#!/bin/bash
set -eo pipefail

# Set language to C.UTF-8 (for easier debugging)
export "LANG=C.UTF-8"
export "LC_MESSAGES=${LANG}"

# Variables
export "BUILDTOOL_ISSUETRACKER=https://git.staropensource.de/StarOpenSource/server-kernel/issues"
## Cloning (update these if you fork this project)
export "BUILDTOOL_REPOSITORY=https://git.staropensource.de/StarOpenSource/server-kernel.git"
export "BUILDTOOL_CLONEDIR=server-kernel"
## Base packages to install, packages will be added by questions
export "BUILDTOOL_PACKAGES=base-devel git rustup"
## Building command line stuff
export "BUILDTOOL_BUILDCMDLINE=nice -20 env MAKEFLAGS=-j$(nproc)"
## OOOOoooo colors! (not true color tho)
export "BUILDTOOL_COLOR_SPECIAL=\e[0;35m"
export "BUILDTOOL_COLOR_DIAG=\e[0;36m"
export "BUILDTOOL_COLOR_WARN=\e[0;33m"
export "BUILDTOOL_COLOR_ERROR=\e[0;31m"
export "BUILDTOOL_COLOR_RESET=\e[0m"

# Logging
## Empty
function empty() {
	echo ""
}
## Special
function special() {
	echo -e "${BUILDTOOL_COLOR_SPECIAL}${*}${BUILDTOOL_COLOR_RESET}"
}
## Diagnostic (header)
function diagh() {
	if [ -z "${BUILDTOOL_DEBUG}" ]; then return; fi
	echo -e "${BUILDTOOL_COLOR_DIAG}[DIAG] ${*}${BUILDTOOL_COLOR_RESET}"
}
## Diagnostic (extension)
function diage() {
	if [ -z "${BUILDTOOL_DEBUG}" ]; then return; fi
	echo -e "${BUILDTOOL_COLOR_DIAG}       ${*}${BUILDTOOL_COLOR_RESET}"
}
## Informational (header)
function infoh() {
	echo -e "${BUILDTOOL_COLOR_RESET}[INFO] ${*}"
}
## Informational (extension)
function infoe() {
	echo -e "${BUILDTOOL_COLOR_RESET}       ${*}"
}
## Warning (header)
function warnh() {
	echo -e "${BUILDTOOL_COLOR_WARN}[WARN] ${*}${BUILDTOOL_COLOR_RESET}"
}
## Warning (extension)
function warne() {
	echo -e "${BUILDTOOL_COLOR_WARN}       ${*}${BUILDTOOL_COLOR_RESET}"
}
## Error (header)
function errorh() {
	echo -e "${BUILDTOOL_COLOR_ERROR}[ERR!] ${*}${BUILDTOOL_COLOR_RESET}"
}
## Error (extension)
function errore() {
	echo -e "${BUILDTOOL_COLOR_ERROR}       ${*}${BUILDTOOL_COLOR_RESET}"
}

# Banner
special "    based on jstm-kernel-optimized _ made by staropensource _ "
special " ___  ___ _ ____   _____ _ __     | | _____ _ __ _ __   ___| |"
special "/ __|/ _ \ '__\ \ / / _ \ '__|____| |/ / _ \ '__| '_ \ / _ \ |"
special "\__ \  __/ |   \ V /  __/ | |_____|   <  __/ |  | | | |  __/ |"
special "|___/\___|_|    \_/ \___|_|       |_|\_\___|_|  |_| |_|\___|_|"
empty

# Print environment configuration
if [ -n "${BUILDTOOL_DEBUG}" ]; then
	warnh "\$BUILDTOOL_DEBUG is set, debug mode is enabled"
fi
if [ -n "${BUILDTOOL_LOCALDIR}" ]; then
	warnh "\$BUILDTOOL_LOCALDIR is set, will build kernel package from current working directory"
fi

