package obchallenge;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

import javax.script.Invocable;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.codehaus.jettison.json.JSONObject;

public class EvaluateJavascript extends HttpServlet {

  private static final long serialVersionUID = 1L;

  public void doGet(HttpServletRequest request, HttpServletResponse response)
      throws ServletException, IOException {
    // Output object
    JSONObject jsonResponse = new JSONObject();

    // Parameter retrieving
    String sqlChallengeId = request.getParameter("sqlChallengeId");
    String incomingScript = request.getParameter("javascriptString");

    // Connection to database
    Connection connection = null;
    try {
      Class.forName("org.postgresql.Driver");
      connection = DriverManager.getConnection("jdbc:postgresql://" + Constants.DB_URL + ":"
          + Constants.DB_PORT + "/" + Constants.DB_SID, Constants.DB_USER, Constants.DB_PASSWORD);

      // Get functionName
      String getFunctionNameQuery = "SELECT function_name FROM javascript_challenge WHERE sql_challenge_id = ?";
      PreparedStatement statement = connection.prepareStatement(getFunctionNameQuery);
      statement.setString(1, sqlChallengeId);
      ResultSet resultSet = statement.executeQuery();
      resultSet.next();
      String functionName = resultSet.getString(1);

      // Create a script engine manager
      ScriptEngineManager scriptEngineManager = new ScriptEngineManager();
      ScriptEngine scriptEngine = scriptEngineManager.getEngineByName("JavaScript");
      Invocable invocable = (Invocable) scriptEngine;
      Object object = scriptEngine.get("test");
      // "var test = new Object(); test.suma = function Suma(num) { this.num = this.num; var result = num*2; print(result)}";

      // Evaluate the incomingScript
      scriptEngine.eval(incomingScript);

      // Prepare output parameter
      boolean correct = true;

      // For each test available for that challenge
      String getTestParametersQuery = "SELECT input_parameters, output_parameter FROM javascript_expected_results WHERE javascript_challenge_id = ?";
      statement = connection.prepareStatement(getTestParametersQuery);
      statement.setString(1, sqlChallengeId);
      resultSet = statement.executeQuery();
      while (resultSet.next()) {
        String inputParameters = resultSet.getString(1);
        String outputParameter = resultSet.getString(1);

        // Execute the function with the corresponding parameters
        Object outputObject = invocable.invokeMethod(object, functionName,
            (Object[]) inputParameters.split(","));
      }

      // Add result to the response
      jsonResponse.put("correct", correct);

      resultSet.close();
      statement.close();
    } catch (Exception e) {
      e.printStackTrace();
    } finally {
      if (connection != null) {
        try {
          connection.close();
        } catch (SQLException e) {
          e.printStackTrace();
        }
      }
    }

    response.setContentType("application/json");
    PrintWriter out = response.getWriter();
    out.print(jsonResponse);
  }
}