From 499c07b27ad9ad94662fdd163d459c89632146da Mon Sep 17 00:00:00 2001
From: Seth Falco <seth@falco.fun>
Date: Sun, 22 Oct 2023 10:33:11 +0100
Subject: [PATCH] fix(removeComments): preserve copyright and licensing and add
 param

---
 plugins/plugins-types.ts           |  4 +++-
 plugins/removeComments.js          | 28 +++++++++++++++++++++++++---
 test/plugins/removeComments.02.svg |  2 ++
 test/plugins/removeComments.03.svg | 15 +++++++++++++++
 4 files changed, 45 insertions(+), 4 deletions(-)
 create mode 100644 test/plugins/removeComments.03.svg

diff --git a/plugins/plugins-types.ts b/plugins/plugins-types.ts
index a4cca210b..849f17e0f 100644
--- a/plugins/plugins-types.ts
+++ b/plugins/plugins-types.ts
@@ -119,7 +119,9 @@ type DefaultPlugins = {
 
   moveElemsAttrsToGroup: void;
   moveGroupAttrsToElems: void;
-  removeComments: void;
+  removeComments: {
+    preservePatterns: Array<RegExp|string> | false
+  };
   removeDesc: {
     removeAny?: boolean;
   };
diff --git a/plugins/removeComments.js b/plugins/removeComments.js
index 70e462714..d985d0f5c 100644
--- a/plugins/removeComments.js
+++ b/plugins/removeComments.js
@@ -5,6 +5,12 @@ const { detachNodeFromParent } = require('../lib/xast.js');
 exports.name = 'removeComments';
 exports.description = 'removes comments';
 
+/**
+ * If a comment matches one of the following patterns, it will be
+ * preserved by default. Particularly for copyright/license information.
+ */
+const DEFAULT_PRESERVE_PATTERNS = [/^!/, /LICENSE/i, /COPYRIGHT/i];
+
 /**
  * Remove comments.
  *
@@ -16,13 +22,29 @@ exports.description = 'removes comments';
  *
  * @type {import('./plugins-types').Plugin<'removeComments'>}
  */
-exports.fn = () => {
+exports.fn = (_root, params) => {
+  const { preservePatterns = DEFAULT_PRESERVE_PATTERNS } = params;
+
   return {
     comment: {
       enter: (node, parentNode) => {
-        if (node.value.charAt(0) !== '!') {
-          detachNodeFromParent(node, parentNode);
+        if (preservePatterns) {
+          if (!Array.isArray(preservePatterns)) {
+            throw Error(
+              `Expected array in removeComments preservePatterns parameter but received ${preservePatterns}`
+            );
+          }
+
+          const matches = preservePatterns.some((pattern) => {
+            return new RegExp(pattern).test(node.value);
+          });
+
+          if (matches) {
+            return;
+          }
         }
+
+        detachNodeFromParent(node, parentNode);
       },
     },
   };
diff --git a/test/plugins/removeComments.02.svg b/test/plugins/removeComments.02.svg
index d62ff2a27..ef594f560 100644
--- a/test/plugins/removeComments.02.svg
+++ b/test/plugins/removeComments.02.svg
@@ -1,5 +1,6 @@
 <!--!ignored comment-->
 <svg xmlns="http://www.w3.org/2000/svg">
+    <!-- This is protected by A Totally Fake Copyright License Agreement. -->
     test
 </svg>
 
@@ -7,5 +8,6 @@
 
 <!--!ignored comment-->
 <svg xmlns="http://www.w3.org/2000/svg">
+<!--This is protected by A Totally Fake Copyright License Agreement.-->
     test
 </svg>
diff --git a/test/plugins/removeComments.03.svg b/test/plugins/removeComments.03.svg
new file mode 100644
index 000000000..339808547
--- /dev/null
+++ b/test/plugins/removeComments.03.svg
@@ -0,0 +1,15 @@
+<!--!ignored comment-->
+<svg xmlns="http://www.w3.org/2000/svg">
+    <!-- This is protected by A Totally Fake Copyright License Agreement. -->
+    test
+</svg>
+
+@@@
+
+<svg xmlns="http://www.w3.org/2000/svg">
+    test
+</svg>
+
+@@@
+
+{"preservePatterns":false}