
# when someone rebases a PR into master, for example).
echo "$(git describe --tags --abbrev=0 ${COMMITISH})-$(git show -s --format='%ct-g%h' ${COMMITISH})${DIRTY_TAG}"