#!/usr/bin/env bash

# Constants

# port of the server in standalone mode, aka the open port
STANDALONE_PORT=25565
# port of the server in proxy mode, aka the internal port
PROXY_PORT=25566
# installs ViaVersion on BungeeCord and standalone mode, removes it in Velocity mode
MANAGE_VIA_VERSION=true
# installs ViaBackwards on BungeeCord and standalone mode, removes it in Velocity mode
MANAGE_VIA_BACKWARDS=$MANAGE_VIA_VERSION

# Prefix of the ViaVersion jar
VIA_VERSION_NAME="ViaVersion"
# Prefix of the ViaBackwards jar
VIA_BACKWARDS_NAME="ViaBackwards"
# Github repo of ViaVersion project
VIA_VERSION_REPO="ViaVersion/ViaVersion"
# Github repo of ViaBackwards project
VIA_BACKWARDS_REPO="ViaVersion/ViaBackwards"

# Runtime variables

quiet=false


function main {

  # parse arguments
  local velocity=false
  local bungeecord=false
  local standalone=false
  local fetch=false
  local help=false

  for arg in "$@"; do
    case "$arg" in
      "velocity")
        velocity=true
        if $bungeecord || $standalone; then
          err "argument velocity can't be used together with bungeecord or standalone"
        fi
        ;;
      "bungeecord")
        bungeecord=true
        if $velocity || $standalone; then
          err "argument bungeecord can't be used together with velocity or standalone"
        fi
        ;;
      "standalone")
        standalone=true
        if $bungeecord || $velocity; then
          err "argument standalone can't be used together with bungeecord or velocity"
        fi
        ;;
      "--fetch")
        fetch=true
        quiet=true
        ;;
      "--quiet" | "-q")
        quiet=true
        ;;
      "--help")
        help=true
        ;;
      *)
        err "Unknown argument: $arg"
        ;;
    esac
  done

  if $help; then
    echo "Configure the server to be used with BungeeCord, Velcity or in standalone mode."
    echo ""
    echo "Usage: $0 [OPTIONS] <mode>"
    echo ""
    echo "mode:"
    echo "  velocity"
    echo "  bungeecord"
    echo "  standalone"
    echo ""
    echo "OPTIONS:"
    echo "  --fetch - print the current mode before reconfiguring the server. Nothing else will be printed."
    echo "  --help - show this message"
    echo "  -q --quiet - Dont print any output, except for output which is caused by --fetch"
    exit 0
  fi

  # fetch current configuration
  if $fetch; then
    if [ "$(yq '.proxies.velocity.enabled // false' config/paper-global.yml)" = "true" ]; then
      echo "velocity"
    elif [ "$(yq '.settings.bungeecord // false' spigot.yml)" = "true" ]; then
      echo "bungeecord"
    else
      echo "standalone"
    fi
  fi

  # Do the actual configuration

  # Velocity
  if $velocity; then
    enable_online_mode false
    set_port "$PROXY_PORT"
    enable_velocity true
    enable_bungeecord false
    if $MANAGE_VIA_VERSION; then
      remove_plugin "$VIA_VERSION_NAME"
    fi
    if $MANAGE_VIA_BACKWARDS; then
      remove_plugin "$VIA_BACKWARDS_NAME"
    fi

  # BungeeCord
  elif $bungeecord; then
    enable_online_mode false
    set_port "$PROXY_PORT"
    enable_velocity false
    enable_bungeecord true
    if $MANAGE_VIA_VERSION; then
      update_plugin "$VIA_VERSION_NAME" "$VIA_VERSION_REPO"
    fi
    if $MANAGE_VIA_BACKWARDS; then
      update_plugin "$VIA_BACKWARDS_NAME" "$VIA_BACKWARDS_REPO"
    fi

  # standalone
  elif $standalone; then
    enable_online_mode true
    set_port "$STANDALONE_PORT"
    enable_velocity false
    enable_bungeecord false
    if $MANAGE_VIA_VERSION; then
      update_plugin "$VIA_VERSION_NAME" "$VIA_VERSION_REPO"
    fi
    if $MANAGE_VIA_BACKWARDS; then
      update_plugin "$VIA_BACKWARDS_NAME" "$VIA_BACKWARDS_REPO"
    fi
  fi
}

# Enables or disables online mode
#
# Usage: enable_online_mode <true|false>
function enable_online_mode {
  sed -ie "/online-mode/c\online-mode=$1" server.properties
}

# Set the port of the server
#
# Usage: set_port <port>
function set_port {
  sed -ie "/server-port/c\server-port=$1" server.properties
}

# Enables or disables velocity in the paper config.
# Does NOT configure the forwarding secret!
#
# Usage: enable_velocity <true|false>
function enable_velocity {
  yq -iy ".proxies.velocity.enabled = $1" config/paper-global.yml
}

# Enables or disables bungeecord in spigot.yml.
#
# Usage: enable_bungeecord <true|false>
function enable_bungeecord {
  yq -iy ".settings.bungeecord = $1" spigot.yml
}

# Removes a plugin
#
# Usage: remove_plugin <jar-prefix>
function remove_plugin {
  local plugin_name=$1
  rm plugins/"$plugin_name"*.jar 2>/dev/null
}

# Update the latest release of a plugin from github
#
# Usage: update_plugin <jar-prefix> <repo>
function update_plugin {
  local plugin_name=$1
  local repo=$2
  remove_plugin $plugin_name
  download_jar_from_github $repo "plugins/"
}

# Download the jar files from the latest release of a github repo
#
# Usage: download_jar_from_github <repo> <destination>
function download_jar_from_github {
  local repo=$1
  local dst=$2
  local url=$(curl -s "https://api.github.com/repos/$repo/releases/latest" | jq -r '.assets[] | select(.name | endswith(".jar")) | .browser_download_url')
  if $quiet; then
    wget -qP "$dst" "$url"
  else
    wget -P "$dst" "$url"
  fi
}

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

main "$@"