#!/bin/bash

function install_dependencies() {
	echo "Installing dependencies..."
	sudo apt -qq update
	sudo apt -qq install -y curl git wget
#	sudo apt -qq install -y bison flex kernel-package libelf-dev libssl-dev
	sudo apt -qq install -y bison flex libelf-dev libssl-dev
}

function init() {
	echo "Get the newest version of the script here: https://gist.github.com/mdPlusPlus/031ec2dac2295c9aaf1fc0b0e808e21a"

	echo "Initializing..."

	kernel_config=$(ls /boot/config-* | grep generic | sort -Vr | head -n 1)
	grub_config="/etc/default/grub"

	current_dir=$(pwd)
	working_dir=$(mktemp -d)
	cd "${working_dir}" || exit

	install_dependencies
}

function get_newest_versions() {
	echo "Retrieving newest version information..."

	stable_releases_3x_url="https://mirrors.edge.kernel.org/pub/linux/kernel/v3.x/"
	stable_releases_4x_url="https://mirrors.edge.kernel.org/pub/linux/kernel/v4.x/"
	stable_releases_5x_url="https://mirrors.edge.kernel.org/pub/linux/kernel/v5.x/"

	stable_releases_3x_html=$(curl -s "${stable_releases_3x_url}")
	stable_releases_4x_html=$(curl -s "${stable_releases_4x_url}")
	stable_releases_5x_html=$(curl -s "${stable_releases_5x_url}")

	stable_releases_combined_html="${stable_releases_3x_html}${stable_releases_4x_html}${stable_releases_5x_html}"
	stable_version=$(echo "${stable_releases_combined_html}" | grep -E -o 'linux-([0-9]{1,}\.)+[0-9]{1,}' | sort -Vru | head -n 1 | cut -d '-' -f 2)

	mainline_link=$(curl -s https://www.kernel.org/ | grep https://git.kernel.org/torvalds/t/linux- | grep -Po '(?<=href=")[^"]*')
	if ! [ -z "${mainline_link}" ]
	then
		mainline_version=$(echo "${mainline_link}" | cut -d '-' -f 2,3 | cut -d '.' -f 1,2)
	else
		mainline_version="unavailable"
	fi

	repo_pkg=$(apt search 'linux-source-' | grep 'linux-source' | cut -d '/' -f 1 | awk -F- 'NF<=3' | sort -Vr | head -n 1)
	#repo_version=$(echo "${repo_pkg}" | cut -d '-' -f 3)
	repo_version=$(apt search 'linux-source-' | grep 'linux-source' | sort -Vr | head -n 1 | cut -d ' ' -f 2)
}

function stable_or_mainline_or_repo() {
	get_newest_versions
	echo "Newest stable version is: ${stable_version}"
	echo "Mainline version is:      ${mainline_version}"
	echo "Repository version is:    ${repo_version}"
	echo -n "Do you want to get a [s]table, the newest [m]ainline release candidate or the newest kernel from your [r]epositories? [S/m/r] "
	read -r s_or_m_or_r

	echo -n "Do you want to apply the acs override patch? Kernels below 4.10 are not supported. [Y/n] "
	read -r acso

	echo -n "Do you want to apply the experimental AMD AGESA patch to fix VFIO setups on AGESA 0.0.7.2 and some others? [y/N] "
	read -r agesa

#	echo -n "Do you want to apply the experimental AMD Vega PCI reset patch? [y/N] "
#	read -r vega

	echo -n "Do you want to install the kernel and its headers after compilation? [Y/n] "
	read -r install

	if [[ -z "${install}" || "${install}" == "y" || "${install}" == "Y" ]]
	then
		echo -n "Do you want to make this kernel the new default? [Y/n] "
		read -r default
	fi

	echo -n "Do you want to install the kernel source? [y/N] "
	read -r source

	if [[ -z "${s_or_m_or_r}" || "${s_or_m_or_r}" == "s" || "${s_or_m_or_r}" == "S" ]]
	then
		stable_preparations
	else
		if [[ "${s_or_m_or_r}" == "m" || "${s_or_m_or_r}" == "M" ]]
		then
			if [ "${mainline_version}" == "unavailable" ]
			then
				echo "Mainline version currently unavailable. Exiting."
				exit
			else
				mainline_preparations
			fi
		else
			if [[ "${s_or_m_or_r}" == "r" || "${s_or_m_or_r}" == "R" ]]
			then
				repo_preparations
			else
				echo "Not a valid option. Exiting."
				exit
			fi
		fi
	fi
}

function try_acso_patch() {
	## TODO: I really should not do this manually ...

