WordPress Plugin Simple Stats

<?php
/**
Plugin Name: Rics Simple Page Stats
Description: Simple plugin to count and show a total number hits (Unique visitors or page-views) to individual Pages and Posts without using any third party code. Based on the great plugin "srs-simple-hits-counter".
Author: Rics
Version: 0.1
Original Author: Atif N
Original Author URI: http://sandyrig.com

Use it as you wish!

 */

// Exit if accessed directly
if ( !defined( 'ABSPATH' ) ) exit;

// Start Session
add_action('init', 'rics_start_session', 1);
function rics_start_session() {
    if(!session_id()) {
        session_start();
    }
}

// UPDATE COUNTER

add_action('wp_head','rics_simple_hits_counter');
function rics_simple_hits_counter(){

    $url = home_url(add_query_arg(array()));
    $id = url_to_postid($url);

    if( !isset( $_SESSION["rics_counter_increased_$id"] ) || ( isset( $_SESSION["rics_counter_increased_$id"] ) && $_SESSION["rics_counter_increased_$id"] != 'yes' ) ) {
        $rics_visitors = intval( get_option("rics_visitors_count_$id") );
        update_option("rics_visitors_count_$id", $rics_visitors+1);
        $_SESSION["rics_counter_increased_$id"] = 'yes';
    }

    $rics_pageViews = intval( get_option("rics_pageViews_count_$id") );
    update_option("rics_pageViews_count_$id", $rics_pageViews+1);
}

// ADD THE "FRONT END" TO EVERY PAGE

 add_filter( 'the_content', 'rics_simple_stats_panel' );
 function rics_simple_stats_panel( $content ) {
    if ( isset($_GET["stats"]) ) {
        $url = home_url(add_query_arg(array()));
        $id = url_to_postid($url);
        $html  = '<div id="rics_hidden_stats"><strong class="rics_stats_title">ESTATÍSTICAS DE ACESSO</strong><br>';
        $html .= "Visitantes únicos: &nbsp; " . intval(get_option("rics_visitors_count_$id"));
        $html .= "<br>";
        $html .= "Visualizações: &nbsp; " . intval(get_option("rics_pageViews_count_$id"));
        $html .= '</div>';
        $content = $content . $html;
    }
    return $content;
}

// ADD STYLES

add_action('wp_enqueue_scripts','rics_load_plugin_css');
function rics_load_plugin_css(){
    wp_enqueue_style( 'rics-styles', plugins_url( 'rics-styles.css' , __FILE__ ) );
}