RedisBungee/RedisBungee-API/src/main/java/com/imaginarycode/minecraft/redisbungee/api/tasks/InitialUtils.java

package com.imaginarycode.minecraft.redisbungee.api.tasks;

import com.imaginarycode.minecraft.redisbungee.api.RedisBungeePlugin;
import com.imaginarycode.minecraft.redisbungee.api.util.RedisUtil;
import com.imaginarycode.minecraft.redisbungee.api.util.io.IOUtil;
import com.imaginarycode.minecraft.redisbungee.api.util.lua.LuaManager;
import redis.clients.jedis.Jedis;
import redis.clients.jedis.JedisCluster;
import redis.clients.jedis.exceptions.JedisException;

import java.io.IOException;
import java.io.InputStream;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.Collections;

public class InitialUtils {

    public static LuaManager.Script getTimeScript(RedisBungeePlugin<?> plugin, LuaManager luaManager) {
        return new RedisTask<LuaManager.Script>(plugin) {
            @Override
            public LuaManager.Script jedisTask(Jedis jedis) {
                // This is more portable than INFO <section>
                String info = jedis.info();
                for (String s : info.split("\r\n")) {
                    if (s.startsWith("redis_version:")) {
                        String version = s.split(":")[1];
                        plugin.logInfo(version + " <- redis version");
                        if (!RedisUtil.isRedisVersionRight(version)) {
                            plugin.logFatal("Your version of Redis (" + version + ") is not at least version 3.0 RedisBungee requires a newer version of Redis.");
                            throw new RuntimeException("Unsupported Redis version detected");
                        }
                        long uuidCacheSize = jedis.hlen("uuid-cache");
                        if (uuidCacheSize > 750000) {
                            plugin.logInfo("Looks like you have a really big UUID cache! Run https://www.spigotmc.org/resources/redisbungeecleaner.8505/ as soon as possible.");
                        }
                        break;
                    }
                }
                return null;
            }

            @Override
            public LuaManager.Script clusterJedisTask(JedisCluster jedisCluster) {
                // This is more portable than INFO <section>
                LuaManager.Script getRedisClusterTimeScript;
                try {
                    getRedisClusterTimeScript = luaManager.createScript(IOUtil.readInputStreamAsString(getResourceAsStream("lua/get_time.lua")));
                } catch (JedisException e) {
                    throw new RuntimeException("possible not supported redis version", e);
                }
                String info = (String) luaManager.createScript(IOUtil.readInputStreamAsString(getResourceAsStream("lua/get_info.lua"))).eval(Collections.singletonList("0"), Collections.emptyList());
                for (String s : info.split("\r\n")) {
                    if (s.startsWith("redis_version:")) {
                        String version = s.split(":")[1];
                        plugin.logInfo(version + " <- redis version");
                        if (!RedisUtil.isRedisVersionRight(version)) {
                            plugin.logFatal("Your version of Redis (" + version + ") is not at least version 3.0 RedisBungee requires a newer version of Redis.");
                            throw new RuntimeException("Unsupported Redis version detected");
                        }
                        long uuidCacheSize = jedisCluster.hlen("uuid-cache");
                        if (uuidCacheSize > 750000) {
                            plugin.logInfo("Looks like you have a really big UUID cache! Run https://www.spigotmc.org/resources/redisbungeecleaner.8505/ as soon as possible.");
                        }
                        break;
                    }
                }
                return getRedisClusterTimeScript;
            }
        }.execute();
    }


    public static void checkIfRecovering(RedisBungeePlugin<?> plugin, Path dataFolder) {
        new RedisTask<Void>(plugin) {
            @Override
            public Void jedisTask(Jedis jedis) {
                Path crashFile = dataFolder.resolve("restarted_from_crash.txt");
                if (Files.exists(crashFile)) {
                    try {
                        Files.delete(crashFile);
                    } catch (IOException e) {
                        throw new RuntimeException(e);
                    }
                    plugin.logInfo("crash file was deleted");
                } else if (jedis.hexists("heartbeats", plugin.getConfiguration().getProxyId())) {
                    try {
                        long value = Long.parseLong(jedis.hget("heartbeats", plugin.getConfiguration().getProxyId()));
                        long redisTime = plugin.getRedisTime(jedis.time());
                        if (redisTime < value + RedisUtil.PROXY_TIMEOUT) {
                            logImposter(plugin);
                           throw new RuntimeException("Possible impostor instance!");
                        }
                    } catch (NumberFormatException ignored) {
                    }
                }
                return null;
            }

            @Override
            public Void clusterJedisTask(JedisCluster jedisCluster) {
                Path crashFile = dataFolder.resolve("restarted_from_crash.txt");
                if (Files.exists(crashFile)) {
                    try {
                        Files.delete(crashFile);
                    } catch (IOException e) {
                        throw new RuntimeException(e);
                    }
                    plugin.logInfo("crash file was deleted");
                } else if (jedisCluster.hexists("heartbeats", plugin.getConfiguration().getProxyId())) {
                    try {
                        long value = Long.parseLong(jedisCluster.hget("heartbeats", plugin.getConfiguration().getProxyId()));
                        long redisTime = plugin.getRedisTime();

                        if (redisTime < value + RedisUtil.PROXY_TIMEOUT) {
                            logImposter(plugin);
                            throw new RuntimeException("Possible impostor instance!");
                        }
                    } catch (NumberFormatException ignored) {
                    }
                }
                return null;
            }
        }.execute();
    }

    private static void logImposter(RedisBungeePlugin<?> plugin) {
       plugin.logFatal("You have launched a possible impostor Velocity / Bungeecord instance. Another instance is already running.");
        plugin.logFatal("For data consistency reasons, RedisBungee will now disable itself.");
        plugin.logFatal("If this instance is coming up from a crash, create a file in your RedisBungee plugins directory with the name 'restarted_from_crash.txt' and RedisBungee will not perform this check.");
    }

    private static InputStream getResourceAsStream(String resource) {
        return InitialUtils.class.getClassLoader().getResourceAsStream(resource);
    }
}