Apache/PHP implementation of the JSON Keys protocol

.htaccess

# Enable the RewriteEngine
RewriteEngine On

# Match requests for .keys.json at any directory level, including the root
RewriteRule ^(.*)/?\.keys\.json$ /keys.php?dir=$1 [L]

keys.php

<?php
// If the 'dir' parameter is omitted, return the contents of this PHP file
if (!isset($_GET['dir'])) {
    $filePath = __FILE__;
    if (file_exists($filePath)) {
        header('Content-Type: text/plain');
        echo file_get_contents($filePath);
    } else {
        header("HTTP/1.0 404 Not Found");
        echo "File not found";
    }
    exit;
}

// Get the directory path from the query parameter
$directory = $_GET['dir'];

$dirPath = $_SERVER['DOCUMENT_ROOT'] . '/' . $directory;

// Ensure the directory exists
if (!is_dir($dirPath)) {
    header("HTTP/1.0 404 Not Found");
    echo json_encode(["error" => "Directory not found"]);
    exit;
}

// Get all files and directories within the specified path
$files = scandir($dirPath);

// Collect the child names
$children = [];
foreach ($files as $file) {
    // Skip the special directories "." and ".."
    if ($file === '.' || $file === '..') continue;

    if (is_dir($dirPath . '/' . $file)) {
        // Add slash to indicate directory
        $children[] = $file . '/';
    } else {
        // Regular file
        $children[] = $file;
    }
}

// Output the child array as JSON
header('Content-Type: application/json');
echo json_encode($children);

An Apache/PHP implementation of the simple JSON Keys protocol that lets a site route indicate the names of the resources available at that point.