#!/bin/bash
# vim: set ts=4 sw=4 sts=4 et :

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

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

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

errecho() {
    >&2 echo "$@"
}

# example of releasever: '29' or 'rawhide'
if [ "x$releasever" != "x" ]; then
    if [[ ! "$releasever" =~ ^[1-9][0-9]$ ]] && [ "$releasever" != "rawhide" ]; then
        errecho "Invalid release format"
        exit 1
    fi
elif [ "x$releasever" == "x" ]; then
    listver="$(curl -s -L https://dl.fedoraproject.org/pub/fedora/linux/releases 2> /dev/null)"
    releasever="$(echo "$listver" | sed -e 's/<[^>]*>//g' | awk '{print $1}' | grep -o "[1-9][0-9]" | tail -1)"
    if ! [[ "$releasever" =~ ^[1-9][0-9]$ ]]; then
        errecho "An error occurred while trying to determine latest Fedora version"
        exit 1
    fi
fi

# get the latest kernel rpm
latestver=$(dnf -q repoquery kernel-core --disablerepo=* --enablerepo=fedora --enablerepo=updates --releasever="$releasever" | tail -1 | cut -d ':' -f2)
latestrpm="kernel-core-$latestver.rpm"

if [ "$releasever" == 'rawhide' ]; then
    releasever="$(echo "$latestver" | grep -o "fc[1-9][0-9]" | sed 's/fc//')"
fi

if [ "x$latestrpm" != "x" ] && [ "x$releasever" != "x" ]; then
    key="$localdir/keys/RPM-GPG-KEY-fedora-$releasever-primary"

    tmpdir="$(mktemp -d -p "$localdir")"
    # download latest kernel rpm
    dnf -q download kernel-core --disablerepo=* --enablerepo=fedora --enablerepo=updates --releasever="$releasever"
    mv "$latestrpm" "$tmpdir/$latestrpm.untrusted"

    # check signature
    mkdir -p "$tmpdir/rpmdb"
    rpmkeys --dbpath="$tmpdir/rpmdb" --import "$key"
    { rpmkeys --dbpath="$tmpdir/rpmdb" --checksig "$tmpdir/$latestrpm.untrusted" | grep -q 'signatures OK' ; } || { errecho "Failed to check signature"; exit 1; }
    mv "$tmpdir/$latestrpm.untrusted" "$tmpdir/$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 --quiet -i --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
    if [ "$debug" == "1" ]; then
        yes '' | make oldconfig
    else
        yes '' | make oldconfig > /dev/null 2>&1
    fi
    ## remove comments in header
    sed -i '1,4d' "$tmpdir/$kernelsrc/.config"

    # create final config
    cat - "$tmpdir/$kernelsrc/.config" > "$localdir/config-base-$(echo "$latestver" | cut -d '-' -f1)" << EOF
# Base config based on Fedora's config ($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
    errecho "Unable to find the latest kernel rpm for Fedora $releasever"; exit 1
fi