#!/usr/bin/bash
set -Eeuo pipefail
PATH=/usr/sbin:/usr/bin
export PATH

readonly PROGRAM=${0##*/}
readonly CONFIG=/etc/nabu/kernel.conf
readonly -a FAMILIES=(kernel mainline mainline-unstable)

selector_for() {
    case ${1:-} in
        kernel|stable|lts) printf '%s\n' senemos-nabu-kernel ;;
        mainline|alpha|mainline-alpha) printf '%s\n' senemos-nabu-kernel-mainline ;;
        mainline-unstable|unstable) printf '%s\n' senemos-nabu-kernel-mainline-unstable ;;
        *) return 2 ;;
    esac
}

preferred_family() {
    local value=mainline
    if [[ -r $CONFIG ]]; then
        value=$(sed -nE 's/^preferred=([^[:space:]]+)$/\1/p' "$CONFIG" | tail -n1)
    fi
    case ${value:-mainline} in
        kernel|stable|lts) printf '%s\n' kernel ;;
        mainline|alpha|mainline-alpha) printf '%s\n' mainline ;;
        mainline-unstable|unstable) printf '%s\n' mainline-unstable ;;
        *) printf '%s\n' mainline ;;
    esac
}

installed_families() {
    local family selector
    for family in "${FAMILIES[@]}"; do
        selector=$(selector_for "$family")
        rpm -q "$selector" >/dev/null 2>&1 && printf '%s\n' "$family"
    done
}

available_family() {
    local selector available
    selector=$(selector_for "$1") || return 2
    available=$(dnf5 -q repoquery --available --queryformat '%{name}' "$selector" 2>/dev/null || :)
    [[ $available == *"$selector"* ]]
}

usage() {
    cat <<'EOF'
Usage:
  nabu kernel status
  nabu kernel list
  nabu kernel use kernel|mainline|mainline-unstable
  nabu kernel add kernel|mainline|mainline-unstable
  nabu branch [status|list|kernel|mainline|unstable]

At least one Nabu kernel family is always required by nabu-core-meta. "use"
installs a family and makes it the preferred UKI target; "add" installs an
additional development family. Each family upgrades in place. Neither command
reboots the device.
EOF
}

show_status() {
    local -a installed=()
    mapfile -t installed < <(installed_families)
    printf 'Running kernel: %s\n' "$(uname -r)"
    printf 'Preferred kernel family: %s\n' "$(preferred_family)"
    printf 'Installed kernel families: %s\n' "${installed[*]:-none}"
    [[ ${#installed[@]} -ge 1 ]]
}

list_families() {
    local family state preferred
    preferred=$(preferred_family)
    for family in "${FAMILIES[@]}"; do
        state=unavailable
        available_family "$family" && state=available
        rpm -q "$(selector_for "$family")" >/dev/null 2>&1 && state=installed
        [[ $family == "$preferred" ]] && state="$state,preferred"
        printf '%-9s %s\n' "$family" "$state"
    done
}

install_family() {
    local mode=$1 family=$2 selector temporary
    case $family in
        stable|lts) family=kernel ;;
        alpha|mainline-alpha) family=mainline ;;
        unstable) family=mainline-unstable ;;
    esac
    selector=$(selector_for "$family") || {
        printf '%s: unknown kernel family: %s\n' "$PROGRAM" "$family" >&2
        return 2
    }
    available_family "$family" || {
        printf '%s: kernel family is unavailable for this Fedora release: %s\n' "$PROGRAM" "$family" >&2
        return 3
    }

    /usr/bin/sudo -v
    /usr/bin/sudo /usr/bin/flock /run/nabu-package-management.lock \
        /usr/bin/dnf5 -y install "$selector"

    if [[ $mode == use ]]; then
        temporary=$(mktemp)
        trap 'rm -f -- "${temporary:-}"' RETURN
        printf 'preferred=%s\n' "$family" >"$temporary"
        /usr/bin/sudo /usr/bin/install -Dm0644 "$temporary" "$CONFIG"
    fi

    rpm -q "$selector" >/dev/null
    /usr/bin/sudo /usr/libexec/nabu-kernel-maintenance
    printf '%s kernel family installed%s. Reboot was not requested.\n' \
        "$family" "$([[ $mode == use ]] && printf ' and preferred' || :)"
}

main() {
    local command=${1:-help} action=${2:-status} family=${3:-}
    case $command in
        kernel)
            case $action in
                status) show_status ;;
                list) list_families ;;
                use|add) [[ -n $family ]] || { usage >&2; return 2; }; install_family "$action" "$family" ;;
                help|-h|--help) usage ;;
                *) usage >&2; return 2 ;;
            esac
            ;;
        branch|brunch|brucnh)
            case $action in
                status) show_status ;;
                list) list_families ;;
                kernel|stable|lts|alpha|mainline-alpha|unstable|mainline|mainline-unstable) install_family use "$action" ;;
                help|-h|--help) usage ;;
                *) usage >&2; return 2 ;;
            esac
            ;;
        help|-h|--help|'') usage ;;
        *) usage >&2; return 2 ;;
    esac
}

if [[ ${BASH_SOURCE[0]} == "$0" ]]; then
    main "$@"
fi