#!/bin/sh

SLEEP=10
PRINT=false
EXIT_ON_ERROR=false
WATCH=false
MYSQL_HOST="localhost"
COMPARE_TYPE="eq"
COMMAND=""
COMMAND_NOK=""

usage() {
    printf "$0 [options] <query> <target>\n"
    printf "  -H <host>         Mysql host\n"
    printf "  -u <user>         Mysql user\n"
    printf "  -d <database>     Mysql database\n"
    printf "  -t <compare_type> eq, lt or gt, defaults to eq\n"
    printf "  -n <frequency>    How often to run sql query\n"
    printf "  -c <command>      Command to run when target is reached\n"
    printf "  -l <command>      Command to run when target is no longer reached, but has been reached\n"
    printf "  -w                Watch mode, this will stop the program from exiting when target is reached,\n"
    printf "                    but continue to run command each time criteria is triggered. \n"
    printf "  -p                Print the current value for each check\n"
    printf "  -e                Exit on error\n"
}

while getopts "H:u:d:c:t:n:l:pewh" opt; do
  case ${opt} in
    H )
      MYSQL_HOST="$OPTARG"
      ;;
    u )
      MYSQL_USER="$OPTARG"
      ;;
    d )
      MYSQL_DATABASE="$OPTARG"
      ;;
    t )
      COMPARE_TYPE="$OPTARG"
      ;;
    n )
      SLEEP="$OPTARG"
      ;;
    c )
      COMMAND="$OPTARG"
      ;;
    l )
      COMMAND_NOK="$OPTARG"
      ;;
    p )
      PRINT=true
      ;;
    w )
      WATCH=true
      ;;
    e )
      EXIT_ON_ERROR=true
      ;;
    h )
      usage
      exit 0
      ;;
    \? )
      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_PWD
echo
export MYSQL_PWD

TARGET_OK=false

while true; do
    RESULT=$(mysql -u"$MYSQL_USER"  -h"$MYSQL_HOST" "$MYSQL_DATABASE" -e "$QUERY" --batch --silent)
    if [ ! "$?" = "0" ]; then
        tput setaf 1
        >&2 echo "[$(date)]: MySQL Error!"
        tput sgr0
        if [ "$EXIT_ON_ERROR" = true ]; then
            exit 1
        fi
        TARGET_OK=false
        sleep $SLEEP
        continue
    fi

    if [ "$PRINT" = true ]; then
        echo "[$(date)]: ${RESULT}"
    fi

    _TARGET_OK=false
    if [ "$COMPARE_TYPE" = "eq" ]; then
        if [ "$RESULT" = "$TARGET" ]; then
            _TARGET_OK=true
            SIGN_OK="="
            SIGN_NOK="="
        fi
    elif [ "$COMPARE_TYPE" = "lt" ]; then
        if (( RESULT < TARGET )); then
            _TARGET_OK=true
            SIGN_OK=">"
            SIGN_NOK="<"
        fi
    elif [ "$COMPARE_TYPE" = "gt" ]; then
        if (( RESULT > TARGET )); then
            _TARGET_OK=true
            SIGN_OK="<"
            SIGN_NOK=">"
        fi
    fi

    if [ "$_TARGET_OK" = true ]; then
        if [ "$TARGET_OK" = false ]; then
            if [ "$PRINT" = true ]; then
                printf "[$(date)]: Target "
                tput setaf 2
                printf "OK  "
                tput sgr0
                tput sitm
                printf "$TARGET "
                tput ritm
                printf "$SIGN_OK "
                tput bold
                printf "$RESULT\n"
                tput sgr0
            fi
            if [ ! "$COMMAND" = "" ]; then
                sh -c "$COMMAND"
            fi
        fi

        TARGET_OK=true


        if [ "$WATCH" = false ]; then
            break
        fi
    else
        if [ "$TARGET_OK" = true ]; then
            if [ "$PRINT" = true ]; then
                printf "[$(date)]: Target "
                tput setaf 1
                printf "NOK "
                tput sgr0
                tput sitm
                printf "$TARGET "
                tput ritm
                printf "$SIGN_NOK "
                tput bold
                printf "$RESULT\n"
                tput sgr0
            fi
            if [ ! "$COMMAND_NOK" = "" ]; then
                sh -c "$COMMAND_NOK"
            fi
        fi
        TARGET_OK=false
    fi

    sleep $SLEEP
done

unset MYSQL_PWD