#!/bin/zsh
# vim: set ft=sh sw=4 ts=4 sts=4 et :

set -eu

function copy_firmware() {
    local dev="$1"
    local efi_part
    local mountpoint=/run/media/coreos-efi

    if [ ! -d RPi4boot ]; then
        download_firmware
    fi

    printf 'Waiting for device to settle ...' >&2
    until [ -n "${efi_part-}" ]; do
        printf '.'
        efi_part=$(
            lsblk -o LABEL,PATH "${dev}" \
            | awk '$1=="EFI-SYSTEM"{print $2}'
        )
        sleep 0.25
    done
    printf '\n'

    mkdir -p "${mountpoint}"
    mount "${efi_part}" "${mountpoint}"
    rsync -rtiOh --ignore-existing RPi4boot/boot/efi/ "${mountpoint}"
    sync; sync; sync
    umount "${mountpoint}"
    rmdir "${mountpoint}"
}

function download_firmware() {
    local rpm

    echo 'Downloading Raspberry Pi Firmware blobs ...'
    mkdir RPi4boot
    podman run --rm -it \
        -v $(PWD)/RPi4boot:/RPi4boot:rw,z \
        registry.fedoraproject.org/fedora:38 \
        dnf install -y \
            --downloadonly \
            --forcearch=aarch64 \
            --destdir=/RPi4boot \
            uboot-images-armv8 \
            bcm283x-firmware \
            bcm283x-overlays
            --
    for rpm in RPi4boot/*.rpm; do
        rpm2cpio "${rpm}" | cpio -idv -D RPi4boot/
    done

    cp RPi4boot/usr/share/uboot/rpi_3/u-boot.bin RPi4boot/boot/efi/rpi3-u-boot.bin
    cp RPi4boot/usr/share/uboot/rpi_4/u-boot.bin RPi4boot/boot/efi/rpi4-u-boot.bin
    cp RPi4boot/usr/share/uboot/rpi_arm64/u-boot.bin RPi4boot/boot/efi/rpi-u-boot.bin
}

function hybridize_gpt() {
    local dev="$1"

    echo 'Creating Hybrid MBR partition table ...'
    sgdisk -h 2:EE "${dev}"
    echo type=0c,bootable | sfdisk -Y mbr -N 1 "${dev}"
}

function install_coreos() {
    local ignition="$1"
    local dev="$2"
    local url="$3"

    if [ -z "${url}" ]; then
        set -- -a aarch64 -s stable
    else
        set -- --image-url "${url}"
    fi

    coreos-installer install "$@" \
        -i "${ignition}" \
        --console ttyS0,115200n8 \
        "${dev}"
    sync; sync; sync
}

function parse_args() {
    pi=4
    image_url=
    while [ $# -gt 0 ]; do
        case "$1" in
        --pi)
            shift
            pi=${1}
            ;;
        --pi=*)
            pi=${1#--pi=}
            ;;
        --image-url)
            shift
            image_url=${1}
            ;;
        --image-url=*)
            image_url=${1#--image-url=}
            ;;
        *)
            if [ -z "${ignition-}" ]; then
                ignition="${1}"
            elif [ -z "${dev-}" ]; then
                dev="${1}"
            else
                usage >&2
                exit 2
            fi
            ;;
        esac
        shift
    done

    if [ -z "${ignition-}" ]; then
        usage >&2
        exit 2
    fi
    if [ -z "${dev-}" ]; then
        dev=/dev/disk/by-id/usb-Generic_STORAGE_DEVICE_000000001206-0:0
    fi
}

function usage() {
    printf 'usage: %s [--pi PI] ignition [device]\n' "${0##*/}"
}

parse_args "$@"

case "${pi}" in
0*|1)
    printf 'Raspberry Pi model %s is not supported\n' "${pi}" >&2
    exit 1
    ;;
esac

if [ $(id -u) -ne 0 ]; then
    exec sudo "$0" "$@"
fi

install_coreos "${ignition}" "${dev}" "${image_url}"

case "${pi}" in
2|3)
    hybridize_gpt "${dev}"
    ;;
esac

copy_firmware "${dev}"