import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.google.gson.Gson;

import java.util.*;
import java.io.*;
import java.sql.*;


/**
 * Servlet implementation class sensorToDB
 */
@WebServlet("/DataValidation")
public class DataValidation extends HttpServlet
{
	private static final long serialVersionUID = 1L;

    Gson gson = new Gson();
    Connection conn = null;
    Statement stmt;

	public void init(ServletConfig config) throws ServletException
	{
	  // init method is run once at the start of the servlet loading
	  // This will load the driver and establish a connection
	    super.init(config);
		String user = "iqbali";
	    String password = "Bredjcwe4";
	    // Note none default port used, 6306 not 3306
	    String url = "jdbc:mysql://mudfoot.doc.stu.mmu.ac.uk:6306/"+user;

		// Load the database driver
		try {  Class.forName("com.mysql.jdbc.Driver").newInstance();
	        } catch (Exception e) {
	            System.out.println(e);
	        }

			// get a connection with the user/pass
        try {
            conn = DriverManager.getConnection(url, user, password);
			  System.out.println("Sensor to DB  server is up and running\n");
			  System.out.println("Upload sensor data with http://localhost:8080/MADServerSide/SensorServerDB?sensordata=some_sensor_data_in_json_format");
			  System.out.println("View last sensor reading at  http://localhost:8080/MADServerSide/SensorServerDB?getdata=true\n\n");

            System.out.println("DEBUG: Connection to database successful.");
            stmt = conn.createStatement();
        } catch (SQLException se) {
            System.out.println(se);
            System.out.println("\nDid you alter the lines to set user/password in the sensor server code?");
        }
	 } // init()

	  public void destroy() {
	        try { conn.close(); } catch (SQLException se) {
	            System.out.println(se);
	        }
	  } // destroy()

    public DataValidation() {
        super();
        // TODO Auto-generated constructor stub
    }

	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
	{
	    response.setStatus(HttpServletResponse.SC_OK);
	    // Declare a SensorData object to hold the incoming data
	    SensorData oneSensor = new SensorData("unknown", "unknown");

	    		// getdata is null, therefore it is receiving data
	    		// Extract the parameter data holding the sensordata
			String sensorJsonString = request.getParameter("sensordata");

			// Problem if sensordata parameter not sent, or is invalid json
			if (sensorJsonString != null)
			{
				// Convert the json string to an object of type SensorData
				oneSensor = gson.fromJson(sensorJsonString, SensorData.class);

				retrieveSensorData(oneSensor.getSensorname());
				// Update sensor values and send back response
				//PrintWriter out = response.getWriter();
				//out.println(resultsJson);
				//out.close();

			} // endif sensorJsonString not null
	    	   // Code to retrieve data

	}



	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
	{
	    // Post is same as Get, so pass on parameters and do same
	    doGet(request, response);
	}

	private Boolean retrieveSensorData(String sensorname)
	{
				String selectSQL = "select * from validation";
					ResultSet rs;

					// Declare ArrayList of sensors to hold results
					ArrayList<String> allSensors = new ArrayList<String>();

					try
					{
					   // create a result set of selected values
						rs = stmt.executeQuery(selectSQL);

						// Declare  a SensorData object to hold individual values,
						// initialise to defaults
						while (rs.next())
						{
						   	// add this sensor to ArrayList of Sensors
						   	allSensors.add(rs.getString("sensorname"));
						}

						return allSensors.contains(sensorname);

					 } catch (SQLException ex)
							{
						       System.out.println("Error in SQL " + ex.getMessage());
						        System.out.println("UNKNOWN TAG. DOOR LOCKED.");

						       return false;
						    }
						// Convert sensor list to json array and send back to user


	}
}