#!/bin/bash
# A quick and dirty script to fetch the latest stable minecraft_server.jar

VERSION_URL="https://launchermeta.mojang.com/mc/game/version_manifest.json"
LATEST_VER=$(wget -qO - "${VERSION_URL}" | jq -r .latest.release)
# Our CURRENT_VER is stored in current_ver and we don't need no stinking error messages

source current_ver > /dev/null 2>&1

# Check if we need a new minecraft_server.jar
if [ ! "${CURRENT_VER:-1}" = "${LATEST_VER}" ] || [ ! -f minecraft_server.jar ]; then
  LATEST_MANIFEST=$(wget -qO - "${VERSION_URL}" | jq -r --arg VERSION_TARGET "${LATEST_VER}" '.versions | .[] | select(.id==$VERSION_TARGET) | .url')
  LATEST_SERVER_URL=$(wget -qO - "${LATEST_MANIFEST}" | jq -r .downloads.server.url)
  wget -q "${LATEST_SERVER_URL}" -O minecraft_server.jar && echo "CURRENT_VER=${LATEST_VER}" > current_ver
fi