<?php

class GridHelper extends AppHelper {

  var $jqGrid_options;
  var $included, $invalid;
  var $columns;
  var $controller;

  function __construct() {
    $this->reset();
  }

  function reset() {
    $this->jqGrid_options
      = array('limit' => 20,
	      'search_fields' => array(),
	      'custom_post_data' => array(),
	      );

    $this->columns  = array();
    $this->included = array();
    $this->invalid  = array();
    $this->controller = null;

    return $this;
  }

  // Add to the set of columns for this grid
  function columns($columns) {
    if (isset($columns)) {
      if (is_array($columns))
	$this->columns = array_merge($this->columns, $columns);
      else
	$this->columns[] = $columns;
    }
    return $this;
  }

  // Default fields will be included unless excluded.
  // This should be used for fields that ALWAYS need
  // to be included unless specifically overridden.
  function defaultFields($fields) {
    if (isset($fields)) {
      if (is_array($fields))
	$this->included = array_merge($this->included, $fields);
      else
	$this->included[] = $fields;
    }
    return $this;
  }

  // Invalid fields will simply not be accepted as
  // part of the inclusion set, even if specified as
  // a column AND explicit requested for inclusion.
  function invalidFields($fields) {
    if (isset($fields)) {
      if (is_array($fields))
	$this->invalid = array_merge($this->invalid, $fields);
      else
	$this->invalid[] = $fields;
    }
    return $this;
  }

  function searchFields($fields) {
    if (isset($fields)) {
      if (is_array($fields))
	$this->jqGrid_options['search_fields']
	  = array_merge($this->jqGrid_options['search_fields'], $fields);
      else
	$this->jqGrid_options['search_fields'][] = $fields;
    }
    return $this;
  }

  function sortField($field, $order = null) {
    $this->jqGrid_options['sort_column'] = $field;
    if ($order)
      $this->jqGrid_options['sort_order'] = $order;
    return $this;
  }

  function limit($limit) {
    $this->jqGrid_options['limit'] = $limit;
    return $this;
  }

  function id_list($items) {
    $this->jqGrid_options['custom_ids']
      = array_map(create_function('$data',
				  'return $data["id"];'),
		  $items);
    $this->jqGrid_options['action'] = 'idlist';
    return $this;
  }

  function customData($data) {
    if (isset($data)) {
      if (is_array($data))
	$this->jqGrid_options['custom_post_data']
	  = array_merge($this->jqGrid_options['custom_post_data'], $data);
      else
	$this->jqGrid_options['custom_post_data'][] = $data;
    }
    return $this;
  }


  /**************************************************************************
   **************************************************************************
   **************************************************************************
   * function: render
   *  - Renders the grid.
   *    Unless manipulated with the included / excluded parameters,
   *    the grid will contain the columns defined as part of the
   *    standard set, as set through use of the the included() function.
   *
   * args
   *   included:
   *     Array of column names to include in the grid.
   *        - OR -
   *     true:  includes all columns.
   *        - OR -
   *     false: includes no additional columns beyond
   *     the standard defined set.

   *   excluded:
   *     Array of column names to exclude from the grid.
   *     These will be excluded even if explicitly  included
   *     through the included parameter.
   *        - OR -
   *     true:  excludes all columns other than those
   *     explicitly included through the included parameter.
   *        - OR -
   *     false: does not exclude any included columns.
   */

  function render($view, $config = null, $included = true, $excluded = false) {
    // Handle null values for included/excluded 
    if (!isset($included))
      $included = false;
    if (!isset($excluded))
      $included = false;

    // Convert true/false into an array
    if (is_bool($included) && $included)
      $included = array_keys($this->columns);
    elseif (is_bool($included) && !$included)
      $included = array();

    // Convert true/false into an array
    if (is_bool($excluded) && $excluded)
      $excluded = array_diff_key(array_keys($this->columns), $included);
    elseif (is_bool($excluded) && !$excluded)
      $excluded = array();

    // Tack on any config include/exclude requests
    if (isset($config['include']))
      $included = array_merge($included, $config['include']);
    if (isset($config['exclude']))
      $excluded = array_merge($excluded, $config['exclude']);
    unset($config['include'], $config['exclude']);

    // Calculate the actual inclusion set
    $included = array_diff(array_merge($this->included, $included),
			   array_merge($this->invalid, $excluded));

    // Defined the columns, based on the inclusion set,
    // remapping column names as necessary.
    $this->jqGrid_options['jqGridColumns'] = array();
    foreach (array_intersect_key($this->columns, array_flip($included)) AS $name => $col) {
      if (!empty($config['remap'][$name]))
	$name = $config['remap'][$name];
      $this->jqGrid_options['jqGridColumns'][$name] = $col;
    }

    // Make sure search fields are all part of the inclusion set
    $this->jqGrid_options['search_fields']
      = array_intersect($this->jqGrid_options['search_fields'], $included);

    // As an exception to the normal config variables,
    // handle 'rows' here.  The reason is so that we
    // ease the burden on views which have a list of
    // items in a CakePHP style array, but jqGrid is
    // expecting just an array if IDs.  So, we'll run
    // as middle man (that is our purpose, after all)
    if (isset($config['rows'])) {
      // Shrink the limit... user can always override
      $this->id_list($config['rows'])->limit(10);
      unset($config['rows']);
    }

    // One more exception, as the search fields get
    // defined, but not passed to jqGrid unless
    // specifically requested.
    if (isset($config['search']))
      unset($config['search']);
    else
      unset($this->jqGrid_options['search_fields']);

    // Figure out what controller we're using to
    // populate the grid via ajax, and set it.
    $controller = $this->controller;
    if (!isset($controller)) {
      // Try to get the controller based on the convention
      // that our grid elements are named after the controller.
      // If this doesn't work, user will have to manually set
      // $this->controller to whatever they need.
      $trace = debug_backtrace(false);
      if (preg_match('%elements[/\\\\]([^.]+)\.ctp$%',
		     $trace[0]['file'], $matches))
	$controller = $matches[1];
    }
    $this->jqGrid_options['controller'] = $controller;

    // Incorporate all other user options
    if (isset($config))
      $this->jqGrid_options = array_merge($this->jqGrid_options, $config);

    //pr(compact('config') + array('jqGrid_options' => $this->jqGrid_options));
    echo $view->element('jqGrid', $this->jqGrid_options);

    // Since we only have one instance of this class
    // as a helper, we must assume it could be used
    // again later to render an entirely different grid.
    // Reset the variables to prevent contamination.
    $this->reset();
    return $this;
  }
  
}