	acso_patch_5_12_13="https://raw.githubusercontent.com/mdPlusPlus/linux-acs-override/master/patches/acso_5_12_13.patch"
	acso_patch_5_6_12="https://raw.githubusercontent.com/mdPlusPlus/linux-acs-override/master/patches/acso_5_6_12.patch"
	acso_patch_5_4="https://raw.githubusercontent.com/mdPlusPlus/linux-acs-override/master/patches/acso_5_4.patch"
	acso_patch_4_18="https://raw.githubusercontent.com/mdPlusPlus/linux-acs-override/master/patches/acso_4_18.patch"
	acso_patch_4_17="https://raw.githubusercontent.com/mdPlusPlus/linux-acs-override/master/patches/acso_4_17.patch"
	acso_patch_4_14="https://raw.githubusercontent.com/mdPlusPlus/linux-acs-override/master/patches/acso_4_14.patch"
	acso_patch_4_10="https://raw.githubusercontent.com/mdPlusPlus/linux-acs-override/master/patches/acso_4_10.patch"

	acso_patch_4_18_ubuntu="https://gist.github.com/mdPlusPlus/bb3df6248ffc7c6b3772ae0901659966/raw/acso_4_18_ubuntu.patch"

	echo "Trying to apply acs override patch for 5.12.13+."
	wget -O ../acso_5_12_13.patch "${acso_patch_5_12_13}"
	if $(git apply --check ../acso_5_12_13.patch)
	then
		echo "Applying acs override patch for 5.12.13+."
		git apply ../acso_5_12_13.patch
	else

		echo "Trying to apply acs override patch for 5.6.12+."
		wget -O ../acso_5_6_12.patch "${acso_patch_5_6_12}"
		if $(git apply --check ../acso_5_6_12.patch)
		then
			echo "Applying acs override patch for 5.6.12+."
			git apply ../acso_5_6_12.patch
		else
			echo "Trying to apply acs override patch for 5.4+."
			wget -O ../acso_5_4.patch "${acso_patch_5_4}"
			if $(git apply --check ../acso_5_4.patch)
			then
				echo "Applying acs override patch for 5.4+."
				git apply ../acso_5_4.patch
			else
				echo "Trying to apply acs override patch for 4.18+."
				wget -O ../acso_4_18.patch "${acso_patch_4_18}"
				if $(git apply --check ../acso_4_18.patch)
				then
					echo "Applying acs override patch for 4.18+."
					git apply ../acso_4_18.patch
				else
					echo "Trying to apply acs override patch for 4.17+."
					wget -O ../acso_4_17.patch "${acso_patch_4_17}"
					if $(git apply --check ../acso_4_17.patch)
					then
						echo "Applying acs override patch for 4.17+."
						git apply ../acso_4_17.patch
					else
						echo "Trying to apply acs override patch for 4.14+."
						wget -O ../acso_4_14.patch "${acso_patch_4_14}"
						if $(git apply --check ../acso_4_14.patch)
						then
							echo "Applying acs override patch for 4.14+."
							git apply ../acso_4_14.patch
						else
							echo "Trying to apply acs override patch for 4.10+."
							wget -O ../acso_4_10.patch "${acso_patch_4_10}"
							if $(git apply --check ../acso_4_10.patch)
							then
								echo "Applying acs override patch for 4.10+."
								git apply ../acso_4_10.patch
							else
								echo "Last resort: Trying to apply acs override patch for Ubuntu repository kernel source."
								wget -O ../acso_4_18_ubuntu.patch "${acso_patch_4_18_ubuntu}"
								if $(git apply --check ../acso_4_18_ubuntu.patch)
								then
									echo "Applying acs override patch for Ubuntu repository kernel source."
									git apply ../acso_4_18_ubuntu.patch
								else
									echo "[ERROR]: Failed to apply acs override patch. Exiting."
									exit
								fi
								rm -f ../acso_4_18_ubuntu.patch
							fi
							rm -f ../acso_4_10.patch
						fi
						rm -f ../acso_4_14.patch
					fi
					rm -f ../acso_4_17.patch
				fi
				rm -f ../acso_4_18.patch
			fi
			rm -f ../acso_5_4.patch
		fi
		rm -f ../acso_5_6_12.patch
	fi
	rm -f ../acso_5_2_13.patch

	kernel_localversion+="-acso"
}

function try_agesa_patch() {
	## by reddit user https://www.reddit.com/user/hansmoman/
	## https://www.reddit.com/r/VFIO/comments/bqeixd/apparently_the_latest_bios_on_asrockmsi_boards/eo4neta
	agesa_patch="https://clbin.com/VCiYJ"
	agesa_patch_filename="agesa.patch"