# Checks
## Check for Arch Linux
(
	# shellcheck disable=SC1091
	source "/etc/os-release"
	if [ "${NAME}" != "Arch Linux" ] || [ "${PRETTY_NAME}" != "Arch Linux" ] || [ "${ID}" != "arch" ]; then
		if [ -z "${BUILDTOOL_COMPILE_NONARCH}" ]; then
			errorh "Not running on Arch Linux"
			errore "This kernel can only compile on Arch Linux"
			errore "If you are sure that you want to compile this kernel on other distributions"
			errore "set the \$BUILDTOOL_COMPILE_NONARCH environment variable to \"true\""
			exit 1
		else
			warnh "\$BUILDTOOL_COMPILE_NONARCH is set, allowing compiling on a non-arch distribution"
		fi
	fi
)
## Check for root
if [ "${UID}" == "0" ]; then
	errorh "Can't build kernel as root"
	errore "Please create a new user for building the kernel"
	exit 1
fi
## Check for sudo
if ! which sudo &> /dev/null; then
	errorh "Could not find sudo in \$PATH"
	errore "Please ensure that you have sudo installed"
	exit 1
fi

# Questions
## Ask if mold should replace ld/lld
function ask_mold() {
	read -rp "$(infoh "Do you want to use mold as your linker (much faster) [Y/n]? ")" BUILDTOOL_MOLD
	case "${BUILDTOOL_MOLD}" in
		"y"|"Y"|"")
			export "BUILDTOOL_PACKAGES=${BUILDTOOL_PACKAGES} mold"
			export "BUILDTOOL_BUILDCMDLINE=${BUILDTOOL_BUILDCMDLINE} LDFLAGS=-fuse-ld=mold RUSTFLAGS=\"-C link-arg=-fuse-ld=mold\""
			;;
		"n"|"N") ;;
		*)
			errorh "Invalid answer. Please answer with Y or N"
			ask_mold
	esac
}
## Ask if the governor should be adjusted
function ask_cpupower() {
	read -rp "$(infoh "Do you want to adjust the cpu governor (improves build performance) [Y/n]? ")" BUILDTOOL_CPUPOWER
	case "${BUILDTOOL_CPUPOWER}" in
		"y"|"Y"|"")
			export "BUILDTOOL_PACKAGES=${BUILDTOOL_PACKAGES} cpupower"
			;;
		"n"|"N") ;;
		*)
			errorh "Invalid answer. Please answer with Y or N"
			ask_cpupower
	esac
}
## Ask for building in tmpfs
function ask_tmpfs() {
	if [ -n "${BUILDTOOL_LOCALDIR}" ]; then
		warnh "Skipped ask_tmpfs, building in local directory instead (\$BUILDTOOL_LOCALDIR is set)"
		export "BUILDTOOL_CLONEDIR=$(pwd)"
		return
	fi
	read -rp "$(infoh "Do you want to build in a tmpfs (improves build performance, protects your disk from wearing out faster, ~32 GiB memory required) [Y/n]? ")" BUILDTOOL_TMPFS
	case "${BUILDTOOL_TMPFS}" in
		"y"|"Y"|"")
			export "BUILDTOOL_CLONEDIR=/tmp/${BUILDTOOL_CLONEDIR}"
			;;
		"n"|"N")
			export "BUILDTOOL_CLONEDIR=$(pwd)/${BUILDTOOL_CLONEDIR}"
			;;
		*)
			errorh "Invalid answer. Please answer with Y or N"
			ask_tmpfs
	esac
}
## Ask for kernel config modification using xconfig
function ask_xconfig() {
	read -rp "$(infoh "Do you want to configure the kernel using xconfig before build [y/N]? ")" BUILDTOOL_XCONFIG
	case "${BUILDTOOL_XCONFIG}" in
		"y"|"Y")
			export "BUILDTOOL_PKGBUILD_XCONFIG=_makexconfig=SET"
			;;
		"n"|"N"|"")
			export "BUILDTOOL_PKGBUILD_XCONFIG=_makexconfig="
			;;
		*)
			errorh "Invalid answer. Please answer with Y or N"
			ask_xconfig
	esac
}
## Ask for kernel config modification using xconfig
function ask_nconfig() {
	read -rp "$(infoh "Do you want to configure the kernel using nconfig before build [y/N]? ")" BUILDTOOL_NCONFIG
	case "${BUILDTOOL_NCONFIG}" in
		"y"|"Y")
			export "BUILDTOOL_PKGBUILD_NCONFIG=_makenconfig=SET"
			;;
		"n"|"N"|"")
