<?php


/**
 * Implementation of hook_help().
 */
function module_weights_help($path, $arg) {
  $output = '';
  switch ($path) {
    case 'admin/help#module_weights':
      $output .= '<p>'. t('Drupal assigns each module a weight. For most operations involving any module that defines a particular hook, the modules are invoked in order first by weight, then by name.') .'</p>';
      $output .= '<p>'. t('This module adds a weight column to the modules table at !modules, allowing weights to be viewed and edited. Once activated, a weight column appears on the modules table. To change a module weight, edit its value and press "Save configuration". Any user who can submit the !modules form will be able to change module weights.', array('!modules' => l('admin/build/modules', 'admin/build/modules'))) .'</p>';
      break;
  }
  return $output;
}

function module_weights_system_module_headers_alter(&$header) {
  //add weight header
  array_unshift($header, 'Weight');
}
function module_weights_system_module_weights_alter(&$row, $module, &$form) {
  array_unshift($row, drupal_render($form['weights'][$module]));  
  //CLEANUP what we added in hook_form_alter()
  unset($form['weights'][$module]);
}

/**
 * Helper function to fetch and cache module weights
 *
 */
function fetch_module_weights($name = NULL) {
  static $module_weights = array();
  if (empty($module_weights)) {
    $query = "SELECT filename, name, type, owner, status, throttle, bootstrap, schema_version, weight FROM {system} WHERE type = 'module' AND status = 1 ORDER BY name";
    $result = db_query($query);
    while( $row = db_fetch_object($result)) {
      $module_weights[$row->name] = $row->weight;
    }
  }
  if ($name === NULL) {
    return $module_weights;
  }
  else if (isset($module_weights[$name])) {
    return $module_weights[$name];
  }
  else {
    return NULL;
  }
}

function module_weights_form_alter(&$form, $form_state, $form_id) {
  switch ($form_id) {
    case 'system_modules':
      $weights = fetch_module_weights();
      $form['weights'] = array(
        '#tree' => TRUE,
      );
      foreach ($weights as $name => $weight) {
        $form['weights'][$name] = array(
          '#type'             => 'textfield',
          '#default_value'    => $weight,
          '#size'             => 4,
        );
      }
      // Do my #submit before system.module's so all the rebuilding
      // operations in system_module_submit use the new weights.
      array_unshift($form['#submit'],'module_weights_system_module_submit');
      $form['#validate'][]  = 'module_weights_system_module_validate';
      break;
  }
}
function module_weights_system_module_validate($form, &$form_state) {
  $weights = fetch_module_weights();
  foreach ($weights as $name => $weight) {
    //submitted weights must be numeric
    if (!is_numeric($form_state['values']['weights'][$name])) {
      form_set_error("weights][{$name}", t(
        'The !module module weight must be a number.',
        array('!module' => $name)
      ));
    }
  }
}

function module_weights_system_module_submit($form, &$form_state) {
  foreach ($form_state['values']['weights'] as $name => $weight) {
    //extra step of optimization, update only weights that changed
    //also skip on module names that dont match our record in fetch_module_weights()
    $module_weight = fetch_module_weights($name);
    if ($module_weight !== NULL && $module_weight != $weight) {
      $query = "UPDATE {system} SET weight = %d WHERE name LIKE '%s'";
      db_query($query, $weight, $name);
    }
  }
}