package extended.forms;

import javax.jcr.Node;
import javax.jcr.RepositoryException;

import org.apache.commons.lang.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;


import info.magnolia.context.MgnlContext;
import info.magnolia.jcr.util.NodeUtil;
import info.magnolia.jcr.wrapper.I18nNodeWrapper;
import info.magnolia.module.form.engine.EndView;
import info.magnolia.module.form.engine.FormStateTokenMissingException;
import info.magnolia.module.form.engine.FormStepState;
import info.magnolia.module.form.engine.NoSuchFormStateException;
import info.magnolia.module.form.engine.RedirectView;
import info.magnolia.module.form.engine.RedirectWithTokenAndParametersView;
import info.magnolia.module.form.engine.RedirectWithTokenView;
import info.magnolia.module.form.engine.View;
import info.magnolia.module.form.processors.FormProcessorFailedException;
import info.magnolia.module.form.templates.components.FormParagraph;
import info.magnolia.module.form.templates.components.multistep.NavigationUtils;
import info.magnolia.module.form.templates.components.multistep.SubStepFormEngine;
import info.magnolia.rendering.context.RenderingContext;

/**
 * Custom form engine which saves data in the session when the user clicks 'back' instead of
 * discarding it.
 * Note: Besides the custom FormDataBinder {@link ExtendedFormDataBinder} that is used by
 * this enting, only two lines of code had to be added for this behavior, these start on line 107.
 */
public class ExtendedSubStepFormEngine extends SubStepFormEngine {

  private final Logger logger = LoggerFactory.getLogger(ExtendedSubStepFormEngine.class);

  /**
   * Constructor.
   * @param configurationNode the config node
   * @param configurationParagraph the config paragraph
   * @param startPage the start page
   * @param context the rendering context
   */
  public ExtendedSubStepFormEngine(Node configurationNode,
      FormParagraph configurationParagraph,
      Node startPage,
      RenderingContext context) {
    super(configurationNode, configurationParagraph, startPage, context);
  }

  @Override
  public View handleRequest(Node content) throws RepositoryException {
    if (!isFormSubmission()) {
      String formStateToken;
      try {
        formStateToken = getFormStateToken();
      } catch (FormStateTokenMissingException e) {
        return handleTokenMissing();
      }

      try {
        setFormState(getFormState(formStateToken));
      } catch (NoSuchFormStateException e) {
        return handleNoSuchFormState(e.getToken());
      }

      View view = getFormState().getView();
      getFormState().setView(null);
      if (view == null) {
        return getFormView(getFormState().getStep(NodeUtil.getNodeIdentifierIfPossible(content)));
      }
      if (getFormState().isEnded()) {
        destroyFormState();
      }
      return view;
    }

    String formStateToken;
    final Node mainContent = new I18nNodeWrapper(context.getMainContent());
    try {
      formStateToken = getFormStateToken();
    } catch (FormStateTokenMissingException e) {
      // Cant post without a token... should never happen
      // Redirect the user to this page
      return new RedirectView(mainContent);
    }

    try {
      setFormState(getFormState(formStateToken));
    } catch (NoSuchFormStateException e) {
      return handleNoSuchFormStateOnSubmit(e.getToken());
    }

    View view = null;
    if (isBackButton()) {
      logger.debug("User pressed back button. Currently executing step number is {}",
          getFormState().getCurrentlyExecutingStep());

      // Only the following two lines have been added to the default SubStepFormEngine:
      FormStepState step = getFormDataBinder().bind(content);
      getFormState().addStep(step);

      String pageUuid = getPreviousPage();
      if (pageUuid == null) {
        return getFormView(getFormState().getStep(NodeUtil.getNodeIdentifierIfPossible(content)));
      }
      // update current step count
      getFormState().setCurrentlyExecutingStep(getFormState().getCurrentlyExecutingStep() - 1);
      logger.debug("Updated currently executing step. Now is {}",
          getFormState().getCurrentlyExecutingStep());
      Node parent = new I18nNodeWrapper(
          NavigationUtils.findParagraphParentPage(NodeUtil.getNodeByIdentifier(content.getSession()
              .getWorkspace()
              .getName(), pageUuid)));
      if (isRedirectWithParams()) {
        return new RedirectWithTokenAndParametersView(parent, formStateToken);
      }
      return new RedirectWithTokenView(parent, formStateToken);
    }
    view = processSubmission(content);

    getFormState().setView(null);

    if (view instanceof EndView) {
      destroyFormState();
      return view;
    }

    if (view instanceof RedirectWithTokenView) {
      return view;
    }

    if (view instanceof RedirectWithTokenAndParametersView) {
      return view;
    }

    getFormState().setView(view);
    if (isRedirectWithParams()) {
      return new RedirectWithTokenAndParametersView(mainContent, getFormState().getToken());
    }
    return new RedirectWithTokenView(mainContent, getFormState().getToken());
  }

  @Override
  protected ExtendedFormDataBinder getFormDataBinder() {
    ExtendedFormDataBinder formDataBinder = new ExtendedFormDataBinder();
    formDataBinder.setI18nBasename(getConfigurationParagraph().getI18nBasename());
    return formDataBinder;
  }

  /**
   * Performs the processing of submitted values. If this method returns a RedirectView this is treated like an exit
   * and the formState is removed from session.
   *
   * @param content
   */
  private View processSubmission(Node content) throws RepositoryException {

      // Validate the input parameters and collect FormField instances
      FormStepState step = getFormDataBinder().bindAndValidate(content);

      // Add the submitted fields to formState
      getFormState().addStep(step);

      // If validation failed proceed and render page
      if (!step.isValid()) {
          return getValidationFailedView(step);
      }

      // Validation succeeded

      View validationSuccessfulView = getValidationSuccessfulView(getFormState());
      if (validationSuccessfulView != null) {
          //on success  we move to the next step, increase count by one
          getFormState().setCurrentlyExecutingStep(getFormState().getCurrentlyExecutingStep() + 1);
          logger.debug("Updated currently executing step. Now is {}", getFormState().getCurrentlyExecutingStep());
          return validationSuccessfulView;
      }

      if (StringUtils.isNotEmpty(MgnlContext.getParameter("field"))) {
          return getValidationFailedView(step);
      }

      getFormState().setEnded(true);

      // Execute processors
      try {
          executeProcessors(getFormState().getValues());
      } catch (FormProcessorFailedException e) {
          return getProcessorFailedView(e.getMessage());
      } catch (Exception e) {
          logger.error("FormProcessor threw unexpected exception", e);
          return getProcessorFailedView(null);
      }
      // Render page with success message
      return getSuccessView();
  }

}