start.sh

#!/bin/bash
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# arguments
SERVER=$1
JSON_FILE=$2

###########
# Imports #
###########

# status file import
STATUS_FILE=$(jq -r ".files.status_file" "$JSON_FILE")

# statuses import
declare -A STATUS=(
    ["on"]="$(jq -r ".statuses.on" "$JSON_FILE")"
    ["run"]="$(jq -r ".statuses.run" "$JSON_FILE")"
    ["res"]="$(jq -r ".statuses.res" "$JSON_FILE")"
    ["off"]="$(jq -r ".statuses.off" "$JSON_FILE")"
    ["err"]="$(jq -r ".statuses.err" "$JSON_FILE")"
)

# log file import
LOG_FILE=$(jq -r ".files.logs_file" "$JSON_FILE")

# ram import
MIN_RAM=$(jq -r ".servers.${SERVER}.min_ram" "$JSON_FILE")
MAX_RAM=$(jq -r ".servers.${SERVER}.max_ram" "$JSON_FILE")

# parameters import
PARAMETER_ID=$(jq -r ".servers.${SERVER}.parameter_id" "$JSON_FILE")
PARAMETERS=$(jq -r ".parameters[${PARAMETER_ID}]" "$JSON_FILE")

# Jar import
JAR_FILE=$(jq -r ".servers.${SERVER}.jar_file" "$JSON_FILE")
if [ "$JAR_FILE" == null ]
then
    JAR_FILE=""
else
    JAR_FILE="-jar ${JAR_FILE}"
fi

#############
# Functions #
#############

# logging handling
function fn_to_log() {
    echo "[$(date)] : ${1}" >> "$LOG_FILE"
}

# change the server status
function fn_change_status() {
    echo "$1" > "$STATUS_FILE"
}

# move to server directory if present
cd "$SERVER" || exit 1

#################
# Crash handler #
#################

# timestamp and tries variables
TIME_STAMP=0
MAX_TRIES=3
TEST_TIME=500
TRIES=$MAX_TRIES

function fn_timer_update() {
    if [ $(($(date +%s) - "$TIME_STAMP")) -ge $TEST_TIME ]
    then
        TIME_STAMP=$(date +%s)
        TRIES=$MAX_TRIES
    else
        ((TRIES -= 1))
    fi
    
    if [ $TRIES -le 0 ]
    then
        fn_change_status "${STATUS[err]}"
    fi
}

#######################
# Server handler loop #
#######################

while true
do
    case $(cat "$STATUS_FILE")
        in
        "${STATUS[on]}")
            fn_to_log "Server started."
            fn_change_status "${STATUS[run]}"
            fn_timer_update
            java -Xmx${MAX_RAM} -Xms${MIN_RAM} ${PARAMETERS} ${JAR_FILE}
        ;;
        
        "${STATUS[run]}")
            fn_to_log "Server closed or crashed, restarting it..."
            fn_change_status "${STATUS[on]}"
        ;;
        
        "${STATUS[res]}")
            fn_to_log "Server restarted."
            fn_change_status "${STATUS[on]}"
        ;;
        
        "${STATUS[off]}")
            fn_to_log "Server stopped."
            exit 0
        ;;
        
        "${STATUS[err]}")
            fn_to_log "Server crashed multiple times, shutting it down..."
            fn_change_status "${STATUS[off]}"
        ;;
        
        *)
            fn_to_log "ERROR Start script."
            fn_to_log "Status file -> $(cat "$STATUS_FILE")"
            rm "$STATUS_FILE"
            exit 1
        ;;
    esac
done