#! /bin/bash

## package name
custom_name=linux-lts-native

## gcc optimization parameters
gcc_patch_version=20240221.2
#gcc_patch_filename="more-uarches-for-kernel-5.15+.patch"
gcc_patch_filename="more-uarches-for-kernel-6.1.79-6.8-rc3.patch"

gcc_patch_src='enable_additional_cpu_optimizations-$_gcc_more_v.tar.gz::https://github.com\/graysky2/kernel_compiler_patch/archive/$_gcc_more_v.tar.gz'
gcc_patch_msg='msg "Applying Additional GCC Optimizations Patch"'
gcc_patch_apply="patch -Np1 -i \"\$srcdir/kernel_compiler_patch-\$_gcc_more_v/$gcc_patch_filename\""

repo_dir=src
build_dir=.build
build_file="$build_dir/PKGBUILD"
hist_dir=config-history
makepkg_dir=$(sed -n 's/^BUILDDIR=\(.*\)/\1/p' /etc/makepkg.conf)

help="$(basename "$0") [-o] [-c] [-h]

Natively builds the latest version of the linux-lts kernel with 
graysky's GCC patch and my own config.

Options:
	-o: use current package build files regardless of newer versions
	-c: launch make nconfig during build
	-h: show this"

get_latest_config() {
	echo "$hist_dir/$(ls -Art "$hist_dir" | tail -n 1)"
}

back_up_config() {
    # pull old config if it exists and is not the most recent
    if [ -e "$build_file" ]; then
        echo "checking for old config file"

        source "$build_file" # get pkgver

        # copy from the tmp dir if this is what makepkg is configured to do
        if [[ "$makepkg_dir" == "" ]]; then
            oldconf="$build_dir/src/linux-$pkgver/.config"
        else
            oldconf="$makepkg_dir/linux-lts-native/src/linux-$pkgver/.config"
        fi

        if [ -e "$oldconf" ]; then
            echo "found old config"

            oldsum=$(md5sum "$oldconf" | awk '{print $1}')
            newsum=$(md5sum "$(get_latest_config)" | awk '{print $1}')

            if [ "$oldsum" != "$newsum" ]; then
                echo "copying old config to $hist_dir"
                cp "$oldconf" "$hist_dir/.config-$(date +%Y%m%d%H%M)"
            else
                echo "config file up to date. nothing to back up"
            fi
        fi
    fi
}

update_build() {
    if [ -z "$old_build" ]; then
        ## update repo tree
        if [ ! -e src ]; then
            echo Retrieving linux-lts source
	    git clone https://gitlab.archlinux.org/archlinux/packaging/packages/linux-lts.git src
        fi

        ## update linux-lts repo
        echo Updating linux-lts source
        cd src || exit
        git pull
        cd ..

        rm -rf $build_dir
        cp -r "$repo_dir" "$build_dir"

        ## copy new config
        latest_conf=$(get_latest_config)
        echo "copying conf: $latest_conf"
        cp "$latest_conf" "$build_dir/config"

        ## use "make nconfig" if we ask for it (see sed cmd below)
        if [ -n "$do_config" ]; then
            make_config_cmds="make oldconfig\n  make nconfig"
        else
            make_config_cmds="make oldconfig"
        fi

        ## if "security patches is not found in prepare(), warn user
        ## that the GCC patch won't be applied
        if ! grep 'Setting version...' "$build_file" > /dev/null; then
            echo "GCC patch not applied!!!"
            exit 1
        fi

        ## modify the PKGBUILD
        ## - remove unnecessary makedeps
        ## - change package name
        ## - change kernelname
        ## - unindent custom name
	## - remove htmldocs make steps (started in 'build' function to speed up package building)
        ## - add gcc path version variable
        ## - add gcc path to sources
        ## - add gcc patch command in prepare
        ## - add make config commands
        ## - delete docs build command
        ## - delete package-docs
        ## - remove package-docs from pkgname
        sed -i -z 's/makedepends=([^()]\+)/makedepends=(libelf cpio tar xz)/' \
            "$build_file"
        sed -i -e "s/pkgbase=.*/pkgbase=$custom_name/g" \
	    -e '/make htmldocs &/d' \
	    -e '/local pid_docs=\$!/d' \
	    -e '/wait \"\${pid_docs\}\"/d' \
            -e "/^pkgrel=.*/a _gcc_more_v=\'$gcc_patch_version\'" \
            -e "s|source=(|source=($gcc_patch_src\n        |" \
            -e "/localversion\.20-pkgname/d" \
            -e "/Setting version\.\.\./i \ \ $gcc_patch_msg\n\ \ $gcc_patch_apply\n" \
            -e "/^\s*make olddefconfig/a \ \ $make_config_cmds" \
            -e "s/\s*htmldocs//" \
            -e '/^_package-docs()\ {/,/^}/d' \
            -e 's/\s*"$pkgbase-docs"//' \
            "$build_file"
        ## remove btfid thingy
        sed -i '/resolve_btfids/d' "$build_file"
        # TEMPORARILY DISABLE THE GCC PATCH
        #sed -i -e "s/pkgbase=.*/pkgbase=$custom_name/g" \
        #    -e "/localversion\.20-pkgname/d" \
        #    -e "/^\s*make olddefconfig/a \ \ $make_config_cmds" \
        #    -e "s/\s*htmldocs//" \
        #    -e '/^_package-docs()\ {/,/^}/d' \
        #    -e 's/\s*"$pkgbase-docs"//' \
        #    "$build_file"

	    updpkgsums "$build_file"
    fi
}

while getopts ":och" OPT; do
	case ${OPT} in
		o)
			old_build="true"
			;;
		c)
			do_config="true"
			;;
		h)
			echo "$help"
			exit 0
			;;
		\?)
			echo "$help"
			exit 0
			;;
	esac
done

update_build

cd "$build_dir" || exit
makepkg -s -r -f -i -L
cd ..

back_up_config