package dk.thoerup.traininfoservice.db;

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

import dk.thoerup.android.traininfo.common.StationBean;
import dk.thoerup.android.traininfo.common.StationEntry;

public class StationDAO {
	
	private interface StatementParamSetter {
		public void setParams(PreparedStatement stmt) throws SQLException ;
	}
	private class NullSetter implements StatementParamSetter {
		@Override
		public void setParams(PreparedStatement stmt) throws SQLException {}
	}
	
	public static class NostationException extends Exception {
		private static final long serialVersionUID = 1L;
	}
	
	final static int LOCATION_LIMIT = 8;
	static final Logger logger = Logger.getLogger(StationDAO.class.getName());
	
	
	private StationEntry convertSingleRow(ResultSet res) throws SQLException {
		StationEntry station = new StationEntry();

		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) );
		
		station.setIsRegional( station.getRegional() != null );
		station.setIsStrain( station.getStrain() != null );
		station.setIsMetro( station.getMetro() != null );

		return station;
	}

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

	}

	private StationBean fetchStations(String SQL, StatementParamSetter setter) throws SQLException {
		StationBean stations;
		Connection conn = null;
		PreparedStatement stmt = null;
		ResultSet res = null;
		try {
			conn = DBConnection.getConnection();
			stmt = conn.prepareStatement(SQL);
			
			setter.setParams(stmt);

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

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

	public StationEntry getById(int id) throws SQLException,NostationException {
		String SQL = "SELECT id,name,latitude,longitude,stationcode_fjrn,stationcode_stog,stationcode_metro,address,0.0 " +
		"FROM trainstations WHERE id=" + id + " AND enabled=true";
				
		StationBean stations =  fetchStations(SQL, new NullSetter() );
		
		if (stations.entries.size() > 0 ) {
			return stations.entries.get(0);
		} else {
			throw new NostationException();
		}
	}
	


	/*
	 * 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 StationBean getByNameNormal(final 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 ";

		class NameSetter implements StatementParamSetter {
			@Override
			public void setParams(PreparedStatement stmt) throws SQLException {
				stmt.setString(1, name + "%");
				stmt.setString(2, name + "%");				
			}			
		}
		
		return fetchStations(SQL, new NameSetter() );
	}
	
	
	public StationBean getByNameFuzzy(final String name) throws SQLException {
		String SQL = "SELECT * FROM (" +
					 "    SELECT id,name,latitude,longitude,stationcode_fjrn,stationcode_stog, stationcode_metro, address, 0.0, " +
					 "    levenshtein(lower(name),lower(?) ) as leven " +
					 "    FROM trainstations " +
					 "    WHERE  enabled = true ) as lev2 " +
					 "WHERE (leven <= 3) " +		
					 "ORDER BY leven " + 
					 "LIMIT 1";

		class NameSetter implements StatementParamSetter {
			@Override
			public void setParams(PreparedStatement stmt) throws SQLException {
				stmt.setString(1, name );
			}			
		}
		
		StationBean stations = fetchStations(SQL, new NameSetter() );
		stations.fuzzystrmatch = true;
		return stations;
	}
	
	public StationBean getByName(final String name) throws SQLException {
		StationBean stations = getByNameNormal(name);
		
		if (stations.entries.size() == 0) {
			logger.info("getByName failover: " + name);
			stations = getByNameFuzzy(name);
		}
		return stations;
	}
	
	

	//Latitude (horizonal), longitude(vertical) so
	// 1 degree latitude is ~ 111320 meters, since the distance between the horizonal lines is always the same 
	// 1 degree longitude is ~111320 meters at equator but gets shorter as we get closer to the poles.
	// so 1 degree longitude is 64.5 km at denmarks southern point (gedser=54.55,11.95)
	// and is 59.4km at northern point (skagen = 57.75,10.65)
	// 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 StationBean getByLocationWorker(final double latitude, final double longitude, final 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;

		
		class LatlongSetter implements StatementParamSetter {
			@Override
			public void setParams(PreparedStatement stmt) throws SQLException {
				stmt.setDouble(1, latitude);
				stmt.setDouble(2, longitude);
				if (geolimit == true) {
					stmt.setDouble(3, latitude);
					stmt.setDouble(4, longitude);
				}				
			}			
		}
		
		return fetchStations(SQL, new LatlongSetter() );
	}
	
	public StationBean getByLocation(double latitude, double longitude) throws SQLException {
		StationBean result = getByLocationWorker(latitude, longitude, true);
		
		if (result.entries.size() < LOCATION_LIMIT) { //failover
			logger.info("getByLocation failover: " +latitude + "," + longitude);
			
			result = getByLocationWorker(latitude, longitude, false);
		}
		
		return result;
	}
	
	

	public 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 ";
		
		return fetchStations(SQL, new NullSetter() );
	}
	

	
	public StationEntry getSimpleByName(final 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 ";

		class NameSetter implements StatementParamSetter {
			@Override
			public void setParams(PreparedStatement stmt) throws SQLException {
				stmt.setString(1, name );
			}			
		}
		
		StationBean stations = fetchStations(SQL, new NameSetter() );
		
		if (stations.entries.size() == 1) {
			return stations.entries.get(0);
		} else {
			return null;
		}
	}
	
	//used to create full dump in order to populate Google Appengine DB
	@Deprecated
	public StationBean dumpAll() throws SQLException {
		
		String SQL = "SELECT id,name,latitude,longitude,stationcode_fjrn,stationcode_stog,stationcode_metro,address,0.0,aliases " +
				"FROM trainstations WHERE enabled = true ORDER BY id";
		
		Connection conn = null;
		Statement stmt = null;
		ResultSet res = null;		

		
		try {
			conn = DBConnection.getConnection();

			stmt = conn.createStatement();
			res = stmt.executeQuery(SQL);		
						
			// Does mostly the same as convertResultset()
			StationBean stations = new StationBean();
			while (res.next()) {
				StationEntry entry = convertSingleRow(res);
				
				Array arr = res.getArray(10);
				if (arr != null) {
					String[] aliases = (String[]) arr.getArray();
					entry.setAliases(aliases);
				}
				
				stations.entries.add( entry );
				
			}
			return stations;
			

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

	@Deprecated
	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;
	}
	
	
	
	@Deprecated
	public int getIdByName(final 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 ";

		class NameSetter implements StatementParamSetter {
			@Override
			public void setParams(PreparedStatement stmt) throws SQLException {
				stmt.setString(1, name );
			}			
		}
		
		StationBean stations = fetchStations(SQL, new NameSetter() );
		
		if (stations.entries.size() == 1) {
			return stations.entries.get(0).getId();
		} else {
			return -1;
		}
	}
}