<?php

/**
 * @file
 * Fill form elements with data from GET or POST values.
 *
 * Originally written by ea. Farris <eafarris@gmail.com>
 * Based on an idea from chx, from the conversation at
 * http://www.drupal.org/node/27155.
 */
/**
 * Implementation of hook_help().
 */
function prepopulate_help($path, $arg){
  switch($path){
    case 'admin/modules#description':
      return t('Pre-populates forms with HTTP GET or POST data');
      break;
  }
}

/**
 * Implementation of hook_form_alter().
 */
function prepopulate_form_alter(&$form, $form_state, $form_id){
  // Provide for accepting base64 encoded fields.
  if(isset($_REQUEST['pp'])){
    parse_str(base64_decode($_REQUEST['pp']), $_REQUEST);
  }
  if(isset($_REQUEST['edit'])){
    $form['#after_build'][] = 'prepopulate_after_build';
  }
}

/**
 * An #after_build function to set the values prepopulated in the request.
 */
function prepopulate_after_build($form, &$form_state){
  if(isset($_REQUEST['pp'])){
    parse_str(base64_decode($_REQUEST['pp']), $_REQUEST);
  }
  if(isset($_REQUEST['edit'])){
    $request = (array)$_REQUEST['edit'];
    _prepopulate_request_walk($form, $request);
  }
  return $form;
}

/**
 * Internal helper to set element values from the $_REQUEST variable.
 *
 * @param &$form
 * Array. A form element.
 * @param &$requestslice
 * String or array. Value(s) to be applied to the element.
 */
function _prepopulate_request_walk(&$form, &$requestslice){
  if(is_array($requestslice)){
    foreach(array_keys($requestslice) as $requestvar){
      if(element_child($requestvar) && !is_null($form[$requestvar]) && $form[$requestvar]['#type'] != "value"){
        if(!isset($form[$requestvar]['#access']) || $form[$requestvar]['#access'] != FALSE){
          _prepopulate_request_walk($form[$requestvar], $requestslice[$requestvar]);
        }
      }
    }
    if(isset($form['#default_value']) && is_array($form['#default_value'])){
      $form['#default_value'] = array_merge($form['#default_value'], $requestslice);
    }
  }else{
    $form['#default_value'] = $requestslice;
    $form['#value'] = $requestslice;
  }
}