			export "BUILDTOOL_PKGBUILD_NCONFIG=_makenconfig="
			;;
		*)
			errorh "Invalid answer. Please answer with Y or N"
			ask_nconfig
	esac
}
## Ask if the final kernel configuration should be copied
function ask_cpfinalconfig() {
	read -rp "$(infoh "Do you want to copy the final kernel configuration before build [y/N]? ")" BUILDTOOL_CPFINALCONFIG
	case "${BUILDTOOL_CPFINALCONFIG}" in
		"y"|"Y")
			export "BUILDTOOL_PKGBUILD_CPFINALCONFIG=_copyfinalconfig=SET"
			;;
		"n"|"N"|"")
			export "BUILDTOOL_PKGBUILD_CPFINALCONFIG=_copyfinalconfig="
			;;
		*)
			errorh "Invalid answer. Please answer with Y or N"
			ask_cpfinalconfig
	esac
}
## Ask if only active modules should be compiled into the kernel
function ask_modprobeddb() {
	read -rp "$(infoh "Do you want to only build active kernel modules (modprobed-db must be installed, read \"https://wiki.archlinux.org/index.php/Modprobed-db\" first) [y/N]? ")" BUILDTOOL_MODPROBEDDB
	case "${BUILDTOOL_MODPROBEDDB}" in
		"y"|"Y")
			if ! which modprobed-db &> /dev/null; then
				errorh "Could not find modprobed-db in \$PATH."
				errore "Please ensure that you have modprobed-db installed."
				ask_modprobeddb
				return 1
			fi
			export "BUILDTOOL_PACKAGES=${BUILDTOOL_PACKAGES} modprobed-db"
			export "BUILDTOOL_PKGBUILD_MODPROBEDDB=_localmodcfg=SET"
			;;
		"n"|"N"|"")
			export "BUILDTOOL_PKGBUILD_MODPROBEDDB=_localmodcfg="
			;;
		*)
			errorh "Invalid answer. Please answer with Y or N"
			ask_modprobeddb
	esac
}
## Ask for sub architecture
function ask_subarchitecture() {
  infoh "Displaying sub architecture list"
	infoe " 1. AMD Opteron/Athlon64/Hammer/K8 (MK8)"
	infoe " 2. AMD Opteron/Athlon64/Hammer/K8 with SSE3 (MK8SSE3)"
	infoe " 3. AMD 61xx/7x50/PhenomX3/X4/II/K10 (MK10)"
	infoe " 4. AMD Barcelona (MBARCELONA)"
	infoe " 5. AMD Bobcat (MBOBCAT)"
	infoe " 6. AMD Jaguar (MJAGUAR)"
	infoe " 7. AMD Bulldozer (MBULLDOZER)"
	infoe " 8. AMD Piledriver (MPILEDRIVER)"
	infoe " 9. AMD Steamroller (MSTEAMROLLER)"
	infoe "10. AMD Excavator (MEXCAVATOR)"
	infoe "11. AMD Zen (MZEN)"
	infoe "12. AMD Zen 2 (MZEN2)"
	infoe "13. AMD Zen 3 (MZEN3)"
	infoe "14. AMD Zen 4 (MZEN4)"
	infoe "15. Intel P4 / older Netburst based Xeon (MPSC)"
	infoe "16. Intel Core 2 (MCORE2)"
	infoe "17. Intel Atom (MATOM)"
	infoe "18. Intel Nehalem (MNEHALEM)"
	infoe "19. Intel Westmere (MWESTMERE)"
	infoe "20. Intel Silvermont (MSILVERMONT)"
	infoe "21. Intel Goldmont (MGOLDMONT)"
	infoe "22. Intel Goldmont Plus (MGOLDMONTPLUS)"
	infoe "23. Intel Sandy Bridge (MSANDYBRIDGE)"
	infoe "24. Intel Ivy Bridge (MIVYBRIDGE)"
	infoe "25. Intel Haswell (MHASWELL)"
	infoe "26. Intel Broadwell (MBROADWELL)"
	infoe "27. Intel Skylake (MSKYLAKE)"
	infoe "28. Intel Skylake X (MSKYLAKEX)"
	infoe "29. Intel Cannon Lake (MCANNONLAKE)"
	infoe "30. Intel Ice Lake (MICELAKE)"
	infoe "31. Intel Cascade Lake (MCASCADELAKE)"
	infoe "32. Intel Cooper Lake (MCOOPERLAKE)"
	infoe "33. Intel Tiger Lake (MTIGERLAKE)"
	infoe "34. Intel Sapphire Rapids (MSAPPHIRERAPIDS)"
	infoe "35. Intel Rocket Lake (MROCKETLAKE)"
	infoe "36. Intel Alder Lake (MALDERLAKE)"
	infoe "37. Intel Raptor Lake (MRAPTORLAKE)"
	infoe "38. Intel Meteor Lake (MMETEORLAKE)"
	infoe "39. Intel Emerald Rapids (MEMERALDRAPIDS)"
	infoe "40. Generic-x86-64 (GENERIC_CPU)"
