From e8b5a32b742aa23ded4a2cfa064774625993e812 Mon Sep 17 00:00:00 2001
From: Andrew Nicols <andrew@nicols.co.uk>
Date: Sun, 8 May 2022 20:54:18 +0800
Subject: [PATCH] [repo] Add markdownlint rule to identify obsolete pages

---
 .markdownlint/find-obsolete-links.js | 69 ++++++++++++++++++++++++++++
 .vscode/settings.json                |  3 +-
 package.json                         |  2 +-
 3 files changed, 72 insertions(+), 2 deletions(-)
 create mode 100644 .markdownlint/find-obsolete-links.js

diff --git a/.markdownlint/find-obsolete-links.js b/.markdownlint/find-obsolete-links.js
new file mode 100644
index 0000000000..41c67814c3
--- /dev/null
+++ b/.markdownlint/find-obsolete-links.js
@@ -0,0 +1,69 @@
+/**
+ * Copyright (c) Moodle Pty Ltd.
+ *
+ * Moodle is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Moodle is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/* eslint-disable import/no-extraneous-dependencies */
+
+const {
+    addError,
+    forEachLine,
+    getLineMetadata,
+} = require('markdownlint-rule-helpers');
+
+const { isObsolete } = require('../migratedPages');
+
+// eslint-disable-next-line max-len
+const linkFinder = /(?<description>\[.*\](?=(?<link>\(https:\/\/docs.moodle.org\/dev\/(?<target>[^)]*)\)|\[[^\]]*\])))/g;
+
+module.exports = {
+    names: ['MDLDOC004', 'find-obsolete-links'],
+    description: 'Identify obsolete links',
+    tags: ['migration'],
+    function: function MDLDOC004(params, onError) {
+        forEachLine(getLineMetadata(params), (line, lineIndex, inCode) => {
+            if (inCode) {
+                // Do not make changes to code stanzas.
+                return;
+            }
+
+            const lineNumber = lineIndex + 1;
+            let matches = linkFinder.exec(line);
+            if (!matches) {
+                return;
+            }
+            do {
+                const { target } = matches.groups;
+                if (!target) {
+                    break;
+                }
+                const [targetPage] = target.split('#');
+                const context = `${matches.groups.description}${matches.groups.link}`;
+                if (isObsolete(targetPage)) {
+                    addError(
+                        onError,
+                        lineNumber,
+                        target,
+                        context,
+                        [matches.index + 1, context.length],
+                        null,
+                    );
+                }
+
+                matches = linkFinder.exec(line);
+            } while (matches !== null);
+        });
+    },
+};
diff --git a/.vscode/settings.json b/.vscode/settings.json
index b24ef00610..b7865bd7db 100644
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -1,7 +1,8 @@
 {
     "markdownlint.customRules": [
         "./.markdownlint/no-directional-quotation-marks",
-        "./.markdownlint/fix-migrated-links"
+        "./.markdownlint/fix-migrated-links",
+        "./.markdownlint/find-obsolete-links"
     ],
     "stylelint.packageManager": "yarn"
 }
diff --git a/package.json b/package.json
index f9345acf10..87743f9f58 100644
--- a/package.json
+++ b/package.json
@@ -15,7 +15,7 @@
     "wikimedia-sync": "scripts/wikimedia-sync.js",
     "component-spellings": "scripts/component-helper.js spelling",
     "test": "jest",
-    "mdlint-doc": "markdownlint --rules .markdownlint/no-directional-quotation-marks --rules .markdownlint/no-wikilinks --rules .markdownlint/fix-migrated-links",
+    "mdlint-doc": "markdownlint --rules .markdownlint/no-directional-quotation-marks --rules .markdownlint/no-wikilinks --rules .markdownlint/fix-migrated-links --rules .markdownlint/find-obsolete-links",
     "mdlint-all": "yarn mdlint-doc '{docs,general}/**/*.md' '*.md'",
     "lint": "yarn mdlint-all",
     "prepare": "husky install",