import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.List;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONArray;
import org.json.JSONObject;

import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.model.BitmapDescriptorFactory;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;
import com.google.android.gms.maps.model.Polyline;
import com.google.android.gms.maps.model.PolylineOptions;

import android.app.ProgressDialog;
import android.content.Context;
import android.graphics.Color;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class Gmap extends FragmentActivity implements OnClickListener {

private GoogleMap myMap;
Polyline line;
Context context;

// Static LatLng
LatLng startLatLng = new LatLng(30.707104, 76.690749);
LatLng endLatLng = new LatLng(30.721419, 76.730017);

public void onCreate(Bundle bd) {
    super.onCreate(bd);
    setContentView(R.layout.activity_gmap);
    context = Gmap.this;


    // Temp GetTrails Button
    Button btntemp = (Button) findViewById(R.id.button1);
    btntemp.setOnClickListener(this);

    // GoogleMap myMap
    myMap = ((SupportMapFragment) getSupportFragmentManager()
            .findFragmentById(R.id.map)).getMap();
    myMap.setMyLocationEnabled(true);
    myMap.moveCamera(CameraUpdateFactory.newLatLng(startLatLng));
    myMap.animateCamera(CameraUpdateFactory.zoomTo(12));

    // Now auto clicking the button
    btntemp.performClick();
}

@Override
public void onClick(View v) {

    switch (v.getId()) {
    case R.id.button1:
        String urlTopass = makeURL(startLatLng.latitude,
                startLatLng.longitude, endLatLng.latitude,
                endLatLng.longitude);
        new connectAsyncTask(urlTopass).execute();
        break;

    default:
        break;
    }

}

private class connectAsyncTask extends AsyncTask<Void, Void, String> {
    private ProgressDialog progressDialog;
    String url;

    connectAsyncTask(String urlPass) {
        url = urlPass;
    }

    @Override
    protected void onPreExecute() {
        // TODO Auto-generated method stub
        super.onPreExecute();
        progressDialog = new ProgressDialog(context);
        progressDialog.setMessage("Fetching route, Please wait...");
        progressDialog.setIndeterminate(true);
        progressDialog.show();
    }

    @Override
    protected String doInBackground(Void... params) {
        JSONParser jParser = new JSONParser();
        String json = jParser.getJSONFromUrl(url);
        return json;
    }

    @Override
    protected void onPostExecute(String result) {
        super.onPostExecute(result);
        progressDialog.hide();
        if (result != null) {
            drawPath(result);
        }
    }
}

public String makeURL(double sourcelat, double sourcelog, double destlat,
        double destlog) {
    StringBuilder urlString = new StringBuilder();
    urlString.append("http://maps.googleapis.com/maps/api/directions/json");
    urlString.append("?origin=");// from
    urlString.append(Double.toString(sourcelat));
    urlString.append(",");
    urlString.append(Double.toString(sourcelog));
    urlString.append("&destination=");// to
    urlString.append(Double.toString(destlat));
    urlString.append(",");
    urlString.append(Double.toString(destlog));
    urlString.append("&sensor=false&mode=driving&alternatives=true");
    return urlString.toString();
}

public class JSONParser {

    InputStream is = null;
    JSONObject jObj = null;
    String json = "";

    // constructor
    public JSONParser() {
    }

    public String getJSONFromUrl(String url) {

        // Making HTTP request
        try {
            // defaultHttpClient
            DefaultHttpClient httpClient = new DefaultHttpClient();
            HttpPost httpPost = new HttpPost(url);

            HttpResponse httpResponse = httpClient.execute(httpPost);
            HttpEntity httpEntity = httpResponse.getEntity();
            is = httpEntity.getContent();

        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        try {
            BufferedReader reader = new BufferedReader(
                    new InputStreamReader(is, "iso-8859-1"), 8);
            StringBuilder sb = new StringBuilder();
            String line = null;
            while ((line = reader.readLine()) != null) {
                sb.append(line + "n");
            }

            json = sb.toString();
            is.close();
        } catch (Exception e) {
            Log.e("Buffer Error", "Error converting result " + e.toString());
        }
        return json;

    }
}

public void drawPath(String result) {
    if (line != null) {
        myMap.clear();
    }
    myMap.addMarker(new MarkerOptions().position(endLatLng).icon(
            BitmapDescriptorFactory.fromResource(R.drawable.redpin_marker)));
    myMap.addMarker(new MarkerOptions().position(startLatLng).icon(
            BitmapDescriptorFactory.fromResource(R.drawable.redpin_marker)));
    try {
        // Tranform the string into a json object
        final JSONObject json = new JSONObject(result);
        JSONArray routeArray = json.getJSONArray("routes");
        JSONObject routes = routeArray.getJSONObject(0);
        JSONObject overviewPolylines = routes
                .getJSONObject("overview_polyline");
        String encodedString = overviewPolylines.getString("points");
        List<LatLng> list = decodePoly(encodedString);

        for (int z = 0; z < list.size() - 1; z++) {
            LatLng src = list.get(z);
            LatLng dest = list.get(z + 1);
            line = myMap.addPolyline(new PolylineOptions()
                    .add(new LatLng(src.latitude, src.longitude),
                            new LatLng(dest.latitude, dest.longitude))
                    .width(5).color(Color.BLUE).geodesic(true));
        }

    } catch (Exception e) {
        e.printStackTrace();
    }
}

private List<LatLng> decodePoly(String encoded) {

    List<LatLng> poly = new ArrayList<LatLng>();
    int index = 0, len = encoded.length();
    int lat = 0, lng = 0;

    while (index < len) {
        int b, shift = 0, result = 0;
        do {
            b = encoded.charAt(index++) - 63;
            result |= (b & 0x1f) << shift;
            shift += 5;
        } while (b >= 0x20);
        int dlat = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
        lat += dlat;

        shift = 0;
        result = 0;
        do {
            b = encoded.charAt(index++) - 63;
            result |= (b & 0x1f) << shift;
            shift += 5;
        } while (b >= 0x20);
        int dlng = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
        lng += dlng;

        LatLng p = new LatLng((((double) lat / 1E5)),
                (((double) lng / 1E5)));
        poly.add(p);
    }

    return poly;
}
}