refactor: added AbstractProxy base class for shortener proxies

lib/AbstractProxy.php

@@ -0,0 +1,139 @@
+<?php declare(strict_types=1);
+/**
+ * PrivateBin
+ *
+ * a zero-knowledge paste bin
+ *
+ * @link      https://github.com/PrivateBin/PrivateBin
+ * @copyright 2012 Sébastien SAUVAGE (sebsauvage.net)
+ * @license   https://www.opensource.org/licenses/zlib-license.php The zlib/libpng License
+ */
+
+namespace PrivateBin;
+
+use Exception;
+
+/**
+ * AbstractProxy
+ *
+ * Forwards a URL for shortening to shlink and stores the result.
+ */
+abstract class AbstractProxy
+{
+    /**
+     * error message
+     *
+     * @access private
+     * @var    string
+     */
+    private $_error = '';
+
+    /**
+     * shortened URL
+     *
+     * @access private
+     * @var    string
+     */
+    private $_url = '';
+
+    /**
+     * constructor
+     *
+     * initializes and runs the proxy class
+     *
+     * @access public
+     * @param string $link
+     */
+    public function __construct(Configuration $conf, $link)
+    {
+        if (!str_starts_with($link, $conf->getKey('basepath') . '?')) {
+            $this->_error = 'Trying to shorten a URL that isn\'t pointing at our instance.';
+            return;
+        }
+
+        $data = $this->_getcontents($conf, $link);
+
+        if ($data == null) {
+            $this->_error = 'Error calling proxy. Probably a configuration issue';
+            error_log('Error calling proxy: ' . $this->_error);
+            return;
+        }
+
+        if ($data === false) {
+            $http_response_header = $http_response_header ?? array();
+            $statusCode           = '';
+            if (!empty($http_response_header) && preg_match('/HTTP\/\d+\.\d+\s+(\d+)/', $http_response_header[0], $matches)) {
+                $statusCode = $matches[1];
+            }
+            $this->_error = 'Error calling proxy. HTTP request failed. Status code: ' . $statusCode;
+            error_log('Error calling proxy: ' . $this->_error);
+            return;
+        }
+
+        try {
+            $data = Json::decode($data);
+        } catch (Exception $e) {
+            $this->_error = 'Error calling proxy. Probably a configuration issue, like wrong or missing config keys.';
+            error_log('Error calling proxy: ' . $e->getMessage());
+            return;
+        }
+
+        $url = $this->_extractShortUrl($data);
+
+        if ($url === null) {
+            $this->_error = 'Error calling proxy. Probably a configuration issue, like wrong or missing config keys.';
+        } else {
+            $this->_url = $url;
+        }
+    }
+
+    /**
+     * Returns the (untranslated) error message
+     *
+     * @access public
+     * @return string
+     */
+    public function getError()
+    {
+        return $this->_error;
+    }
+
+    /**
+     * Returns the shortened URL
+     *
+     * @access public
+     * @return string
+     */
+    public function getUrl()
+    {
+        return $this->_url;
+    }
+
+    /**
+     * Returns true if any error has occurred
+     *
+     * @access public
+     * @return bool
+     */
+    public function isError()
+    {
+        return !empty($this->_error);
+    }
+
+    /**
+     * Abstract method to get contents from a URL.
+     *
+     * @param Configuration $conf
+     * @param string $link
+     * @return mixed
+     */
+    abstract protected function _getcontents(Configuration $conf, string $link);
+
+    /**
+     * Abstract method to extract the shortUrl from the response
+     *
+     * @param array $data
+     * @return ?string
+     */
+    abstract protected function _extractShortUrl(array $data): ?string;
+}