#! /usr/bin/env sh

set -e

cleanup() {
  if [ "${CLEAN_EXIT}" = false ]; then
    echo "something went wrong"
    echo "continue with the pipeline"
    exit 0
  fi
}

trap cleanup EXIT
CLEAN_EXIT=false

if [ -z "${BASE}" ]; then
  echo "the environment variable BASE is not set"
  exit 1
fi

if [ -z "${TARGET}" ]; then
  echo "the environment variable TARGET is not set"
  exit 1
fi

if [ -z "${REPO_URL}" ]; then
  REPO_URL="https://hub.docker.com/v2/repositories"
fi

if [ -z "${BASE_REPO_URL}" ]; then
  BASE_REPO_URL="${REPO_URL}"
fi

if [ -z "${TARGET_REPO_URL}" ]; then
  TARGET_REPO_URL="${REPO_URL}"
fi

if [ -z "${BASE_REPO_USERNAME}" && -n "${REPO_USERNAME}" ]; then
  BASE_REPO_USERNAME="${REPO_USERNAME}"
fi

if [ -z "${BASE_REPO_PASSWORD}" && -n "${REPO_PASSWORD}" ]; then
  BASE_REPO_PASSWORD="${REPO_PASSWORD}"
fi


if [ -z "${TARGET_REPO_USERNAME}" && -n "${REPO_USERNAME}" ]; then
  TARGET_REPO_USERNAME="${REPO_USERNAME}"
fi

if [ -z "${TARGET_REPO_PASSWORD}" && -n "${REPO_PASSWORD}" ]; then
  BASE_REPO_PASSWORD="${REPO_PASSWORD}"
fi


# add "library/" if its a "official" docker image (it has no username)
echo "${BASE}" | grep -q "/" || BASE="library/${BASE}"
echo "${TARGET}" | grep -q "/" || TARGET="library/${TARGET}" 

# if no tag is give default to latest
echo "${BASE}" | grep -q ":" || BASE="${BASE}:latest"
echo "${TARGET}" | grep -q ":" || TARGET="${TARGET}:latest" 


# move the tag to its own var and remove it from the repo name
BASE_TAG=$(echo "${BASE}" | sed 's/[^:]*://')
TARGET_TAG=$(echo "${TARGET}" | sed 's/[^:]*://')

BASE_REPO=$(echo "${BASE}" | sed 's/:.*//')
TARGET_REPO=$(echo "${TARGET}" | sed 's/:.*//') 


# build the url to the repo
BASE_URL="${BASE_REPO_URL}/${BASE_REPO}/tags/${BASE_TAG}"
TARGET_URL="${TARGET_REPO_URL}/${TARGET_REPO}/tags/${TARGET_TAG}"

# login if credentias are passed
HEADER=""
if [ -n "${DOCKER_USERNAME}" ] && [ -n "${DOCKER_PASSWORD}" ]; then
  TOKEN=$(curl -s -H "Content-Type: application/json" -X POST -d '{"username": "'"${DOCKER_USERNAME}"'", "password": "'"${DOCKER_PASSWORD}"'"}' https://hub.docker.com/v2/users/login/ | jq -r .token) 
  HEADER="Authorization: JWT ${TOKEN}"
fi


# compare the update time of the BASE and TARGET images
BASE_DATE=$(curl -s -H "${HEADER}" "${BASE_URL}" | jq -r .last_updated | sed 's/T/ /' | sed 's/\..*//' ) 
TARGET_DATE=$(curl -s -H "${HEADER}" "${TARGET_URL}" | jq -r .last_updated | sed 's/T/ /' | sed 's/\..*//' )

BASE_TIMESTAMP=$(date -d "${BASE_DATE}" +%s)
TARGET_TIMESTAMP=$(date -d "${TARGET_DATE}" +%s)

CLEAN_EXIT=true

if [ "$BASE_TIMESTAMP" -le "$TARGET_TIMESTAMP" ]; then
  echo "no update needed"
  exit 1
fi

echo "$TARGET needs updating"
exit 0