#!/usr/bin/env bash
set -e

# scp root@servi.home.sjau.ch:/root/nix-tests/kexec/result/tarball/nixos-system-x86_64-linux.tar.xz /
# apt-get install xz-utils
# cd /
# tar xf nixos-system-x86_64-linux.tar.xz

getDevice() {
    read -r -e -p "Enter the path to the file: " -i "/dev/sda" rootDev
}

getBootSize() {
    read -r -e -p "Enter the size of the boot partition (in MB): " -i "2000" bootSize
    bootSectors=$((bootSize * 2048))
}

getPoolName() {
    read -r -e -p "Enter the Poolname for ZFS: " -i "tankOnline" zfsPool
}

doInstall() {
    # Turn off LVM
    vgchange -a n
    # Remove partition info
    dd if="/dev/zero" of="${rootDev}" bs=512 count=10000
    # Do the partitioning
    sfdisk -f "${rootDev}" << EOF
        label: dos
        device: ${rootDev}
        unit: sectors

        ${rootDev}1 : start=2048, size=${bootSectors}, type=83, bootable
        ${rootDev}2 : type=83
EOF
    # Create Filesystems
    mkfs.ext4 "${rootDev}1" -L "NIXOS_BOOT"
    zpool create -f -o ashift=12 -o altroot="/mnt" -O mountpoint=none -O compression=lz4 -O atime=off -O xattr=sa -O acltype=posixacl -O normalization=formD -O relatime=on "${zfsPool}" "${rootDev}2"
    zfs create -o mountpoint=legacy -o encryption=aes-256-gcm -o keyformat=passphrase "${zfsPool}/encZFS"
    zfs create "${zfsPool}/encZFS/Nixos"
    # Mount root to /mnt
    mkdir -p "/mnt"
    mount -t zfs "${zfsPool}/encZFS/Nixos" "/mnt"
    # Create more folders
    mkdir -p "/root/.nixos"
    mkdir -p "/mnt/boot"
    mkdir -p "/mnt/root/.nixos"
    chmod 0700 "/mnt/root"
    mount -t ext4 "/dev/sda1" "/mnt/boot"
    # Generate default nixos configs
    nixos-generate-config --root "/mnt/"
    # Replace generation configuration.nix with default custom one
    curl -o "/mnt/etc/nixos/configuration.nix" "https://raw.githubusercontent.com/sjau/nix-expressions/master/customIsoFiles/online_net_minimal_enczfs_configuration.nix" || ( printf "%s\n" "Couldn't scp the configuration.nix. Quitting."; exit 1)
    # Also get .tmux.conf file
    scp root@servi.home.sjau.ch:/root/.tmux.conf "/mnt/root/.tmux.conf" || ( printf "%s\n" "Couldn't scp the .tmux.conf. Quitting."; exit 1)
    # Change to unstable small channel due to zfs
    nix-channel --add https://nixos.org/channels/nixos-unstable-small nixos
    nix-channel --update
    # Get Dropbear ECDSA
    nix-shell -p dropbear --command "dropbearkey -t ecdsa -f /tmp/initrd-ssh-key"
    cp "/tmp/initrd-ssh-key" "/mnt/root/.nixos/"
    cp "/tmp/initrd-ssh-key" "/root/.nixos/"
    # Run Nixos Installer
    nixos-install
}

getDevice
getBootSize
getPoolName

doInstall

printf '%s\n\n' "Minimal installation done - you can reboot now into the new system."
printf '%s\n\n' "Since it's encrypted, don't forget ssh -p2222 root@IP for unlocking."