#!/bin/bash

if [[ $EUID -ne 0 ]]; then
   echo "This script must be run as root" 
   exit 1
fi

if [ -z "${MONGO_PASSWORD}" ]; then
  echo "You need to set then environment variable MONGO_PASSWORD"
  exit 1
fi

COMMAND=${1}

if [ -z "${COMMAND}" ]; then
  echo "Please pass one of the following commands: create, restore, remove."
  exit 1
fi

MONGO_VOLUME="/dev/host-vg/mongo-data"
MONGO_SNAPSHOT_VOLUME="/dev/host-vg/mongo-snapshot"
MONGO_USER="administrator"
MONGO_CMD="/usr/bin/mongo --username $MONGO_USER --password $MONGO_PASSWORD --authenticationDatabase admin --quiet"

function print_error() {
  RED="\033[0;31m"
  NC="\033[0m"
  message=$1
  echo -e "${RED}${message}${NC}"
}

function create_snapshot() {
  echo -n "Locking database before creating snapshot. You're using MongoDB "
  $MONGO_CMD --eval "db.version();"

  $MONGO_CMD -eval "d=db.fsyncLock(); printjson(d.info);" | sed s/\"//g >/dev/null 2>&1
  if [ $? -ne 0 ]; then
    print_error "  Error: Could not lock DB. Aborting."
    exit 1
  else
    echo "Database is locked for creating snapshot."
  fi

  lvcreate -L 10GB --snapshot -n mongo-snapshot ${MONGO_VOLUME}
  if [ $? -ne 0 ]; then
    print_error "Creation of snapshot failed"
  else
    echo "Snapshot created successfully"
  fi

  echo -en "  Unlocking MongoDB. "
  $MONGO_CMD -eval "d=db.fsyncUnlock(); printjson(d);" >/dev/null 2>&1

  mkdir -p /mongo-snapshot

  echo "You can mount the snapshot with mount -t xfs -o nouuid ${MONGO_SNAPSHOT_VOLUME} /mongo-snapshot"
  lvdisplay ${MONGO_SNAPSHOT_VOLUME}
}

function remove_snapshot() {
  echo "Removing snapshot ${MONGO_SNAPSHOT_VOLUME}..."
  lvremove ${MONGO_SNAPSHOT_VOLUME}
}

function restore_snapshot() {
  echo -n "Do you really want to restore the snapshot (y/n)? "
  read answer 
  if [ "${answer}" == "y" ]; then
    echo "Unmounting mongodb volume and restoring snapshot..."
    unmount ${MONGO_VOLUME}
    lvconvert --merge ${MONGO_SNAPSHOT_VOLUME}
  fi
}

case "${COMMAND}" in
  "create" )
    create_snapshot;;
  "restore" )
    restore_snapshot;;
  "remove" )
    remove_snapshot;;
  *)
    print_error "The command ${COMMAND} is not supported..." ;;
esac