	echo "Trying to apply AMD AGESA patch."
	wget -O ../${agesa_patch_filename} "${agesa_patch}"
	if $(git apply --check ../${agesa_patch_filename})
	then
		echo "Applying AMD AGESA patch."
		git apply ../${agesa_patch_filename}
	else
		echo "[ERROR]: Failed to apply AMD AGESA patch. Exiting."
		exit
	fi

	rm -f ../${agesa_patch_filename}

	kernel_localversion+="-agesa"
}

#function try_vega_patch() {
#	## Original by github user https://gist.github.com/numinit
#
#	vega_patch_new="https://gist.github.com/mdPlusPlus/1754d82b53269ead770133829874fbfd/raw/"
#	vega_patch="https://gist.github.com/numinit/1bbabff521e0451e5470d740e0eb82fd/raw/0ec757c30cec041c3d0553bb246b5bc327d67abb/fix-vega-reset.patch"
#	vega_patch_filename="fix-vega-reset.patch"
#
#	echo "Trying to apply AMD Vega reset patch."
#	wget -O ../${vega_patch_filename} "${vega_patch_new}"
#
#	if $(git apply --check ../${vega_patch_filename})
#	then
#		echo "Applying AMD Vega reset patch."
#		git apply ../${vega_patch_filename}
#	else
#		rm -f ../${vega_patch_filename}
#		wget -O ../${vega_patch_filename} "${vega_patch}"
#
#		if $(git apply --check ../${vega_patch_filename})
#		then
#			echo "Applying AMD Vega reset patch."
#			git apply ../${vega_patch_filename}
#		else
#			echo "[ERROR]: Failed to apply AMD Vega reset patch. Exiting."
#			exit
#		fi
#	fi
#
#	rm -f ../${vega_patch_filename}
#
#	kernel_localversion+="-vega"
#}

function stable_preparations() {
	echo "The newest available stable kernel version is ${stable_version}. Kernels below 4.10 are not supported."
	echo -n "Which version do you want to download? [${stable_version}] "
	read -r user_version

	if  ! [ -z "${user_version}" ]
	then
		stable_version="${user_version}"
	fi

	kernel_version="${stable_version}"
	kernel_name="linux-${kernel_version}"


	## Test whether the version string starts with 3, 4, or 5 and sets the URL accordingly
	if [[ $stable_version == 5* ]]
	then
		stable_link="${stable_releases_5x_url}linux-${stable_version}.tar.xz"
	else
		if [[ $stable_version == 4* ]]
		then
			stable_link="${stable_releases_4x_url}linux-${stable_version}.tar.xz"
		else
			if [[ $stable_version == 3* ]]
			then
				stable_link="${stable_releases_3x_url}linux-${stable_version}.tar.xz"
			else
				echo "${stable_version} is not a vaild version number. Exiting."
				exit
			fi
		fi
	fi

	wget "${stable_link}"
	tar xf "${kernel_name}.tar.xz"
	cd "${kernel_name}" || exit

	independent_code
}

function mainline_preparations() {
	kernel_version="${mainline_version}"
	kernel_name="linux-${kernel_version}"

	wget "${mainline_link}"
	tar xf "${kernel_name}.tar.gz"
	cd "${kernel_name}" || exit

	independent_code
}

function repo_preparations() {
	kernel_name="${repo_pkg}"

	sudo apt install "${repo_pkg}"
	tar xf "/usr/src/${kernel_name}.tar.bz2"
	cd "${kernel_name}" || exit

	makefile_version=$(grep "^VERSION" Makefile |  tr -d '[:space:]' | cut -d '=' -f 2)
	makefile_patchlevel=$(grep "^PATCHLEVEL" Makefile|  tr -d '[:space:]' | cut -d '=' -f 2)
	makefile_sublevel=$(grep "^SUBLEVEL" Makefile |  tr -d '[:space:]' | cut -d '=' -f 2)
	#makefile_extraversion=$(grep "^EXTRAVERSION" Makefile|  tr -d '[:space:]' | cut -d '=' -f 2)

	if ! [ -z "${makefile_version}" ]
	then
		kernel_version="${makefile_version}"
		if ! [ -z "${makefile_patchlevel}" ]
		then
			kernel_version="${makefile_version}.${makefile_patchlevel}"
			if ! [ -z "${makefile_sublevel}" ]
			then
				kernel_version="${makefile_version}.${makefile_patchlevel}.${makefile_sublevel}"
			fi
		fi
	fi

