Bash_Scripts/CentOS/Minecraft/Minecraft-Start-Server.bash

#!/bin/bash

### CONSTANTS ###

#gigabytes
MAX_RAM=8

#gigabytes
INITIAL_MEM=2


log() {
  # Print a message and send it to stdout or stderr depending upon log level, also configurable with debug etc.
  #
  # Arguments:
  #   level <type: string> <position: 1> <required: true>
  #     - The log level, defined within a case check in this function
  #   message <type: string> <position: 2> <required: true>
  #     - The info message
  #   line_number <type: int> <position: 3> <required: false>
  #     - The line number of the calling function (${LINNO})
  #
  # Usage:
  #   log "info" "Could not find that directory"
  #
  # POSIX Compliant:
  #   Yes
  #

  # Set debug status depending if a global debug variable has been set to either 1 or 0
  local debug
  if [ ${DEBUG} ]; then
    debug=${DEBUG}
  else
    debug=0
  fi

  local FORMAT
  FORMAT="[$(date +%Y-%m-%dT%H:%M:%S%z)]"

  # Convert the level to uppercase
  local level
  level=$(echo "${1}" | tr '[:lower:]' '[:upper:]')

  local message
  message="${2}"

  case "${level}" in
    INFO)
      # Output all info log levels to stdout
      printf "${FORMAT}[INFO] %s\n" "${message}" >&1
      return 0
      ;;
    DEBUG)
      [[ ${debug} == 0 ]] && return 0
      printf "${FORMAT}[DEBUG] %s\n" "${message}" >&1
      return 0
      ;;
    ERROR)
      # Output all error log levels to stderr
      printf "${FORMAT}[ERROR] %s\n" "${message}" >&2
      return 0
      ;;
    # Further log levels can be added by extending this switch statement with more comparisons

    *) # Default case, no matches
      # Returns non-zero code as an improper log option was passed, this helps with using `set -e`
      log "ERROR" "Invalid log level passed, received level \"${level}\" with message \"${message}\""
      return 1
  esac
}

usage() {
  # Print out usage instructions for the local script
  #
  # Arguments:
  #   None
  #
  # Usage:
  #   usage
  #
  # POSIX Compliant:
  #   Yes
  #
  printf "Usage: %s%s\n" \
  "$(basename ${0}) " \
  "
  -i \"this is some input\" -t \"this is some more example input\"
  --input <string> | -i <string>
    Example:
      --input \"this is an example input\"
  --test <string> | -t <string>
    Example:
      --test \"this is more example input\""
}


server_id=""
minecraft_jar=""

parse_args() {
  # Parse input arguments
  #
  # Arguments:
  #   Consult the `usage` function
  #
  # Usage:
  #   parse_args "$@"
  #     - All arguments should be ingested by parse_args first for variable setting
  #
  # POSIX Compliant:
  #   Yes
  #

  while :; do
    case ${1} in
      -h | -\? | --help)
        usage # Display a usage synopsis.
        exit
        ;;
      --) # End of all options.
        break
        ;;
      -s | --server)
        shift
        server_id="${1}"
        ;;
      -j | --jar)
        shift
        minecraft_jar="${1}"
        ;;
      -?*)
        printf 'Unknown option: %s\n' "$1" >&2
        usage
        ;;
      *) # Default case: No more options, so break out of the loop.
        break ;;
    esac
    shift
  done
}

parse_args "$@"

# Check and see that the correct variables were set, some may not be expanded as if they're empty they're useless
# anyhow
[[ -z "${server_id}" ]] && log "error" "No server ID provided" && exit 1
[[ "${server_id}" =~ [0-9] ]] || (log "error" "Server ID must be a number, received: ${server_id}" && exit 1)

minecraft_directory=~/Minecraft/Server-"${server_id}"

mkdir -p "${minecraft_directory}"
cd "${minecraft_directory}" || (log "error" "Unable to change directory to ${minecraft_directory}" && exit 1)

if [ ! -z "${minecraft_jar}" ]; then
  [[ -d "${minecraft_jar}" ]] || (log "error" "Could not find a minecraft server jar at \"${minecraft_jar}\"" && exit 1)
  minecraft_jar_name="$(basename ${minecraft_jar})"
  mv "${minecraft_jar}" "${minecraft_directory}/server.jar"
  java -jar "${minecraft_directory}/${minecraft_jar_name}"
elif [ ! -d "${minecraft_directory}" ]; then
  log "error" "The minecraft server \"${minecraft_directory}\" did not exist, to create it please pass the \"--jar\" flag..."
  exit 1
fi

server_port=$(("12000" + "${server_id}"))
query_port=$(("12100" + "${server_id}"))
rcon_port=$(("12200" + "${server_id}"))


## Set the correct ports
sed -i "s/server-port=.+/server-port=${server_port}/g" server.properties \
  && log "info" "Set the server port to ${server_port}"
sed -i "s/query.port=.+/query.port=${query_port}/g" server.properties \

sed -i "s/rcon.port=.+/rcon.port=${rcon_port}/g" server.properties

## Turn RCON On
# set the rcon password to the default
log "info" "Setting the RCON password..."

default_rcon_password=""
[[ -z "${default_rcon_password}" ]] \
  && log "error" "No RCON password has been defined within $(basename "${0}") -- exiting!" \
    && exit 1

sed -i "s/rcon.password=.+/rcon.password=${default_rcon_password}/g" server.properties \
  && log "info" "RCON password set"