#!/bin/bash
# Customized kernel from system: fetch Distro's kernel sources, patch configuration, recompile

# This overrides get_kernel_version from kernel.inc, so the variables will be set properly
get_kernel_version() {
	# Do not use MODULE_DIR here as this function might run when we process another module!
	[ -n "${TARGET_KERNEL_LONG}" ] && return 0
	[ ! -e "${ROOT_DIR}/tmp/work/kernel/ksrc/include/generated/utsrelease.h" ] && pinfo "No UTS information" && return 0
	# determine kernel version that will be running in the generated system

	# declare kernel version stuff
	declare -rg TARGET_KERNEL_LONG=$(grep 'UTS_RELEASE' "${ROOT_DIR}/tmp/work/kernel/ksrc/include/generated/utsrelease.h" | awk -F '"' '{print $2}')
	declare -rg TARGET_KERNEL_SHORT=$(echo "$TARGET_KERNEL_LONG" | grep -o -E '^[0-9\.]+')

	# declare path to kernel headers and modules/firmware
	declare -rg KERNEL_HEADERS_DIR="${ROOT_DIR}/tmp/work/kernel/ksrc"
	declare -rg KERNEL_BASE_DIR="${ROOT_DIR}/tmp/work/kernel/build"

	# print debug info
	pinfo  "TARGET_KERNEL_LONG:  '$TARGET_KERNEL_LONG'"
	pinfo  "TARGET_KERNEL_SHORT: '$TARGET_KERNEL_SHORT'"
	pdebug "KERNEL_BASE_DIR:     '$KERNEL_BASE_DIR'"
	pdebug "KERNEL_HEADERS_DIR:  '$KERNEL_HEADERS_DIR'"
}

fetch_source() {
	# Fetch all the firmware
	if ! [ -s "./fw/Makefile" ]; then
		rm -rf -- "./fw"
		git clone --depth 1 "https://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git" "./fw" \
			|| perror "Could not clone linux-firmware repo."
		rm -rf -- ./fw/LICENSE.* ./fw/*.txt
	fi
	if ! [ -s "./sof/install.sh" ]; then
		rm -rf -- "./sof"
		git clone --depth 1 "https://github.com/thesofproject/sof-bin.git" "./sof" \
			|| perror "Could not clone SOF"
	fi

	# Kernel - cached or freshly fetched
	if nfs_cache_avail; then
		local id tar
		id="$( kernel_build_id )"
		pinfo "Build id is $id"
		tar="${NFS_CACHE_DIR}/cache/${id}.tar.zstd"
		if [ -s "$tar" ]; then
			pinfo "Extracting cached kernel build"
			if < "$tar" zstd -d -T0 | tar -C "${MODULE_WORK_DIR}" -x; then
				touch "$tar" # We use last modified as last used, as atime is unreliable
				return 0
			fi
			pwarning "Extracting cached kernel failed, building..."
		fi
	fi
	fetch_kernel_source
}

fetch_kernel_source() {
	pdebug "getting kernel sources via git ...."
	if grep -q -- "${REQUIRED_GIT}" "./ksrc/.git/config" && grep -q -- "v${REQUIRED_KERNEL}" "./ksrc/.git/config"; then
		pinfo "Trying to update existing clone"
		cde ksrc
		git pull || perror "Could not pull already checked out repo"
		cde ..
	else
		rm -rf "./ksrc"
		git clone --depth 1 "${REQUIRED_GIT}" -b "v${REQUIRED_KERNEL}"  ksrc || perror "Could not clone kernel git."
	fi
	if [ -z "$MLTK_INSTALL" ]; then
		# check for aufs
		local RSL="$( find ksrc/ -type d -name aufs )"
		if [ -z "$RSL" ]; then
			pinfo "aufs not found in kernel sources, patching it..."
			patch_aufs
		else
			pinfo "aufs detected in kernel source :)"
		fi
	fi
	# Other patches
	local patch
	cde "$MODULE_WORK_DIR/ksrc"
	for patch in "${MODULE_DIR}/patches/"*${TARGET_KERNEL_SHORT%.*}*; do
		[ -f "$patch" ] || continue
		grep -q -F "$patch" "patches-done" && continue
		pinfo "Applying $(basename "$patch")"
		git apply < "$patch" || perror "Could not apply $patch"
		echo "$patch" >> "patches-done"
	done
}

build() {
	local bf="${MODULE_WORK_DIR}/ksrc/.mltk-build-flag"
	if ! [ -e "$bf"  ]; then
		local TARGET_CONFIG_FILE="${MODULE_WORK_DIR}/openslx.config"
		rm -f -- "${TARGET_CONFIG_FILE}"
		# update config and copy to ksrc
		pinfo "Updating kernel config..."
		update_config
		cp "${TARGET_CONFIG_FILE}" "ksrc/.config"
		# make kernel with the new config
		cde ksrc
		pinfo "Preparing kernel for new config ('make oldconfig')."
		if [ "x$MLTK_QUIET" = "x1" ]; then
			make olddefconfig || perror "make oldconfig failed."
		else
			make oldconfig || perror "make oldconfig failed."
		fi

