import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;

public class DB{

	private static Connection _connection = null;


	private boolean IsConnected(){
		if(_connection == null)
		{
			System.out.println("connection was failed");
			return false;
		}
		else
		{
			System.out.println("connected successfully");
			return true;
		}
	}

	public boolean Connect(){
		try{
			System.out.println("Connecting...");
			//System.out.println("Error line: "+ Class.forName("com.mysql.jdbc.Driver"));
			System.out.println("Next line");
			try {
				Class.forName("com.mysql.jdbc.Driver") ;
			} catch (ClassNotFoundException e) {
				System.out.println("can not find driver");
				e.printStackTrace();
			}
			String url = "jdbc:mysql://localhost:3306/testdata";
			_connection = DriverManager.getConnection(url,"root","pass1234");
			System.out.println("Connected");
			return IsConnected();
		}
		catch(SQLException e){
			System.out.println("SQLException");
			e.printStackTrace();
			return false;
		}


	}

	public boolean Init(){
		Queries queries = new Queries();
		/*
		System.out.println("Dropping tables...");
		if(!RunInitQueries(queries.DropTableQueries())){
			System.out.println("Error occured while dropping tables");
			return false;
		}
		if(!RunInitQueries(queries.CreateTableQueries)){
			System.out.println("Error occured while creating tables");
			return false;
		}
		for(String query : queries.SuperMarketData()){
			if(!Update(query)){
				System.out.println("Error occured while inserting super market: \n"+query);
				return false;
			}
		}*/
		return true;
	}

	private boolean RunInitQueries(ArrayList<String> queries){
		System.out.println("RunInitQueries...");
		if(!IsConnected()){
			System.out.println("Database is not connected");
			return false;
		}
		try {
			System.out.println("RunInitQueries...inside try");
			Statement stmt = _connection.createStatement();
			System.out.println("RunInitQueries...stmt");
			for (String query : queries) {
				System.out.println("RunInitQueries...query = " + query);
				stmt.executeUpdate(query);
			}
		}
		catch (SQLException e) {
			e.printStackTrace();
			return false;
		}
		return true;
	}

	public boolean Update(String query){
		if(!IsConnected()){
			System.out.println("Database is not connected");
			return false;
		}
		try {
			Statement stmt = _connection.createStatement();
			int numOfRowEffected = stmt.executeUpdate(query);
			if(numOfRowEffected > 0){
				System.out.println("Number of rows effected : " + numOfRowEffected);
				return true;
			}
			else{
				System.out.println("None of the rows effected");
				return false;
			}

		}
		catch (SQLException e) {
			e.printStackTrace();
			return false;
		}
	}

	public ArrayList<DbObject> GetDbObject(String tableName, String idColumn, String nameColumn){
		ArrayList<DbObject> rows = new ArrayList<DbObject>();
		if(!IsConnected()){
			System.out.println("Database is not connected");
			return rows;
		}
		try {
			Statement stmt = _connection.createStatement();

			String query = "SELECT "+idColumn+", "+ nameColumn +" FROM "+tableName;
			ResultSet rs = stmt.executeQuery(query);
			while(rs.next()){
				DbObject obj = new DbObject();
				obj.Id = rs.getInt(idColumn);
				obj.Name = rs.getString(nameColumn);
				rows.add(obj);
			}
		}
		catch (SQLException e) {
			e.printStackTrace();
		}
		return rows;
	}
}