<?php
/**
 * Query By Form
 *
 * This module allows node modules to add a query by form tab for their node
 * types to the default search form
 *
 * @copyright 2008 Ouest Systemes Informatiques (OSInet)
 * @author Frederic G. MARAND
 * @version $Id: qbf.module,v 1.5 2008-08-27 10:45:50 marand Exp $
 * @license CeCILL 2.0
 * @package QBF
 */

define('QBF_LEVEL_REMOVE',           0);
define('QBF_LEVEL_DISPLAY',          1); // Display only, don't use
define('QBF_LEVEL_OPTIONAL',         2);
define('QBF_LEVEL_REQUIRED',         3);

define('QBF_PATH_QUERY',             'qbf/query');

define('QBF_PERM_QUERY',             'use qbf search functions');

/**
 * Experiment in creating a new "hook_qbf_rewrite_form()".
 *
 * @todo check whether this is redundant with hook_form_alter()
 *
 * @param array $form
 * @return array
 */
function qbf_rewrite_form($form)
  {
  $hookName = 'qbf_rewrite_form';

  foreach (module_implements($hookName) as $module)
    {
    $function = "${module}_$hookName";
    $form = $function($form);
    }
  return drupal_get_form($form);
  }

/**
 * Transform a form array for QBF.
 *
 * This function obtains the form array using Forms API, and transforms it by
 * modifying widgets to other types where needed.
 *
 * Any additional parameter passed to the function is transmitted to the form
 * generating function.
 *
 * @param string $form_id
 * @return array
 */
function qbf_transform_form($form_id)
  {
  $arArgs = func_get_args();
//dsm(array('qtf' => $arArgs));
  // Fetch the basic form and rename it, passing it the caller's arguments
  $form = call_user_func_array('drupal_retrieve_form', $arArgs);
  $newFormId = "qbf_$form_id";

  // Only keep the children of the form and QBF properties on the form itself
  $elements = array();
  $newForm = array();
  $newForm['#qbf_source_form_id'] = $form_id;
  if (in_array('#qbf', element_properties($form)))
    {
    $newForm += $form['#qbf'];
    }

  foreach (element_children($form) as $key)
    {
    // dsm("Transforming $key, type " . $form[$key]['#type']);
    $newElement = _qbf_transform_element($key, $form[$key]);
    if (!is_null($newElement))
      {
      $newForm[$key] = $newElement;
      }
    }

  $newForm['#id'] = $newFormId;
  $newForm['#multistep'] = TRUE;
  $newForm['#redirect']  = FALSE;
  $newForm['#after_build'][] = 'qbf_after_build';
// dsm($newForm);
  return $newForm;
  }

/**
 * Transform a form element for QBF.
 *
 * QBF-specific properties are:
 * - #qbf : array of properties
 * - #level: only within #qbf @see QBF_* constants
 *
 * @param array &$element
 * @return void
 */
function _qbf_transform_element($key, array $element)
  {
  // dsm(array('key' => $key, 'element' => $element));

  // Types without a default transformation are not transformed
  static $arDefaultTypeTransformations = array
    (
    'button'         => NULL,
    'file'           => NULL,
    // 'hidden'         => NULL,
    'markup'         => NULL,
    'password'       => NULL,
    'radio'          => NULL,
    'submit'         => NULL,
    'textarea'       => 'textfield',
    // 'value'          => 'value',
    );

  // Properties without a default transformation are not transformed
  static $arDefaultPropertyTransformations = array
    (
    // Standard properties
    '#action'        => NULL,
    '#after_build'   => NULL,
    '#base'          => NULL,
    '#button_type'   => NULL,
    '#built'         => NULL,
    '#description'   => NULL,
    '#method'        => NULL,
    '#parents'       => NULL,
    '#redirect'      => NULL,
    '#ref'           => NULL,
    '#required'      => NULL,
    '#rows'          => NULL,
    '#submit'        => NULL,
    '#tree'          => NULL,
    '#validate'      => NULL,
    );

