#!/bin/bash

### CONSTANTS ###

#gigabytes
MAX_MEM=8

#gigabytes
INITIAL_MEM=2

#rcon password
DEFAULT_RCON_PASSWORD="bqMLwxCJKRktrQoir2pg4KkTeBDQLjb4C+RYesdmeKF4sie8"

echo_rgb() {
  # Echo a colored string to the terminal based on rgb values
  #
  # Positional Arguments:
  #
  #   message <type: string> <position: 1> <required: true>
  #     - The message to be printed to stdout
  #   red <type: int> <position: 2> <required: true>
  #     - The red value from 0 to 255
  #   green <type: int> <position: 3> <required: true>
  #     - The green value from 0 to 255
  #   blue <type: int> <position: 4> <required: true>
  #     - The blue value from 0 to 255
  #
  # Usage:
  #   echo_rgb 10 80 3 "Yep"
  #
  # POSIX Compliant:
  #   N/A
  #

  local red
  local green
  local blue
  local input

  input="${1}"
  red="${2}"
  green="${3}"
  blue="${4}"

  printf "\e[0;38;2;%s;%s;%sm%s\e[m\n" "${red}" "${green}" "${blue}" "${input}"
}

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="[$(echo_rgb "$(date +%Y-%m-%dT%H:%M:%S)" 180 140 255)]"

  # 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}[$(echo_rgb "INFO" 0 140 255)] %s\n" "${message}" >&1
      return 0
      ;;
    WARN | WARNING)
      # Output all info log levels to stdout
      printf "${FORMAT}[$(echo_rgb "WARNING" 255 255 0)] %s\n" "${message}" >&1
      return 0
      ;;
    DEBUG)
      [[ ${debug} == 0 ]] && return 0
      printf "${FORMAT}[$(echo_rgb "DEBUG" 0 160 110)] %s\n" "${message}" >&1
      return 0
      ;;
    ERROR)
      # Output all error log levels to stderr
      printf "${FORMAT}[$(echo_rgb "ERROR" 255 0 0)] %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`
      printf "${FORMAT}[ERROR] %s\n" "Invalid log level passed, received level \"${level}\" with message \"${message}\"" >&2
      return 1
      ;;
  esac
}


confirmation() {
  # Receive confirmation from user as y, Y, n, or N
  # returns 0 when answer is yes and 1 when answer is no
  #
  # Arguments:
  #   message <type: string> <position: 1> <required: true>
  #     - The confirmation prompt sent to the user, for example:
  #       Would you like to overwrite foobar.txt (y/N)?
  #
  # Usage:
  #   confirmation "Some prompt"
  #     - Sends "Some prompt" to the user and gets their input
  #
  # POSIX Compliant:
  #   Yes
  #

  local message
  message="${1}"

  local choice

  while true; do
    read -p "${message} " -n 1 -r choice
    case "$choice" in
      y | Y)
      echo ""
      return 0
      ;;
      n | N)
      echo ""
      return 1
      ;;
      *) echo -e "\nInput must be either y, Y, n, or N" ;;
    esac
  done
}


usage() {
  # Print out usage instructions for the local script
  #
  # Arguments:
  #   None
  #
  # Usage:
  #   usage
  #
  # POSIX Compliant:
  #   Yes
  #
  printf "Usage: %s\n" \
  "$(basename "${0}") -s <server id> | $(basename "${0}") -s <server id> -r | $(basename "${0}") -s <server id> -j <path/to/minecraft/jar>
  --server <server id> -s <server id>
    Which minecraft server to start, see the ~/Minecraft directory -- each number corresponds to an ID

    Example:
      --server 1
  --r  | --rcon-ignore
    Flag that takes no parameters -- when enabled this script will not overwrite the RCON password in the targeted server

    Example:
      --rcon-ignore
  --jar <path/to/mc/server/jar/file> | -j <path/to/mc/server/jar/file>
    Takes in a path to a minecraft server jar file. It copies that file to create the new server

