#!/bin/bash

set -e
if [ "${VERBOSE:-0}" -ge 2 ] || [ "${DEBUG:-0}" -eq 1 ]; then
    set -x
fi

localdir="$(dirname "$(readlink -f "$0")")"
releasever="$1"

kernelver="$(cat "$localdir/version")"
kernelsrc="linux-$kernelver"

[[ "x$releasever" == "x" ]] && { echo "Please provide Fedora release version as first argument, e.g. '29'."; exit 1; }

# baseurl for latest kernel rpm
url="https://dl.fedoraproject.org/pub/fedora/linux/updates/$releasever/Everything/x86_64/Packages/k"

# get the latest kernel rpm
content="$(curl "$url/")"
latestrpm="$(echo "$content" | sed -e 's/<[^>]*>//g' | awk '{print $1}' | grep -E "kernel-core-[0-9]+.[0-9]+.[0-9]+-[0-9]+.fc29.x86_64.rpm")"
latestver="$(echo "$latestrpm" | sed 's/kernel-core-//; s/\.rpm//')"

if [ "x$latestrpm" != "x" ]; then
    tmpdir=$(mktemp -d)
    # download latest kernel rpm
    wget -q -O "$tmpdir/$latestrpm" "$url/$latestrpm"

    # extract kernel sources in qubes-linux-kernel
    tar xf "$localdir/$kernelsrc.tar.xz" -C "$tmpdir"

    # get latest config and put it in extracted sources
    rpm2cpio "$tmpdir/$latestrpm" | cpio -iv --to-stdout "./lib/modules/$latestver/config" > "$tmpdir/$kernelsrc/.config"

    # generate new config with: yes '' | make oldconfig
    cd "$tmpdir/$kernelsrc/"
    ## drop config settings which depend on Fedora patches and adjust for the small version difference
    yes '' | make oldconfig
    ## remove comments in header
    sed -i '1,4d' "$tmpdir/$kernelsrc/.config"

    # create final config
cat - "$tmpdir/$kernelsrc/.config" > "$localdir/config-base-$latestver" << EOF
# Base config based on Fedora's config ($latestrpm)
# Only modification is \`yes '' | make oldconfig\` to drop config settings which
# depend on Fedora patches and adjust for the small version difference.
EOF
    rm -rf "$tmpdir"
else
    echo "Unable to find the latest kernel rpm for Fedora $releasever"; exit 1
fi