package xyz.veronie.bgg.localdb;

import java.io.File;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.sql.Connection;
import java.sql.DriverManager;
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 xyz.veronie.bgg.result.Thing;
import xyz.veronie.bgg.result.ThingMetaData;
import xyz.veronie.bgg.ui.helpers.Resources;

public class SqliteController {

	private static final SqliteController dbcontroller = new SqliteController();
    private static Connection connection;
    private String dbPath;

    static {
        try {
            Class.forName("org.sqlite.JDBC");
        } catch (ClassNotFoundException e) {
            System.err.println("Error while loading JDBC driver");
            e.printStackTrace();
        }
    }
    
    public Path getDbPath() {
    	return Paths.get(dbPath);
    }
    
    private SqliteController() {
    	dbPath = Resources.INSTANCE.getTmpDir() + File.separator + "bggtool.db";
    	initDBConnection();
    }
    
    public static SqliteController getInstance() {
        return dbcontroller;
    }
    
    private void initDBConnection() {
        try {
            if (connection != null)
                return;
            System.out.println("Creating Connection to Database...");
            connection = DriverManager.getConnection("jdbc:sqlite:" + dbPath);
            if (!connection.isClosed())
                System.out.println("...Connection established");

            // init connection
            Statement stmt = connection.createStatement();
            stmt.execute("PRAGMA foreign_keys = ON;");
            stmt.close();
	    	
        } catch (SQLException e) {
            // throw new RuntimeException(e);
			System.out.println("Could not init local DB.");
        }

        Runtime.getRuntime().addShutdownHook(new Thread() {
            public void run() {
                try {
                    if (!connection.isClosed() && connection != null) {
                        connection.close();
                        if (connection.isClosed())
                            System.out.println("Connection to Database closed");
                    }
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
        });
    }
    
    public void createSchema() {
    	if(connection == null) {
			throw new RuntimeException("ERROR: Couldn't create Schema, connection is null.");
    	}
    	try {
	    	Statement stmt = connection.createStatement();
	        stmt.executeUpdate("CREATE TABLE IF NOT EXISTS Thing (ThingId INTEGER PRIMARY KEY, Name, ImgUrl, ThumbUrl, Comment, NumPlays);");
	        stmt.executeUpdate("CREATE TABLE IF NOT EXISTS ThingList (ListId INTEGER PRIMARY KEY, Name);");
	        stmt.executeUpdate("CREATE UNIQUE INDEX IF NOT EXISTS  idx1 ON ThingList(Name)");
	        stmt.executeUpdate("CREATE TABLE IF NOT EXISTS ThingListToThing (ListId INTEGER, ThingId INTEGER, FOREIGN KEY (ListId) REFERENCES ThingList(ListId), FOREIGN KEY (ThingId) REFERENCES Thing(ThingId));");
	        stmt.executeUpdate("CREATE UNIQUE INDEX IF NOT EXISTS idx2 ON ThingListToThing(ListId, ThingId)");
	        stmt.close();
    	} catch (SQLException e) {
	        System.err.println("Couldn't create Schema");
	        e.printStackTrace();
    	}
    }

	public void createThingListIfNotExists(String name) {
		if(connection == null) {
			throw new RuntimeException("ERROR: Couldn't create Schema, connection is null.");
		}

		try {
			Statement stmt = connection.createStatement();
			// insert new thing list if one with that name does not exist already
			System.err.println("Opening thing list '" + name + "'.");
			stmt.execute("INSERT OR IGNORE INTO ThingList (name) VALUES ('" + name + "');");
			stmt.close();
		} catch (SQLException e) {
	        System.err.println("Couldn't add to thing list with handle " + name);
	        e.printStackTrace();
    	}
	}
	
	public void deleteThingList(String name) throws SQLException {
		if(connection == null) {
			throw new RuntimeException("ERROR: Couldn't create Schema, connection is null.");
		}
		
		if(!hasThingList(name)) { 
			System.err.println("INFO: deleteThingList: Thing list '" + name + "' does not exist.");
			return;
		}
		
		int listId = getThingListId(name);
		Statement stmt = connection.createStatement();
		// insert new thing list if one with that name does not exist already
		System.err.println("INFO: deleteThingList: Deleting thing list '" + name + "'.");
		stmt.execute("DELETE FROM ThingListToThing where ListId = " + Integer.toString(listId) + ";");
		stmt.execute("DELETE FROM ThingList where ListId = " + Integer.toString(listId) + ";");
		stmt.close();
	}
	
	public boolean hasThingList(String name) throws SQLException {
		if(getThingListId(name) != -1) {
			return true;
		}
		return false;
	}
	
	public int getThingListId(String name) throws SQLException {
		if(connection == null) {
			throw new RuntimeException("ERROR: Couldn't create Schema, connection is null.");
		}

