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<!-- catalog/view/theme/default/template/module/category.tpl -->
<div class="list-group">
  <?php foreach ($categories as $category) { ?>
  <?php //if ($category['category_id'] == $category_id) { ?>
  <a href="<?php echo $category['href']; ?>" class="list-group-item active"><?php echo $category['name']; ?></a>
  <?php if ($category['children']) { ?>
  <?php foreach ($category['children'] as $child) { ?>
  <?php if ($child['category_id'] == $child_id) { ?>
  <a href="<?php echo $child['href']; ?>" class="list-group-item active">   - <?php echo $child['name']; ?></a>
  <?php } else { ?>
  <a href="<?php echo $child['href']; ?>" class="list-group-item">   - <?php echo $child['name']; ?></a>
  <?php } ?>
  <?php } ?>
  <?php } ?>
  <?php /*} else { ?>
  <a href="<?php echo $category['href']; ?>" class="list-group-item"><?php echo $category['name']; ?></a>
  <?php }*/ ?>
  <?php } ?>
</div>

<?php // catalog/controller/module/category.php
class ControllerModuleCategory extends Controller {
    public function index() {
        $this->load->language('module/category');

        $data['heading_title'] = $this->language->get('heading_title');

        if (isset($this->request->get['path'])) {
            $parts = explode('_', (string)$this->request->get['path']);
        } else {
            $parts = array();
        }

        if (isset($parts[0])) {
            $data['category_id'] = $parts[0];
        } else {
            $data['category_id'] = 0;
        }

        if (isset($parts[1])) {
            $data['child_id'] = $parts[1];
        } else {
            $data['child_id'] = 0;
        }

        $this->load->model('catalog/category');

        $this->load->model('catalog/product');

        $data['categories'] = array();

        $categories = $this->model_catalog_category->getCategories(0);

        foreach ($categories as $category) {
            $children_data = array();

            //if ($category['category_id'] == $data['category_id']) { 
                $children = $this->model_catalog_category->getCategories($category['category_id']);

                foreach($children as $child) {
                    $filter_data = array('filter_category_id' => $child['category_id'], 'filter_sub_category' => true);

                    $children_data[] = array(
                        'category_id' => $child['category_id'],
                        'name' => $child['name'] . ($this->config->get('config_product_count') ? ' (' . $this->model_catalog_product->getTotalProducts($filter_data) . ')' : ''),
                        'href' => $this->url->link('product/category', 'path=' . $category['category_id'] . '_' . $child['category_id'])
                    );
                }
            //}

            $filter_data = array(
                'filter_category_id'  => $category['category_id'],
                'filter_sub_category' => true
            );

            $data['categories'][] = array(
                'category_id' => $category['category_id'],
                'name'        => $category['name'] . ($this->config->get('config_product_count') ? ' (' . $this->model_catalog_product->getTotalProducts($filter_data) . ')' : ''),
                'children'    => $children_data,
                'href'        => $this->url->link('product/category', 'path=' . $category['category_id'])
            );
        }

        if (file_exists(DIR_TEMPLATE . $this->config->get('config_template') . '/template/module/category.tpl')) {
            return $this->load->view($this->config->get('config_template') . '/template/module/category.tpl', $data);
        } else {
            return $this->load->view('default/template/module/category.tpl', $data);
        }
    }
}