web/app/core/App.php

<?php

class App
{
    public array    $config;
    public Database $database;
    public Session  $session;
    public User     $user;

    public function __construct(
        array    $config,
        Database $database,
        Session  $session,
        User     $user
    )
    {
        $this->config   = $config;
        $this->database = $database;
        $this->session  = $session;
        $this->user     = $user;
    }

    // Grab model
    public function model(string $model, $injection = NULL): object
    {
        // Require model file
        $path = __DIR__ . '/../model/' . $model . '.php';
        if (!file_exists($path))
        {
            throw new Exception("Model does not exist");
        }
        require $path;
        // Instantiate model
        if (!$injection)
        {
            $injection = $this->database;
        }
        return new $model($injection);
    }

    // Render given view
    public function view(string $view, array $data = []): void
    {
        // Import variables into the current symbol table from an array
        extract($data);
        // Require view file
        $path = __DIR__ . '/../view/' . $view . '.php';
        if (!file_exists($path))
        {
            throw new Exception("View does not exist");
        }
        require $path;
    }

    // Turn data array into JSON response
    public function api(array $data, int $status_code = 200): void
    {
        // Set headers
        http_response_code($status_code);
        header('Content-type: application/json');
        // Convert and respond with data
        echo json_encode($data);
        die();
    }

    // Redirect to given url
    public function redirect(string $url): void
    {
        header("Location: $url");
        die();
    }
}