Improve JSON parsing

[fonbot.git] / src / ro / ieval / fonbot / PollServerAsyncTask.java

package ro.ieval.fonbot;

import static ro.ieval.fonbot.Utils.toNonNull;

import java.io.IOException;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;

import org.eclipse.jdt.annotation.Nullable;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import ro.ieval.fonbot.Address.Protocol;
import android.content.Context;
import android.os.AsyncTask;
import android.preference.PreferenceManager;
import android.util.Base64;
import android.util.Log;

import com.google.android.gcm.GCMRegistrar;

/*
 * Copyright © 2013 Marius Gavrilescu
 * 
 * This file is part of FonBot.
 *
 * FonBot 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.
 *
 * FonBot 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 FonBot.  If not, see <http://www.gnu.org/licenses/>. 
 */

/**
 * AsyncTask that polls the server for pending commands and executes any commands found.
 *
 * @author Marius Gavrilescu <marius@ieval.ro>
 */
public final class PollServerAsyncTask extends AsyncTask<Void, Void, List<PollServerAsyncTask.Command>> {
	/**
	 * POJO that represents a command in a basic form: a command name, a list of arguments and a reply address, all of them being strings
	 *
	 * @author Marius Gavrilescu <marius@ieval.ro>
	 */
	final class Command{
		/**
		 * The command name
		 */
		final String command;//NOPMD no confusion here
		/**
		 * The list of command arguments
		 */
		final String[] args;
		/**
		 * The reply address, excluding the protocol
		 */
		final String replyto;

		/**
		 * Construct a Command from its three parts
		 *
		 * @param command the command name
		 * @param args the command arguments
		 * @param replyto the reply address
		 */
		Command(final String command, final String[] args, final String replyto) {//NOPMD array is immutable
			this.command=command;
			this.args=args;
			this.replyto=replyto;
		}
	}

	/** Context instance */
	private final Context context;

	/**
	 * Constructs a PollServerAsyncTask.
	 *
	 * @param context Context instance
	 */
	public PollServerAsyncTask(final Context context) {
		this.context=context;
	}

	@Override
	protected List<Command> doInBackground(final @Nullable Void... params) {
		Log.d(getClass().getName(), "Polling server");
		final List<Command> commands=new ArrayList<Command>(10);
		try {
			final URL url=Utils.getServerURL(toNonNull(context),"/get");
			final HttpURLConnection conn=(HttpURLConnection) url.openConnection();
			conn.setRequestProperty("X-ID", GCMRegistrar.getRegistrationId(context));
			final String user=PreferenceManager.getDefaultSharedPreferences(context).getString("username", null);
			final String password=PreferenceManager.getDefaultSharedPreferences(context).getString("password", null);
			if(user == null || password == null)
				return commands;

			conn.setRequestProperty("Authorization", "Basic "+Base64.encodeToString(
					(user+':'+password).getBytes(), Base64.NO_WRAP));
			conn.connect();
			Log.d(getClass().getName(), "Server poll got response code "+conn.getResponseCode()+" and message "+conn.getResponseMessage());
			if(conn.getResponseCode()!=200)
				return commands;

			final JSONArray array;
			{
				final byte[] buf=new byte[4096*1024];
				conn.getInputStream().read(buf);
				array=new JSONArray(new String(buf));
			}

			for(int i=0;i<array.length();i++){
				final JSONObject object=array.getJSONObject(i);

				final JSONArray jsonargs=object.getJSONArray("args");
				final String[] args=new String[jsonargs.length()];
				for(int j=0;j<args.length;j++)
					args[j]=jsonargs.getString(j);

				commands.add(new Command(//NOPMD command changes for each JSON object
						toNonNull(object.getString("command")),
						args,
						toNonNull(object.getString("replyto"))));
			}
		} catch (MalformedURLException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} catch (JSONException e) {
			e.printStackTrace();
		}
		if(commands==null)
			throw new AssertionError("commands is null in PollServerAsyncTask#doInBackground");//silence Eclipse bug
		return commands;
	}

	@Override
	protected void onPostExecute(final @Nullable List<Command> commands) {
		if(commands==null)
			return;
		for (Command command : commands) {
			Log.d(getClass().getName(), "Poll got command "+command.command+" with "+((command.args.length==0)?"no args":"args "+Utils.join(
					" ",toNonNull(command.args))));
			Utils.processCommand(
					toNonNull(context),
					toNonNull(command.command),
					toNonNull(command.args),
					new Address(toNonNull(Protocol.HTTP), command.replyto));//NOPMD address depends on command
		}
	}
}