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("/Validation")
public class Validation extends HttpServlet {

    private static final long serialVersionUID = 1L;

    Gson gson = new Gson();

   Connection conn = null;
   Statement stmt;
   String tagItemsList = null;

  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 = "hussamoh";
    String password = "Brenkoil8";
    // 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/MobileAppServer/Validation?sensordata=some_sensor_data_in_json_format");
          System.out.println("View last sensor reading at  http://localhost:8080/MobileAppServer/Validation?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 Validation() {
        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", "unknown", "unknown");



        // if no getdata parameter, client is sending data
                // getdata is null, therefore it is receiving data
                // Extract the parameter data holding the sensordata
            String sensorJsonString = request.getParameter("sensordata");
            System.out.println(sensorJsonString);
            // 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);

                Boolean result = retrieveSensorData("", oneSensor.getSensorName());
                PrintWriter out = response.getWriter();
                if (result == true )
                    out.println("true");
                else out.println("false");
                out.close();

            } // endif sensorJsonString not null
        } // end if getdata is null
       // Retrieve and return data (JSON format)
               // 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 void updateSensorTable(SensorData oneSensor){
        try {
            // Create the INSERT statement from the parameters
            // set time inserted to be the current time on database server
            String updateSQL =
                "insert into sensorusage(userid, sensorname, sensorvalue, sensordate) " +
                "values('"+oneSensor.getUserId()  + "'," +
                		oneSensor.getSensorName() + "','" +
                           oneSensor.getSensorValue()  + "','" +
                           "now());";

                System.out.println("DEBUG: Update: " + updateSQL);
                stmt.executeUpdate(updateSQL);
                System.out.println("DEBUG: Update successful ");
        } catch (SQLException se) {
            // Problem with update, return failure message
            System.out.println(se);
            System.out.println("\nDEBUG: Update error - see error trace above for help. ");
            return;
        }
    }

    public boolean retrieveSensorData(String locks, String tagname) {

        try {
            PreparedStatement ps = null;
            String query = "select * from unlocks where tagname ='" +tagname+"'";
            System.out.println (query);
            ps = conn.prepareStatement(query);
            ResultSet rs = ps.executeQuery();
            if (rs.next()) {
                return true;
            } else {
                return false;
            }
        } catch (SQLException ex) {

        }

        return false;
    }
}