Add Giscus comment support

layout/_third-party/comments/giscus.njk

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+{{ next_data('giscus', theme.giscus) }}
+{{ next_js('third-party/comments/giscus.js') }}

scripts/filters/comment/giscus.js

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+/* global hexo */
+
+'use strict';
+
+const path = require('path');
+
+const REQUIRED_OPTIONS = ['repo', 'repo_id', 'category', 'category_id'];
+
+// Add Giscus comment support.
+hexo.extend.filter.register('theme_inject', injects => {
+  const config = hexo.theme.config.giscus;
+  if (!config.enable) return;
+
+  const missingOptions = REQUIRED_OPTIONS.filter(option => !config[option]);
+  if (missingOptions.length > 0) {
+    hexo.log.warn(`giscus.${missingOptions.join(', giscus.')} can't be null.`);
+    return;
+  }
+
+  injects.comment.raw('giscus', '<div class="comments giscus-container"></div>', {}, { cache: true });
+  injects.bodyEnd.file('giscus', path.join(hexo.theme_dir, 'layout/_third-party/comments/giscus.njk'));
+});

source/js/third-party/comments/giscus.js

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+/* global NexT, CONFIG */
+
+document.addEventListener('page:loaded', async () => {
+  if (!CONFIG.page.comments) return;
+
+  const giscusConfig = CONFIG.giscus;
+  const container = document.querySelector('.giscus-container');
+  if (!container || !giscusConfig) return;
+
+  await NexT.utils.loadComments('.giscus-container');
+  await NexT.utils.getScript('https://giscus.app/client.js', {
+    attributes: {
+      async                   : true,
+      crossOrigin             : giscusConfig.crossorigin || 'anonymous',
+      'data-repo'             : giscusConfig.repo,
+      'data-repo-id'          : giscusConfig.repo_id,
+      'data-category'         : giscusConfig.category,
+      'data-category-id'      : giscusConfig.category_id,
+      'data-mapping'          : giscusConfig.mapping || 'pathname',
+      'data-strict'           : String(giscusConfig.strict ?? 0),
+      'data-reactions-enabled': String(giscusConfig.reactions_enabled ?? 1),
+      'data-emit-metadata'    : String(giscusConfig.emit_metadata ?? 0),
+      'data-input-position'   : giscusConfig.input_position || 'top',
+      'data-theme'            : giscusConfig.theme || 'preferred_color_scheme',
+      'data-lang'             : giscusConfig.lang || 'zh-CN',
+      'data-loading'          : giscusConfig.loading || 'lazy'
+    },
+    parentNode: container
+  });
+});