package e4s.tutorial;

import e4s.html.*;
import e4s.html.input.extended.*;
import e4s.servlet.E4ModuleImplementation;

/**
 * This is an example how to deal with E4Methods. 
 * E4Method cover the messaging of your application and each 
 * E4Method is associated with a Java function. So we can treat 
 * them as "normal" arguments in our application, for example if we 
 * want an Anchor (<A>) tag to call another function. It is typically 
 * for web applications, that  either a form (<FORM>) or an anchor will 
 * make branches to other functions. This example does not make
 * use of E4CSS definitions, so font attributes are included in the 
 * application now.
 */
public class Example_Method extends E4ModuleImplementation
{
   /**
    * This a placeholder for a Java function called "start". You can 
    * find it below. From the tutorial framework, this is also the entry 
    * into our module. Please note, that the variable is not initialized 
    * (so it has a value of null) unless it will be initialized by the 
    * E4S framework during servlet startup.
    */
   public static E4Method start = null;
   
   /**
    * This is another placehold for another function.
    */
   public static E4Method foo = null;
   
   /**
    * This is another placehold for another function.
    */
   public static E4Method buh = null;

   /**
    * This defines our first input field, we do not care it's name.
    */
   private final static E4InputFieldName PARAM_UNNAMED = E4InputFieldName.ANY();
   
   /**
    * This is another input field, we named it "ALPHA".
    */
   private final static E4InputFieldName PARAM_NAMED = new E4InputFieldName("ALPHA");
   
   /**
    * Our first function, becoming involved by the tutorial framework either 
    * or when you click on that anchor tag generated in function buh. 
    * 
    * @param html the HTML object where we can let E4S render output
    * @param params an object containing all CGI parameters passed to that URL
    */
   public void start(HTML html, E4CgiParams params) 
   throws Exception
   {
      // create a form with two input fields and function "foo" as receiver
      FORM form = html.FORM(foo);
      form.TEXTFIELD(PARAM_UNNAMED,"Enter a value here",20);
      form.BR();
      form.TEXTFIELD(PARAM_NAMED,"Enter another value here",20);
      form.BR();
      form.BUTTON_Submit("Send");
    
      // set any previous values to that form 
      form.setValue(params);
      
      html.P();
   }
   
   /**
    * This function receives data from the form defined in function start above. 
    * We display the parameters, and call another function called "buh" using 
    * an anchor tag.
    * 
    * @param html the HTML object where we can let E4S render output
    * @param params an object containing all CGI parameters passed to that URL
    */
   public void foo( HTML html, E4CgiParams params )
   {
      html.FONT(FONT.ARIAL).SMALL().println("The value you have entered was: " 
            + params.get(PARAM_UNNAMED) + " and " + params.get(PARAM_NAMED));
      html.BR();
      
      A href = html.A(buh);
      href.FONT(FONT.ARIAL).SMALL().print("Click here to call another function now");
      href.addParameter(params);
   }

   /**
    * Offer an back button to function "start" here, pass the parameters.
    * 
    * @param html the HTML object where we can let E4S render output
    * @param params an object containing all CGI parameters passed to that URL
    */
   public void buh( HTML html, E4CgiParams params )
   {
      A href = html.A(start);
      href.FONT(FONT.ARIAL).SMALL().print("Click here to go back to the beginning");
      href.addParameter(params);
   }
}