<?php
// $Id: module_weights.module,v 1.1.2.3 2009-09-30 05:03:03 nancyw Exp $

/**
 * @file
 * Allows module weights to be viewed and edited.
 */

/**
 * 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_menu() {
  $menu['admin/settings/util/module_weights'] = array(
    'title'            => 'Module Weights',
    'description'      => 'Module weight information.',
    'page callback'    => 'drupal_get_form',
    'page arguments'   => array('module_weights_settings'),
    'access arguments' => array('administer site configuration'),
    'type'             => MENU_LOCAL_TASK,
  );
  return $menu;
}

/**
 * Add weight header.
 */
function module_weights_system_module_headers_alter(&$header) {
  array_unshift($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' ORDER BY name";
    $result = db_query($query);
    while ($row = db_fetch_object($result)) {
      $module_weights[$row->name] = $row->weight;
    }
  }
  if ($name === NULL) {
    return $module_weights;
  }
  elseif (isset($module_weights[$name])) {
    return $module_weights[$name];
  }
  else {
    return NULL;
  }
}

function module_weights_form_alter(&$form, $form_state, $form_id) {
  switch ($form_id) {
    // The admin modules page.
    case 'system_modules':
      $weights = fetch_module_weights();
      $form['weights'] = array('#tree' => TRUE);
      foreach ($weights as $name => $weight) {
        // We add "w_" to the name so as not to upset system module.
        $form['description'][$name]['weights']["w_$name"] = array(
          '#type'          => 'textfield',
          '#default_value' => $weight,
          '#title'         => t('Module weight'),
          '#size'          => 4,
          '#prefix'        => '<div class="container-inline">',
          '#suffix'        => '</div>',
          );
      }

      // 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.
    $found = $form_state['values']["w_$name"];
    if (!is_numeric($found)) {
      form_set_error("weights][w_{$name}",
        t('The !module module weight must be a number (found "@found").',
          array('!module' => $name, '@found' => $found))
        );
    }
  }
}

function module_weights_system_module_submit($form, &$form_state) {
  foreach ($form_state['values'] as $key => $weight) {
    // Extra step of optimization, update only weights that changed
    // also skip on module names that don't match our record in fetch_module_weights().
    if (drupal_substr($key, 0, 2) == 'w_') {
      $name = drupal_substr($key, 2);
      $module_weight = fetch_module_weights($name);
      if ($module_weight !== NULL && $module_weight != $weight) {
        $query = "UPDATE {system} SET weight = %d WHERE name LIKE '%s'";
        db_query($query, (int) $weight, $name);
      }
    }
  }
}

function module_weights_settings() {
  $form = array();

  $weighted = $missing = array();
  $header = array(t('Module'), t('Weight'));
  $result = db_query("SELECT name, weight, filename FROM {system} WHERE TYPE = 'module' ORDER BY name");
  while ($row = db_fetch_object($result)) {
    if (!file_exists($row->filename)) {
      $missing[] = $row->name;
    }

    if ($row->weight != 0) {
      $weighted[] = array(
        $row->name,
        array('data' => $row->weight, 'align' => 'right'),
        );
    }
  }

  if ($missing) {
    $form['missing'] = array(
      '#type' => 'fieldset',
      '#title' => t('Missing module files'),
      '#description' => t('These module files could not be found and mess up the modules administration page. The system table needs to be cleaned up.'),
      '#collapsible' => TRUE,
      '#collapsed' => FALSE,
      );
    $form['missing']['list'] = array(
      '#type' => 'markup',
      '#value' => theme('item_list', $missing),
      );
  }

  $form['weights'] = array(
    '#type' => 'fieldset',
    '#title' => t('Weighted modules'),
    '#collapsible' => TRUE,
    '#collapsed' => FALSE,
    );

  $form['weights']['list'] = array(
    '#type' => 'markup',
    '#value' => theme('table', $header, $weighted, array('style' => 'width: auto;')),
    );

  return $form;
}