#!/bin/bash
VAR_DIR="/var/local/machinepi"
TAG_DIR="/var/local/machinepi/tag"

source "${TAG_DIR}/vars"

function fetch {
  ssh -q -o StrictHostKeyChecking=no -i "${TAG_DIR}/ssh-key" -p "${MPI_MASTER_PORT}" -l "${MPI_MASTER_USER}" "${MPI_MASTER_HOST}" $@
}

function load_client_hash {
  if [ -f "${VAR_DIR}/package.hash" ]; then
    cat "${VAR_DIR}/package.hash"
  else
    return 1
  fi
}

function load_master_hash {
  fetch package hash
}

function load_package_hash {
  hash=$( sha256sum "${VAR_DIR}/package.tar.gz" )
  echo "${hash:0:64}"
}

function update {
  local client_hash=$( load_client_hash )
  local master_hash=$( load_master_hash )

  if [ -z "$master_hash" ] || [ "$master_hash" = "$client_hash" ]; then
    return 0
  fi

  if [ -f "${VAR_DIR}/package/teardown.sh" ]; then
    "${VAR_DIR}/package/teardown.sh"
    if [ "$?" -ne "0" ]; then
      echo "Unable to teardown old package!"
      return 1
    fi
  fi
  rm -r "${VAR_DIR}/package"

  fetch package code > "${VAR_DIR}/package.tar.gz"
  if [ "$?" -ne "0" ]; then
    echo "Unable to fetch new package!"
    return 1
  fi
  local package_hash=$( load_package_hash )

  if [ "$master_hash" != "$package_hash" ]; then
    echo "Unable to validate new package hash!"
    return 1
  fi

  tar -C "${VAR_DIR}" -xzf "${VAR_DIR}/package.tar.gz"
  if [ "$?" -ne "0" ]; then
    echo "Unable to extract new package!"
    return 1
  fi
  rm "${VAR_DIR}/package.tar.gz"

  if [ -f "${VAR_DIR}/package/setup.sh" ] ; then
    "${VAR_DIR}/package/setup.sh"
    if [ "$?" -ne "0" ]; then
      echo "Unable to setup new package!"
      return 1
    fi
  fi

  echo "$master_hash" > "${VAR_DIR}/package.hash"
}

update