	infoe "41. Generic-x86-64-v2 (GENERIC_CPU2)"
	infoe "42. Generic-x86-64-v3 (GENERIC_CPU3)"
	infoe "43. Generic-x86-64-v4 (GENERIC_CPU4)"
	infoe "44. Intel-Native optimizations autodetected by the compiler (MNATIVE_INTEL)"
	infoe "45. AMD-Native optimizations autodetected by the compiler (MNATIVE_AMD)"
	read -rp ":: Which sub architecture do you want to build Linux for (see above, enter 40 if unsure) [40]? " BUILDTOOL_SUBARCHITECTURE
	case "${BUILDTOOL_SUBARCHITECTURE}" in
		"")
			export "BUILDTOOL_PKGBUILD_SUBARCHITECTURE=_subarch=40"
			;;
		*[!0-9]*)
			errorh "Invalid subarchitecture"
			ask_subarchitecture
			return 1
			;;
		*)
			if [ ! "${BUILDTOOL_SUBARCHITECTURE}" -gt 0 ] || [ ! "${BUILDTOOL_SUBARCHITECTURE}" -lt 46 ]; then
				errorh "Invalid subarchitecture"
				ask_subarchitecture
			else
				export "BUILDTOOL_PKGBUILD_SUBARCHITECTURE=_subarch=${BUILDTOOL_SUBARCHITECTURE}"
			fi
			;;
	esac
}
## Ask for kernel debug mode
function ask_debug() {
	read -rp "$(infoh "Do you want to enable kernel debug mode [y/N/i(gnore)]? ")" BUILDTOOL_KERNELDEBUG
	case "${BUILDTOOL_KERNELDEBUG}" in
		"y"|"Y")
			export "BUILDTOOL_PKGBUILD_DEBUG=_debug=y"
			;;
		"n"|"N"|"")
			export "BUILDTOOL_PKGBUILD_DEBUG=_debug=n"
			;;
		"i"|"I")
			export "BUILDTOOL_PKGBUILD_DEBUG=_debug="
			;;
		*)
			errorh "Invalid answer. Please answer with Y, N or I"
			ask_debug
	esac
}
## Ask for clone directory conflict resolution (includes check)
function ask_clonedir_conflictresolution() {
	if [ -n "${BUILDTOOL_LOCALDIR}" ]; then
		warnh "Skipped conflict resolution (\$BUILDTOOL_LOCALDIR is set)"
		export "BUILDTOOL_CLONEDIR_CONFLICT=r"
		if [ -a "${BUILDTOOL_CLONEDIR}/src" ]; then
			diagh "src/ directory present, appending \"--noextract\""
			export "BUILDTOOL_MAKEPKG_REUSE= --noextract"
		fi
		if [ -a "${BUILDTOOL_CLONEDIR}/pkg" ]; then
			diagh "pkg/ directory present, appending \"--force\""
			export "BUILDTOOL_MAKEPKG_REUSE=${BUILDTOOL_MAKEPKG_REUSE} --force"
		fi
		return
	fi
	if [ ! -d "${BUILDTOOL_CLONEDIR}" ] && [ ! -L "${BUILDTOOL_CLONEDIR}" ]; then
		return
	elif [ -a "${BUILDTOOL_CLONEDIR}" ] && [ ! -d "${BUILDTOOL_CLONEDIR}" ] && [ ! -L "${BUILDTOOL_CLONEDIR}" ]; then
		warnh "Something that isn't a directory or symlink exists at location \"${BUILDTOOL_CLONEDIR}\""
	fi
	read -rp "$(infoh "Warning: \"${BUILDTOOL_CLONEDIR}\" already exists. What should be done to resolve the conflict [A(bort)/r(ecompile)/f(resh)]? ")" BUILDTOOL_CLONEDIR_CONFLICT
	case "${BUILDTOOL_CLONEDIR_CONFLICT}" in
		"a"|"A"|"")
			errorh "Conflict resolution failed"
			exit 1
			;;
		"r"|"R")
			if [ -a "${BUILDTOOL_CLONEDIR}/src" ]; then
				diagh "src/ directory present, appending \"--noextract\""
				export "BUILDTOOL_MAKEPKG_REUSE= --noextract"
			elif [ -a "${BUILDTOOL_CLONEDIR}/pkg" ]; then
				diagh "pkg/ directory present, appending \"--force\""
				export "BUILDTOOL_MAKEPKG_REUSE=${BUILDTOOL_MAKEPKG_REUSE} --force"
			fi
			;;
		"f"|"F")
			infoh "Removing existing \$BUILDTOOL_CLONEDIR directory"
			rm -rf "${BUILDTOOL_CLONEDIR}"
			;;
		*)
			errorh "Invalid answer. Please answer with Y, N or I"
			ask_debug
	esac
}
ask_mold
ask_cpupower
ask_tmpfs
ask_xconfig
ask_nconfig
ask_cpfinalconfig
ask_modprobeddb
ask_subarchitecture
ask_debug
ask_clonedir_conflictresolution

