#!/bin/bash

# Copyright (c) 2015 The CoreOS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

SCRIPT_ROOT=$(dirname "$(readlink -f "$0")")
. "${SCRIPT_ROOT}/common.sh" || exit 1

# Script must run inside the chroot
restart_in_chroot_if_needed "$@"

assert_not_root_user

# Flags
DEFINE_string board "${DEFAULT_BOARD}" \
  "Board to use for kernel source and architecture."
DEFINE_string overlay "coreos" \
  "Portage repo containing the kernel ebuild."
DEFINE_string package "sys-kernel/coreos-modules" \
  "Portage ebuild name for the kernel."

# Parse command line
FLAGS "$@" || exit 1
eval set -- "${FLAGS_ARGV}"

# Die on any errors.
switch_to_strict_mode

if [[ -z "${FLAGS_board}" ]] ; then
  die_notrace "--board is required."
fi

. "${BUILD_LIBRARY_DIR}/toolchain_util.sh"
. "${BUILD_LIBRARY_DIR}/board_options.sh"

KERNEL_ARCH=$(get_kernel_arch "${CHOST}")
KERNEL_CLFAGS="-nopie -fstack-check=no"
KERNEL_SRC="${BOARD_ROOT}/usr/src/linux"
if [[ ! -f "${KERNEL_SRC}/Makefile" ]]; then
  die_notrace "No kernel source found at ${KERNEL_SRC}"
fi

KERNEL_BUILD=$(mktemp -d)
trap "rm -rf '${KERNEL_BUILD}'" EXIT

# Set up a ccache friendly build tree
mkdir -p "${KERNEL_BUILD}/build"
ln -s "${KERNEL_SRC}"/* "${KERNEL_BUILD}"

if [[ -d /usr/lib/ccache/bin ]]; then
  export PATH="/usr/lib/ccache/bin:${PATH}"
  export CCACHE_BASEDIR="${KERNEL_BUILD}"
fi

kmake() {
  make -C "${KERNEL_BUILD}" \
    ARCH="${KERNEL_ARCH}" \
    CROSS_COMPILE="${CHOST}-" \
    KBUILD_OUTPUT="build" \
    KCFLAGS="${KERNEL_CFLAGS}" \
    LDFLAGS="" \
    "$@"
}

kmake_var() {
  echo -e "e:\\n\\t@echo \$(${1})\\ninclude Makefile" | kmake -s -f -
}

KERNEL_MAJOR=$(kmake_var VERSION)
KERNEL_MINOR=$(kmake_var PATCHLEVEL)

OVERLAY=$(portageq get_repo_path / "${FLAGS_overlay}")
FILESDIR="${OVERLAY}/${FLAGS_package}/files"
DEFCONFIG_NAME="${ARCH}_defconfig-${KERNEL_MAJOR}.${KERNEL_MINOR}"
DEFCONFIG_PATH="${FILESDIR}/${DEFCONFIG_NAME}"
COMMONCONFIG_NAME="commonconfig-${KERNEL_MAJOR}.${KERNEL_MINOR}"
COMMONCONFIG_PATH="${FILESDIR}/${COMMONCONFIG_NAME}"

cat "${DEFCONFIG_PATH}" "${COMMONCONFIG_PATH}" > "${KERNEL_BUILD}/build/.config"
kmake olddefconfig
cp "${KERNEL_BUILD}/build/.config" "${KERNEL_BUILD}/build/.config.bak"
kmake menuconfig
kmake savedefconfig
diff -u "${KERNEL_BUILD}/build/.config.bak" "${KERNEL_BUILD}/build/.config" || true