#!/bin/sh

SCRIPT="2part.sh"

case "$1" in
    installer)
        # Substitute partman with this script
        sed -i "s|partman|/tmp/$SCRIPT partman|" /var/lib/dpkg/info/partman-base.postinst
        logger "Modified partman-base.postinst. Partitioning will be handled by /tmp/$SCRIPT instead of partman."
    ;;

    partman)
        logger "$SCRIPT partition configuration progress started"

        # Ensure that the device mapper module is loaded
        modprobe dm_mod

        # Wipe the MBR and initialise a new partition table
        dd if=/dev/zero of=/dev/sda bs=512 count=1
        parted -s /dev/sda -- mklabel msdos

        # Create a 2G partition for the root filesystem. Use the rest for LVM.
        parted -s /dev/sda -- mkpart primary 2048s 4196351s
        parted -s /dev/sda -- mkpart primary 4196352s -1s
        parted -s /dev/sda -- toggle 2 lvm

        # Create a single physical volume then create a volume group with it
        pvcreate -ff -y /dev/sda2
        vgcreate vg0 /dev/sda2

        # Allocate 10G for /usr
        lvcreate -L10G -nusr vg0

        # Allocate as much space as possible for /var but leave 100G free. It
        # gives us room to maneuver and also allows for snapshotting.
        LVM2_VG_FREE=`vgs --noheadings --units m -o vg_free vg0 | cut -d. -f1`
        VAR_SIZE=`expr $VG_FREE - 1000000`
        lvcreate -nvar -L${VAR_SIZE}M vg0

        # Create and mount the root filesystem
        mkfs.ext4 -q -FF /dev/sda1
        mkdir /target
        mount /dev/sda1 /target

        # Create and mount the other filesystems
        for fs in usr var; do
            mkfs.xfs -q -f /dev/vg0/$fs
            mkdir -p /target/$fs
            mount /dev/vg0/$fs /target/$fs
        done

        # Create fstab ... TODO

    ;;

    *)
        echo "$0: This script is destructive and should only be run as part of the debian-installer process!"
    ;;
esac