#!/bin/bash

set -e
#set -x

CWD=$(pwd)
PRGNAM=$(basename "$CWD")
BUILD=${BUILD:-20}
BRANCH=${BRANCH:-stable}        # stable ; mainline
ARCH=$(uname -m)

TAG=gwh
TMP=/tmp/$TAG
PKG=$TMP/pkg-$PRGNAM
OUTPUT=/tmp

NUMJOBS=${NUMJOBS:-$(nproc)}

CONFIG=${CONFIG:-""}

REPOSITORY=${REPOSITORY:-/home/installs/SlackBuilds/_repositories/$PRGNAM}

VERSION=${VERSION:-$(curl https://www.kernel.org/feeds/kdist.xml | grep -o "[0-9.rc-]*: $BRANCH" | head -n1 | cut -d: -f1)}

mkdir -p "$REPOSITORY"

rm -fr "$PKG"

mkdir -p "$PKG/usr/src/"
if [ "$BRANCH" == "stable" ]; then
    SRC_URL="https://cdn.kernel.org/pub/linux/kernel/v$(echo "$VERSION" | cut -d. -f1).x"
else
    SRC_URL="https://git.kernel.org/torvalds/t"
fi

[ ! -e "$REPOSITORY"/linux-"$VERSION".tar.gz ] && wget -c "$SRC_URL/linux-$VERSION.tar.gz" -O "$REPOSITORY/linux-$VERSION.tar.gz"
tar xf "$REPOSITORY/linux-$VERSION.tar.gz" -C "$PKG/usr/src/"

cd "$PKG/usr/src/" || exit 1
mv "linux-$VERSION" "linux-gwh"
cd "linux-gwh" || exit 1

if [ -n "$CONFIG" ] && [ -e "$CONFIG" ]; then
    cat "$CONFIG" > .config
fi
if [ ! -f .config ]; then
    zcat /proc/config.gz > .config
fi

make oldconfig "$@"

make -j"$NUMJOBS"
make modules -j"$NUMJOBS"
make modules_install INSTALL_MOD_PATH="$PKG"

if [ -z "${HEADERS_ARCH}" ]; then
    case "$(uname -m)" in
    i?86) HEADERS_ARCH=x86 ;;
    x86_64) HEADERS_ARCH=x86 ;;
    aarch64) HEADERS_ARCH=arm64 ;;
    # Use uname -m for all other archs:
    *) HEADERS_ARCH=$(uname -m) ;;
  esac
fi

# Generate the kernel headers and clean them up:
( echo "Generating headers from the Linux kernel source tree in ${KERNEL_SOURCE}:"
  make headers_install ARCH="${HEADERS_ARCH}" INSTALL_HDR_PATH="$PKG/usr"
  cd "$PKG/usr/include" || exit 1
  # You won't want these files. The ones in libdrm work better.
  rm -rf drm
  # This next part seems pretty much cosmetic, but since we've been doing this
  # for a long time (and others also do), we'll stick with it:
  mv asm "asm-${HEADERS_ARCH}"
  ln -sf "asm-${HEADERS_ARCH}" asm
  # Remove unneeded dotfiles:
  find . -name ".??*" -exec rm -f {} \+
)

VERSION=$(basename "$(find "$PKG/lib/modules/" -type d -maxdepth 1 -mindepth 1 | head -n1)")

cd ..
mv "$PKG/usr/src/linux-gwh" "$PKG/usr/src/linux-${VERSION}"
cd "$PKG/usr/src/linux-${VERSION}" || exit 1

# Fix build and source symlinks if they are pointing into $TMP:
( cd "$PKG"/lib/modules/"${VERSION}"
  target=$(readlink build)
  if echo "$target" | grep -q "^$PKG/" ; then
      rm -f build
      ln -sf "/usr/src/linux-${VERSION}" build
  fi
)

mkdir -p "$PKG/boot/"
cp System.map "$PKG/boot/System.map-$VERSION"
cp .config "$PKG/boot/config-$VERSION"
cp "arch/${ARCH}/boot/bzImage" "$PKG/boot/vmlinuz-$VERSION"

make clean

mkdir -p "$PKG/install"
cat <<EOF > "$PKG/install/doinst.sh"
echo -n "updating grub... "
grub-install --target=x86_64-efi --efi-directory=/boot/efi --bootloader-id=grub
echo OK

echo -n "building initrd… "
cd /
UCODE=""
[ -e /boot/intel-ucode.cpio ] && UCODE="-P /boot/intel-ucode.cpio"
eval "\$(/usr/share/mkinitrd/mkinitrd_command_generator.sh -k $VERSION -r | sed "s|/boot/initrd.gz|/boot/initrd-${VERSION}.gz|") \${UCODE}"
echo "OK"

grub-mkconfig -o /boot/grub/grub.cfg
EOF

cat <<EOF > "$PKG/install/slack-desc"
$PRGNAM: $PRGNAM (kernel)
$PRGNAM:
$PRGNAM: Linux is a clone of the operating system Unix, written from scratch by
$PRGNAM: Linus Torvalds with assistance from a loosely-knit team of hackers
$PRGNAM: across the Net. It aims towards POSIX and Single UNIX Specification
$PRGNAM: compliance.
$PRGNAM:
$PRGNAM: It has all the features you would expect in a modern fully-fledged Unix
$PRGNAM:
$PRGNAM: http://www.kernel.org
$PRGNAM:
EOF

cd "$PKG" || exit 1
rm -f "$PKG/{,usr/}lib$(uname -m | grep -o 64)/*.la"
/sbin/makepkg --linkadd y --prepend --chown n "$OUTPUT/$PRGNAM-$(echo "$VERSION" | tr - _)-$ARCH-$BUILD$TAG.txz"