package dk.thoerup.traininfoservice;

import java.io.IOException;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.logging.Level;
import java.util.logging.Logger;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import dk.thoerup.traininfoservice.DBConnection;

/**
 * Servlet implementation class LocateStations
 */
public class LocateStations extends HttpServlet {
	private static final long serialVersionUID = 1L;

	Logger logger = Logger.getLogger( LocateStations.class.toString() );
	
	/**
	 * @see HttpServlet#HttpServlet()
	 */
	public LocateStations() {
		super();
		// TODO Auto-generated constructor stub
	}

	public enum Requested {
		BY_NAME,
		BY_LOCATION,
		NONE
	}


	protected String getStations(Connection conn, double latitude, double longitude, String name, Requested method) throws SQLException {
		String SQL = "";
		PreparedStatement stmt = null;
		ResultSet res = null;

		StringBuffer buff = new StringBuffer();

		buff.append("<?xml version=\"1.0\" ?>\n");
		buff.append("<stations>\n");	
		
		try
		{

			switch (method)
			{
			case BY_LOCATION:
				//inner select is workaround from not being able to use a calculated column directly in where clause
				SQL = "SELECT * FROM ( "+
						"               SELECT id,name,latitude,longitude,stationcode_fjrn,stationcode_stog, " + 
						"                     earth_distance( ll_to_earth(latitude,longitude), ll_to_earth(?,?))::int AS calcdist " + 
						"               FROM trainstations " +
						"               WHERE enabled = true AND latitude IS NOT NULL AND longitude IS NOT NULL " +
						"       ) AS trainstations2 " +
						"ORDER BY calcdist ASC " + 
						"LIMIT 4 ";
				stmt = conn.prepareStatement(SQL);
				stmt.setDouble(1, latitude);
				stmt.setDouble(2, longitude);

				break;
			case BY_NAME:
				SQL = "SELECT id,name,latitude,longitude,stationcode_fjrn,stationcode_stog,0.0 " + 
					"FROM trainstations " + 
					"WHERE name ILIKE ? AND latitude IS NOT NULL AND longitude IS NOT NULL " +
					"ORDER BY name ";
				stmt = conn.prepareStatement(SQL);
				stmt.setString(1, name + "%");
				break;
			default:
				// This should not be possible
				logger.severe("getStations(): default switch case");
			}




			res = stmt.executeQuery();

			while (res.next()) {
				buff.append("<station>\n");

				buff.append("<id>").append( res.getInt(1) ).append("</id>\n");
				buff.append("<name>").append( res.getString(2) ) .append("</name>\n");
				buff.append("<latitude>").append( res.getDouble(3) ) .append("</latitude>\n");
				buff.append("<longitude>").append( res.getDouble(4) ) .append("</longitude>\n");
				res.getString(5);
				buff.append("<fjerntog>").append( !res.wasNull() ) .append("</fjerntog>\n");
				res.getString(6);
				buff.append("<stog>").append( !res.wasNull() ) .append("</stog>\n");
				buff.append("<calcdist>").append( res.getInt(7) ) .append("</calcdist>\n");

				buff.append("</station>\n");				
			}
		} finally {
			if (res != null && !res.isClosed())
				res.close();
			if (stmt != null && !stmt.isClosed())
				stmt.close();
		}
		buff.append("</stations>\n");
		return buff.toString();
	}

	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

		double longitude = 0.0;
		double latitude = 0.0;
		String name = "";

		Requested method = Requested.NONE;

		if (request.getParameter("latitude") != null && request.getParameter("latitude") != null) { 
			latitude = Double.parseDouble( request.getParameter("latitude") );
			longitude = Double.parseDouble( request.getParameter("longitude") );
			method = Requested.BY_LOCATION;
		}

		if (request.getParameter("name") != null) {
			name = request.getParameter("name");
			method = Requested.BY_NAME;
		}


		if (method != Requested.NONE) {

			Connection conn = null;
			try {
				conn = DBConnection.getConnection();

				String xml = getStations(conn, latitude, longitude, name, method);

				response.setContentType("text/xml");
				response.getWriter().print(xml);

				conn.close();
				conn = null;
 
			} catch (Exception e) {				
				logger.log(Level.SEVERE, "Exception while finding stations", e);
				response.sendError(500);						
			} finally {
				try {
					if (conn != null)
						conn.close();
				} catch (Throwable t) {}
			}
		} else {
			response.sendError(400, "not enough parameters");
		}
	}

}