/*
 * Copyright (C) 2008 Google Inc.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */
package com.google.marvin.there;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.HashSet;

import org.json.JSONException;
import org.json.JSONObject;

import android.location.Location;
import android.location.LocationManager;
import android.util.Log;

/**
 * This class implements methods to get street address from lat-lon using
 * reverse geocoding API through HTTP.
 * 
 * @author chaitanyag@google.com (Chaitanya Gharpure)
 */
public class StreetLocator {
  public interface StreetLocatorListener {
    public void onIntersectionLocated(String[] streetnames);

    public void onAddressLocated(String address);
    
    public void onFrontBackLocated(String[] streetsFront, String[] streetsBack);
  }

  private StreetLocatorListener cb;

  private static final String ENCODING = "UTF-8";

  // URL for obtaining navigation directions
  private static final String URL_NAV_STRING = "http://maps.google.com/maps/nav?";
  // URL for obtaining reverse geocoded location
  private static final String URL_GEO_STRING = "http://maps.google.com/maps/geo?";

  public StreetLocator(StreetLocatorListener callback) {
    cb = callback;
  }

  /**
   * Queries the map server and obtains the street names at the specified
   * location. This is done by obtaining street name at specified location, and
   * at locations X meters to the N, S, E, and W of the specified location.
   * 
   * @param lat The latitude in degrees
   * @param lon The longitude in degrees
   */
  public void getStreetIntersectionAsync(double lat, double lon) {
    final double latitude = lat;
    final double longitude = lon;
    class IntersectionThread implements Runnable {
      public void run() {
        cb.onIntersectionLocated(getStreetIntersection(latitude, longitude));
      }
    }
    (new Thread(new IntersectionThread())).start();
  }

  /**
   * Queries the map server and obtains the street names at the specified
   * location. This is done by obtaining street name at specified location, and
   * at locations X meters to the N, S, E, and W of the specified location.
   * 
   * @param lat The latitude in degrees
   * @param lon The longitude in degrees
   */
  public void getStreetsInFrontAndBackAsync(double lat, double lon, double heading) {
    final double latitude = lat;
    final double longitude = lon;
    final double direction = heading;
    class IntersectionThread implements Runnable {
      public void run() {
        getStreetsInFrontAndBack(latitude, longitude, direction);
      }
    }
    (new Thread(new IntersectionThread())).start();
  }



  /**
   * Queries the map server and obtains the reverse geocoded address of the
   * specified location.
   * 
   * @param lat The latitude in degrees
   * @param lon The longitude in degrees
   */
  public void getAddressAsync(double lat, double lon) {
    final double latitude = lat;
    final double longitude = lon;
    class AddressThread implements Runnable {
      public void run() {
        cb.onAddressLocated(getAddress(latitude, longitude));
      }
    }
    (new Thread(new AddressThread())).start();
  }


  /**
   * Queries the map server and obtains the street names at the specified
   * location. This is done by obtaining street name at specified location, and
   * at locations X meters to the N, S, E, and W of the specified location.
   * 
   * @param lat The latitude in degrees
   * @param lon The longitude in degrees
   * @return Returns the string array containing street names
   */
  public String[] getStreetIntersection(double lat, double lon) {
    HashSet<String> streets = new HashSet<String>();
    try {
      for (int i = 0; i < 5; i++) {
        // Find street address at lat-lon x meters to the N, S, E and W of
        // the given lat-lon
        String street = parseStreetName(getResult(makeNavURL(lat, lon, lat, lon)));
        if (street != null) {
          streets.add(street);
        }
        // get points 150m away, towards N, E, S, and W
        if (i < 4) {
          Location nextLoc = endLocation(lat, lon, i * 90, 15);
          lat = nextLoc.getLatitude();
          lon = nextLoc.getLongitude();
        }
      }
    } catch (MalformedURLException mue) {
      Log.d("Locator", "Malformed URL: " + mue.getMessage());
    } catch (IOException e) {
      Log.d("Locator", "Error reading from Map server: " + e.toString());
    } catch (JSONException e) {
      Log.d("Locator", "Error in JSON response: " + e.getMessage());
    }
    String[] st = new String[streets.size()];
    int i = 0;
    for (String s : streets) {
      st[i++] = s;
    }
    return st;
  }



  /**
   * Queries the map server and obtains the street names at the specified
   * location. This is done by obtaining street name at specified location, and
   * at locations X meters to the N, S, E, and W of the specified location.
   * 
   * @param lat The latitude in degrees
   * @param lon The longitude in degrees
   */
  public void getStreetsInFrontAndBack(double lat, double lon, double heading) {
    HashSet<String> streetsFront = new HashSet<String>();
    HashSet<String> streetsBack = new HashSet<String>();
    double searchDistance = 15; // 15m (? - is there really a factor of 10 here)

    try {
      // Get the current street
      String street = parseStreetName(getResult(makeNavURL(lat, lon, lat, lon)));
      if (street != null) {
        streetsFront.add(street);
        streetsBack.add(street);
      }
      Log.i("Current street", "lat: " + Double.toString(lat) + ", lon: " + Double.toString(lon));
            
