Plugin-Navigation.php

/** Return your navigation in this array */
public function getCpNavItem(): ?array
{
    $subNavs = [];
    $navItem = [
        'label' => 'AI Content',
        'url' => 'ai',
        'icon' => $this->cpNavIconPath(),
    ];
    $currentUser = Craft::$app->getUser()->getIdentity();
    $subNavs['dashboard'] = [
        'label' => 'Dashboard',
        'url' => 'ai/dashboard',
    ];
    if ($currentUser->can('ai:digest')) {
        $subNavs['digest'] = [
            'label' => 'Email Digest',
            'url' => 'ai/digest',
        ];
    }
    if ($currentUser->can('ai:digest:prompts')) {
        $subNavs['digestPrompts'] = [
            'label' => 'Digest Prompts',
            'url' => 'ai/digest/prompts',
        ];
    }
    if ($currentUser->can('ai:field-generation:view') || $currentUser->can('ai:field-generation:edit')) {
        $subNavs['prompts'] = [
            'label' => 'Field Generation',
            'url' => 'ai/field-generation',
        ];
    }
    if (empty($subNavs)) {
        return null;
    }
    // A single sub nav item is redundant
    if (count($subNavs) === 1) {
        $subNavs = [];
    }
    $navItem = array_merge($navItem, [
        'subnav' => $subNavs,
    ]);

    return $navItem;
}


/** Add you custom routes here */

Event::on(
    UrlManager::class,
    UrlManager::EVENT_REGISTER_CP_URL_RULES,
    function (RegisterUrlRulesEvent $event) {
        Craft::debug(
            'UrlManager::EVENT_REGISTER_CP_URL_RULES',
            __METHOD__
        );
        // Register our Control Panel routes
        $event->rules = array_merge(
            $event->rules,
            $this->customAdminCpRoutes()
        );
    }
);


/** Configure custom routes

You can see I'm relying on a few controllers to handle
the view of specific pages */

protected function customAdminCpRoutes(): array
{
    return [
        'ai' => [
            'template' => '_ai-content/cp/dashboard',
        ],
        'ai/field-generation' => [
            'route' => '_ai-content/field-generation/index'
        ],
        'ai/digest' => [
            'route' => '_ai-content/digest/index'
        ],
        'ai/digest/prompts' => [
            'route' => '_ai-content/digest/prompts'
        ],
        'ai/dashboard' => [
            'template' => '_ai-content/cp/dashboard',
        ],
    ];
}