From d0302ef3dc874c1db42d7741faffd153733e31bd Mon Sep 17 00:00:00 2001
From: David Sanders <dsanders11@ucsbalum.com>
Date: Tue, 20 May 2025 23:35:41 -0700
Subject: [PATCH] feat(lint-markdown-links): disallow absolute links

---
 bin/lint-markdown-links.ts               | 32 +++++++++++++++++++++---
 tests/fixtures/absolute-internal-link.md |  9 +++++++
 tests/fixtures/ignorepaths               |  1 +
 tests/lint-roller-markdown-links.spec.ts | 26 ++++++++++++++++++-
 4 files changed, 63 insertions(+), 5 deletions(-)
 create mode 100644 tests/fixtures/absolute-internal-link.md

diff --git a/bin/lint-markdown-links.ts b/bin/lint-markdown-links.ts
index b804357..4d72baf 100644
--- a/bin/lint-markdown-links.ts
+++ b/bin/lint-markdown-links.ts
@@ -67,6 +67,7 @@ async function fetchExternalLink(link: string, checkRedirects = false) {
 }
 
 interface Options {
+  allowAbsoluteLinks?: boolean;
   fetchExternalLinks?: boolean;
   checkRedirects?: boolean;
   ignoreGlobs?: string[];
@@ -75,7 +76,12 @@ interface Options {
 async function main(
   workspaceRoot: string,
   globs: string[],
-  { fetchExternalLinks = false, checkRedirects = false, ignoreGlobs = [] }: Options,
+  {
+    allowAbsoluteLinks = false,
+    fetchExternalLinks = false,
+    checkRedirects = false,
+    ignoreGlobs = [],
+  }: Options,
 ) {
   const workspace = new DocsWorkspace(workspaceRoot, globs, ignoreGlobs);
   const parser = new MarkdownParser();
@@ -95,11 +101,17 @@ async function main(
   try {
     // Collect diagnostics for all documents in the workspace
     for (const document of await workspace.getAllMarkdownDocuments()) {
+      const absoluteLinks = new Set<any>();
+
       for (let link of await languageService.getDocumentLinks(document, cts.token)) {
         if (link.target === undefined) {
           link = (await languageService.resolveDocumentLink(link, cts.token)) ?? link;
         }
 
+        if (!allowAbsoluteLinks && link.data && link.data.source.hrefText.startsWith('/')) {
+          absoluteLinks.add(link);
+        }
+
         if (
           link.target &&
           link.target.startsWith('http') &&
@@ -114,7 +126,7 @@ async function main(
         cts.token,
       );
 
-      if (diagnostics.length) {
+      if (diagnostics.length || absoluteLinks.size) {
         console.log(
           'File Location:',
           path.relative(URI.file(workspace.root).path, URI.parse(document.uri).path),
@@ -128,6 +140,14 @@ async function main(
         );
         errors = true;
       }
+
+      for (const link of absoluteLinks) {
+        console.log(
+          `\tAbsolute link on line ${link.range.start.line + 1}:`,
+          link.data.source.hrefText,
+        );
+        errors = true;
+      }
     }
   } finally {
     cts.dispose();
@@ -147,8 +167,8 @@ async function main(
 function parseCommandLine() {
   const showUsage = (): never => {
     console.log(
-      'Usage: lint-roller-markdown-links [--root <dir>] <globs> [-h|--help] [--fetch-external-links] ' +
-        '[--check-redirects] [--ignore <globs>]',
+      'Usage: lint-roller-markdown-links [--root <dir>] <globs> [-h|--help] [--allow-absolute-links]' +
+        '[--fetch-external-links] [--check-redirects] [--ignore <globs>]',
     );
     process.exit(1);
   };
@@ -157,6 +177,9 @@ function parseCommandLine() {
     const opts = parseArgs({
       allowPositionals: true,
       options: {
+        'allow-absolute-links': {
+          type: 'boolean',
+        },
         'fetch-external-links': {
           type: 'boolean',
         },
@@ -209,6 +232,7 @@ if (process.argv[1] === fileURLToPath(import.meta.url)) {
   }
 
   main(path.resolve(process.cwd(), opts.root), positionals, {
+    allowAbsoluteLinks: opts['allow-absolute-links'],
     fetchExternalLinks: opts['fetch-external-links'],
     checkRedirects: opts['check-redirects'],
     ignoreGlobs: opts.ignore,
diff --git a/tests/fixtures/absolute-internal-link.md b/tests/fixtures/absolute-internal-link.md
new file mode 100644
index 0000000..606de57
--- /dev/null
+++ b/tests/fixtures/absolute-internal-link.md
@@ -0,0 +1,9 @@
+# Test
+
+## Target section
+
+This is the target section
+
+## Other Section
+
+Link to [target section](/broken-internal-link.md)
diff --git a/tests/fixtures/ignorepaths b/tests/fixtures/ignorepaths
index 0d0547a..25113d1 100644
--- a/tests/fixtures/ignorepaths
+++ b/tests/fixtures/ignorepaths
@@ -1,3 +1,4 @@
+**/absolute-internal-link.md
 **/broken-{external,internal}-link.md
 **/broken-cross-file-link.md
 **/valid-cross-file-link.md
diff --git a/tests/lint-roller-markdown-links.spec.ts b/tests/lint-roller-markdown-links.spec.ts
index be08723..10be822 100644
--- a/tests/lint-roller-markdown-links.spec.ts
+++ b/tests/lint-roller-markdown-links.spec.ts
@@ -30,7 +30,7 @@ describe('lint-roller-markdown-links', () => {
       '--root',
       FIXTURES_DIR,
       '--ignore',
-      '**/{{broken,valid}-*-link.md,*angle-brackets.md,api-history-*.md}',
+      '**/{{absolute,broken,valid}-*-link.md,*angle-brackets.md,api-history-*.md}',
       '*.md',
     );
 
@@ -42,6 +42,8 @@ describe('lint-roller-markdown-links', () => {
       '--root',
       FIXTURES_DIR,
       '--ignore',
+      '**/absolute-internal-link.md',
+      '--ignore',
       '**/broken-{external,internal}-link.md',
       '--ignore',
       '**/{broken,valid}-cross-file-link.md',
@@ -153,4 +155,26 @@ describe('lint-roller-markdown-links', () => {
 
     expect(status).toEqual(0);
   });
+
+  it('should disallow absolute links by default', () => {
+    const { status, stdout } = runLintMarkdownLinks(
+      '--root',
+      FIXTURES_DIR,
+      'absolute-internal-link.md',
+    );
+
+    expect(stdout).toContain('Absolute link');
+    expect(status).toEqual(1);
+  });
+
+  it('should allow absolute links by with --allow-absolute-links', () => {
+    const { status } = runLintMarkdownLinks(
+      '--root',
+      FIXTURES_DIR,
+      'absolute-internal-link.md',
+      '--allow-absolute-links',
+    );
+
+    expect(status).toEqual(0);
+  });
 });