#!/bin/bash
#
# Script: mjact_mysql
#
# Usage: mjact_mysql -D <DB name> -U <DB username> -H <hostname> -P -G
#
# Description: A tool for creating MySQL/MariaDB databases, database users and granting privileges
#
# Author: Nikita Shchetinin
#
# Changelog:
# * 05.03.2021: Nikita Shchetinin
# - Initial write

if [ "$(whoami)" != 'root' ]
then
	echo "You must execute this script as the root user!"
	exit 1
fi

ADD () {
if ! systemctl is-active --quiet mysqld
then
	echo "MySQL/MariaDB is not running!"
	exit 1
fi
if [ -z "$hostname" ]
then
	hostname="localhost"
fi
if [ -z "$database" ]
then
	echo "The database name is required!"
	exit 1
else
	if [[ ! $database =~ ^[0-9a-zA-Z_]+$ ]]
	then
		echo "The database name contains ivalid characters!"
		exit 1
	elif [ ${#database} -gt 64 ]
	then
		echo "The database name contains more than 64 characters!"
		exit 1
	fi
	if [ -z "$user" ]
	then
	user=$database
	else
		if [[ ! $user =~ ^[0-9a-zA-Z_]+$ ]]
		then
			echo "The username contains ivalid characters!"
			exit 1
		elif [ ${#user} -gt 80 ]
		then
			echo "The useranme contains more than 80 characters!"
			exit 1
		fi
	fi
fi
if [ "$passprompt" == "YES" ]
then
	read -p "Enter the password: " password
	while [ -z "$password" ]
	do
	echo "The password is required!"
	read -p "Enter the password: " password
	done
else
	password=$(</dev/urandom tr -dc A-Za-z0-9 | head -c16)
fi
if [ $(mysql -e "SELECT Host,User FROM mysql.user WHERE User='$user' AND Host='$hostname'" | wc -l) != 0 ]
then
	echo "The $user@$hostname username is already added to this server!"
	exit 1
fi
if [ -z "$grantonly" ]
then
	if mysql -e "SHOW DATABASES" | grep -qw "$database"
	then
		echo "The $database database is already added to this server!"
		exit 1
	else
		mysql -e "CREATE DATABASE $database"
		mysql -e "CREATE USER '$user'@'$hostname' IDENTIFIED BY '$password'"
		mysql -e "GRANT ALL PRIVILEGES on $database.* TO '$user'@'$hostname'"
	fi
else
mysql -e "CREATE USER '$user'@'$hostname' IDENTIFIED BY '$password'"
mysql -e "GRANT ALL PRIVILEGES on $database.* TO '$user'@'$hostname'"
fi
echo "Hostname: localhost"
echo "Database name: $database"
echo "Database username: $user"
echo "Database username's password: $password"
}

HELP () {
echo "A tool for creating MySQL/MariaDB databases, database users and granting privileges"
echo "usage: mjact_mysql -D <DB name> -U <DB username> -H <hostname> -P (to submit password using a password prompt) -G (to create a user and add grants only)"
}

if [[ "${1}" == "" ]] || [[ "${1}" == "-h" ]] || [[ "${1}" == "--help" ]]
then
	HELP
else
	while getopts ":D:U:H:PG" OPTION
	do
		case "${OPTION}" in
			D)
				database="${OPTARG}"
			;;
			U)
				user="${OPTARG}"
			;;
			H)
				hostname="${OPTARG}"
			;;
			P)
				passprompt="YES"
			;;
			G)
				grantonly="YES"
			;;
		esac
	done
	ADD
fi