      // Get the street in front of the current street
      Location nextLoc = endLocation(lat, lon, heading, searchDistance);
      lat = nextLoc.getLatitude();
      lon = nextLoc.getLongitude();
      street = parseStreetName(getResult(makeNavURL(lat, lon, lat, lon)));
      if (street != null) {
        streetsFront.add(street);
      }
      Log.i("Front street", "lat: " + Double.toString(lat) + ", lon: " + Double.toString(lon));


      // Get the street behind the current street
      heading = heading + 180;
      if (heading >= 360){
        heading = heading - 360;
      }
      nextLoc = endLocation(lat, lon, heading, searchDistance);
      lat = nextLoc.getLatitude();
      lon = nextLoc.getLongitude();
      street = parseStreetName(getResult(makeNavURL(lat, lon, lat, lon)));
      if (street != null) {
        streetsBack.add(street);
      }
      Log.i("Back street", "lat: " + Double.toString(lat) + ", lon: " + Double.toString(lon));

      String[] sf = new String[streetsFront.size()];
      int i = 0;
      for (String s : streetsFront) {
        sf[i++] = s;
      }

      String[] sb = new String[streetsBack.size()];
      i = 0;
      for (String s : streetsBack) {
        sb[i++] = s;
      }      
      cb.onFrontBackLocated(sf, sb);
    } catch (MalformedURLException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    } catch (JSONException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    } catch (IOException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }
  }



  /**
   * Queries the map server and obtains the reverse geocoded address of the
   * specified location.
   * 
   * @param lat The latitude in degrees
   * @param lon The longitude in degrees
   * @return Returns the reverse geocoded address
   */
  public String getAddress(double lat, double lon) {
    try {
      String resp = getResult(makeGeoURL(lat, lon));
      JSONObject jsonObj = new JSONObject(resp);
      int code = jsonObj.getJSONObject("Status").getInt("code");
      if (code == 200) {
        return extendShorts(jsonObj.getJSONArray("Placemark").getJSONObject(0).getString("address"));
      }
    } catch (MalformedURLException mue) {
      Log.d("Locator", "Malformed URL: " + mue.getMessage());
    } catch (IOException e) {
      Log.d("Locator", "Error reading from Map server: " + e.toString());
    } catch (JSONException e) {
      Log.d("Locator", "Error in JSON response: " + e.getMessage());
    }
    return null;
  }

  /**
   * Parses the JSON response to extract the street name.
   * 
   * @param resp The String representation of the JSON response
   * @return Returns the street name
   * @throws JSONException
   */
  private String parseStreetName(String resp) throws JSONException {
    JSONObject jsonObj = new JSONObject(resp);
    int code = jsonObj.getJSONObject("Status").getInt("code");
    if (code == 200) {
      return extendShorts(jsonObj.getJSONArray("Placemark").getJSONObject(0).getString("address"));
    }
    return null;
  }

  /**
   * Sends a request to the specified URL and obtains the result from the sever.
   * 
   * @param url The URL to connect to
   * @return the server response
   * @throws IOException
   */
  private String getResult(URL url) throws IOException {
    Log.d("Locator", url.toString());
    HttpURLConnection conn = (HttpURLConnection) url.openConnection();
    conn.setDoInput(true);
    conn.setDoOutput(true);
    InputStream is = conn.getInputStream();
    String result = toString(is);
    return result;
  }

  /**
   * Prepares the URL to connect to navigation server, from the specified start
   * and end location coordinates
   * 
   * @param lat1 Start location latitude in degrees
   * @param lon1 Start location longitude in degrees
   * @param lat2 End location latitude in degrees
   * @param lon2 End location longitude in degrees
   * @return a well-formed URL
   * @throws MalformedURLException
   */
  private URL makeNavURL(double lat1, double lon1, double lat2, double lon2)
      throws MalformedURLException {
    StringBuilder url = new StringBuilder();
    url.append(URL_NAV_STRING).append("hl=EN&gl=EN&output=js&oe=utf8&q=from%3A").append(lat1)
        .append(",").append(lon1).append("+to%3A").append(lat2).append(",").append(lon2);
    return new URL(url.toString());
  }

  /**
   * Prepares the URL to connect to the reverse geocoding server from the
   * specified location coordinates.
   * 
   * @param lat latitude in degrees of the location to reverse geocode
   * @param lon longitude in degrees of the location to reverse geocode
   * @return URL The Geo URL created based on the given lat/lon
   * @throws MalformedURLException
   */
  private URL makeGeoURL(double lat, double lon) throws MalformedURLException {
    StringBuilder url = new StringBuilder();
    url.append(URL_GEO_STRING).append("q=").append(lat).append(",").append(lon);
    return new URL(url.toString());
  }

