Get uploads from RAW multipart post-request that is sent by some frontend async uploaders

JsonUploader.php

<?php

namespace App\Support;


/**
 * Get files from raw multipart input generated by frontend ajax uploaders
 *
 * Class JsonUploader
 * @package App\Support
 * @link http://stackoverflow.com/a/9469615/1114816
 */
/**
 * Class JsonUploader
 * @package App\Support
 */
class JsonUploader
{
    /**
     * Where to store tmp files
     * @var string
     */
    protected $tmpDir;
    /**
     * @var array
     */
    protected $data = [];
    /**
     * @var array
     */
    protected $errors = [];

    /**
     * JsonUploader constructor.
     *
     * @param $validation
     * @param string|null $tmpDir
     */
    public function __construct($validation = null, $tmpDir = null)
    {
        $this->tmpDir = $tmpDir ?: sys_get_temp_dir();
        //TODO: inject validation rules, or validator instance... Need to think
    }

    /**
     * Get files from request
     *
     * @return array
     */
    public function files(array $meta = null)
    {
        $this->parseRawRequest(file_get_contents('php://input'), $meta);
        return $this->data;
    }

    /**
     * Check signature of provided payload
     *
     * @param array $payload
     * @return bool
     */
    public function checkSignature(array $payload)
    {
        if (!isset($payload['signature'])) return false;
        $signature = $payload['signature'];
        unset($payload['signature']);
        $signed = $this->sign($payload);
        return $signature === $signed['signature'];
    }

    public function getTmpDir() {
        return $this->tmpDir;
    }

    /**
     * Check presence of upload validation errors
     *
     * @return bool
     */
    public function hasErrors() {
        return count($this->errors) > 0;
    }

    /**
     * Get upload validation errors
     *
     * @return array
     */
    public function getErrors() {
        return $this->errors;
    }


    /**
     * Parse raw request data
     *
     * @param string $raw_data
     */
    protected function parseRawRequest($raw_data, array $meta = null)
    {
        $boundary = substr($raw_data, 0, strpos($raw_data, "\r\n"));

        // Fetch each part of multipart request
        $parts = array_slice(explode($boundary, $raw_data), 1);

        foreach ($parts as $part) {
            // If this is the last part, break
            if ($part == "--\r\n") break;

            $payload = $this->parseRequestPart($part);
            if (!$payload) continue;
            try {
                $this->validate($payload);
            } catch (\Exception $e) {
                $this->errors[] = $e->getMessage();
            }
            $payload = $this->sign($payload, $meta);
            $this->data[] = $payload;
        }
    }

    /**
     * Parse separated part of multipart request, save file to tmp and return it's data
     *
     * @param string $part
     * @return array
     */
    protected function parseRequestPart($part)
    {
        // Separate content from headers
        $part = ltrim($part, "\r\n");
        list($raw_headers, $body) = explode("\r\n\r\n", $part, 2);

        // Parse the headers list
        $raw_headers = explode("\r\n", $raw_headers);
        $headers = array();
        foreach ($raw_headers as $header) {
            list($name, $value) = explode(':', $header);
            $headers[strtolower($name)] = ltrim($value, ' ');
        }

        // Parse the Content-Disposition to get the field name, etc.
        if (isset($headers['content-disposition'])) {
            $filename = null;
            preg_match(
                '/^(.+); *name="([^"]+)"(; *filename="([^"]+)")?/',
                $headers['content-disposition'],
                $matches
            );
            list(, $type, $name) = $matches;
            isset($matches[4]) and $filename = $matches[4];
            $tmpfname = tempnam("/tmp", md5($filename . microtime()));
            file_put_contents($tmpfname, $body);

            $payload = [
                'name' => $name,
                'original-filename' => $filename,
                'filename' => pathinfo($tmpfname, PATHINFO_FILENAME),
                'content-type-provided' => array_get($headers, 'content-type'),
                'content-type-parsed' => mime_content_type($tmpfname)
            ];

            // other fields can be handled here
            /*switch ($name) {
                // this is a file upload
                case 'file':
                    file_put_contents($filename, $body);
                    break;

                // default for all other files is to populate $data
                default:
                    $data[$name] = substr($body, 0, strlen($body) - 2);
                    break;
            }*/

            return $payload;
        }
    }

    /**
     * Validate payload over injected validation rules
     *
     * @param $payload
     * @return bool
     */
    protected function validate($payload)
    {
        // TODO: validate and throw exception on error
        return true;
    }

    /**
     * Sign the payload for preventing falsing the data in future
     *
     * @param $payload
     * @return mixed
     */
    protected function sign($payload, array $meta = null)
    {
        if ($meta) {
            $payload['meta'] = $meta;
        }
        ksort($payload);
        $signature = hash('sha256', base64_encode(json_encode($payload)) . config('app.key'));
        $payload['signature'] = $signature;
        return $payload;
    }


}