		pinfo "Compiling kernel... (this will take some time)"
		# explicitly state number of cores here, as MAKEFLAGS seems to be overridden
		# also pass CC if set by core/includes/system.inc
		make $MAKEFLAGS ${CC:+CC=${CC}} || perror "make failed."
		touch "$bf"
		if nfs_cache_avail; then
			local id tar
			id="$( kernel_build_id )"
			tar="${NFS_CACHE_DIR}/cache/${id}.tar.zstd"
			pinfo "Copying built kernel to NFS cache with id $id"
			mkdir -p "$( dirname "$tar" )"
			tar -C "${MODULE_WORK_DIR}" -c -k ksrc | zstd -T0 -2 -z > "$tar" \
				|| pwarning "Could not write kernel to NFS cache"
		fi
	fi

	# install modules to build directory
	pinfo "Installing kernel modules..."
	cde "${MODULE_WORK_DIR}/ksrc"
	if [ -d "${MODULE_BUILD_DIR}/lib/modules" ]; then
		rm -r "${MODULE_BUILD_DIR}/lib/modules" || pwarning "Could not clean old modules."
	fi
	make INSTALL_MOD_PATH="${MODULE_BUILD_DIR}" INSTALL_MOD_STRIP=1 modules_install || perror "make modules_install failed in ${MODULE_BUILD_DIR}."

	# copy most recent firmware
	cde "${MODULE_WORK_DIR}"
	mkdir -p "${MODULE_BUILD_DIR}/lib/firmware/intel" "${MODULE_BUILD_DIR}/usr/bin"
	rm -rf -- "${MODULE_BUILD_DIR}/lib/firmware/intel/sof" "${MODULE_BUILD_DIR}/lib/firmware/intel/sof-tplg"
	cp -r ./fw/* "${MODULE_BUILD_DIR}/lib/firmware/" || perror "Could not copy linux-firmware to '${MODULE_BUILD_DIR}/lib/firmware/'"
	cde sof
	FW_DEST="${MODULE_BUILD_DIR}/lib/firmware/intel" \
		TOOLS_DEST="${MODULE_BUILD_DIR}/usr/bin" \
		./install.sh v2.1.x/v2.1.1 || perror "Installing sof firmware failed"
	cde ..

	# copy kernel to build
	cp ksrc/arch/x86/boot/bzImage "${MODULE_BUILD_DIR}/kernel" || perror "Could not copy bzImage"
	pinfo "Kernel was successfully built at ${MODULE_BUILD_DIR}/kernel"
	[ -z "${KERNEL_BUILD_DIR}" ] && KERNEL_BUILD_DIR="${MODULE_BUILD_DIR}"
}

post_copy() {
	:
}

# Get unique ID for this build configuration and environment
kernel_build_id() {
	local conf
	conf="$( kernel_config_base )"
	{
		[ -n "$conf" ] && grep -E '^(# )?CONFIG_' "$conf" # Base config
		cat "${ROOT_DIR}/data/kernel.wanted.config" # Wanted config
		gcc --version 2>&1 # gcc version might be important
		echo "${REQUIRED_KERNEL} ${MLTK_INSTALL}" # wanted kernel version, whether we run install mode
		cat "${MODULE_DIR}/patches/"* 2> /dev/null # any local patches
	} | md5sum | cut -c1-32
}

# Get path of kernel config zu base this kernel on; empty if none exists
kernel_config_base() {
	local src
	for src in "/boot/config-mltk" "/boot/config-$(uname -r)"; do
		if [ -s "$src" ]; then
			echo "$src"
			return 0
		fi
	done
	if [ -f "/proc/config.gz" ]; then
		zcat "/proc/config.gz" > "${ROOT_DIR}/tmp/kernel-config"
		echo "${ROOT_DIR}/tmp/kernel-config"
	fi
}

# helper function to update the current kernel config with our parameters
update_config() {
	local src_config_file wanted_config_file wanted_line option value current_line
	# first we need to update the current config
	src_config_file="$( kernel_config_base )"
	if [ -n "$src_config_file" ]; then
		pinfo "Using $src_config_file as a starting point"
	else
		pwarning "Using default config in the kernel repository as base config."
		make -C "${MODULE_WORK_DIR}/ksrc" defconfig
		[ -e "${MODULE_WORK_DIR}/ksrc/.config" ] || perror "Failed to create default kernel config."
		src_config_file="${MODULE_WORK_DIR}/ksrc/.config"
	fi

	# check for our wanted config parameter
	wanted_config_file="${ROOT_DIR}/data/kernel.wanted.config"

	[ -e "${wanted_config_file}" ] || perror "$wanted_config_file does not exist! Please add a list of wanted kernel config parameters."

