#!/bin/bash

copy_binary() {
    BINARY="$1"
    PREFIX="$2"
    ldd "${BINARY}" | awk '{print $3}' | grep '^/' | \
	while read lib; do
	    if [ -f "${lib}" ]; then
		mkdir -p $(dirname "${PREFIX}/${lib}")
		cp --archive "${lib}" "${PREFIX}/${lib}"
		cp --archive $(readlink -f "${lib}") $(dirname "${PREFIX}/${lib}")/
	    fi
	done

    cp --archive "${BINARY}" "${PREFIX}${BINARY}"
}

INITROOT="./initroot"

mkdir -p ${INITROOT}

mkdir -p ${INITROOT}/{dev,etc,mnt/root,proc,root,sys,run,usr/share,usr/bin,usr/lib,usr/libexec,usr/lib/modules}

cd ${INITROOT}
ln -s usr/bin bin
ln -s usr/bin sbin

cd usr
ln -s bin sbin
ln -s lib lib64
cd ..

ln -s usr/lib lib
ln -s usr/lib lib64
cd ..

cp --archive /dev/{null,console,tty,nvme0n1,nvme0n1p2,zfs} ${INITROOT}/dev/

cp --archive /lib64/ld-linux-x86* ${INITROOT}/usr/lib/

copy_binary /usr/bin/zfs ${INITROOT}
copy_binary /usr/bin/mount.zfs ${INITROOT}
copy_binary /usr/bin/zpool ${INITROOT}

cp --archive /usr/bin/busybox ${INITROOT}/bin/busybox

cp --archive /usr/libexec/zfs ${INITROOT}/usr/libexec/zfs
cp --archive /usr/share/zfs ${INITROOT}/usr/share/zfs

cp --archive /usr/lib/modules/$(uname -r) ${INITROOT}/usr/lib/modules/

pushd ${INITROOT}/usr/lib/modules/$(uname -r)/kernel
rm -r drivers/gpu
rm -r drivers/firewire
rm -r drivers/gpio
rm -r drivers/leds
rm -r drivers/media
rm -r drivers/net
rm -r drivers/vfio
rm -r drivers/virtio
rm -r drivers/virt
rm -r drivers/soundwire
rm -r drivers/firmware
rm -r drivers/i2c
rm -r drivers/iommu
rm -r drivers/misc
rm -r drivers/powercap
rm -r drivers/pwm
rm -r drivers/scsi
rm -r drivers/usb
rm -r drivers/hid
rm -r drivers/extcon
rm -r drivers/mux
rm -r drivers/thermal
rm -r drivers/vdpa
rm -r drivers/dma
rm -r lib/test*
rm -r net
rm -r sound
rm -r fs
rm -r mm
popd

cp --archive ./extras/* ${INITROOT}/

cd ${INITROOT}

cat > init <<EOF
#!/bin/busybox sh

rescue_shell() {
	echo "Oopsies something broke :("
	exec sh
}

mount -t proc none /proc
mount -t sysfs none /sys

modprobe zfs

zpool import -N -d /dev/nvme0n1p2 soil || rescue_shell

zfs load-key soil || rescue_shell

mount.zfs -o zfsutil soil/ROOT/gentoo /mnt/root || rescue_shell

umount /proc
umount /sys

exec switch_root /mnt/root /sbin/init
EOF

chmod +x init

find . -print0 | cpio --null --create --verbose --format=newc | gzip --best > ../initramfs-$(uname -r).img