Including Requested File, Rewriting Url, Managing 404 Error in PHP - php

Question

Please read the all. I know it is long but I really need help.
What I am trying to do is including the requested file in the "main-container", then rewrite the requested url, if it does not exists, show up 404 error page with .htaccess like ErrorDocument 404 /404.php
So, I know there is a lot of article about that things, but no matter I do, I could'nt succeed on this. There is always a problem. For example;
I tried to use .htaccess like that
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^ /page_handler.php
so every requests comes to page_handler.php first, it passes the requested page variable with $page to index.php, and index.php uses it to fill the page.
$page = $_SERVER['REQUEST_URI'];
if(empty($page) OR $page == '/') {
$page= "main";
}
include "index.php";
The problem with this one is, I can't use ErrorDocument 404 /404.php because whatever page is requested, it calls page_handler.php ,so the pages gets filled, no 404 error.
The second approach I tried is using .htaccess like that
<IfModule mod_rewrite.c>
Options +FollowSymLinks
RewriteEngine On
RewriteBase /
RewriteRule ^(admin|user)($|/) - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.+)$ index.php?page=$1 [L,QSA]
</IfModule>
and in the index.php
global $pages;
$pages = #$_GET["page"];
$pages = explode("/", $pages);
and check $pages[0],[1] etc to calculate the page and include through it. With this one, you cant use
ErrorDocument 404 /404.php
so I tried to check if file exists, if not
header("HTTP/1.0 404 Not Found");
echo "<div class='content-wrapper'>";
include('404.php');
echo "</div>";
but it only simulates a 404 page, it does not send a real 404 error to bots and when I use it, you can call a page like www.example.com/articles/1/whateveryoutype like www.example.com/articles/1/1294ajgakshja1
it calls article with id 1 but what is that last part?
So as you see, I am a rookie and a LOST one. Don't know what to do. I tried a lot of thing, read a lot of webpage, tried much more things than these mentioned ones, but cannot solve my problem. I need someone to direct me to the right path. As I mentioned, I just want to fill the main-content area with the requested file, rewrite url to SEO friendly, and 404 the page if it does not exists. Thank you

Answer 1

I might have not understood your question properly.
I better use this:
.htaccess:
ErrorDocument 404 /404.php
404.php:
<?php
header("HTTP/2 404 Not Found"); // Or use HTTP/1.0 or HTTP 1.1
// Any other includes
echo "The requested URL ". parse_url($_SERVER["REQUEST_URI"], PHP_URL_PATH). " was not found on this server.";
// Any other includes
?>
While including, use the correct path from the / directory (if using linux)
/home/username/public_html/include.php