package dk.thoerup.traininfoservice;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;
import java.util.logging.Logger;

public class StationDAO {
	final static int LOCATION_LIMIT = 5;
	static final Logger logger = Logger.getLogger(StationDAO.class.getName());
	
	
	private StationBean convertSingleRow(ResultSet res) throws SQLException {
		StationBean station = new StationBean();

		station.setId( res.getInt(1) );
		station.setName( res.getString(2) );
		station.setLatitude( res.getDouble(3) );
		station.setLongitude( res.getDouble(4) );
		station.setRegional( res.getString(5) );
		station.setStrain( res.getString(6) );
		station.setMetro( res.getString(7) );
		station.setAddress( res.getString(8) );
		station.setCalcdist( (int)res.getDouble(9) );

		return station;
	}

	private List<StationBean> convertResultset(ResultSet res) throws SQLException {
		List<StationBean> stations = new ArrayList<StationBean>();
		while (res.next()) {
			stations.add( convertSingleRow(res) );
		}
		return stations;

	}


	public StationBean getById(int id) throws SQLException {
		String SQL = "SELECT id,name,latitude,longitude,stationcode_fjrn,stationcode_stog,stationcode_metro,address,0.0 " +
		"FROM trainstations WHERE id=" + id + " AND enabled=true";

		Connection conn = null;
		Statement stmt = null;
		ResultSet res = null;
		StationBean result;

		try {
			conn = DBConnection.getConnection();

			stmt = conn.createStatement();
			res = stmt.executeQuery(SQL);		
			res.next();
			result = convertSingleRow(res);
		} finally {
			if (res != null)
				res.close();
			if (stmt != null)
				stmt.close();
			if (conn != null)
				conn.close();
		}

		return result;
	}

	/*
	 * this code requires theses statements are run on database in order to do ILIKE searches against aliases (which is defines as array of varchar(64) )
	 *     create function rlike(text,text) returns bool as 
	 *     'select $2 ilike $1' language sql strict immutable;
	 *     create operator ~~~ (procedure = rlike, leftarg = text, rightarg = text, commutator = ~~);
	 */
	public List<StationBean> getByName(String name) throws SQLException {
		String SQL = "SELECT id,name,latitude,longitude,stationcode_fjrn,stationcode_stog, stationcode_metro, address, 0.0 " + 
		"FROM trainstations " + 
		"WHERE (name ILIKE ? OR ? ~~~ ANY(aliases)) AND enabled = true " +
		"ORDER BY name ";


		List<StationBean> result;
		Connection conn = null;
		PreparedStatement stmt = null;
		ResultSet res = null;
		try {
			conn = DBConnection.getConnection();
			stmt = conn.prepareStatement(SQL);

			stmt.setString(1, name + "%");
			stmt.setString(2, name + "%");

			res = stmt.executeQuery();
			result = convertResultset(res);

		} finally {
			if (res != null)
				res.close();
			if (stmt != null)
				stmt.close();
			if (conn!= null)
				conn.close();
		}
		return result;
	}

	//the "hack" with max 0.4 degrees latitude and 0.75 degrees longitude is only valid since we only service danish trains,
	// in denmark 0.4dg latitude ~ 44km, 0.75dg longitude ~ 47km

	// the ultra fast method  (and only slightly inaccurate as long as we only cover a limited geographically area)
	// is using an aproximation of the length of 1 latitude degree and 1 longitude degree and just use pythagoras to 
	// calculate the distance:
	//     sqrt( power(abs(latitude-?)*111320, 2) + power(abs(longitude-?)*63000,2) )::int as calcdist 

	public List<StationBean> getByLocationWorker(double latitude, double longitude, boolean geolimit) throws SQLException {
		
		String limitExpression = (geolimit == true) ? "AND abs(latitude-?)<0.4 AND abs(longitude-?)<0.75 " : "";
		
		String SQL = "SELECT id,name,latitude,longitude,stationcode_fjrn,stationcode_stog, stationcode_metro, address, " + 
			"earth_distance( earth_coord, ll_to_earth(?,?))::int AS calcdist " + 
			"FROM trainstations " +
			"WHERE enabled = true " + limitExpression +
			"ORDER BY calcdist ASC " + 
			"LIMIT " + LOCATION_LIMIT;


		
		List<StationBean> result;
		Connection conn = null;
		PreparedStatement stmt = null;
		ResultSet res = null;
		try {
			conn = DBConnection.getConnection();
			stmt = conn.prepareStatement(SQL);
			stmt.setDouble(1, latitude);
			stmt.setDouble(2, longitude);
			if (geolimit == true) {
				stmt.setDouble(3, latitude);
				stmt.setDouble(4, longitude);
			}
			res = stmt.executeQuery();
			result = convertResultset(res);
		
		} finally {
			if (res != null)
				res.close();
			if (stmt != null)
				stmt.close();
			if (conn!= null)
				conn.close();
		}
		return result;
	}
	
	public List<StationBean> getByLocation(double latitude, double longitude) throws SQLException {
		List<StationBean> result = getByLocationWorker(latitude, longitude, true);
		
		if (result.size() < LOCATION_LIMIT) { //failover
			logger.info("getByLocation failover: " +latitude + "," + longitude);
			
			result = getByLocationWorker(latitude, longitude, false);
		}
		
		return result;
	}
	
	

	public List<StationBean> getByList(String list) throws SQLException {
		String SQL = "SELECT id,name,latitude,longitude,stationcode_fjrn,stationcode_stog,stationcode_metro, address,0.0 " + 
		"FROM trainstations " + 
		"WHERE id IN " + list + " AND enabled = true " +
		"ORDER BY name ";

		Connection conn = null;
		Statement stmt = null;
		ResultSet res = null;
		List<StationBean> result;

		try {
			conn = DBConnection.getConnection();
			stmt = conn.createStatement();
			res = stmt.executeQuery(SQL);
			result = convertResultset(res);
		} finally {
			if (res != null)
				res.close();
			if (stmt != null)
				stmt.close();
			if (conn!= null)
				conn.close();
		}

		return result;

	}
	public static String getStationName(int stationID) {
		String station = "";

		Connection conn = null;
		try {
			conn = DBConnection.getConnection();
			Statement stmt = conn.createStatement();
			ResultSet rs = stmt.executeQuery("SELECT name FROM trainstations WHERE id=" + stationID);
			if (rs.next()) {
				station = rs.getString(1);
			}

		} catch (Exception e) {	
		} finally {
			try {
				if (conn != null && !conn.isClosed())
					conn.close();
			} catch (Exception e) {}
		}

		return station;
	}

	public int getIdByName(String name) throws SQLException {
		String SQL = "SELECT id,name,latitude,longitude,stationcode_fjrn,stationcode_stog, stationcode_metro, address, 0.0 " + 
		"FROM trainstations " + 
		"WHERE name = ?  AND enabled = true " +
		"LIMIT 1 ";

		List<StationBean> result;
		Connection conn = null;
		PreparedStatement stmt = null;
		ResultSet res = null;
		try {
			conn = DBConnection.getConnection();
			stmt = conn.prepareStatement(SQL);

			stmt.setString(1, name );

			res = stmt.executeQuery();
			result = convertResultset(res);

		} finally {
			if (res != null)
				res.close();
			if (stmt != null)
				stmt.close();
			if (conn!= null)
				conn.close();
		}

		if (result.size() == 1) {
			return result.get(0).getId();
		} else {
			return -1;
		}
	}
}