#!/bin/bash

TARGET_HOST="pallas"

SNAPSHOT_NAME="meran"
ZFS_SNAPSHOT_NAME="zpool1/ROOT/arch@$SNAPSHOT_NAME"
ZFS_SNAPSHOT_DIR="/.zfs/snapshot/$SNAPSHOT_NAME"

on_exit()
{
	sudo zfs destroy "$ZFS_SNAPSHOT_NAME" || true
	sudo umount /boot/efi || true
	kill $SUDO_REFRESH_PID 2>/dev/null
}

ping_host()
{
    TEST=$(dig @127.0.0.1 $TARGET_HOST +short)
    if [ -z "$TEST" ]; then
        echo "Error: Host $TARGET_HOST not found, bailing out." >&2
        exit 1
    fi
}

run_backup()
{
	if [ -z "$DT" ]; then
		echo "Error: No sequence number set." >&2
		exit 1
	fi

    time sudo ionice -c3 nice -n19 chrt -i 0 \
    tar \
		--use-compress-program="/usr/bin/zstd -T0 -6" \
        --warning=no-file-ignored \
        --preserve-permissions \
        --one-file-system \
        --numeric-owner \
        --sort=name \
        --xattrs \
        --xattrs-include='*' \
        --totals \
        --create \
        --sparse \
        --acls \
        --file - \
        --directory=/boot efi \
        --directory="$ZFS_SNAPSHOT_DIR/.." "$SNAPSHOT_NAME" | \
    ssh \
        -c aes128-ctr \
        -o Compression=no \
        root@"$TARGET_HOST" \
        "dd bs=16M status=progress of=/mnt/nvme/meran-$DT.tar.zst"
}

lucky_digit()
{
	DOJ=$(date +%j)
	DOJ2=$((10#$DOJ))
	DT=$(( DOJ2 % 5 ))
	echo "Lucky Digit: $DT"
}

prepare()
{
	sudo true || exit 1

	while :; do sudo -v ; sleep 60 ; done &
	SUDO_REFRESH_PID=$!
	trap on_exit TERM EXIT

	if ! mountpoint -q /boot/efi; then
		echo "Mounting /boot/efi"
		sudo mount /boot/efi
	fi

	sudo zfs destroy "$ZFS_SNAPSHOT_NAME" 2>/dev/null || true
	sudo zfs snapshot "$ZFS_SNAPSHOT_NAME" || exit 1

	for i in $(seq 1 300); do
		if [ -d "$ZFS_SNAPSHOT_DIR" ]; then
			break
		fi
		if [ $i = 300 ]; then
			echo "Error: Timeout creating snapshot $ZFS_SNAPSHOT_NAME." >&2
			exit 1
		fi
		sleep 0.1
	done
}

#
# Main
#
lucky_digit
ping_host
prepare
run_backup
beep -f 2637 -l 50