#!/usr/bin/env bash

# Please Use Google Shell Style: https://google.github.io/styleguide/shell.xml

# ---- Start unofficial bash strict mode boilerplate
# http://redsymbol.net/articles/unofficial-bash-strict-mode/
set -o errexit  # always exit on error
set -o errtrace # trap errors in functions as well
set -o pipefail # don't ignore exit codes when piping output
set -o posix    # more strict failures in subshells
# set -x          # enable debugging

IFS=$'\n\t'
# ---- End unofficial bash strict mode boilerplate

# outputs each tag we're attaching to this docker image
SHA="${1:-HEAD}"
BRANCH=$2
SHA1=$(git rev-parse --verify "${SHA}")

# Echo to stderr
echoerr() { echo "$@" 1>&2; }

# Ensure that git SHA was provided
if [[ -x "${SHA1}" ]]; then
    echoerr "Error, no git SHA provided"
    exit 1
fi

# tag with the branch
if [[ -n "${BRANCH}" ]]; then
    echo "${BRANCH}"
fi

# Tag with each git tag
git show-ref --tags -d |
grep "^${SHA1}" |
sed -e 's,.* refs/tags/,,' -e 's/\^{}//' 2>/dev/null |
xargs -I % echo "%"

# Tag with latest if certain conditions are met
if [[ "$BRANCH" == "master" || "$BRANCH" == "trunk" || "$BRANCH" == "release-latest" ]]; then
    # Check to see if we have a valid `vX.X.X` tag and assign to CURRENT_TAG
    CURRENT_TAG=$(
        git show-ref --tags -d |
        grep "^${SHA1}" |
        sed -e 's,.* refs/tags/,,' -e 's/\^{}//' |
        grep "^v[0-9]\\+\\.[0-9]\\+\\.[0-9]\\+$" |
        sort
    )
    
    # Find the highest tagged version number
    HIGHEST_TAG=$(git --no-pager tag | grep "^v[0-9]\\+\\.[0-9]\\+\\.[0-9]\\+$" | sort -r | head -n 1)
    
    # We tag :latest only if
    # 1. We have a current tag
    # 2. The current tag is equal to the highest tag, OR the highest tag does not exist
    if [[ -n "${CURRENT_TAG}" ]]; then
        if [[ "${CURRENT_TAG}" == "${HIGHEST_TAG}" ]] || [[ -z "${HIGHEST_TAG}" ]]; then
            echo "latest"
        fi
    fi
fi