rest-endpoint-example.php

<?php
//try http://example/wp-json/sap/v1/angular
function sap_rest_angular( $data ) {
    $json = new stdClass();
    // bloginfo
    $json->bloginfo = new stdClass();
    $json->bloginfo->name = get_bloginfo('name');
    $json->bloginfo->description = get_bloginfo('description');
    //$json->bloginfo->wpurl = get_bloginfo('wpurl');
    //$json->bloginfo->url = get_bloginfo('url');
    //$json->bloginfo->admin_email = get_bloginfo('admin_email');
    $counter = 1;
    // pages
    $json->pages = new stdClass();
    $pages = get_pages(array(
        'sort_order' => 'asc',
        'sort_column' => 'menu_order',
        'hierarchical' => 0,
        'exclude' => '',
        'include' => '',
        'meta_key' => '',
        'meta_value' => '',
        'authors' => '',
        'child_of' => 0,
        'parent' => -1,
        'exclude_tree' => '',
        'number' => '',
        'offset' => 0,
        'post_type' => 'page',
        'post_status' => 'publish',
    ));
    foreach ($pages AS $page) {
        $page->wp_id = (string) $page->ID;
        unset($page->ID);
        $page->id = (string) $counter;
        unset($page->comment_status);
        unset($page->ping_status);
        unset($page->post_password);
        unset($page->to_ping);
        unset($page->pinged);
        unset($page->post_parent);
        unset($page->guid);
        unset($page->comment_count);
        $json->pages->{$page->post_name} = $page;
        $counter++;
    }
    // categories
    $categories = get_categories(array(
        'child_of' => 0,
        'parent' => '',
        'orderby' => 'name',
        'order' => 'ASC',
        'hide_empty' => 1,
        'hierarchical' => 0,
        'exclude' => '',
        'include' => '',
        'number' => '',
        'pad_counts' => false
    ));
    foreach ($categories AS $category) {
        $category->id = (string) $counter;
        $json->pages->{$category->slug} = $category;
        $counter++;
    }
    return $json;
}
add_action( 'rest_api_init', function () {
    register_rest_route( 'sap/v1', '/angular', array(
        'methods' => 'GET',
        'callback' => 'sap_rest_angular'
    ) );
} );