#!/bin/sh

set -e

EXEC_NAME="$(basename -- "$0")"

options="$(getopt -n "$EXEC_NAME" -s sh  -o hvfdx -l help -l version -- "$@")"
eval set -- "$options"

SCREEN_OPTS=

while :; do
    case "$1" in
        -h|--help)
            echo "Usage: $EXEC_NAME [-fdx] [MCA_NAME|MCA_JAR|MCA_DIR] [--] [INPUT]…"
            exit
            ;;
        -v|--version)
            echo "MCA 1.0.0"
            exit
            ;;
        -f)
            SCREEN_OPTS=Dm
            ;;
        -d)
            SCREEN_OPTS=d
            ;;
        -x)
            SCREEN_OPTS=x
            ;;
        --)
            shift
            break
    esac
    shift
done

MCA_NAME=$1

if [ -z "$MCA_NAME" ]; then
    MCA_DIR="$PWD"
    MCA_NAME="$(basename -- "$MCA_DIR")"
elif echo "$MCA_NAME" | grep -qE '^\.{,2}/' && MCA_NAME="$(readlink -f -- "$MCA_NAME")"; then
    if [ -d "$MCA_NAME" ]; then
        MCA_DIR="$MCA_NAME"
        MCA_NAME="$(basename -- "$MCA_DIR")"
    else
        MCA_DIR="$(dirname -- "$MCA_NAME")" MCA_JAR="$MCA_NAME"
        MCA_NAME="$(basename -- "$MCA_DIR")"
    fi
else
    MCA_DIR="$HOME/mca/$MCA_NAME"
fi

command -v screen > /dev/null || { echo "$EXEC_NAME: screen not found" >&2; exit 2; }

if [ -n "$2" ]; then
    shift
    INPUT="$(echo "$*" | sed 's/"/\\\0/g')"
    screen -S "$MCA_NAME" -X eval "stuff \"$INPUT\"\\015" > /dev/null || {
        echo "$EXEC_NAME: no screen found" >&2
        exit 2
    }
    exit
fi

MCA_SCREENRC_FILE="/etc/mca/screenrc"
[ -r "$MCA_SCREENRC_FILE" ] || { echo "$EXEC_NAME: can't read $MCA_SCREENRC_FILE" >&2; exit 2; }

if screen -c "$MCA_SCREENRC_FILE" "-$SCREEN_OPTS"rS "$MCA_NAME" > /dev/null 2>&1; then
    exit
elif screen -S "$MCA_NAME" -X select . > /dev/null 2>&1; then
    echo "$EXEC_NAME: this screen has already been attached to someone" >&2
    exit 2
fi

[ -d "$MCA_DIR" ] || { echo "$EXEC_NAME: $MCA_DIR: not found" >&2; exit 2; }

cd "$MCA_DIR"

MCA_RC_FILE="$MCA_DIR/.mcarc"

# this file is taken from a dynamic variable, so we cannot specify an explicit path to the file
# shellcheck disable=SC1090
# `--` is supported in dash
# shellcheck disable=SC2240
[ -e "$MCA_RC_FILE" ] && . -- "$MCA_RC_FILE"

if [ -z "$PLATFORM" ]; then
    if [ -z "$MCA_JAR" ]; then
        MCA_JAR="$(find "$MCA_DIR" -maxdepth 1 -type f -name \*.jar | head -1)"
        [ -z "$MCA_JAR" ] && {
            echo "$EXEC_NAME: no jar found in $MCA_DIR" >&2
            exit 2
        }
    fi

    if [ -e "$MCA_JAR" ]; then
        PLATFORM="$(basename -- "$MCA_JAR")"
        PLATFORM="$(echo "$PLATFORM" | tr '[:upper:]' '[:lower:]' | grep -oE '[a-z]+' | head -1)"
    else
        echo "$EXEC_NAME: $MCA_JAR: no such file" >&2
        exit 2
    fi
else
    [ -z "$MCA_JAR" ] && MCA_JAR="$MCA_DIR/$PLATFORM.jar"
    [ ! -e "$MCA_JAR" ] && {
        echo "$EXEC_NAME: $MCA_JAR: no such file" >&2
        exit 2
    }
fi

[ -n "$JVM_FLAGS" ] && JVM_FLAGS="$JVM_FLAGS "
JVM_FLAGS="$JVM_FLAGS-Dfile.encoding=UTF-8 -Djava.awt.headless=true"

case "$PLATFORM" in
    bungee)
        ;;
    waterfall|velocity)
        [ "$PLATFORM" = "bungee" ] || JVM_FLAGS="$JVM_FLAGS -XX:+UseG1GC \
-XX:G1HeapRegionSize=4M \
-XX:+UnlockExperimentalVMOptions \
-XX:+ParallelRefProcEnabled \
-XX:+AlwaysPreTouch \
-DIReallyKnowWhatIAmDoingISwear=true"
        ;;
    minecraft|bukkit|craftbukkit|spigot|paper)
        JVM_FLAGS="$JVM_FLAGS -Dcom.mojang.eula.agree=true \
-DIReallyKnowWhatIAmDoingISwear=true"
        [ "$PLATFORM" = "paper" ] && JVM_FLAGS="$JVM_FLAGS -XX:+UseG1GC \
-XX:+ParallelRefProcEnabled \
-XX:MaxGCPauseMillis=200 \
-XX:+UnlockExperimentalVMOptions \
-XX:+DisableExplicitGC \
-XX:+AlwaysPreTouch \
-XX:G1NewSizePercent=30 \
-XX:G1MaxNewSizePercent=40 \
-XX:G1HeapRegionSize=8M \
-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"
        ;;
    custom)
        ;;
    *)
        echo "$EXEC_NAME: invalid platform: $PLATFORM. Valid: \
bungee, waterfall, velocity, minecraft, bukkit, craftbukkit, spigot, paper, custom" >&2
        exit 2
        ;;
esac

[ -n "$JAVA_HOME" ] && [ -d "$JAVA_HOME/bin" ] && PATH="$JAVA_HOME/bin:$PATH"

java -version > /dev/null 2>&1 || {
    echo "$EXEC_NAME: unable to get Java version (is Java installed?)" >&2
    exit 2
}

[ -n "$MAX_MEMORY" ] && JVM_FLAGS="-Xmx$MAX_MEMORY $JVM_FLAGS"
[ -n "$MIN_MEMORY" ] && JVM_FLAGS="-Xms$MIN_MEMORY $JVM_FLAGS"

MCA_CMD="$(which java) -server $JVM_FLAGS -jar $MCA_JAR"

# papermc prints uncolored text if the COLORTERM variable is set to `truecolor`
export COLORTERM=

# we don't quote $MCA_CMD because screen treats arguments after the second one as a command
# shellcheck disable=SC2086
exec screen -c "$MCA_SCREENRC_FILE" "-$SCREEN_OPTS"S "$MCA_NAME" -- $MCA_CMD