Redirect to canonical URLs and add the canonical tag in concrete5 v5.7 (including /index.php?cID=123 format)

app.php

<?php // application/bootstrap/app.php

/**
 * Redirect to Canonical URLs
 */
 
// Setup the CanonicalUrls helper
Core::bind('helper/canonical_urls', function() {
    return new \Application\Src\Helpers\CanonicalUrls();
});

// Redirect to the Canonical URL on page view
Events::addListener('on_page_view', function($event) {
    \Core::make('helper/canonical_urls')->redirectToCanonicalURL();
});

CanonicalUrls.php

<?php // application/src/Helpers/CanonicalUrls.php

namespace Application\Src\Helpers;

use Concrete\Core\Routing\Redirect;
use Config;
use Page;

/**
 * Class CanonicalUrls
 *
 * @package Application\Src\Helpers
 */
class CanonicalUrls {

    /**
     * We can make all the methods non-static, here. The __callStatic magic method will translate them for us,
     * so that we can either do CanonicalUrls::someMethod() or $canonicalUrls->someMethod()
     */
    public static function __callStatic( $methodName, $arguments ) {
        // create a new instance of self
        $obj = new static();

        // call the method
        return call_user_func_array( array( $obj, $methodName ), $arguments );
    }


    /**
     *
     * Checks if the current page is using the canonical path
     *
     * @return boolean
     */

    public function isCanonicalURL() {

        $c = Page::getCurrentPage();

        // Stop if we're not in a page object
        if ( !is_object($c) ) {
            return;
        }

        $isCanonicalURL = (strpos($_SERVER["REQUEST_URI"], $c->getCollectionPath()) == false) && (strpos($_SERVER["REQUEST_URI"], "cID=$c->cID") == false);

        return (bool) $isCanonicalURL;
    }


    /**
     * Redirects to the canonical URL
     */
    public function redirectToCanonicalURL() {
        $c = Page::getCurrentPage();
        $redirectToCanonicalUrl = \Config::get('concrete.seo.redirect_to_canonical_url');
        $canonicalUrl = (string) \URL::to($c);

        // Stop if we're already on the canonical URL, in in edit mode, or in the dashboard
        if ($this->isCanonicalURL() || $c->isEditMode() || $c->isSystemPage() || $c->getCollectionHandle() == null ) {
            return;
        }

        // Add the canonical tag to the header of the page
        $v = \View::getInstance();
        $v->addHeaderItem( sprintf('<link rel="canonical" href="%s" />', $canonicalUrl) );

        // Redirect to the canonical URL
        if ($redirectToCanonicalUrl == true) {
            return Redirect::page( $c )->send();
        }
    }
}

concrete.php

<?php // application/config/concrete.php

return array(
    'seo' => array(
        'url_rewriting'     => true,
        'url_rewriting_all' => true,
        'redirect_to_canonical_url' => true,
    )
);

Great Work!!
There is just one thing, I think the condition in isCanonicalURL() Method show read:

        if (is_object($c) && $c->isSystemPage() ) {
            return true;
        }

@patelashishpatel, What I was intending with that code was to exit/not redirecit if $c was not a page object.

I've updated the gist with some more comments and also added a conditional to exit if we're in the dashboard or trying to edit page defaults.