#!/usr/bin/env dash

# nixos-config - My current NixOS configuration
#
# Copyright (C) 2025 Benedikt Peetz <benedikt.peetz@b-peetz.de>
# SPDX-License-Identifier: GPL-3.0-or-later
#
# This file is part of my nixos-config.
#
# You should have received a copy of the License along with this program.
# If not, see <https://www.gnu.org/licenses/gpl-3.0.txt>.

# FIXME(@bpeetz): Ideally I could replace this script with a deployment tool. Thus we
# would have the same tool on the server as I use in my config. <2025-04-14>

# Shell library {{{
die() {
    error "$1"
    if [ -n "$2" ]; then
        exit "$2"
    else
        exit 1
    fi
}
print() {
    # shellcheck disable=SC2059
    printf "$*"
}
println() {
    # shellcheck disable=SC2059
    printf "$*\n"
}
eprint() {
    >&2 print "$@"
}
eprintln() {
    >&2 println "$@"
}
if [ "${NO_COLOR-unset}" != "unset" ]; then
    error() {
        eprintln "==> ERROR:" "$*"
    }
    warning() {
        eprintln "==> WARNING:" "$*"
    }
    debug() {
        [ -n "$SHELL_LIBRARY_DEBUG" ] && eprintln "==> [Debug:]" "$*"
    }
    debug2() {
        [ -n "$SHELL_LIBRARY_DEBUG" ] && eprintln " -> [Debug:]" "$*"
    }
    msg() {
        eprintln "==>" "$*"
    }
    msg2() {
        eprintln " ->" "$*"
    }
    prompt() {
        eprint "..>" "$*"
    }
else
    error() {
        eprintln "\033[1;91m==> ERROR:\033[0m" "\033[1;93m$*\033[0m"
    }
    warning() {
        eprintln "\033[1;91m==> WARNING:\033[0m" "\033[1;93m$*\033[0m"
    }
    debug() {
        [ -n "$SHELL_LIBRARY_DEBUG" ] && eprintln "\033[1;94m==> [Debug:]\033[0m" "\033[1;93m$*\033[0m"
    }
    debug2() {
        [ -n "$SHELL_LIBRARY_DEBUG" ] && eprintln "\033[1;94m -> [Debug:]\033[0m" "\033[1;93m$*\033[0m"
    }
    msg() {
        eprintln "\033[1;96m==>\033[0m" "\033[1;93m$*\033[0m"
    }
    msg2() {
        eprintln "\033[1;96m ->\033[0m" "\033[1;93m$*\033[0m"
    }
    prompt() {
        eprint "\033[1;96m..>\033[0m" "\033[1;93m$*\033[0m"
    }
fi
# }}}

NAME="update-sys"
help() {
    cat <<EOF
This is a NixOS System flake update manager.

USAGE:
    $NAME [--branch <branchname>] [--help]

OPTIONS:
    --branch | -b  BRANCHNAME
                                select a branch to update from.

    --mode   | -m  MODE
                                select a mode to update with

    --help   | -h
                                output this help.
ARGUMENTS:
    BRANCHNAME := [[ git branch --list --format '%(refname:short)' ]]
                                The name of the branch to deploy the config from

    MODE := switch|boot|test|build|dry-build|dry-activate|edit|repl|build-vm|build-vm-with-bootloader
                                See the 'nixos-rebuild' manpage for more information about these modes.
EOF
    exit "$1"
}
BRANCH=""

while [ "$#" -gt 0 ]; do
    case "$1" in
    "--help" | "-h")
        help 0
        ;;
    "--branch" | "-b")
        if [ "${2-unset}" != "unset" ]; then
            BRANCH="$2"
        else
            error "$1 requires an argument"
            help 1
        fi
        shift 2
        ;;
    "--mode" | "-m")
        if [ "${2-unset}" != "unset" ]; then
            MODE="$2"
        else
            error "$1 requires an argument"
            help 1
        fi
        shift 2
        ;;
    *)
        error "the option $1 does not exist!"
        help 1
        ;;
    esac
done

cd /etc/nixos || die "No /etc/nixos"
msg "Starting system update..."
git remote update origin --prune >/dev/null 2>&1
if ! [ "$BRANCH" = "" ]; then
    git switch "$BRANCH" >/dev/null 2>&1 && msg2 "Switched to branch '$BRANCH'"
fi
msg2 "Updating git repository..."
git pull --rebase

# We use a tempfile, to make this truly async.
default_branch=$(mktemp)
cleanup() {
    rm "$default_branch"
}
trap cleanup EXIT

git remote show origin | grep 'HEAD' | cut -d':' -f2 | sed -e 's/^ *//g' -e 's/ *$//g' >"$default_branch" &

msg2 "Updating system..."
nixos-rebuild "${MODE-switch}"

git switch "$(cat "$default_branch")" >/dev/null 2>&1 && msg2 "Switched to branch '$(cat "$default_branch")'"
msg "Finished Update!"

# vim: ft=sh