		Statement stmt = connection.createStatement();
		
		String countStr = "SELECT COUNT(*) as count from ThingList where name = '" + name + "'";
		ResultSet res = stmt.executeQuery(countStr);
		int count = res.getInt("count");
		if(count == 0) {
			stmt.close();
			return -1; 
		}
		
		String str = "SELECT ListId from ThingList where name = '" + name + "'";
		System.out.println("TRACE: executeQuery: " + str);
		res = stmt.executeQuery(str);
		int listId = res.getInt(1);
		System.out.println("DEBUG: ListId = " + listId);
		stmt.close();
		return listId;
	}
	
	public void addToThingList(String name, List<Thing> things) throws SQLException {
		if(connection == null) {
			throw new RuntimeException("ERROR: Couldn't create Schema, connection is null.");	
		}

		int listId = getThingListId(name);

		PreparedStatement thingStatement = connection
                .prepareStatement("INSERT OR REPLACE INTO Thing VALUES (?, ?, ?, ?, ?, ?);");
		PreparedStatement listToThingStatement = connection
				.prepareStatement("INSERT OR IGNORE INTO ThingListToThing VALUES (?, ?);");
		
		for (Thing thing : things) {
			ThingMetaData metaData = thing.getMetaData();
			thingStatement.setInt(1, metaData.getId());
			thingStatement.setString(2, metaData.getName());
			thingStatement.setString(3, metaData.getImgURL());
			thingStatement.setString(4, metaData.getThumbURL());
			thingStatement.setString(5, metaData.getComment());
			if(metaData.getNumPlays() != null) {
				thingStatement.setInt(6, metaData.getNumPlays());
			} else {
				thingStatement.setNull(6, java.sql.Types.INTEGER);
			}
			thingStatement.execute();
			// get generated id
			ResultSet keys = thingStatement.getGeneratedKeys();
			int thingId = keys.getInt(1);

			System.out.println("TRACE: ThingId = " + thingId + ", ListId = " + listId);
			listToThingStatement.setInt(1, listId);
			listToThingStatement.setInt(2, thingId);
			listToThingStatement.addBatch();
		}
		
		connection.setAutoCommit(false);
        listToThingStatement.executeBatch();
        connection.setAutoCommit(true);
        
	}
	
	
	/// Retrieve the list of names of ThingLists.
	public List<String> getThingLists() throws SQLException {
		if(connection == null) {
			throw new RuntimeException("ERROR: Couldn't create Schema, connection is null.");
		}
		
		Statement stmt = null;

		stmt = connection.createStatement();
	
		String str = "SELECT Name from ThingList order by Name asc";
		System.out.println("TRACE: executeQuery: " + str);
		ResultSet res = stmt.executeQuery(str);

		List<String> listNames = new ArrayList<String>();

		while(res.next()) {
			listNames.add(res.getString(1));
		}
		
		stmt.close();
		return listNames;		
	}


	/// Retrieve all Things (with metadata, no details) for a given ThingList.
	public List<Thing> getThingList(String name) throws SQLException {
		if(connection == null) {
			throw new RuntimeException("ERROR: Couldn't create Schema, connection is null.");
		}
		
		Statement stmt = null;

		stmt = connection.createStatement();
	
		String str = "SELECT t.ThingId, t.Name, ImgUrl, ThumbUrl, Comment, NumPlays from Thing t " + 
				"join ThingListToThing tltt on t.ThingId = tltt.ThingId " + 
				"join ThingList tl on tl.ListId = tltt.ListId " + 
				"where tl.Name = '" + name + "' order by t.Name asc";
		System.out.println("TRACE: executeQuery: " + str);
		ResultSet res = stmt.executeQuery(str);

		List<Thing> thingList = new ArrayList<Thing>();

		while(res.next()) {
			int id = res.getInt(1);
			ThingMetaData metaData = new ThingMetaData(id, 
					res.getString(2),
					res.getString(3), 
					res.getString(4),
					res.getString(5),
					res.getInt(6));
			Thing thing = new Thing(id, metaData);
			thingList.add(thing);
		}
		
		stmt.close();
		return thingList;		
	}



}