#!/bin/bash

set -ex

# Caluclate Memory Limit from cgroups/maxmemory
MEMSIZE=$(grep MemTotal /proc/meminfo | awk '{print $2 * 1024}')

if [ -f "/sys/fs/cgroup/memory/memory.limit_in_bytes" ]; then
    MEMLIMIT=$(cat /sys/fs/cgroup/memory/memory.limit_in_bytes)
elif [ -f "/sys/fs/cgroup/memory.max" ]; then
    MEMLIMIT=$(cat /sys/fs/cgroup/memory.max)
else
    MEMLIMIT=$(grep MemTotal /proc/meminfo | awk '{print $2 * 1024}')
fi

if ! [[ $MEMLIMIT =~ ^[0-9]+$ ]]; then
    MEMLIMIT=$MEMSIZE
fi

MEMLIMIT=$((MEMLIMIT<MEMSIZE ? MEMLIMIT : MEMSIZE))

MEMOFFSET_THRESH=4294967296
G1PARAM_THRESH=12884901888

# Offset memory for Java by 1-1.5G depending on memory available
if [ $MEMLIMIT -lt $MEMOFFSET_THRESH ]; then
    MEMOFFSET=1073741824
else
    MEMOFFSET=1610612736
fi
SERVER_MEM=$((MEMLIMIT-MEMOFFSET))

# Configure G1 parameters based on Java memory limits
if [ $SERVER_MEM -lt $G1PARAM_THRESH ]; then
    G1NEWSIZE=30
    G1MAXNEWSIZE=40
    G1HEAP=8M
else
    G1NEWSIZE=40
    G1MAXNEWSIZE=50
    G1HEAP=16M
fi

if [ -e "/server/modpack.json" ]; then
    mrpack-install --server-dir /server --server-file server.jar update "$@" <<EOF
y
EOF
else
    mrpack-install --server-dir /server --server-file server.jar "$@"
fi

cd /server
echo "eula=true" > /server/eula.txt
cat eula.txt
java -Xms$SERVER_MEM -Xmx$SERVER_MEM -XX:+UseG1GC \
     -XX:+ParallelRefProcEnabled -XX:MaxGCPauseMillis=200 \
     -XX:+UnlockExperimentalVMOptions -XX:+DisableExplicitGC \
     -XX:+AlwaysPreTouch -XX:G1NewSizePercent=$G1NEWSIZE \
     -XX:G1MaxNewSizePercent=$G1MAXNEWSIZE -XX:G1HeapRegionSize=$G1HEAP \
     -XX:G1ReservePercent=20 -XX:G1HeapWastePercent=5 \
     -XX:G1MixedGCCountTarget=4 -XX:InitiatingHeapOccupancyPercent=15 \
     -XX:G1MixedGCLiveThresholdPercent=90 -XX:G1RSetUpdatingPauseTimePercent=5 \
     -XX:SurvivorRatio=32 -XX:+PerfDisableSharedMem -XX:MaxTenuringThreshold=1 \
     -Dusing.aikars.flags=https://mcflags.emc.gs -Daikars.new.flags=true \
     -jar server.jar