YwxAppThink/addon/articles/service/ContentRenderService.php

<?php
// +----------------------------------------------------------------------
// | YwxApp [ WE CAN DO IT JUST THINK ]
// +----------------------------------------------------------------------
// | Copyright (c) 2026-2036 http://ywxapp.cn All rights reserved.
// +----------------------------------------------------------------------
// | Author: ywxapp<admin@ywxapp.cn>
// +----------------------------------------------------------------------
declare (strict_types = 1);

namespace addon\articles\service;

/**
 * 正文渲染服务（输出期增强，不改动入库内容）
 *
 * 三件事：
 *   1. 图片懒加载：给 <img> 加 loading="lazy" decoding="async"
 *   2. WebP：浏览器支持时把站内图片替换为 .webp 副本（见 ImageService）
 *   3. 内链：把命中的关键词（如本文标签）替换为站内链接，利于收录与导流
 *
 * 全部基于 DOM 操作，不会破坏原有 HTML 结构；DOM 不可用时原样返回。
 */
class ContentRenderService
{
    /** 单篇文章最多生成的内链数 */
    const MAX_LINKS = 5;

    /**
     * 渲染正文
     *
     * @param string $html          已净化的正文
     * @param array  $linkKeywords  [关键词 => 链接地址]
     * @param bool   $useWebp       是否启用 WebP 替换
     */
    public static function render(string $html, array $linkKeywords = [], bool $useWebp = false): string
    {
        $html = trim($html);
        if ($html === '' || !class_exists('DOMDocument')) {
            return $html;
        }

        $prev   = libxml_use_internal_errors(true);
        $doc    = new \DOMDocument('1.0', 'UTF-8');
        $loaded = $doc->loadHTML('<?xml encoding="UTF-8">' . $html);
        libxml_clear_errors();
        libxml_use_internal_errors($prev);

        if (!$loaded) {
            return $html;
        }

        $body = $doc->getElementsByTagName('body')->item(0);
        if (!$body) {
            return $html;
        }

        self::enhanceImages($doc, $useWebp);

        if (!empty($linkKeywords)) {
            self::linkKeywords($doc, $linkKeywords);
        }

        $out = '';
        foreach ($body->childNodes as $child) {
            $out .= $doc->saveHTML($child);
        }

        return trim($out);
    }

    /**
     * 图片增强：懒加载 + WebP
     */
    private static function enhanceImages(\DOMDocument $doc, bool $useWebp): void
    {
        $images = [];
        foreach ($doc->getElementsByTagName('img') as $img) {
            $images[] = $img;
        }

        foreach ($images as $img) {
            $img->setAttribute('loading', 'lazy');
            $img->setAttribute('decoding', 'async');

            if (!$useWebp) {
                continue;
            }

            $src  = (string) $img->getAttribute('src');
            $webp = ImageService::webpUrl($src);
            if ($webp !== '') {
                $img->setAttribute('src', $webp);
            }
        }
    }

    /**
     * 内链替换（跳过已在 <a> 内的文本，避免链接套链接）
     */
    private static function linkKeywords(\DOMDocument $doc, array $keywords): void
    {
        $xpath = new \DOMXPath($doc);
        $nodes = $xpath->query('//text()[not(ancestor::a)]');
        if (!$nodes || $nodes->length === 0) {
            return;
        }

        // 先快照，避免替换过程中结构变化影响遍历
        $list = [];
        foreach ($nodes as $node) {
            $list[] = $node;
        }

        $used  = [];
        $count = 0;

        foreach ($list as $node) {
            if ($count >= self::MAX_LINKS) {
                break;
            }

            $text = (string) $node->nodeValue;
            if (mb_strlen(trim($text), 'UTF-8') < 2) {
                continue;
            }

            foreach ($keywords as $kw => $url) {
                $kw = (string) $kw;
                if ($count >= self::MAX_LINKS || isset($used[$kw]) || mb_strlen($kw, 'UTF-8') < 2) {
                    continue;
                }

                $pos = mb_stripos($text, $kw, 0, 'UTF-8');
                if ($pos === false) {
                    continue;
                }

                $before = mb_substr($text, 0, $pos, 'UTF-8');
                $after  = mb_substr($text, $pos + mb_strlen($kw, 'UTF-8'), null, 'UTF-8');

                $a = $doc->createElement('a', htmlspecialchars($kw, ENT_QUOTES, 'UTF-8'));
                $a->setAttribute('href', (string) $url);
                $a->setAttribute('class', 'article-inner-link');

                $frag = $doc->createDocumentFragment();
                $frag->appendChild($doc->createTextNode($before));
                $frag->appendChild($a);
                $frag->appendChild($doc->createTextNode($after));

                $parent = $node->parentNode;
                if (!$parent) {
                    continue;
                }
                $parent->replaceChild($frag, $node);

                $used[$kw] = true;
                $count++;

                break; // 每个文本节点只处理一个关键词
            }
        }
    }
}