RedisBungee/src/main/java/com/imaginarycode/minecraft/redisbungee/util/NameFetcher.java

/**
 * Copyright © 2013 tuxed <write@imaginarycode.com>
 * This work is free. You can redistribute it and/or modify it under the
 * terms of the Do What The Fuck You Want To Public License, Version 2,
 * as published by Sam Hocevar. See http://www.wtfpl.net/ for more details.
 */
package com.imaginarycode.minecraft.redisbungee.util;

import com.google.common.collect.ImmutableList;
import com.google.gson.reflect.TypeToken;
import com.imaginarycode.minecraft.redisbungee.RedisBungee;

import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.UUID;
import java.util.concurrent.Callable;

/* Credits to evilmidget38 for this class. I modified it to use Gson. */
class NameFetcher implements Callable<Map<UUID, String>> {
    private static final String PROFILE_URL = "https://sessionserver.mojang.com/session/minecraft/profile/";
    private final List<UUID> uuids;

    public NameFetcher(List<UUID> uuids) {
        this.uuids = ImmutableList.copyOf(uuids);
    }

    @Override
    public Map<UUID, String> call() throws Exception {
        Map<UUID, String> uuidStringMap = new HashMap<>();
        for (UUID uuid : uuids) {
            HttpURLConnection connection = (HttpURLConnection) new URL(PROFILE_URL + uuid.toString().replace("-", "")).openConnection();
            Map<String, String> response = RedisBungee.getGson().fromJson(new InputStreamReader(connection.getInputStream()), new TypeToken<Map<String, String>>() {
            }.getType());
            String name = response.get("name");
            if (name == null) {
                continue;
            }
            String cause = response.get("cause");
            String errorMessage = response.get("errorMessage");
            if (cause != null && cause.length() > 0) {
                throw new IllegalStateException(errorMessage);
            }
            uuidStringMap.put(uuid, name);
        }
        return uuidStringMap;
    }
}