#!/usr/bin/env bash
set -e

if command -v schedtool >/dev/null 2>&1; then
	# Set current shell and all descendents as SCHED_BATCH, see schedtool(8)
	schedtool -B $$
	prefix_cmd='schedtool -B -n20 -e '
fi

venv() {
	virtualenv ".venv" -p python3
	. ".venv/bin/activate"
}

prepare() {
	if [[ -n "$USE_VENV" ]]; then
		venv
	fi
	
	if command -v autobuild >/dev/null 2>&1 && [[ "$(autobuild --version)" == "autobuild 9.0.0" ]]; then
		pip3 uninstall --yes autobuild --quiet
	elif ! command -v autobuild; then
		echo "Installing autobuild..."
		pip3 install --upgrade certifi --quiet
		pip3 install --upgrade llbase --quiet
		pip3 install --no-cache --upgrade autobuild --quiet
	fi
}

build() {
	# we have a lot of files, relax ulimit to help performance
	if [[ -n "$USE_VENV" ]]; then
		. ".venv/bin/activate"
	fi
	ulimit -n 20000
	build_jobs=$(nproc)
	if [[ -z "$NO_SMART_JOB_COUNT" ]]; then
		if [[ ${build_jobs} -gt 1 ]]; then
			jobs=1
			# The viewer requires an average of 4GB of memory per core to link
			# Note: Behaviour change compared to the previous versions:
			# This script will no longer try to allocate build memory into swap
			# This is bad practice, and swap should be reserved to evict process
			# memory from physical ram to make place for the current workset.
			# This script will now try to check if swap is present and sufficent
			# for the current used memory to be stored in swap before allocating,
			# and will fallback to conservative allocation if swap is not available
			gigperlinkprocess=4
			mempercorekb=$((gigperlinkprocess * 1048576))
			requiredmemorykb=$(($(nproc) * mempercorekb))
			free_output="$(free --kilo --total | tail -n+2| tr -s ' ')"
			physical_output=$(grep "Mem:" <<< "$free_output")
			#total_output=$(grep Total: <<< "$free_output")
			usedmemorykbphysical=$(cut -d ' ' -f 3 <<< "$physical_output")
			totalmemorykbphysical=$(cut -d ' ' -f 2 <<< "$physical_output")
			swap_output=$(grep Swap: <<< "$free_output")
			# Determine available swap space
			availableswapkb=0
			if [[ -n "$swap_output" ]]; then
				availableswapkb=$(cut -d ' ' -f 4 <<< "$swap_output")
			fi
			availablememorykbphysical=$(cut -d ' ' -f 7 <<< "$free_output")
			echo "Total memory:         $totalmemorykbphysical (includes swap)"
			echo "Available memory:     $availablememorykbphysical"
			echo "Required memory:      $requiredmemorykb"
			echo "Available physical memory on this system: $((availablememorykbphysical/1024/1024)) GB"
			echo "Estimated required memory to build with all cores: $((requiredmemorykb/1024/1024)) GB"
			if [[ ${requiredmemorykb} -gt ${availablememorykbphysical} ]]; then
				echo "Warning: Not enough available physical memory to build with all cores"
				if [[ ${usedmemorykbphysical} -lt ${availableswapkb} ]]; then
					# use all physical ram as swap will do its job
					echo "There is enough free swap to store the currently used memory"
					jobs=$(((totalmemorykbphysical/1024/1024)/gigperlinkprocess))
				else
					# Not enough swap to hold ram contents, calculate manually
					echo "Allocating build jobs according to available physical memory ("$((availablememorykbphysical/1024/1024))"/"$((requiredmemorykb/1024/1024))"GB)..."
					# FIXME: Goes one iteration beyond what it should
					while [[ $((jobs * mempercorekb)) -lt ${availablememorykbphysical} ]]; do
						jobs=$((jobs+1))
						echo -e "${jobs} jobs would consume $(((jobs * mempercorekb)/1024/1024))GB"
					done
					# Back off one job count. Not sure why I have to do this but
					# the loop is doing one extra iteration.
					jobs=$((jobs-1))
				fi
				build_jobs=${jobs}
				echo "Computed job count: ${build_jobs}"
			fi
		fi
	fi
	export AUTOBUILD_CPU_COUNT=$build_jobs
	AL_ARCH_FLAGS=${AL_ARCH_FLAGS:-'-march=native -mtune=native -w'}
	AL_CMAKE_CONFIG=(
		-DLL_TESTS:BOOL=OFF
		-DDISABLE_FATAL_WARNINGS=ON
		-DUSE_LTO:BOOL=OFF
		-DVIEWER_CHANNEL="Alchemy Test"
		-DCMAKE_C_FLAGS="$AL_ARCH_FLAGS"
		-DCMAKE_CXX_FLAGS="$AL_ARCH_FLAGS"
		-DCMAKE_C_COMPILER="${CC:-gcc}"
		-DCMAKE_CXX_COMPILER="${CXX:-g++}"
		)
	# I could not find the documentation on how to handle BUILDENV/OPTION in
	# makepkg.conf. If you are reading this and know where it is,
	# please send it my way.
	# if [[ -n "$AL_NO_CCACHE" ]] || ! command -v ccache 2 > /dev/null 2>&1; then
		# echo "ccache disabled"
		# AL_CMAKE_CONFIG+=(-UCMAKE_CXX_COMPILER_LAUNCHER)
	# else
		# echo "ccache available and enabled"
		# export CCACHE_SLOPPINESS="file_macro,locale,time_macros"
		# export CCACHE_NOHASHDIR="true"
		# AL_CMAKE_CONFIG+=(-DCMAKE_CXX_COMPILER_LAUNCHER=ccache)
	# fi
	$prefix_cmd autobuild configure -A 64 -c ReleaseOS -- "${AL_CMAKE_CONFIG[@]}"
	echo "Building with ${AUTOBUILD_CPU_COUNT} jobs (adjusted)"
	$prefix_cmd autobuild build -A64 -c ReleaseOS --no-configure
}

cleanbuild()
{
	rm -rf build-linux-64
	git pull --prune
	build
}
if [[ -n "$1" ]]; then
	$1
else
	echo "Running unattended batch build..."
	prepare
	build
fi