#!/bin/bash

set -e

usage()
{
	echo "usage: $0 <kernel source tree>" >&2
	exit 1
}

[ "$#" -eq 1 ] || usage
KERNEL_DIR="$(readlink --canonicalize-existing "$1")"

MODULES=()
MODULES+="spl"
for MODULE_DIR in module/*
do
	[ -d "$MODULE_DIR" ] || continue
	[ "spl" = "${MODULE_DIR##*/}" ] && continue
	MODULES+=("${MODULE_DIR##*/}")
done

if ! [ -e 'zfs_config.h' ]
then
	echo >&2
	echo "    $0: you did not run configure, or you're not in the ZFS source directory." >&2
	echo "    $0: run configure with --with-linux=$KERNEL_DIR and --enable-linux-builtin." >&2
	echo >&2
	exit 1
fi

make clean || true
scripts/make_gitrev.sh || true

rm -rf "$KERNEL_DIR/include/zfs" "$KERNEL_DIR/fs/zfs"
cp --recursive include "$KERNEL_DIR/include/zfs"
cp --recursive module "$KERNEL_DIR/fs/zfs"
cp zfs_config.h "$KERNEL_DIR/include/zfs/"

for MODULE in "${MODULES[@]}"
do
	sed -i.bak '/obj =/d' "$KERNEL_DIR/fs/zfs/$MODULE/Makefile"
	sed -i.bak '/src =/d' "$KERNEL_DIR/fs/zfs/$MODULE/Makefile"
done

cat > "$KERNEL_DIR/fs/zfs/Kconfig" <<"EOF"
config ZFS
	tristate "ZFS filesystem support"
	depends on EFI_PARTITION
	select ZLIB_INFLATE
	select ZLIB_DEFLATE
	help
	  This is the ZFS filesystem from the ZFS On Linux project.

	  See http://zfsonlinux.org/

	  To compile this file system support as a module, choose M here.

	  If unsure, say N.
EOF

{
	cat <<-"EOF"
	ZFS_MODULE_CFLAGS  = -I$(srctree)/include/zfs
	ZFS_MODULE_CFLAGS += -I$(srctree)/include/zfs/spl
	ZFS_MODULE_CFLAGS += -include $(srctree)/include/zfs/zfs_config.h
	ZFS_MODULE_CFLAGS += -std=gnu99 -Wno-declaration-after-statement
	ZFS_MODULE_CPPFLAGS  = -D_KERNEL
	ZFS_MODULE_CPPFLAGS += -UDEBUG -DNDEBUG
	export ZFS_MODULE_CFLAGS ZFS_MODULE_CPPFLAGS

	obj-$(CONFIG_ZFS) :=
	EOF

	for MODULE in "${MODULES[@]}"
	do
		echo 'obj-$(CONFIG_ZFS) += ' "$MODULE/"
	done
} > "$KERNEL_DIR/fs/zfs/Kbuild"

add_after()
{
	local FILE="$1"
	local MARKER="$2"
	local NEW="$3"
	local LINE

	while IFS='' read -r LINE
	do
		echo "$LINE"

		if [ -n "$MARKER" -a "$LINE" = "$MARKER" ]
		then
			echo "$NEW"
			MARKER=''
			if IFS='' read -r LINE
			then
				[ "$LINE" != "$NEW" ] && echo "$LINE"
			fi
		fi
	done < "$FILE" > "$FILE.new"

	mv "$FILE.new" "$FILE"
}

add_after "$KERNEL_DIR/fs/Kconfig" 'if BLOCK' 'source "fs/zfs/Kconfig"'
add_after "$KERNEL_DIR/fs/Makefile" 'endif' 'obj-$(CONFIG_ZFS) += zfs/'

echo >&2
echo "    $0: done." >&2
echo "    $0: now you can build the kernel with ZFS support." >&2
echo "    $0: make sure you enable ZFS support (CONFIG_ZFS) before building." >&2
echo >&2