#!/bin/bash

set -o errexit
set -o nounset
set -o pipefail

DIR=$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )

PROJECT=$(gcloud config list --format 'value(core.project)')
CLUSTER=$(gcloud config list --format 'value(container.cluster)')
ZONE=$(gcloud config list --format 'value(compute.zone)')

GCE_IMAGE=${CLUSTER}-ubuntu-1604
GCE_IMAGE_FAMILY=ubuntu-1604-lts

BASE_INSTANCE=${CLUSTER}-foo-base-image

function get-base-image-name {
  gcloud compute images list --filter ${GCE_IMAGE_FAMILY} | awk '{if(NR>1)print $1}'
}

function get-base-image-project {
  gcloud compute images list --filter ${GCE_IMAGE_FAMILY} | awk '{if(NR>1)print $2}'
}

function get-foo-image-name {
  gcloud compute images list --filter foo --format json | jq -r ".[0].name"
}

create-base-instance() {
  echo "Creating instance ${BASE_INSTANCE}..."
  local base_image=$(get-base-image-name)
  local base_image_project=$(get-base-image-project)
  gcloud compute instances create ${BASE_INSTANCE} \
     --image ${base_image} \
     --image-project ${base_image_project}
}

stop-base-instance() {
  echo "Stopping instance ${BASE_INSTANCE}..."
  gcloud compute instances stop ${BASE_INSTANCE} --quiet
}

delete-base-instance() {
  echo "Deleting instance ${BASE_INSTANCE}..."
  gcloud compute instances delete ${BASE_INSTANCE} --quiet
  }

create-base-image() {
  echo "Creating base image ${GCE_IMAGE}..."
  gcloud compute images create ${GCE_IMAGE} \
     --source-disk ${BASE_INSTANCE} \
     --family ${GCE_IMAGE_FAMILY}
}

apply-configure-script() {
  echo "Applying configure script to ${BASE_INSTANCE}..."
  gcloud compute scp $DIR/configure-image.sh ${BASE_INSTANCE}: --quiet
  gcloud compute ssh ${BASE_INSTANCE} --command "sudo ./configure-image.sh &> configure-image.log" --quiet
}

echo
echo "========================================"
echo "create base OS image"
echo "========================================"
echo

foo_image=$(get-foo-image-name)
if [ "${foo_image}" != "null" ]; then
  echo "Found image ${foo_image} ... skipping"
  echo
  exit 0
fi

create-base-instance
apply-configure-script
stop-base-instance
create-base-image
delete-base-instance