#!/bin/bash

#sources:
#https://wiki.archlinux.org/title/bcache
#https://stackoverflow.com/questions/20797819/command-to-change-the-default-home-directory-of-a-user
#https://unix.stackexchange.com/questions/156102/optimizing-bcache
#https://evilpiepirate.org/git/linux-bcache.git/tree/Documentation/bcache.txt

#Block devices
hdddev0=/dev/sdb
hdddev1=/dev/sdc
hdddev2=/dev/sdd

#Name of the raid device:
devname=/dev/md0

#Name of the mounted raid device:
mountname=/mnt/raid0


partition_settings="start=2048, type=83"


set -e

if [ "$EUID" -ne 0 ]; then
  echo "Please run as root"
  exit
fi

read -p "Block devices ${hdddev0}, ${hdddev1} and ${hdddev2} will be wiped, are you sure proceed?" -n 1 -r
echo
if [[ ! $REPLY =~ ^[Yy]$ ]]; then
  exit
fi

while [ -b /dev/bcache0 ]; then
  echo "Canceld, device /dev/bcache0 is allready present"
  exit
fi

echo
echo "Clean disks, remove partition tables... "
wipefs -a $hdddev0
wipefs -a $hdddev1
wipefs -a $hdddev2

echo "Partition disks... "
echo $partition_settings | sfdisk $hdddev0
echo $partition_settings | sfdisk $hdddev1
echo $partition_settings | sfdisk $hdddev2

echo
echo "Create raid 5... "
mdadm --create $devname --level=5 --raid-devices=3 ${hdddev0}1 ${hdddev1}1 ${hdddev2}1


echo
echo "Wait until device is ready... "
while [ ! -b $devname ]; do sleep 1; done

echo
echo "Format and mount bcache device..."
mkfs.ext4 $devname
mkdir $mountname
mount $devname $mountname
echo "$devname $mountname ext4 rw 0 0" >> /etc/fstab

echo
echo "Config default home directory for new users on bcache partition... "
echo "home path of exising users will not be moved automaticaly"
mkdir $mountname/home
echo "#" >> /etc/default/useradd
echo "# Modifications:" >> /etc/default/useradd
echo "HOME=$mountname/home" >> /etc/default/useradd

echo
echo "Setup successfully finished"