package solutions;

import java.io.IOException;
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.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.ArrayList;

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;

@WebServlet("/ValidateTag")

public class ValidateTag extends HttpServlet {

    // Collects or returns data for sensorname, sensorvalue parameters
	private static final long serialVersionUID = 1L;

	// Local variables holding last values stored for each parameter
    SensorData lastSensor = new SensorData("unknown", "unknown");
    Gson gson = new Gson();
    Connection conn = null;
	Statement stmt;

    public ValidateTag() {
        super();
    }
	  public void init(ServletConfig config) throws ServletException {
		  super.init(config);
		  System.out.println("Sensor server is up and running\n");
		  System.out.println("Upload sensor data with http://localhost:8080/PhidgetServer2019/ValidateTag?sensordata=someSensorJson");
		  System.out.println("View last sensor reading at  http://localhost:8080/PhidgetServer2019/ValidateTag?getdata=true \n\n");
	  }

	  private void getConnection() {
		  // This will load the driver and establish a connection
			String user = "jadczakd";
		    String password = "labenTra8";

		    // 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("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?");
		        }
	  }

	  private void closeConnection() {
			// get a connection with the user/pass
	        try {
	            conn.close();
	        } catch (Exception e) {
	            System.out.println(e);
	        }

	  }

	  public void destroy() {
	        try { // conn.close();  // should have no need to close connection
	        	  // add anything extra to do when servlet closes
	        } catch (Exception e) {
	            System.out.println(e);
	        }
	  } // destroy()

	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");

	    // Check to see whether the client is requesting data or sending it
	    String getdata = request.getParameter("getdata");

	    // if no getdata parameter, client is sending data
	    if (getdata == null){
	    		// 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);
				// now update the table

			} // endif sensorJsonString not null
		} // end if getdata is null
	    else {  // Retrieve and return data (JSON format)
	    	   // Code to retrieve data
	    	String tagId = request.getParameter("tagid");
			String resultsJson = retrieveSensorData(tagId);
				// Update sensor values and send back response
			PrintWriter out = response.getWriter();
			out.println(resultsJson);
			System.out.println("validated card, sending back json"+resultsJson.toString());
			out.close();

			//sendJSONString(response);

	    	}

	}

	/*private String updateSensorValues(SensorData oneSensor){
		// all ok, update last known values and return
		lastSensor = oneSensor;
		System.out.println("DEBUG : Last sensor tagid " + oneSensor.getTagid() + ", readerid "+oneSensor.getReaderid() +", roomid "+oneSensor.getReaderid());
		return "Sensor value updated.";
	}*/

	/*private void sendJSONString(HttpServletResponse response) throws IOException{
		  response.setContentType("application/json");
	      String json = gson.toJson(lastSensor);

	      PrintWriter out = response.getWriter();
	      System.out.println("DEBUG: sensorServer JSON: "+lastSensor.toString());

	      out.println(json);
	      out.close();
	}*/

	private String retrieveSensorData(String tagid ) {
		String selectSQL = "select * from validtags where tagid='" +
					tagid + "'";
		ResultSet rs;

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

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

			// iterate over the result set
			while (rs.next()) {
				// Declare  a SensorData object to hold individual values,
				// initialise to defaults
				 // fill in statement
				SensorData oneSensor = new SensorData("unknown", "unknown","unknown");
			   	oneSensor.setTagid(rs.getString("tagid"));
			   	oneSensor.setReaderid(rs.getString("readerid"));
			   	oneSensor.setDoorid(rs.getString("roomid"));
			   	oneSensor.valid = true;
			   	// add this sensor to ArrayList of Sensors
			   	allSensors.add(oneSensor);
			   	// debug print this sensor to console

			}

		    } catch (SQLException ex) {
		            System.out.println("Error in SQL " + ex.getMessage());
		    }
			// close connection to databse
			closeConnection();

			// Convert sensor list to json array and send back to user
			String allSensorsJson = gson.toJson(allSensors);

			// return this String from method
			return allSensorsJson;

	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
	    doGet(request, response);
	}

}