1 files changed, 53 insertions, 0 deletions
diff --git a/app/assets/javascripts/vue_shared/components/rich_content_editor/services/build_html_to_markdown_renderer.js b/app/assets/javascripts/vue_shared/components/rich_content_editor/services/build_html_to_markdown_renderer.js
new file mode 100644
index 00000000000..ed04765c871
--- /dev/null
+++ b/app/assets/javascripts/vue_shared/components/rich_content_editor/services/build_html_to_markdown_renderer.js
@@ -0,0 +1,53 @@
+import { defaults, repeat } from 'lodash';
+
+const DEFAULTS = {
+  subListIndentSpaces: 4,
+};
+
+const countIndentSpaces = text => {
+  const matches = text.match(/^\s+/m);
+
+  return matches ? matches[0].length : 0;
+};
+
+const buildHTMLToMarkdownRender = (baseRenderer, formattingPreferences = {}) => {
+  const { subListIndentSpaces } = defaults(formattingPreferences, DEFAULTS);
+  // eslint-disable-next-line @gitlab/require-i18n-strings
+  const sublistNode = 'LI OL, LI UL';
+
+  return {
+    TEXT_NODE(node) {
+      return baseRenderer.getSpaceControlled(
+        baseRenderer.trim(baseRenderer.getSpaceCollapsedText(node.nodeValue)),
+        node,
+      );
+    },
+    /*
+     * This converter overwrites the default indented list converter
+     * to allow us to parameterize the number of indent spaces for
+     * sublists.
+     *
+     * See the original implementation in
+     * https://github.com/nhn/tui.editor/blob/master/libs/to-mark/src/renderer.basic.js#L161
+     */
+    [sublistNode](node, subContent) {
+      const baseResult = baseRenderer.convert(node, subContent);
+      // Default to 1 to prevent possible divide by 0
+      const firstLevelIndentSpacesCount = countIndentSpaces(baseResult) || 1;
+      const reindentedList = baseResult
+        .split('\n')
+        .map(line => {
+          const itemIndentSpacesCount = countIndentSpaces(line);
+          const nestingLevel = Math.ceil(itemIndentSpacesCount / firstLevelIndentSpacesCount);
+          const indentSpaces = repeat(' ', subListIndentSpaces * nestingLevel);
+
+          return line.replace(/^ +/, indentSpaces);
+        })
+        .join('\n');
+
+      return reindentedList;
+    },
+  };
+};
+
+export default buildHTMLToMarkdownRender;