    Example:
      --jar ~/Minecraft-Server-Jars/minecraft_server1.17.1.jar"
}



server_id=""
minecraft_jar=""
rcon_ignore=0

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}"
        ;;
      -r | --rcon-ignore)
        rcon_ignore=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}"

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

create_directories

if [ -n "${minecraft_jar}" ]; then
  if [ ! -f "${minecraft_jar}" ]; then
    log "error" "Could not find a minecraft server jar \"${minecraft_jar}\""
    exit 1
  fi

  minecraft_jar_name="$(basename "${minecraft_jar}")"
  log "info" "Copying minecraft server files..."
  cp "${minecraft_jar}" "${minecraft_directory}" \
    && log "info" "Finished copying files"
  mv "${minecraft_directory}/${minecraft_jar_name}" "${minecraft_directory}/server.jar"
  log "info" "Installed a minecraft server.jar to Minecraft-Server-${server_id}"
  java -jar "${minecraft_directory}"/server.jar > /dev/null 2>&1
  log "info" "Successfully installed the minecraft server.jar to Minecraft-Server-${server_id}, continuing with setup"
elif [ ! -f "${minecraft_directory}"/server.jar ]; then
  log "error" "No server.jar found within ${minecraft_directory}, to create a new server there use the \"--jar\" flag"
  exit 1
fi

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


## Create a backup of the config file
backup_extension="$(date +%Y-%m-%dT%H:%M:%S%z)"

log "info" "Making a backup of the server.properties file in ${minecraft_directory}/backups/server.properties.${backup_extension}"
rm -f
cp "${minecraft_directory}/server.properties" "${minecraft_directory}/backups/server.properties.${backup_extension}" \
  && log "info" "Successfully created backup"

## 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}" || exit 1

sed -i "s/query.port=.*/query.port=${query_port}/g" server.properties \
  && log "info" "Set the query port to ${query_port}" || exit 1

sed -i "s/rcon.port=.*/rcon.port=${rcon_port}/g" server.properties \
  && log "info" "Set the RCON port to ${rcon_port}" || exit 1


## Turn RCON On
# set the rcon password to the default if rcon-ignore is not set
if [[ "${rcon_ignore}" == 0 ]]; then
  log "info" "Setting the RCON password..."

  [[ -z "${DEFAULT_RCON_PASSWORD}" ]] \
    && log "warning" "No RCON password has been defined within $(basename "${0}"), consider generating one with \"openssl rand -base64 36\""

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

  sed -i "s/enable-rcon=false/enable-rcon=true/g" server.properties \
    && log "info" "RCON Enabled"
fi

## Accept the eula
sed -i "s/eula=false/eula=true/g" eula.txt \
  && log "info" "Minecraft eula accepted"

## Go ahead and start 'er on up

tmux has-session -t "Minecraft-Server-${server_id}" > /dev/null 2>&1

if [ "${?}" == 0 ]; then
  log "warning" "That minecraft server is currently running"
  confirmation "Would you like to kill it and then run the new one (y/N)?"
  if [ "${?}" == 0 ]; then
    log "info" "Ok, killing server..."
    tmux kill-session -t "Minecraft-Server-${server_id}" \
       && log "info" "Successfully killed the server"
  else
    log "info" "Not ending current Minecraft-Server-${server_id}, exiting..."
    exit 0
  fi
fi

log "info" \
"Startup Arguments:
  -Xms${INITIAL_MEM}G
  -Xmx${MAX_MEM}G
  -jar"

log "info" "Starting Minecraft-Server-${server_id}"

tmux new-session -d -s \
  "Minecraft-Server-${server_id}" \
    java -Xms"${INITIAL_MEM}G" -Xmx"${MAX_MEM}G" -jar server.jar --nogui \
      && log "info" \
"Server Minecraft-Server-${server_id} started successfully:
  Game Port: ${server_port}
  Query Port: ${query_port}
  RCON Port: ${rcon_port}"