Category and sub-category API Magento

Category and sub-category API Magento

<?php
error_reporting(0);
include("../app/Mage.php"); //call Magento mage file
umask(0);
Mage::app();
$result_array = array();
$result_array_sub = array();

$_helper = Mage::helper('catalog/category');
$_categories = $_helper->getStoreCategories();
$currentCategory = Mage::registry('current_category');
if (count($_categories) > 0):
    foreach($_categories as $_category):
        $result_array_cat["category_name"]=$_category->getName();
        $result_array_cat["categoryid"]=$categoryId=$_category->getId();
        $_category1 = Mage::getModel('catalog/category')->load($categoryId);
        $result_array_cat["status"]=$_category1->getIsActive();
        $result_array_cat["description"]=htmlentities(preg_replace('/"/',' ',$_category1->getDescription()));
        $result_array_cat["image"]=$_category1->getImageUrl();
        $result_array_cat["count"]=$_category1->getProductCount();


        $result_array_cat["subcategory_name"]=array();

        $_category = Mage::getModel('catalog/category')->load($_category->getId());
        $_subcategories = $_category->getChildrenCategories();
        if (count($_subcategories) > 0):
            foreach($_subcategories as $_subcategory):
                $result_array_sub["sub_category_name"]=$_subcategory->getName();
                $result_array_sub["sub_categoryid"]=$categoryId2=$_subcategory->getId();
                $_category2 = Mage::getModel('catalog/category')->load($categoryId2);
                $result_array_sub["status"]=$_category2->getIsActive();
                $result_array_sub["description"]=htmlentities(preg_replace('/"/',' ',$_category2->getDescription()));
                $result_array_sub["image"]=$_category2->getImageUrl();
                $result_array_sub["count"]=$_category2->getProductCount();
                array_push($result_array_cat["subcategory_name"], $result_array_sub);
            endforeach;
        endif;

        array_push($result_array, $result_array_cat);

    endforeach;
endif;

echo json_encode($result_array);
?>