  /**
   * Reads an InputStream and returns its contents as a String.
   * 
   * @param inputStream The InputStream to read from.
   * @return The contents of the InputStream as a String.
   */
  private static String toString(InputStream inputStream) throws IOException {
    StringBuilder outputBuilder = new StringBuilder();
    String string;
    if (inputStream != null) {
      BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream, ENCODING));
      while (null != (string = reader.readLine())) {
        outputBuilder.append(string).append('\n');
      }
    }
    return outputBuilder.toString();
  }

  /**
   * Replaces the short forms in the address by their longer forms, so that TTS
   * speaks the addresses properly
   * 
   * @param addr The address from which to replace short forms
   * @return the modified address string
   */
  private String extendShorts(String addr) {
    addr = addr.replace("St,", "Street");
    addr = addr.replace("St.", "Street");
    addr = addr.replace("Rd", "Road");
    addr = addr.replace("Fwy", "Freeway");
    addr = addr.replace("Pkwy", "Parkway");
    addr = addr.replace("Blvd", "Boulevard");
    addr = addr.replace("Expy", "Expressway");
    addr = addr.replace("Ave", "Avenue");
    addr = addr.replace("Dr", "Drive");
    return addr;
  }

  /**
   * Computes the new location at a particular direction and distance from the
   * specified location using the inverse Vincenti formula.
   * 
   * @param lat1 latitude of source location in degrees
   * @param lon1 longitude of source location in degrees
   * @param brng Direction in degrees wrt source location
   * @param dist Distance from the source location
   * @return the new location
   */
  private Location endLocation(double lat1, double lon1, double brng, double dist) {
    double a = 6378137, b = 6356752.3142, f = 1 / 298.257223563;
    double s = dist;
    double alpha1 = Math.toRadians(brng);
    double sinAlpha1 = Math.sin(alpha1), cosAlpha1 = Math.cos(alpha1);

    double tanU1 = (1 - f) * Math.tan(Math.toRadians(lat1));
    double cosU1 = 1 / Math.sqrt((1 + tanU1 * tanU1)), sinU1 = tanU1 * cosU1;
    double sigma1 = Math.atan2(tanU1, cosAlpha1);
    double sinAlpha = cosU1 * sinAlpha1;
    double cosSqAlpha = 1 - sinAlpha * sinAlpha;
    double uSq = cosSqAlpha * (a * a - b * b) / (b * b);
    double A = 1 + uSq / 16384 * (4096 + uSq * (-768 + uSq * (320 - 175 * uSq)));
    double B = uSq / 1024 * (256 + uSq * (-128 + uSq * (74 - 47 * uSq)));

    double sigma = s / (b * A), sigmaP = 2 * Math.PI;
    double cos2SigmaM = 0, sinSigma = 0, deltaSigma = 0, cosSigma = 0;
    while (Math.abs(sigma - sigmaP) > 1e-12) {
      cos2SigmaM = Math.cos(2 * sigma1 + sigma);
      sinSigma = Math.sin(sigma);
      cosSigma = Math.cos(sigma);
      deltaSigma =
          B
              * sinSigma
              * (cos2SigmaM + B
                  / 4
                  * (cosSigma * (-1 + 2 * cos2SigmaM * cos2SigmaM) - B / 6 * cos2SigmaM
                      * (-3 + 4 * sinSigma * sinSigma) * (-3 + 4 * cos2SigmaM * cos2SigmaM)));
      sigmaP = sigma;
      sigma = s / (b * A) + deltaSigma;
    }
    double tmp = sinU1 * sinSigma - cosU1 * cosSigma * cosAlpha1;
    double lat2 =
        Math.atan2(sinU1 * cosSigma + cosU1 * sinSigma * cosAlpha1, (1 - f)
            * Math.sqrt(sinAlpha * sinAlpha + tmp * tmp));
    double lambda =
        Math.atan2(sinSigma * sinAlpha1, cosU1 * cosSigma - sinU1 * sinSigma * cosAlpha1);
    double C = f / 16 * cosSqAlpha * (4 + f * (4 - 3 * cosSqAlpha));
    double L =
        lambda
            - (1 - C)
            * f
            * sinAlpha
            * (sigma + C * sinSigma
                * (cos2SigmaM + C * cosSigma * (-1 + 2 * cos2SigmaM * cos2SigmaM)));
    Location l = new Location(LocationManager.GPS_PROVIDER);
    l.setLatitude(Math.toDegrees(lat2));
    l.setLongitude(lon1 + Math.toDegrees(L));
    return l;
  }
}