Cascading content proof of concept

cc-proof.php

<?php

error_reporting(E_ALL);
ini_set('display_errors', 1);

define('BASE', str_replace('index.php', '', $_SERVER['SCRIPT_NAME']));
define('DS', DIRECTORY_SEPARATOR);
define('WEBDIR', dirname(__FILE__));

function cache($path, $output=null){
    
    $cache = WEBDIR . DS . 'cache' . DS . str_replace('/', DS, $path) . '.html';
    
    if(null === $output){
        if(file_exists($cache)){
            readfile($cache);
            exit(0);
        }
    }
    else{
        if(!file_exists(dirname($cache))) mkdir(dirname($cache), 0777, true);
        file_put_contents($cache, $output);
    }
}

$path = trim( isset($_GET['p']) ? $_GET['p'] : 'index' , ' /');

cache($path);

require_once 'lib/markdown.php';
require_once 'lib/spyc.php';

$filepath = WEBDIR . DS . 'content' . DS . str_replace('/', DS, $path);

define('DIR', is_dir($filepath));

$script = $style = $content = $layout = null;

// content
function fixlinks($content) { return str_replace('](/', ']('.BASE, $content); }

$f = DIR ? $filepath . DS . 'content' : $filepath;

if( file_exists("$f.markdown") )
    $content = Markdown(fixlinks(file_get_contents("$f.markdown")));
else
    $content = @file_get_contents("$f.html");

// meta
function meta($meta){
    $result = array();
    unset($meta['title']);
    foreach($meta as $name => $content)
        $result[] = sprintf('<meta name="%s" content="%s"/>', $name, $content);
    return implode("\n",$result);
}

$f = WEBDIR . DS . 'meta.yml';

if( file_exists($f) )
    $meta = spyc_load_file($f);
else
    $meta = array();

$f = DIR ? $filepath . DS . 'meta.yml' : "$filepath.yml";

if( file_exists($f) )
    $meta += spyc_load_file($f);

// script
function script($src) {
    return $src ? sprintf('<script src="%s"></script>', $src) : '';
}

$f = DIR ? $filepath . DS . 'script.js' : "$filepath.js";

if( file_exists($f) )
    $script = DIR ? BASE."content/$path/script.js" : BASE."content/$path.js";

// style
function style($href){
    $link = '<link href="%s" rel="stylesheet" type="text/css">';
    return $href ? sprintf($link, $href) : '';
}

$f = DIR ? $filepath . DS . 'style.css' : "$filepath.css";

if( file_exists($f) )
    $style = DIR ? BASE."content/$path/style.css" : BASE."content/$path.css";

// layout
$f = DIR ? $filepath . DS . 'layout' : "$filepath.layout";

if(file_exists("$f.php")){
    include "$f.php";
    exit(0);
}

if( file_exists("$f.html") )
    $layout = @file_get_contents("$f.html");
else
    $layout = @file_get_contents('layout.html');

// render
if($layout && $content){
    $output = strtr($layout, array(
        '%script%'   => script($script),
        '%style%'    => style($style),
        '%title%'    => isset($meta['title']) ? $meta['title'] : $path,
        '%content%'  => $content,
        '%meta%'     => meta($meta),
        '%relpath%'  => BASE . $path,
        '%basepath%' => BASE
    ));
    cache($path, $output);
    
    echo $output;
}
else{
    @header( CGI ? "Status: 404 Not Found" : "HTTP/1.1 404 Not Found");
    readfile(WEBDIR.DS.'404.html');    
}