#!/bin/bash

OS_CODENAME=focal
OS_VERSION=20.04
DEV=/dev/sda
# NBD=yes, NBD=
NBD=
# TYPE=maas, TYPE=cloud
TYPE=maas
# DOWNLOAD=yes, DOWNLOAD=
DOWNLOAD=yes
MAAS_ID=

# partition block device
lastchar=${DEV: -1}
BOOTPART="${DEV}1"
ROOTPART="${DEV}2"
if [ "$lastchar" -eq "$lastchar" ] 2>/dev/null; then
	BOOTPART="${DEV}p1"
	ROOTPART="${DEV}p2"
fi

function get_maas_id(){
	if [ -n "$MAAS_ID" ]; then
		return
	fi
	streams=$(mktemp)
	wget -O $streams https://images.maas.io/ephemeral-v3/stable/streams/v1/com.ubuntu.maas:stable:v3:download.json
	MAAS_ID=$(jq -r '.products[]|select(.version=="'"$OS_VERSION"'" and .arch=="amd64" and .kflavor=="generic" and .subarch=="ga-'"$OS_VERSION"'")|.versions|keys|max' \
		        "$streams")
	rm -f $streams
	echo "MAAS_ID=$MAAS_ID"
}

function download(){
	if [ -z "$DOWNLOAD" ]; then
		return
	fi
	echo "Downloading"
	wget -N -P download \
		https://cloud-images.ubuntu.com/$OS_CODENAME/current/unpacked/${OS_CODENAME}-server-cloudimg-amd64-initrd-generic \
		https://cloud-images.ubuntu.com/${OS_CODENAME}/current/unpacked/${OS_CODENAME}-server-cloudimg-amd64-vmlinuz-generic \
		https://cloud-images.ubuntu.com/${OS_CODENAME}/current/${OS_CODENAME}-server-cloudimg-amd64-root.tar.xz \
		https://images.maas.io/ephemeral-v3/stable/${OS_CODENAME}/amd64/${MAAS_ID}/ga-${OS_VERSION}/generic/boot-initrd \
		https://images.maas.io/ephemeral-v3/stable/${OS_CODENAME}/amd64/${MAAS_ID}/ga-${OS_VERSION}/generic/boot-kernel \
		https://images.maas.io/ephemeral-v3/stable/${OS_CODENAME}/amd64/${MAAS_ID}/squashfs


	# CLOUD
	ln -f download/${OS_CODENAME}-server-cloudimg-amd64-vmlinuz-generic cloud-vmlinuz
	ln -f download/${OS_CODENAME}-server-cloudimg-amd64-initrd-generic cloud-initrd.img
	ln -f download/${OS_CODENAME}-server-cloudimg-amd64-root.tar.xz rootfs.tar.xz

	# MAAS
	ln -f download/boot-kernel maas-vmlinuz
	ln -f download/boot-initrd maas-initrd.img
}

sudo apt -yq install syslinux syslinux-common syslinux-efi extlinux f2fs-tools dosfstools jq

mkdir -p build/${TYPE} download mnt out squashmount

get_maas_id
download

KERNEL_VERSION="$(file ${TYPE}-vmlinuz |cut -d, -f2|cut -d\  -f3)"
echo "Detected kernel ${KERNEL_VERSION}"

if [ "$NBD" ]; then
	echo "Creating empty image"
	qemu-img create -f qcow2 build/${TYPE}/ubuntu-${OS_CODENAME}.qcow2 5G || exit 1
	echo "attaching image"
	sudo modprobe nbd
	sudo qemu-nbd -c "${DEV}" build/${TYPE}/ubuntu-${OS_CODENAME}.qcow2 || exit 1
fi

echo "partitioning"
sudo parted -s "${DEV}" -- \
       	mklabel gpt \
       	unit MiB \
       	mkpart '"Boot"' btrfs 1 512MiB \
       	mkpart '"Ubuntu"' btrfs 512MiB 100% \
        set 1 esp on \
       	set 1 legacy_boot on
until [ -b "$BOOTPART" ] && [ -b "$ROOTPART" ]; do
	sleep 1
done


echo "installing hybrid bootloader"
sudo dd bs=440 count=1 conv=notrunc \
	if=/usr/lib/syslinux/mbr/gptmbr.bin of="$DEV" 2> /dev/null
sync

echo "mkfs.btrfs (boot)"
sudo mkfs.btrfs -f -L boot ${BOOTPART} || exit 1

if [ ${TYPE} == "cloud" ]; then
	echo "mkfs.btrfs (root)"
	sudo mkfs.btrfs -f -L rootfs ${ROOTPART} || exit 1
else
	echo "mkfs.f2fs (root)"
	sudo mkfs.f2fs -f -l rootfs -O extra_attr ${ROOTPART} || exit 1
fi
sync

echo "mounting root"
if [ ${TYPE} == "cloud" ]; then
	sudo mount -t btrfs ${ROOTPART} mnt || exit 1
else
	sudo mount -t f2fs ${ROOTPART} mnt || exit 1
fi
echo "mounting boot"
sudo mkdir -p mnt/boot
sudo mount -t btrfs ${BOOTPART} mnt/boot || exit 1

echo "unpacking root fs"
if [ ${TYPE} == "cloud" ]; then
	sudo tar xJf rootfs.tar.xz -C mnt || exit 1
else
	sudo mount -t squashfs download/squashfs squashmount -o ro,loop || exit 1
	sudo cp -ar squashmount/. mnt
	sudo umount squashmount
fi

echo "installing kernel and inintd"
sudo cp -ar ${TYPE}-initrd.img "mnt/boot/initrd.img-${KERNEL_VERSION}"
sudo cp -ar ${TYPE}-vmlinuz "mnt/boot/vmlinuz-${KERNEL_VERSION}"
sudo ln -s "vmlinuz-${KERNEL_VERSION}" mnt/boot/vmlinuz
sudo ln -s "initrd.img-${KERNEL_VERSION}" mnt/boot/initrd.img

echo "installing legacy syslinux files"
sudo mkdir -p mnt/boot/syslinux
sudo cp /usr/lib/syslinux/modules/bios/*.c32 mnt/boot/syslinux/
sudo cp syslinux/{mainmenu,syslinux}.cfg mnt/boot/syslinux
if [ -n "$1" ]; then
    echo "Patching UUID $1"
    sudo sed -i -e "s/?/?uuid=$1\&/g" mnt/boot/syslinux/mainmenu.cfg
    cat mnt/boot/syslinux/mainmenu.cfg
fi

echo "here is the fstab"
if [ ${TYPE} == "cloud" ]; then
	echo "LABEL=rootfs / btrfs defaults 0 1" | sudo tee mnt/etc/fstab
else
	echo "LABEL=rootfs / f2fs defaults 0 1" | sudo tee mnt/etc/fstab
fi
echo "LABEL=boot /boot btrfs defaults 0 1" | sudo tee -a mnt/etc/fstab

echo "installing syslinux bootloader"
sudo extlinux -i mnt/boot/syslinux

echo "umounting"
sync
sudo umount mnt/boot
sudo umount mnt

if [ "$NBD" ]; then
	echo "detaching"
	sudo qemu-nbd -d "${DEV}"
	echo "compressing"
	qemu-img convert -cpO qcow2 build/${TYPE}/ubuntu-${OS_CODENAME}.qcow2 out/ubuntu-${OS_CODENAME}-${TYPE}.qcow2
	# rm -f out/ubuntu-${OS_CODENAME}.qcow2
fi


echo "done"