  // Property values causing element removal
  static $arKillerProperties = array
    (
    '#disabled'      => TRUE,
    );

  // Transform type
  $sourceType = $element['#type'];
  // .. Default transformation
  $destType = array_key_exists($sourceType, $arDefaultTypeTransformations)
    ? $arDefaultTypeTransformations[$sourceType]
    : $sourceType;
  // .. Apply form-defined type override
  if (isset($element['#qbf']['#type']))
    {
    $destType = $element['#qbf']['#type'];
    }

  if (is_null($destType))
    {
    $ret = NULL;
    }
  else
    {
    $ret = $element;
    $ret['#type'] = $destType;
    if (!array_key_exists('#qbf', $element) || $element['#qbf']['#level'] == QBF_LEVEL_REMOVE)
      {
      $ret = NULL;
      }
    else
      {
      foreach (element_properties($element) as $propertyName)
        {
        // Apply killer properties first to avoid useless work
        if (array_key_exists($propertyName, $arKillerProperties)
          && ($element[$propertyName] = $arKillerProperties[$propertyName]))
          {
          $ret = NULL;
          break;
          }

        // Now transform or copy remaining properties
        if (array_key_exists($propertyName, $arDefaultPropertyTransformations))
          {
          $ret[$propertyName] = $arDefaultPropertyTransformations[$propertyName];
          }
        else
          {
          $ret[$propertyName] = $element[$propertyName];
          }

        // And apply form-defined property overrides
        if ($propertyName == '#qbf')
          {
          foreach ($element[$propertyName] as $overrideName => $overrideValue)
            {
          	$ret[$overrideName] = $overrideValue;
            }
          }
        }

      // Recursively transform children
      foreach (element_children($element) as $childName)
        {
        $child = _qbf_transform_element($childName, $element[$childName]);
        if (is_null($child))
          {
          unset($ret[$childName]);
          }
        else
          {
          $ret[$childName] = $child;
          }
        }
      }
    }

  //dsm(array('key' => $key, 'transformed element' => $ret));
  return $ret;
  }

/**
 * Implement hook_perm().
 *
 * @return array
 */
function qbf_perm()
  {
  $ret = array
    (
    QBF_PERM_QUERY,
    );

  return $ret;
  }

/**
 * Implement hook_forms().
 *
 * @todo dynamically build the list of forms
 *
 * @return array
 */
function qbf_forms()
  {
  $forms['qbf_job_form'] = array
    (
    'callback'           => 'qbf_transform_form',
    'callback arguments' => array('job_form'),
    );
  return $forms;
  }

/**
 * Insert the query results at the bottom of the query form.
 *
 * @param array $form
 * @param array $form_values
 * @return array
 */
function qbf_after_build($form, $form_values)
  {
  $arQuery = _qbf_extract_query($form, $form_values);

  $form['food'] = array
    (
    '#type'    => 'markup',
    '#value'   => "<p>" . dvr($arQuery, true) . "</p>",
    );
  return $form;
  }

/**
 * Recursively build a query array from the form and its values
 *
 * In the current version, element names are supposed to be unique, even at
 * different levels in the tree.
 *
 * @param array $form
 * @param array $form_values
 */
function _qbf_extract_query($form, $form_values)
  {
  $name = $form['#parents'][0];
  // Elements which are removed or display-only have no place in the query
  if (array_key_exists('#qbf', $form) && array_key_exists('#level', $form['#qbf'])
    && $form['#qbf']['#level'] >= QBF_LEVEL_OPTIONAL)
    {
    $ret = array($name => $form_values[$name]);
    }
  else
    {
    $ret = array();
    }

  // QBF level is not inherited, so this loop is outside the "if" above
  foreach (element_children($form) as $childName)
    {
  	$ret += _qbf_extract_query($form[$childName], $form_values);
    }

  return $ret;
  }