UnitTypeUpdater.java

package com.llamacorp.equate.unit;

import android.content.Context;
import android.os.AsyncTask;

import com.llamacorp.equate.R;
import com.llamacorp.equate.view.ViewUtils;

import org.xmlpull.v1.XmlPullParserException;

import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;

/**
 * Helper class is used to update dynamic unit types such as currency by
 * calling all the necessary async tasks and such
 * Created by Evan on 10/2/2015.
 */
public class UnitTypeUpdater {
	public static int UPDATE_TIMEOUT_MIN = 90;
	private Context mContext;
	private ArrayList<Integer> mUnitsToUpdate;

	public UnitTypeUpdater(Context mContext) {
		this.mContext = mContext;
		mUnitsToUpdate = new ArrayList<>();
	}

	public void update(UnitType ut, boolean forced) {
		if (!ut.containsDynamicUnits()) return;

		//only do update if timeout period has passed
		if (isTimeoutReached(ut) || forced){
			//add "Updating" text
			ut.setUpdating(true);
			new UpdateYahooXMLAsyncTask(ut, forced).execute();
		} else {
			ViewUtils.toast(mContext.getText(R.string.words_units_up_to_date)
					  .toString(), mContext);
		}
	}

	private boolean isTimeoutReached(UnitType ut) {
		Date now = new Date();
		if (ut.getLastUpdateTime() != null && (now.getTime() -
				  ut.getLastUpdateTime().getTime())
				  < (60 * 1000 * UPDATE_TIMEOUT_MIN)){
			return false;
		} else
			return true;
	}

	/**
	 * This class is used to create a background task that handles
	 * the actual retrieval of the Yahoo XML file that contains the current rates
	 */
	private class UpdateYahooXMLAsyncTask extends AsyncTask<Void, Void, Boolean> {
		private UnitType mUnitType;
		private Boolean mForced;

		public UpdateYahooXMLAsyncTask(UnitType unitType, Boolean forced) {
			mUnitType = unitType;
			mForced = forced;
		}

		//This method is called first
		@Override
		protected Boolean doInBackground(Void... voids) {
			return updateRatesWithXML(mUnitType);
		}

		// This method is called after doInBackground completes
		@Override
		protected void onPostExecute(Boolean successful) {
			if (successful){
				mUnitType.setLastUpdateTime(new Date());
				String text = "Updated at ";
				if (mForced) text = "FORCED update at ";
				ViewUtils.toastLong(text + mUnitType.getLastUpdateTime().toString(),
						  mContext);
			}

			//update the remaining units that got missed by yahoo xml
			if (mUnitsToUpdate != null){
				for (int i = 0; i < mUnitsToUpdate.size(); i++) {
					UnitCurrency u = (UnitCurrency) mUnitType.getUnitPosInUnitArray(mUnitsToUpdate.get(i));
					if (u.isTimeoutReached(mContext))
						u.asyncRefresh(mContext);
				}
			}

			//remove text "Updating"
			mUnitType.setUpdating(false);
		}
	}


	private boolean updateRatesWithXML(UnitType ut) {
		//only try to update currencies if we have XML currency URL to work with
		if (ut.getXMLCurrencyURL() == null) return false;

		HashMap<String, YahooXmlParser.Entry> currRates = null;

		//grab the array of yahoo currency units
		try {
			currRates = getCurrRates(ut.getXMLCurrencyURL());
		} catch (XmlPullParserException | IOException e) {
			e.printStackTrace();
		}

		//leave if we have not updated rates
		if (currRates == null) return false;

		//update each existing curr with new rates
		for (int i = 0; i < ut.size(); i++) {
			//skip unit support that don't support updating (not hist)
			if (!ut.getUnitPosInUnitArray(i).isDynamic()) continue;

			UnitCurrency u = ((UnitCurrency) ut.getUnitPosInUnitArray(i));
			YahooXmlParser.Entry entry = currRates.get(u.getAbbreviation());
			if (entry != null){
				u.setValue(entry.price);
				u.setUpdateTime(entry.date);
			} else {
				//this is for BTC and other units that don't get updated by yahoo
				mUnitsToUpdate.add(i);
			}
		}
		return true;
	}


	/**
	 * Downloads XML file of current Yahoo finance currency rates
	 *
	 * @param urlString URL of XML string
	 * @return Array of currencies with updated values
	 * @throws XmlPullParserException
	 * @throws IOException
	 */
	private HashMap<String, YahooXmlParser.Entry> getCurrRates(String urlString)
			  throws XmlPullParserException, IOException {
		InputStream stream = null;
		YahooXmlParser yahooXmlParser = new YahooXmlParser();
		HashMap<String, YahooXmlParser.Entry> currRates = null;

		try {
			stream = downloadUrl(urlString);
			currRates = yahooXmlParser.parse(stream);
			// Makes sure that the InputStream is closed after the app is
			// finished using it.
		} finally {
			if (stream != null){
				stream.close();
			}
		}
		return currRates;
	}


	/**
	 * Given a string representation of a URL, sets up a connection and gets
	 * an input stream.
	 */
	private InputStream downloadUrl(String urlString) throws IOException {
		URL url = new URL(urlString);
		HttpURLConnection conn = (HttpURLConnection) url.openConnection();
		conn.setReadTimeout(10000 /* milliseconds */);
		conn.setConnectTimeout(15000 /* milliseconds */);
		conn.setRequestMethod("GET");
		conn.setDoInput(true);
		// Starts the query
		conn.connect();
		return conn.getInputStream();
	}
}