ServerModsAPIQuery.java

/*
 * This file is part of QuarterBukkit-Plugin.
 * Copyright (c) 2012 QuarterCode <http://www.quartercode.com/>
 *
 * QuarterBukkit-Plugin is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * QuarterBukkit-Plugin is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with QuarterBukkit-Plugin. If not, see <http://www.gnu.org/licenses/>.
 */

package com.quartercode.quarterbukkit.api.query;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.nio.charset.Charset;
import org.json.simple.JSONArray;
import org.json.simple.JSONValue;
import com.quartercode.quarterbukkit.QuarterBukkit;
import com.quartercode.quarterbukkit.api.FileUtils;
import com.quartercode.quarterbukkit.api.query.QueryException.QueryExceptionType;

/**
 * A server mods api query can be used to query the official server mods api (https://api.curseforge.com/servermods).
 * For example, you can create updaters or version checkers with this query.
 *
 * @see SearchQuery
 * @see FilesQuery
 */
public class ServerModsAPIQuery {

    private static final String HOST               = "https://api.curseforge.com/servermods/";
    private static final String USER_AGENT         = "QuarterBukkit/" + ServerModsAPIQuery.class.getSimpleName();
    private static final int    CONNECTION_TIMEOUT = 5 * 1000;

    private final String        query;

    /**
     * Creates a new query whose GET request {@link URL} is made out of the given query string attached to {@code https://api.curseforge.com/servermods/}.
     *
     * @param query The query string for the server mods api to process.
     */
    public ServerModsAPIQuery(String query) {

        this.query = query;
    }

    /**
     * Returns the query string which is used by the {@link #execute()} method to build the request {@link URL}.
     *
     * @return The query string for the server mods api to process.
     */
    public String getQuery() {

        return query;
    }

    /**
     * Executes the stored query and returns the result as a {@link JSONArray}.
     * The query string ({@link #getQuery()}) is attached to {@code https://api.curseforge.com/servermods/}.
     * The GET response of that {@link URL} is then parsed to a {@link JSONArray}.
     *
     * @return The response of the server mods api.
     * @throws QueryException Something goes wrong while querying the server mods api.
     */
    public JSONArray execute() throws QueryException {

        // Build request url using the query
        URL requestUrl = null;
        try {
            requestUrl = new URL(HOST + query);
        } catch (MalformedURLException e) {
            throw new QueryException(QueryExceptionType.MALFORMED_URL, this, HOST + query, e);
        }

        // Open connection to request url
        HttpURLConnection request = null;
        try {
            request = FileUtils.resolveRedirects((HttpURLConnection) requestUrl.openConnection());
        } catch (IOException e) {
            throw new QueryException(QueryExceptionType.CANNOT_OPEN_CONNECTION, this, requestUrl.toExternalForm(), e);
        }

        // Set connection timeout
        request.setConnectTimeout(CONNECTION_TIMEOUT);
        request.setReadTimeout(CONNECTION_TIMEOUT);

        // Set user agent
        request.addRequestProperty("User-Agent", USER_AGENT);

        // Set api key (if provided)
        String apiKey = QuarterBukkit.getPlugin().getConfig().getString("server-mods-api-key");
        if (apiKey != null && !apiKey.isEmpty()) {
            request.addRequestProperty("X-API-Key", apiKey);
        }

        // We want to read the results
        request.setDoOutput(true);

        // Read first line from the response
        BufferedReader reader = null;
        String response = null;
        try {
            reader = new BufferedReader(new InputStreamReader(request.getInputStream(), Charset.forName("UTF-8")));
            response = reader.readLine();
        } catch (IOException e) {
            if (e.getMessage().contains("HTTP response code: 403")) {
                throw new QueryException(QueryExceptionType.INVALID_API_KEY, this, requestUrl.toExternalForm(), e);
            } else {
                throw new QueryException(QueryExceptionType.CANNOT_READ_RESPONSE, this, requestUrl.toExternalForm(), e);
            }
        } finally {
            if (reader != null) {
                try {
                    reader.close();
                } catch (IOException e) {
                    // Ignore
                }
            }
        }

        // Parse the response
        Object jsonResponse = JSONValue.parse(response);

        if (jsonResponse instanceof JSONArray) {
            return (JSONArray) jsonResponse;
        } else {
            throw new QueryException(QueryExceptionType.INVALID_RESPONSE, this, requestUrl.toExternalForm());
        }
    }

}