Merge branch 'dm-paste-code-inside-gfm-code' into 'master'

Don't wrap pasted code when it's already inside code tags

Closes #32507

See merge request !11524

4 files changed, 81 insertions, 9 deletions

diff --git a/app/assets/javascripts/copy_as_gfm.js b/app/assets/javascripts/copy_as_gfm.js
index 459cdd53f9b..cba4b656363 100644
--- a/app/assets/javascripts/copy_as_gfm.js
+++ b/app/assets/javascripts/copy_as_gfm.js
@@ -273,12 +273,12 @@ const gfmRules = {
 
 class CopyAsGFM {
   constructor() {
-    $(document).on('copy', '.md, .wiki', (e) => { this.copyAsGFM(e, CopyAsGFM.transformGFMSelection); });
-    $(document).on('copy', 'pre.code.highlight, .diff-content .line_content', (e) => { this.copyAsGFM(e, CopyAsGFM.transformCodeSelection); });
-    $(document).on('paste', '.js-gfm-input', this.pasteGFM.bind(this));
+    $(document).on('copy', '.md, .wiki', (e) => { CopyAsGFM.copyAsGFM(e, CopyAsGFM.transformGFMSelection); });
+    $(document).on('copy', 'pre.code.highlight, .diff-content .line_content', (e) => { CopyAsGFM.copyAsGFM(e, CopyAsGFM.transformCodeSelection); });
+    $(document).on('paste', '.js-gfm-input', CopyAsGFM.pasteGFM);
   }
 
-  copyAsGFM(e, transformer) {
+  static copyAsGFM(e, transformer) {
     const clipboardData = e.originalEvent.clipboardData;
     if (!clipboardData) return;
 
@@ -292,19 +292,36 @@ class CopyAsGFM {
     e.stopPropagation();
 
     clipboardData.setData('text/plain', el.textContent);
-    clipboardData.setData('text/x-gfm', CopyAsGFM.nodeToGFM(el));
+    clipboardData.setData('text/x-gfm', this.nodeToGFM(el));
   }
 
-  pasteGFM(e) {
+  static pasteGFM(e) {
     const clipboardData = e.originalEvent.clipboardData;
     if (!clipboardData) return;
 
+    const text = clipboardData.getData('text/plain');
     const gfm = clipboardData.getData('text/x-gfm');
     if (!gfm) return;
 
     e.preventDefault();
 
-    window.gl.utils.insertText(e.target, gfm);
+    window.gl.utils.insertText(e.target, (textBefore, textAfter) => {
+      // If the text before the cursor contains an odd number of backticks,
+      // we are either inside an inline code span that starts with 1 backtick
+      // or a code block that starts with 3 backticks.
+      // This logic still holds when there are one or more _closed_ code spans
+      // or blocks that will have 2 or 6 backticks.
+      // This will break down when the actual code block contains an uneven
+      // number of backticks, but this is a rare edge case.
+      const backtickMatch = textBefore.match(/`/g);
+      const insideCodeBlock = backtickMatch && (backtickMatch.length % 2) === 1;
+
+      if (insideCodeBlock) {
+        return text;
+      }
+
+      return gfm;
+    });
   }
 
   static transformGFMSelection(documentFragment) {
diff --git a/app/assets/javascripts/lib/utils/common_utils.js b/app/assets/javascripts/lib/utils/common_utils.js
index 7e62773ae6c..a537267643e 100644
--- a/app/assets/javascripts/lib/utils/common_utils.js
+++ b/app/assets/javascripts/lib/utils/common_utils.js
@@ -198,10 +198,12 @@
 
       const textBefore = value.substring(0, selectionStart);
       const textAfter = value.substring(selectionEnd, value.length);
-      const newText = textBefore + text + textAfter;
+
+      const insertedText = text instanceof Function ? text(textBefore, textAfter) : text;
+      const newText = textBefore + insertedText + textAfter;
 
       target.value = newText;
-      target.selectionStart = target.selectionEnd = selectionStart + text.length;
+      target.selectionStart = target.selectionEnd = selectionStart + insertedText.length;
 
       // Trigger autosave
       $(target).trigger('input');
diff --git a/changelogs/unreleased/dm-paste-code-inside-gfm-code.yml b/changelogs/unreleased/dm-paste-code-inside-gfm-code.yml
new file mode 100644
index 00000000000..d078ca449a5
--- /dev/null
+++ b/changelogs/unreleased/dm-paste-code-inside-gfm-code.yml
@@ -0,0 +1,4 @@
+---
+title: Don't wrap pasted code when it's already inside code tags
+merge_request:
+author:
diff --git a/spec/javascripts/copy_as_gfm_spec.js b/spec/javascripts/copy_as_gfm_spec.js
new file mode 100644
index 00000000000..1a850bb56ab
--- /dev/null
+++ b/spec/javascripts/copy_as_gfm_spec.js
@@ -0,0 +1,49 @@
+require('~/copy_as_gfm');
+
+(() => {
+  describe('gl.CopyAsGFM', () => {
+    describe('gl.CopyAsGFM.pasteGFM', () => {
+      function callPasteGFM() {
+        const e = {
+          originalEvent: {
+            clipboardData: {
+              getData(mimeType) {
+                // When GFM code is copied, we put the regular plain text
+                // on the clipboard as `text/plain`, and the GFM as `text/x-gfm`.
+                // This emulates the behavior of `getData` with that data.
+                if (mimeType === 'text/plain') {
+                  return 'code';
+                }
+                if (mimeType === 'text/x-gfm') {
+                  return '`code`';
+                }
+                return null;
+              },
+            },
+          },
+          preventDefault() {},
+        };
+
+        window.gl.CopyAsGFM.pasteGFM(e);
+      }
+
+      it('wraps pasted code when not already in code tags', () => {
+        spyOn(window.gl.utils, 'insertText').and.callFake((el, textFunc) => {
+          const insertedText = textFunc('This is code: ', '');
+          expect(insertedText).toEqual('`code`');
+        });
+
+        callPasteGFM();
+      });
+
+      it('does not wrap pasted code when already in code tags', () => {
+        spyOn(window.gl.utils, 'insertText').and.callFake((el, textFunc) => {
+          const insertedText = textFunc('This is code: `', '`');
+          expect(insertedText).toEqual('code');
+        });
+
+        callPasteGFM();
+      });
+    });
+  });
+})();