#!/usr/bin/env bash

# THe name of the screen in which the proxy server will run
PROXY_SCREEN="proxy"
# The relative path of the velocity proxy server
VELOCITY_DIR="proxy"
# The relative path of the bungeecord proxy server
BUNGEE_DIR="bungee"
# How many seconds to sleep before starting the server again, unless it is explicitly specified
DEFAULT_SLEEP_SECONDS=3


function show_help {
  local cmd=$0

  echo "Create a start loop for the minecraft server, additionally behind a velocity proxy or bungeecord proxy"
  echo ""
  echo "Usage $cmd [OPTIONS]"
  echo ""
  echo "OPTIONS:"
  {
    local fmt="  %s\t%s\t%s\n"

    printf "$fmt" "-c" "--config <mode>" "How to configure the server (see ./configure.sh --help). Possible values for mode are: proxy, bungee, standalone"
    printf "$fmt" "-t" "--temp" "Apply the configuration only temporary, while the server is running. Requires --config."
    printf "$fmt" "" "--tmp" "Alias to --temp"
    printf "$fmt" "-s" "--sleep <secs>" "How many seconds to sleep after the server has stopped before starting it again"
    printf "$fmt" "-n" "--no-loop" "Don't restart the server once it stopped"
    printf "$fmt" "-h" "--help" "Show this message"
    printf "$fmt" "" "--proxy" "Temporary configure this server for use with Velocity and start a Velocity proxy in the screen $PROXY_SCREEN while this server is running"
    printf "$fmt" "" "--bungee" "Temporary configure this server for use with Bungeecord and start a Bungeecord proxy in the screen $PROXY_SCREEN while this server is running"
  } | column -t -s $'\t'

  exit
}

function main {
  local proxy=false
  local bungee=false
  local help=false
  local sleep_seconds=$DEFAULT_SLEEP_SECONDS
  local config=""
  local start_proxy=false
  local tmp=false
  local loop=true

  local cmd=$0

  # Parse arguments
  while [[ $# -gt 0 ]]; do
    local arg=$1
    case "$arg" in
      "--config" | "-c")
        local mode=$2
        case "$mode" in
          "proxy")
            config="velocity"
            ;;
          "bungee")
            config="bungeecord"
            ;;
          "standalone")
            config="standalone"
            ;;
          *)
            err "Invalid mode for --config: $mode"
            ;;
        esac

        if $proxy; then
          err "--config can't be used together with --proxy"
        elif $bungee; then
          err "--config can't be used together with --bungee"
        fi
        shift 2
        ;;
      "--temp" | "--tmp" | "-t")
        tmp=true
        shift
        ;;
      "--sleep" | "-s")
        sleep_seconds=$2
        shift 2
        ;;
      "--no-loop" | "-n")
        loop=false
        shift
        ;;
      "--proxy")
        proxy=true
        if $bungee; then
          err "--proxy can't be used together with --bungee"
        elif [[ -n $config ]]; then
          err "--proxy can't be used together with --config"
        fi
        shift
        ;;
      "--bungee")
        bungee=true
        if $proxy; then
          err "--bungee can't be used together with --proxy"
        elif [[ -n $config ]]; then
          err "--bungee can't be used together with --config"
        fi
        shift
        ;;
      "--help" | "-h")
        help=true
        shift
        ;;
      *)
        err "Unknown argument: $arg"
        ;;
    esac
  done

  # Late parsing:
  if $tmp && [[ -z $config ]]; then
    err "--temp requires --config parameter"
  fi
  if $proxy; then
    start_proxy=true
    config="velocity"
    tmp=true
  elif $bungee; then
    start_proxy=true
    config="bungeecord"
    tmp=true
  fi

  if $help; then
    show_help "$cmd"
  fi

  # Apply configuration
  local previous_config=$(./configure.sh --fetch)
  echo "Current configuration is $previous_config"
  if [[ -n $config ]]; then
    ./configure.sh "$config"
  fi

  # Start proxy
  if $start_proxy; then
    # create proxy screen if it doesn't exist yet
    screen -ls | grep -q "$PROXY_SCREEN" || screen -dmS "$PROXY_SCREEN"
    # start the proxy
    local proxy_dir=""
    case "$config" in
      "velocity")
        proxy_dir=$VELOCITY_DIR
        ;;
      "bungeecord")
        proxy_dir=$BUNGEE_DIR
        ;;
    esac
    screen -S "$PROXY_SCREEN" -X stuff "cd $(pwd)/$proxy_dir; ./launch.sh\n"
    echo "The proxy has been started in screen $PROXY_SCREEN"
  fi

  function cleanup {
    if $start_proxy; then
      # stop the proxy
      screen -S "$PROXY_SCREEN" -X stuff "end\n"
      echo "The proxy has been stopped"
    fi
    if $tmp; then
      ./configure.sh "$previous_config"
    fi

    exit
  }

  trap cleanup SIGINT

  while :; do
    echo "Starting server..."
    ./launch.sh

    $loop || break

    echo "Sleeping for $sleep_seconds seconds..."
    sleep "$sleep_seconds"
  done

  cleanup
}

# Shows an error message and exits the program with code 1
#
# Usage: err <msg>
function err {
  echo "$1"
  exit 1
}

main "$@"