	## linux-hwe (5.0.0-25.26~18.04.1) bionic; urgency=medium
	## ->
	## 5.0.0-25.26~18.04.1
	#kernel_version=$(head -n 1 debian/changelog | cut -d '(' -f 2 | cut -d ')' -f 1)
	## This somehow comes out empty when run in the script, but is successful when issued manually

	independent_code
}

function independent_code() {
	kernel_localversion=""

	if [[ -z "${acso}" || ( "${acso}" != "n" && "${acso}" != "N" ) ]]
	then
		try_acso_patch
	fi

	if [[ "${agesa}" == "y" || "${agesa}" == "Y" ]]
	then
		try_agesa_patch
	fi

#	if [[ "${vega}" == "y" || "${vega}" == "Y" ]]
#	then
#		try_vega_patch
#	fi

	cp "${kernel_config}" .config
	yes '' | make oldconfig

	##set xhci_hcd to load as a module instead of including it directly into the kernel
	##results in vfio_pci being able to grab usb controllers before xhci_hcd is able to
	sed -i -e 's/^CONFIG_USB_XHCI_HCD=y/CONFIG_USB_XHCI_HCD=m/g' .config

	##Enable AMD's HSA driver for ROCm support. Thanks at https://github.com/jfturcot
	sed -i -e 's/^#\ CONFIG_HSA_AMD\ is\ not\ set/CONFIG_HSA_AMD=y/g' .config

#	## Disable debug builds
#	sed -i -e 's/^CONFIG_DEBUG_INFO=y/CONFIG_DEBUG_INFO=n/g' .config
#	sed -i -e 's/^CONFIG_DEBUG_KERNEL=y/CONFIG_DEBUG_KERNEL=n/g' .config

	## check for versions containing only a single dot instead of two
	## but only when not choosing the repo source
	if [[ "${s_or_m_or_r}" != "r" && "${s_or_m_or_r}" != "R" ]]
	then
		dots=$(echo "${kernel_version}" | awk -F "." '{print NF-1}')
		dashes=$(echo "${kernel_version}" | awk -F "-" '{print NF-1}')
		if [ "${dots}" -lt 2 ]
		then
			if [ "${dashes}" -lt 1 ]
			then
				##5.1 -> 5.1.0
				kernel_version="${kernel_version}.0"
			else
				##5.1-rc1 -> 5.1.0-rc1
				kernel_version="$(echo "${kernel_version}" | sed 's/-/.0-/')"
			fi
			kernel_name="linux-${kernel_version}"
		fi
	fi

	## Install kernel source, thanks https://github.com/meberlein
	if [[ "${source}" == "y" || "${source}" == "Y" ]]
	then
		source_dir="/usr/src/linux-source-${kernel_version}${kernel_localversion}"
		sudo mkdir -p "${source_dir}"
		sudo cp -a "${working_dir}/${kernel_name}/." "${source_dir}"
	fi

	make clean
	make -j "$(nproc)" bindeb-pkg LOCALVERSION="${kernel_localversion}" || exit


	if [[ -z "${install}" || "${install}" == "y" || "${install}" == "Y" ]]
	then
		sudo dpkg -i ../linux-image-${kernel_version}${kernel_localversion}*.deb ../linux-headers-${kernel_version}${kernel_localversion}*.deb
		if [[ -z "${default}" || "${default}" == "y" || "${default}" == "Y" ]]
		then
			if [ "$(lsb_release -s -d | cut -d ' ' -f 1)" == "Ubuntu" ]
			then
				## removing previous commented line
				sudo sed -i -e 's/^#GRUB_DEFAULT=.*//g' "${grub_config}"

				## commenting current line
				sudo sed -i 's/^GRUB_DEFAULT=/#GRUB_DEFAULT=/' "${grub_config}"

				## adding line
				## TODO: multilanguage! only works for en-US (and other en-*) right now!
				grub_line="GRUB_DEFAULT=\"Advanced options for Ubuntu>Ubuntu, with Linux ${kernel_version}${kernel_localversion}\""
				sudo sed -i -e "s/^#GRUB_DEFAULT=.*/\0\n${grub_line}/" "${grub_config}"

				sudo update-grub
			fi
		fi
	fi

	cd "${current_dir}" || exit
	rm -rf "${working_dir}"

	echo "Done."
	echo "Make sure to check out https://github.com/gnif/vendor-reset"
}

## actual logic
init
stable_or_mainline_or_repo