	# copy basic config file
	cp "$src_config_file" "$TARGET_CONFIG_FILE"

	while read -r wanted_line || [ -n "$wanted_line" ]; do
		option="${wanted_line%%=*}"
		value="${wanted_line#*=}"
		current_line="$( grep -E -m1 "^(# )?${option}[= ]" "$src_config_file" )"

		[ "$current_line" = "$wanted_line" ] && continue
		[ "$value" = "n" ] && [ "$current_line" = "# ${option} is not set" ] && continue
		#echo "Process: $SEARCH_RESULT"
		# analyse results
		if [ -z "$current_line" ]; then
			# no match, add it
			echo "$wanted_line" >> "$TARGET_CONFIG_FILE"
		else
			# match, change to our setting if they differ
			sed -r -i "s/^(# )?${option}[= ].*\$/${wanted_line}/" "$TARGET_CONFIG_FILE"
		fi
	done < "$wanted_config_file"
}

# helper to patch aufs
patch_aufs() {
	local KERNEL_MAJOR=${REQUIRED_KERNEL%%.*}
	local AUFS="aufs${KERNEL_MAJOR}"
	pinfo "Cloning ${AUFS} standalone git"
	cde "${MODULE_WORK_DIR}"
	[ -d "${AUFS}-standalone/.git" ] && rm -rf "${AUFS}-standalone"		# if already there, kill it.
	# git: --depth 1 won't work here due to later "checkout origin/branch"
	if [ "$KERNEL_MAJOR" = "3" ]; then
		git clone "git://aufs.git.sourceforge.net/gitroot/aufs/${AUFS}-standalone.git" || perror "Cloning ${AUFS} failed."
	else
		git clone "https://github.com/sfjro/${AUFS}-standalone.git" || perror "Cloning ${AUFS} failed."
		#git clone "https://github.com/bnied/${AUFS}-standalone.git" || perror "Cloning ${AUFS} failed."
	fi
	# get the needed version
	cde "${MODULE_WORK_DIR}/${AUFS}-standalone"
	local branches=( $( git branch -r | grep -oE 'aufs[0-9\.\+]+$' ) )
	local major minor patch
	IFS=. read major minor patch _ <<<"$REQUIRED_KERNEL"
	if [ -z "$major" ] || [ -z "$minor" ]; then
		perror "REQUIRED_KERNEL not in properly set, this should not happen!"
	fi
	local testvar outer NEEDED_BRANCH
	while (( minor >= 0 )); do
		NEEDED_BRANCH="aufs${major}.${minor}"
		outer=false
		while (( patch > 0 )); do
			for testvar in "${branches[@]}"; do
				if [ "$testvar" = "${NEEDED_BRANCH}.${patch}" ] || [ "$testvar" = "${NEEDED_BRANCH}.${patch}+" ]; then
					NEEDED_BRANCH="$testvar"
					break 3
				elif [ "$testvar" = "${NEEDED_BRANCH}" ]; then
					outer=true
				fi
			done
			(( patch-- ))
		done
		$outer && break
		if (( patch == 0 )); then
			patch=500
			(( minor-- ))
		fi
	done
	pinfo "Getting branch origin/$NEEDED_BRANCH"
	git checkout "origin/$NEEDED_BRANCH" || git checkout "origin/${AUFS}.x-rcN" || perror "Could not checkout needed branch."
	pinfo "Starting to patch... $NEEDED_BRANCH"
	tarcopy "Documentation fs" "$MODULE_WORK_DIR/ksrc"

	# Quick-and-dirty aufs_type.h copying:
	[ -e "include/linux/aufs_type.h" ] && cp "include/linux/aufs_type.h" "$MODULE_WORK_DIR/ksrc/include/linux/"
	[ -e "include/uapi/linux/aufs_type.h" ] && cp "include/uapi/linux/aufs_type.h" "$MODULE_WORK_DIR/ksrc/include/uapi/linux/"

	cde "$MODULE_WORK_DIR/ksrc"

	local PATCH
	# Mandatory
	for PATCH in "${AUFS}-kbuild" "${AUFS}-base" "${AUFS}-mmap"; do
		patch -p1 < "$MODULE_WORK_DIR/${AUFS}-standalone/${PATCH}.patch" || perror "${PATCH}.patch failed!"
		pinfo "Applied '$MODULE_WORK_DIR/${AUFS}-standalone/${PATCH}.patch'"
	done
	# Optional - should we error too?
	for PATCH in "${AUFS}-loopback" "tmpfs-idr" "vfs-ino"; do
		[ -e "$MODULE_WORK_DIR/${AUFS}-standalone/${PATCH}.patch" ] || continue
		patch -p1 < "$MODULE_WORK_DIR/${AUFS}-standalone/${PATCH}.patch" || pwarning "${PATCH}.patch failed!"
		pinfo "Applied '$MODULE_WORK_DIR/${AUFS}-standalone/${PATCH}.patch'"
	done
	pinfo "Patched kernel source with ${NEEDED_BRANCH}"
	cde "$MODULE_WORK_DIR"
}