# Pre-building
## Install dependencies
infoh "Installing dependencies"
# shellcheck disable=SC2086
if ! sudo pacman -Syu --asdeps --needed ${BUILDTOOL_PACKAGES}; then
	errorh "Installing dependencies failed: pacman returned with non-zero exit code"
	exit 1
fi
if ! rustup default nightly; then
	errorh "Installing dependencies failed: rustup returned with non-zero exit code"
	exit 1
fi
## Adjust cpu governor
case "${BUILDTOOL_CPUPOWER}" in
	"y"|"Y"|"")
		infoh "Adjusting cpu governor"
		if ! sudo cpupower frequency-set -g performance; then
			errorh "Adjusting cpu governor failed: cpupower returned with non-zero exit code"
			return 1
		fi
		;;
	"n"|"N") ;;
	*)
		errorh "Internal inconsistency detected: Value of \$BUILDTOOL_CPUPOWER is not a valid boolean answer"
		exit 2
		;;
esac

# Clone repository
if [ "${BUILDTOOL_CLONEDIR_CONFLICT}" == "r" ] || [ "${BUILDTOOL_CLONEDIR_CONFLICT}" == "R" ]; then
	warnh "Skipping cloning process"
else
	infoh "Cloning repository"
	git clone "${BUILDTOOL_REPOSITORY}" "${BUILDTOOL_CLONEDIR}"
fi
cd "${BUILDTOOL_CLONEDIR}"

# Print debug information
if [ -n "${BUILDTOOL_DEBUG}" ]; then
	diagh "Printing debug information"
	diage "Environment variables:"
	env|grep "BUILDTOOL_"|sort
	diagh "More debug information:"
	diage "Build cmdline=${BUILDTOOL_BUILDCMDLINE} ${BUILDTOOL_PKGBUILD_XCONFIG} ${BUILDTOOL_PKGBUILD_NCONFIG} ${BUILDTOOL_PKGBUILD_CPFINALCONFIG} ${BUILDTOOL_PKGBUILD_MODPROBEDDB} ${BUILDTOOL_PKGBUILD_SUBARCHITECTURE} ${BUILDTOOL_PKGBUILD_DEBUG} makepkg --syncdeps -p PKGBUILD.buildtool"
	diage "Cwd=$(pwd)"
fi

# Build package
infoh "Building package"
# shellcheck disable=SC2086
if ! ${BUILDTOOL_BUILDCMDLINE} "${BUILDTOOL_PKGBUILD_XCONFIG}" "${BUILDTOOL_PKGBUILD_NCONFIG}" "${BUILDTOOL_PKGBUILD_CPFINALCONFIG}" "${BUILDTOOL_PKGBUILD_MODPROBEDDB}" "${BUILDTOOL_PKGBUILD_SUBARCHITECTURE}" "${BUILDTOOL_PKGBUILD_DEBUG}" makepkg --syncdeps${BUILDTOOL_MAKEPKG_REUSE} -p PKGBUILD.buildtool; then
	errorh "Failed package compilation: makepkg returned with non-zero exit code"
	errore "Please report this at \"${BUILDTOOL_ISSUETRACKER}\""
	exit 1
fi

# Finish message
infoh "Finished kernel compilation successfully"
infoe "You can now install your kernel and kernel headers."