<?php
    error_reporting(2048);
    class Auth {
        public $logged_in = false;
        private $static_username = 'user';
        private $static_password = 'password';

        public $username = '';

        public function login($username, $password) {
            if (($username == $this->static_username) and ($password == $this->static_password)) {
                $this->username = $username;
                $this->logged_in = true;
            }
            return $this->logged_in;
        }
    }

    class Cache {
        private $default_cache_time = 30;
        private $cache_folder = 'cache';

        public function store($content, $key = 'default', $time = null) {
            $cache_file = $this->default_cache_folder.'/'.$key;
            if ($time !== null) {
                $cache_life = $time;
            } else {
                $cache_life = $this->default_cache_time;
            }

            if ( ! file_exists($cache_file)) {
                $file = fopen($cache_file, 'w+');
                fwrite($file, $content);
                fclose($file);

                return $content;
            }

            $cache_modified_time = filemtime($cache_file);

            if ((time() - $cache_modified_time) >= $cache_life) {
                file_put_contents($cache_file, $content);
            } else {
                $content = file_get_contents($cache_file);
            }
            return $content;
        }
    }

    $auth = new Auth;
    $cache = new Cache;

    if ($auth->logged_in == true) {
        $header_content = 'Website Name. The date is: '.date('m/d/Y');
        $header = $cache->store($header_content, 'header', 30);

        $body_content = 'Welcome '.$auth->username.'! Current time is: '.date('h:i:s A');
        $body = $cache->store($body_content, 'body', 45);

        $footer_content = 'Current time is: '.date('h:i:s A').'. Random number is: '.mt_rand(1,100).'.';
        $footer = $cache->store($footer_content, 'footer', 60);

        echo $header.'<br/>';
        echo $body.'<br/>';
        echo $footer.'<br/>';
    } else {
        $static_content = 'This is static guest content that will be cached.';
        ob_start(array($cache, 'store'));
        echo $static_content;
        ob_end_flush();
    }

?>