workflow_progress_bar.module

<?php

/**
 * Implements hook_block_info().
 */
function workflow_progress_bar_block_info() {
    $blocks = array();
    $blocks['progress'] = array(
        'info' => t('Workflow Progress Bar'),
    );

    return $blocks;
}

/**
 * Implements hook_block_view().
 */
function workflow_progress_bar_block_view($delta = '') {
    $block = array();

    if ($delta == 'progress') {
        $nid = "0";

        if (arg(0) == 'node' && is_numeric(arg(1))) {
            $nid = arg(1);
            $node = node_load($nid);

            if ($node->type == '[your_node_type]') {
                $status = get_bar_status(workflow_node_current_state($node));
                $block['content'] = theme(
                        'workflow_progress_bar',
                        array(
                            'status' => $status
                        )
                );
            }
        }
    }

    return $block;
}

/**
 * Implements hook_theme().
 */
function workflow_progress_bar_theme() {
    return array(
        'workflow_progress_bar' => array(
            'template' => 'progress-bar',
            'path' => drupal_get_path('module', 'workflow_progress_bar') . '/templates',
            'variables' => array(
                "status" => array(
                    "percentage" => 0,
                    "active_nodes" => 0
                )
            )
        )
    );
}

// get percentage and active nodes
function get_bar_status($status) {
    switch ($status) {
        case 1: {
                $percentage = 0;
                $active_nodes = 1;
                break;
            }
        case 2: {
                $percentage = 25;
                $active_nodes = 2;
                break;
            }
        case 3: {
                $percentage = 0;
                $active_nodes = 1;
                break;
            }
        case 4: {
                $percentage = 50;
                $active_nodes = 3;
                break;
            }
        case 5: {
                $percentage = 75;
                $active_nodes = 4;
                break;
            }
        case 6: {
                $percentage = 100;
                $active_nodes = 5;
                break;
            }
        default : {
                $percentage = 0;
                $active_nodes = 0;
            }
    }

    $bar_status = array(
        "percentage" => $percentage,
        "active_nodes" => $active_nodes
    );

    return $bar_status;
}