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typo3/sysext/seo/Classes/Canonical/CanonicalGenerator.php

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+<?php
+declare(strict_types = 1);
+
+namespace TYPO3\CMS\Seo\Canonical;
+
+/*
+ * This file is part of the TYPO3 CMS project.
+ *
+ * It is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License, either version 2
+ * of the License, or any later version.
+ *
+ * For the full copyright and license information, please read the
+ * LICENSE.txt file that was distributed with this source code.
+ *
+ * The TYPO3 project - inspiring people to share!
+ */
+
+use TYPO3\CMS\Core\Utility\GeneralUtility;
+use TYPO3\CMS\Extbase\SignalSlot\Dispatcher;
+use TYPO3\CMS\Frontend\Controller\TypoScriptFrontendController;
+use TYPO3\CMS\Frontend\Page\PageRepository;
+use TYPO3\CMS\Frontend\Utility\CanonicalizationUtility;
+
+/**
+ * Class to add the canonical tag to the page
+ *
+ * @internal this class is not part of TYPO3's Core API.
+ */
+class CanonicalGenerator
+{
+    /**
+     * @var TypoScriptFrontendController
+     */
+    protected $typoScriptFrontendController;
+
+    /**
+     * @var PageRepository
+     */
+    protected $pageRepository;
+
+    /**
+     * @var Dispatcher
+     */
+    protected $signalSlotDispatcher;
+
+    /**
+     * CanonicalGenerator constructor
+     *
+     * @param TypoScriptFrontendController $typoScriptFrontendController
+     * @param Dispatcher $signalSlotDispatcher
+     */
+    public function __construct(TypoScriptFrontendController $typoScriptFrontendController = null, Dispatcher $signalSlotDispatcher = null)
+    {
+        if ($typoScriptFrontendController === null) {
+            $typoScriptFrontendController = $this->getTypoScriptFrontendController();
+        }
+        if ($signalSlotDispatcher === null) {
+            $signalSlotDispatcher = GeneralUtility::makeInstance(Dispatcher::class);
+        }
+        $this->typoScriptFrontendController = $typoScriptFrontendController;
+        $this->signalSlotDispatcher = $signalSlotDispatcher;
+        $this->pageRepository = GeneralUtility::makeInstance(PageRepository::class);
+    }
+
+    /**
+     * @return string
+     * @throws \TYPO3\CMS\Extbase\SignalSlot\Exception\InvalidSlotException
+     * @throws \TYPO3\CMS\Extbase\SignalSlot\Exception\InvalidSlotReturnException
+     */
+    public function generate(): string
+    {
+        $href = '';
+        $this->signalSlotDispatcher->dispatch(self::class, 'beforeGeneratingCanonical', [&$href]);
+
+        if (empty($href) && (int)$this->typoScriptFrontendController->page['no_index'] === 1) {
+            return '';
+        }
+
+        if (empty($href)) {
+            // 1) Check if page show content from other page
+            $href = $this->checkContentFromPid();
+        }
+        if (empty($href)) {
+            // 2) Check if page has canonical URL set
+            $href = $this->checkForCanonicalLink();
+        }
+        if (empty($href)) {
+            // 3) Fallback, create canonical URL
+            $href = $this->checkDefaultCanonical();
+        }
+
+        if (!empty($href)) {
+            $canonical = '<link ' . GeneralUtility::implodeAttributes([
+                    'rel' => 'canonical',
+                    'href' => $href
+                ], true) . '/>' . LF;
+            $this->typoScriptFrontendController->additionalHeaderData[] = $canonical;
+            return $canonical;
+        }
+        return '';
+    }
+
+    /**
+     * @return string
+     */
+    protected function checkForCanonicalLink(): string
+    {
+        if (!empty($this->typoScriptFrontendController->page['canonical_link'])) {
+            return $this->typoScriptFrontendController->cObj->typoLink_URL([
+                'parameter' => $this->typoScriptFrontendController->page['canonical_link'],
+                'forceAbsoluteUrl' => true,
+            ]);
+        }
+        return '';
+    }
+
+    /**
+     * @return string
+     */
+    protected function checkContentFromPid(): string
+    {
+        if (!empty($this->typoScriptFrontendController->page['content_from_pid'])) {
+            $parameter = (int)$this->typoScriptFrontendController->page['content_from_pid'];
+            if ($parameter > 0) {
+                $targetPage = $this->pageRepository->getPage($parameter, true);
+                if (!empty($targetPage['canonical_link'])) {
+                    $parameter = $targetPage['canonical_link'];
+                }
+                return $this->typoScriptFrontendController->cObj->typoLink_URL([
+                    'parameter' => $parameter,
+                    'forceAbsoluteUrl' => true,
+                ]);
+            }
+        }
+        return '';
+    }
+
+    /**
+     * @return string
+     */
+    protected function checkDefaultCanonical(): string
+    {
+        return $this->typoScriptFrontendController->cObj->typoLink_URL([
+            'parameter' => $this->typoScriptFrontendController->id . ',' . $this->typoScriptFrontendController->type,
+            'forceAbsoluteUrl' => true,
+            'addQueryString' => true,
+            'addQueryString.' => [
+                'method' => 'GET',
+                'exclude' => implode(
+                    ',',
+                    CanonicalizationUtility::getParamsToExcludeForCanonicalizedUrl(
+                        (int)$this->typoScriptFrontendController->id,
+                        (array)$GLOBALS['TYPO3_CONF_VARS']['FE']['additionalCanonicalizedUrlParameters']
+                    )
+                )
+            ]
+        ]);
+    }
+
+    /**
+     * @return TypoScriptFrontendController
+     */
+    protected function getTypoScriptFrontendController(): TypoScriptFrontendController
+    {
+        return $GLOBALS['TSFE'];
+    }
+}