#!/usr/bin/env nix-shell
#! nix-shell -i bash
#! nix-shell -p bash nixos-install-tools

set -euo pipefail
SCRIPT_DIR=$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )

# Parse arguments
function help {
    echo "Usage: $0 [-e] [-h] profile"
    echo
    echo "Arguments:"
    echo "  file: OS/disk profile to use"
    echo
    echo "Options:"
    echo "  -h: Display this help message."
    echo "  -e: Erase the disk. This can be used in case the wanted partition scheme doesn't match."
}

disko_mode=mount
while getopts "e" OPTION
do
    case "$OPTION" in
        h)
            help
            exit 0
            ;;
        e)
            disko_mode=disko
            ;;
        ?)
            help
            exit 2
            ;;
    esac
done
shift "$(($OPTIND -1))"

if [ "$#" -ne 1 ]
then
    help
    exit 2
fi
profile="$1"

profile_dir="${SCRIPT_DIR}/${profile}"
if [ ! -d "$profile_dir" ]
then
    echo "Profile not found."
fi

disko_config="${profile_dir}/disko.nix"
if [ ! -f "$disko_config" ]
then
    echo "Disk configuration not found."
fi

nixos_config="${profile_dir}/os.nix"
if [ ! -f "$nixos_config" ]
then
    echo "NixOS configuration not found."
fi

mountpoint="/mnt/nixos"
nix_flakes_cmd="nix --extra-experimental-features nix-command --extra-experimental-features flakes"

set -x

sudo mkdir -p "$mountpoint"

# Add channels to root user, as nixos-install uses those.
# Not great, but fixable with flakes I guess
sudo ./add_channels.sh

# Format or mount disk
sudo $nix_flakes_cmd run github:nix-community/disko -- --root-mountpoint "$mountpoint" --mode "$disko_mode" "$disko_config"

# Generate hardware-config.nix
sudo nixos-generate-config --no-filesystems --root "$mountpoint"
# --no-filesystems because they are imported via disko

# Plug system configuration into this git repo
sudo mkdir -p "${mountpoint}/etc/nixos"
echo "{ ... }: { imports = [ ./hardware-configuration.nix ${nixos_config} ]; }" | sudo tee "${mountpoint}/etc/nixos/configuration.nix" > /dev/null
# Everything there should be covered by (and conflicts with) the repo anyways.

# Install NixOS! Or create a new generation.
sudo nixos-install --no-root-password --root "$mountpoint"

# Install dotfiles. Actually not needed by nixos-install since it doesn't rewrite global paths to the mountpoint.
# Without it no nixos-rebuild from the system itself once installed though.
# Should probably be replaced with something like git-sync
# sudo mkdir -p $mountpoint/home/geoffrey/.config/
# sudo cp -a ../dotfiles $mountpoint/home/geoffrey/.config/
# sudo chown geoffrey:geoffrey $mountpoint/home/geoffrey -R

# Signal the installation is done!
echo