#!/bin/sh
set -e

PRINT_FLAG=false
MYSQL_HOST="localhost"
COMPARE_TYPE="eq"

usage() {
    printf "$0 [options] <query> <target>\n"
    printf "\t-H <host>\tMysql host\n"
    printf "\t-u <user>\tMysql user\n"
    printf "\t-d <database>\tMysql database\n"
    printf "\t-c <compare_typw>\teq, lt or gt, defaults to eq\n"
    printf "\t-p\t\tPrint the current value for each check\n"
}


while getopts "H:u:d:c:p" opt; do
  case ${opt} in
    H )
      MYSQL_HOST="$OPTARG"
      ;;
    u )
      MYSQL_USER="$OPTARG"
      ;;
    d )
      MYSQL_DATABASE="$OPTARG"
      ;;
    c )
      COMPARE_TYPE="$OPTARG"
      ;;
    p )
      PRINT_FLAG=true
      ;;
    \? )
      echo "Invalid option: $OPTARG" 1>&2
      exit 1
      ;;
    : )
      echo "Option -$OPTARG requires an argument." 1>&2
      exit 1
      ;;
  esac
done
shift $((OPTIND -1))

if [ -z "$1" ]; then
  echo "Error: <query> argument is missing." >&2
  usage
  exit 1
fi
QUERY="$1"

if [ -z "$2" ]; then
  echo "Error: <target> argument is missing." >&2
  usage
  exit 1
fi
TARGET="$2"

if [ -z "$MYSQL_HOST" ]; then
  echo "Error: -H <host> argument is missing." >&2
  usage
  exit 1
fi

if [ -z "$MYSQL_USER" ]; then
  echo "Error: -u <user> argument is missing." >&2
  usage
  exit 1
fi

if [ -z "$MYSQL_DATABASE" ]; then
  echo "Error: -d <database> argument is missing." >&2
  usage
  exit 1
fi

read -s -p "Enter password: " MYSQL_PASSWORD
echo

while true; do
    RESULT=$(mysql -u"$MYSQL_USER" -p"$MYSQL_PASSWORD" -h"$MYSQL_HOST" "$MYSQL_DATABASE" -e "$QUERY" --batch --silent 2> /dev/null)
    if [ "$PRINT_FLAG" = true ]; then
        echo "[$(date)]: ${RESULT}"
    fi

    if [ "$COMPARE_TYPE" = "eq" ]; then
        if [ "$RESULT" = "$TARGET" ]; then
            if [ "$PRINT_FLAG" = true ]; then
                echo "[$(date)]: Target reached $RESULT = $TARGET"
            fi
            break
        fi
    elif [ "$COMPARE_TYPE" = "lt" ]; then
        if (( RESULT < TARGET )); then
            if [ "$PRINT_FLAG" = true ]; then
                echo "[$(date)]: Target reached $RESULT < $TARGET"
            fi
            break
        fi
    elif [ "$COMPARE_TYPE" = "gt" ]; then
        if (( RESULT > TARGET )); then
            if [ "$PRINT_FLAG" = true ]; then
                echo "[$(date)]: Target reached $RESULT > $TARGET"
            fi
            break
        fi
    fi

    sleep 10
done