#!/bin/sh

set -e

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

USAGE="Usage: $EXEC_NAME [OPTION]... [NAME|JAR|DIR] [INPUT]..."
VERSION="mca 1.0.0"

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

SCREEN_OPTS=
REATTACH_ONLY=0
SKIP_CONFIGURE=0
CONFIGURE_ONLY=0

while :; do
    case "$1" in
        -h|--help)
            echo "$USAGE"
            exit
            ;;
        -v|--version)
            echo "$VERSION"
            exit
            ;;
        -f)
            SCREEN_OPTS=Dm
            ;;
        -d)
            SCREEN_OPTS=d
            ;;
        -x)
            SCREEN_OPTS=x
            ;;
        -r)
            REATTACH_ONLY=1
            ;;
        -s)
            SKIP_CONFIGURE=1
            ;;
        -c)
            CONFIGURE_ONLY=1
            ;;
        --)
            shift
            break
    esac
    shift
done

if [ "$SKIP_CONFIGURE" -eq 1 ] && [ "$CONFIGURE_ONLY" -eq 1 ]; then
    echo "$EXEC_NAME: can't skip configuration and only configure at \
the same time" >&2
    exit 2
fi

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

if [ "$CONFIGURE_ONLY" -eq 0 ]; then
    if ! command -v screen > /dev/null; then
        echo "$EXEC_NAME: screen not found" >&2
        exit 2
    fi

    SCREEN_NAME="$(echo "$MCA_NAME" | tr / -)"

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

    SCREEN_RC_FILE=
    for i in "$HOME/.config" /etc; do
        j="$i/mca/screenrc"
        if [ -r "$j" ]; then
            SCREEN_RC_FILE=$j
            break
        fi
    done

    if [ -z "$SCREEN_RC_FILE" ]; then
        echo "$EXEC_NAME: can't find screenrc" >&2
        exit 2
    fi

    if screen -c "$SCREEN_RC_FILE" "-$SCREEN_OPTS"rS \
        "$SCREEN_NAME" > /dev/null 2>&1; then
        exit 0
    elif screen -S "$SCREEN_NAME" -X select . > /dev/null 2>&1; then
        echo "$EXEC_NAME: this screen has already been attached to someone" >&2
        exit 2
    fi

    if [ "$REATTACH_ONLY" -eq 1 ]; then
        echo "$EXEC_NAME: $SCREEN_NAME: no such screen found" >&2
        exit 2
    fi

    if [ ! -d "$MCA_DIR" ]; then
        echo "$EXEC_NAME: $MCA_DIR: such directory not found" >&2
        exit 2
    fi
fi

cd "$MCA_DIR"

MCA_RC_FILE="$MCA_DIR/.mcarc"

if [ -e "$MCA_RC_FILE" ]; then
    # don't use `-p` in `read` for line breaks to avoid long lines.
    # shellcheck disable=SC2162
    while IFS= read line; do
        # skip lines starting with '#'
        case "$line" in
            ''|\#*)
                continue
                ;;
        esac

        # to get `$1` and `$2` as key and value.
        # shellcheck disable=SC2086
        set $line

        if echo "$1" | grep -i '[^a-zA-Z0-9_]'; then
            echo "$EXEC_NAME: $1: option key contains invalid characters" >&2
        else
            KEY="MCA_$(echo "$1" | tr '[:lower:]' '[:upper:]')"
            if [ -n "$2" ]; then
                shift
                VALUE=$*
            fi
            export "$KEY"="$VALUE"
        fi
    done < "$MCA_RC_FILE"
    MCA_RC_FILE_READ=1
else
    MCA_RC_FILE_READ=0
fi

if [ "$CONFIGURE_ONLY" -eq 0 ]; then
    if [ -z "$MCA_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 "$MCA_JAR" ]; then
            MCA_PLATFORM="$(basename -- "$MCA_JAR")"
            MCA_PLATFORM="$(echo "$MCA_PLATFORM" \
                | tr '[:upper:]' '[:lower:]' | grep -oE '[a-z]+' | head -1)"
        else
            echo "$EXEC_NAME: $MCA_JAR: no such file" >&2
            exit 2
        fi
    else
        [ -z "$MCA_JAR" ] && MCA_JAR="$MCA_DIR/$MCA_PLATFORM.jar"
        if [ ! -e "$MCA_JAR" ]; then
            echo "$EXEC_NAME: $MCA_JAR: no such file" >&2
            exit 2
        fi
    fi

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

    case "$MCA_PLATFORM" in
        bungee)
            ;;
        waterfall|velocity)
            [ "$MCA_PLATFORM" = "bungee" ] || MCA_JVM_FLAGS="$MCA_JVM_FLAGS \
    -XX:+UseG1GC \
    -XX:G1HeapRegionSize=4M \
    -XX:+UnlockExperimentalVMOptions \
    -XX:+ParallelRefProcEnabled \
    -XX:+AlwaysPreTouch \
    -DIReallyKnowWhatIAmDoingISwear=true"
            ;;
        minecraft|bukkit|craftbukkit|spigot|paper)
            MCA_JVM_FLAGS="$MCA_JVM_FLAGS -Dcom.mojang.eula.agree=true \
    -DIReallyKnowWhatIAmDoingISwear=true"
            [ "$MCA_PLATFORM" = "paper" ] && MCA_JVM_FLAGS="$MCA_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: $MCA_PLATFORM. Valid: bungee, \
                waterfall, velocity, minecraft, bukkit, craftbukkit, spigot, \
                paper, custom" >&2
            exit 2
            ;;
    esac

    if [ -n "$MCA_OPT_JAVA_HOME" ] && [ -d "$MCA_OPT_JAVA_HOME/bin" ]; then
        PATH="$MCA_OPT_JAVA_HOME/bin:$PATH"
    fi

    if ! command -v java > /dev/null; then
        echo "$EXEC_NAME: unable to get Java version (is Java installed?)" >&2
        exit 2
    fi

    [ -n "$MCA_OPT_MAX_MEMORY" ] \
        && MCA_JVM_FLAGS="-Xmx$MCA_OPT_MAX_MEMORY $MCA_JVM_FLAGS"
    [ -n "$MCA_OPT_MIN_MEMORY" ] \
        && MCA_JVM_FLAGS="-Xms$MCA_OPT_MIN_MEMORY $MCA_JVM_FLAGS"

    SCREEN_CMD="$(which java) -server $MCA_JVM_FLAGS -jar $MCA_JAR"
fi

if [ "$SKIP_CONFIGURE" -eq 0 ] && [ "$MCA_RC_FILE_READ" -eq 1 ]; then
    ENV_LIST="$(env | grep ^MCA_ | cut -d= -f1 | sed 's/^/$/g')"
    FILE_LIST="$(find . -name '*.in' -type f)"

    [ -z "$FILE_LIST" ] || echo "$FILE_LIST" | while read -r line; do
        envsubst "$ENV_LIST" < "$line" > "${line%*.in}"
    done
fi

if [ "$CONFIGURE_ONLY" -eq 0 ]; then
    # papermc prints uncolored text if the COLORTERM variable is set to
    # `truecolor`.
    export COLORTERM=

    # we don't quote $SCREEN_CMD because screen treats arguments after the
    # second one as a command.
    # shellcheck disable=SC2086
    exec screen -c "$SCREEN_RC_FILE" "-$SCREEN_OPTS"S "$SCREEN_NAME" \
        -- $SCREEN_CMD
fi