Plugin ActionUrl not being set

Question

Trying to add an actionUrl to this plugin. When I set offset manually to a number, everything works, so I think the controller is working properly.

I can't seem to get the offset from the button using getParam (or anything else).

What's the best way to get a offset back into the template?

Controller

<?php

namespace Craft;

class TumblrController extends BaseController{

    public function actionOffset(){

        $offset = craft()->request->getRequiredParam('offset', null);

        craft()->tumblr->getSubmissionData($offset);

        $this->redirect($_SERVER['HTTP_REFERER']);
    }
}

Service

public function getSubmissionData($offset){

$submission_data = array();

// some variables that will be pretttty useful
$settings       = craft()->plugins->getPlugin('tumblr')->getSettings();
$publicKey      = 'example';
$secretKey      = 'example';
$token          = 'example';
$tokenSecret    = 'example';
$callback_url   = 'tumblr/callback';
$blogName       = 'example.tumblr.com';

$client = new \Tumblr\API\Client($publicKey, $secretKey, $token, $tokenSecret);

//SETTING UP OFFSET
//$offset = (!isset($offset) || is_null($offset)) ? '0' : $offset; 

$submissions = $client->getSubmissionPosts($blogName, array('offset' => $offset, 'limit' => 50));

$i = 0;

foreach($submissions->posts as $submission) {
    $i++;
    foreach($submission as $key => $value){
        if ($key == "timestamp" || $key ==  "publisher" || $key == "video_type" || $key == "thumbnail_url" || $key == "thumbnail_width" || $key == "thumbnail_height" ||     $key == "html5_capable" || $key == "id" || $key == "short_url" || $key == "video" || $key == "content_raw" || $key == "player" || $key == "highlighted" || $key     == "photos" || $key == "trail" || $key == "tags" || $key == "description" || $key == "reblog" || $key == "followed" || $key == "blog_name" || $key ==     "reblog_key" || $key == "liked" || $key == "note_count" || $key == "link_author" || $key == "excerpt" || $key == "can_send_in_message" || $key == "can_reply" ||     $key == "recommended_source" || $key == "recommended_color" || $key == "font" || $key == "background" || $key == "format" || $key == "post_url" || $key ==     "slug" || $key == "is_submission" || $key == "is_anonymous")
            continue;
        $submission_data[$i][$key][] = isset($value) ? $value : "Nothing set"; 

    } 
}


$charset = craft()->templates->getTwig()->getCharset();
$twig_html = new \Twig_Markup(json_encode($submission_data), $charset);

$tagdata = $submission_data;
foreach($submission_data as $key => $value){
    foreach($value as $k => $v){
        $tagdata = str_replace("{".$key."}", $v[0], $submission_data);
    }
}

// // // // replace the embed code with the Twig object
$tagdata['embed_code'] = $twig_html;


return $tagdata;
}

Template

{% extends "_layouts/cp" %}
{% set title = "Tumblr Submissions"|t %}
{% includeCssResource "tumblr/css/table.css" %}

{% set offset = craft.request.getParam('offset') %}
{% set submissions = craft.tumblr.submissions(offset) %}

{% block content %}

<pre>{{ dump(offset) }}</pre>
    <div id="page-wrap">
        {% for i in range(1, 10, 1) %}
            <a href="{{ actionUrl('tumblr/offset', {offset: i}) }}"><button type="button">{{i}}</button></a>
        {% endfor %}
        <table class="table">
            {% for key,submit in submissions %}
                {% if loop.index == 1 %}
                    <thead>
                        <tr class="row header">
                            {% for ref,items in submit %}
                                <th class="cell">{{ ref }}</th>
                            {% endfor %}
                        </tr>
                    </thead>
                    <tbody>
                {% endif %}
                    <tr class="row">
                        {% for ref,items in submit %}
                            <td class="cell">{{ items[0]|e }}</td>
                        {% endfor %}
                    </tr>
            {% endfor %}
            </tbody>
        </table>
    </div>
{% endblock %}    

Answer 1

After some testing the answer to this was that I needed to setup custom CP routes to pass the offset variable from template to controller and back to template.

public function registerCpRoutes(){
    return array(
        'tumblr/offset' => array('action' => 'tumblr/offset')
    );
}