#!/bin/bash

printf "Better to run as root, because of permisions handeling.\n"

sleep 2


### Firewall ###  needs to update

printf "Do you want to set up firewall rules by iptables? [Y/n]: \n"
read ansFirewallSetup


if [[ "$ansFirewallSetup" =~ ("N"|"n") ]]; then

	printf "+ Thanks, working on next bit\n"


elif [[ "$ansFirewallSetup" =~ ("Y"|"y") || -z $ansFirewallSetup ]]; then
	
	printf "Do you want to block non-LAN ssh connections? [Y/n/castom]: "
	read sshBlockRange


	if [[ $sshBlockRange =~ ("n"|"N") ]]; then
	
		printf "+ OK, working on next bit\n"
		ipList=""

	elif [[ $sshBlockRange =~ ("y"|"Y") || -z $sshBlockRange ]]; then
	
		#Pipes all informations about ip interfaces
		ipList=$(ip -o -4 a show scope global)

		#Founds data in pattern
		ipList=$(echo $ipList | grep -Eo "([0-9]*\.){3}[0-9]*/[0-9]*")

		#substitues space for coma
		ipList=$(echo $ipList | tr " " ",") 

		printf "+ Accepting SSH connections only on these ip's: $ipList\n"


	else
			printf "\nHope you know what you are doing, I am not checking these :]"
			
			printf "\nSubmit your IP range to acces SSH in format 192.168.1.1/24 
				\nYour IP range: "
			read ipList
			printf "\n+ Allowing SSH on this range: $ipList \n"
	fi
fi

### RAM ### needs to update

printf "How much of RAM are you willing to allocate in GB (Max) [4G/?G]: \n"
read maxRam

printf "How little you want to let RAM go down to in GB (Min) [1G/?G]: \n"
read minRam

if [[ "$minRam" > "$maxRam" ]]; then
	pritf "\n You allocated too low max ram or too much min ram. Manual intervention at the end will be needed\n"
	echo "-Xmx?G # in place of ? put number of RAM you want to set ass maximum"
	$maxRam="Error"
elif [[ "$maxRam" =~ ("G"|"M") ]]; then
	printf "\n+ Allocating $maxRam as RAM maximum."
	echo "-Xmx$maxRam" >> data/user_jvm_args.txt
elif [[ -z $maxRam ]]; then
	$maxRam=4G
	printf "\n+ Allocating $MaxRam as RAM maximum"
	echo "-Xmx$maxRam" >> data/user_jvm_args.txt
elif [[ ! "$maxRam" =~ ("G"|"MB") ]]; then
	printf "\n+ Allocating ${maxRam}G as RAM maximum"
	echo "-Xmx${maxRam}G" >> data/user_jvm_args.txt
else
	pritnf "\n \n!!! Sorry I have no idea what are you trying to do :/ Manual intervention will be needed at the end \n"
	$maxRam="Error"
	echo "-Xmx?G # in place of ? put number of RAM you want to set ass maximum"

fi


if [[ "$minRam" > "$maxRam" ]]; then
	echo "-Xms?G # in place of ? put number of RAM you want to se ass minimum"
elif [[ "$minRam" =~ ("G"|"M") ]]; then
	printf "\n+ Allocating $minRam as RAM minimum."
	echo "-Xms$minRam" >> data/user_jvm_args.txt
elif [[ -z $minRam ]]; then
	$minRam=1G
	printf "\n+ Allocating $minRam as RAM minimum"
	echo "-Xms$minRam" >> data/user_jvm_args.txt
elif [[ ! "$minRam" =~ ("G"|"MB") ]]; then
	printf "Allocating ${minRam}G as RAM maximum"
	echo "-Xms${minRam}G" >> data/user_jvm_args.txt
else
	pritnf "\n!!! Sorry I have no idea what are you trying to do :/ Manual intervention will be needed at the end \n"
	$minRam="Error"
	echo "-Xms?G # in place of ? put number of RAM you want to set ass minimum"
fi


### Update ### need update

sleep 2

apt update && apt upgrade -y

apt install openjdk-17-jre-headless screen


if [[ "$ansFirewallSetup" =~ ("Y"|"y") || -z $ansFirewallSetup  ]]; then
	 apt install iptables -y
fi

### User managment ### needs update

groupadd minecraft

useradd --system --shell /usr/sbin/nologin --home /opt/minecraft -g minecraft minecraft


### File structure ###

mkdir /opt/velocity

mv data/velocity*.jar start.sh /opt/velocity/

mkdir /opt/velocity/plugins
mv data/Ambassador*.jar /opt/velocity/plugins

### Nestopne se samo, mozna lepsi vytvorit strukturu za nej vlozit config a spustit az pres systemD
./start.sh
end
### Screen usige alert

rm /opt/velocity/velocity.toml
mv data/velocity.toml /opt/velocity/



### Permisions ### needs update

chown -R godot:godot  /opt/velocity/



### SystemD service ### needs update
printf "+ Preparign systemD service\n"
mv data/mc-forge.service /etc/systemd/system/

systemctl daemon-reload

### integration of Maxopoly's instructions on firewall ### needs update

if [[ "$ansFirewallSetup" =~ ("Y"|"y") || -z "$ansFirewallSetup" ]]; then
	
		printf "+ Executing firewall setup"

		iptables -P INPUT ACCEPT #Clears existing rules

		iptables -A INPUT -i lo -j ACCEPT #Allow loopback

		iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT #Allow continuing connections

		iptables -A INPUT -p tcp --dport 22 --source $ipList -j ACCEPT #Allow ssh from set network

		iptables -A INPUT -p tcp --dport 25565 -j ACCEPT #Allow MC port

		iptables -L ### Good place to paste a manual check to not lock yourself out 

		printf "\n Does it looks right? [Y/n]: "
			read ansFirewallOK

		if [[ "$ansFirewallOK" =~ ("Y"|"y") || -z "$ansFirewallOK" ]]; then	
		
			iptables -P INPUT DROP #Disallow everythink else

			iptables -P FORWARD DROP #Block all forwarding

			iptables -P OUTPUT ACCEPT #Allow all outgouing
	
			 apt install iptables-persistent -y

		else
			
			printf "\nOK it is time for manual configuration"
			printf "\nAfter you are done ramamber to run 'apt install iptables-persistent' to save your config. System will automaticly remove your work after restart"

		fi
fi

  ### Error handeling ### needs update
if [[ "$minRam" = "Error" || "$maxRam" = "Error" ]]; then

	printf "\n Encountred some eror in Ram settings"
	pritnf "\n Manual configuration needed" 
	printf "\n Open /opt/minecraft/user_jvm_args.txt in your favorite editor. File contains more instructions"

else
	
	printf "Do you want to start server right now? [Y/n]: \n"
	read startServer

	if [[ "$startServer" =~ ("y"|"Y") || -z $startServer ]]; then
		systemctl start mc-forge.serice
	fi
	
	systemctl enable mc-forge

fi

printf "\n+ Done, thanks for your time. It is goode idea to chack if everythink is alright by running:"
printf "\nsystemctl status mc-forge"
printf "\nsu minecraft -s /bin/bash"
printf "\n+ it is good idea to have some fun with screen before trying to open minecraft conesole 'screen -r' while loged wia minecraft user"