Quick recursive function to replace $refs in json schema.

JsonSchema.php

<?php

namespace App\Libs;

class JsonSchema {
    public static function flatten_spec($file) {
        $path = dirname($file);
        $json = static::load_json($file);
        $contents = json_encode(static::replace_refs($path, $json));
        file_put_contents($path . '/openapi.json', $contents);
    }

    public static function replace_refs($path, $value) {
        if (!is_array($value)) {
            return $value;
        }

        if (isset($value['$ref'])) {
            return static::evaluate_ref($path, $value);
        }

        return array_map(function ($v) use ($path) {
            return static::replace_refs($path, $v);
        }, $value);
    }

    public static function evaluate_ref($path, $value) {
        echo "\nevaluating ref " . $path . '/' . $value['$ref'];
        $file = realpath($path . '/' . $value['$ref']);
        if (!file_exists($file)) {
            echo "\nfile does not exist";
            return $value;
        }
        echo "\nfile exists";
        $json = static::load_json($file);
        $path = dirname($file);
        return static::replace_refs($path, $json);
    }

    public static function load_json($file) {
        $contents = file_get_contents($file);
        $json = json_decode($contents, true);
        return $json;
    }
}