fix: Ctrl-a/e in code fences

shared/editor/commands/backspaceToParagraph.ts

@@ -2,6 +2,13 @@ import { NodeType } from "prosemirror-model";
 import { EditorState } from "prosemirror-state";
 import { Dispatch } from "../types";
 
+/**
+ * Converts the current node to a paragraph when pressing backspace at the
+ * beginning of the node and not already a paragraph.
+ *
+ * @param type The node type
+ * @returns A prosemirror command.
+ */
 export default function backspaceToParagraph(type: NodeType) {
   return (state: EditorState, dispatch: Dispatch) => {
     const { $from, from, to, empty } = state.selection;

shared/editor/commands/codeFence.ts

@@ -0,0 +1,122 @@
+import { EditorState, TextSelection } from "prosemirror-state";
+import isInCode from "../queries/isInCode";
+import { Dispatch } from "../types";
+
+/**
+ * Moves the current selection to the previous newline, this is used inside
+ * code fences only, prosemirror handles this functionality fine in other nodes.
+ *
+ * @returns A prosemirror command.
+ */
+export const moveToPreviousNewline = (
+  state: EditorState,
+  dispatch: Dispatch
+) => {
+  if (!isInCode(state)) {
+    return false;
+  }
+
+  const $pos = state.selection.$from;
+  if (!$pos.parent.type.isTextblock) {
+    return false;
+  }
+
+  // The easiest way to find the previous newline is to reverse the string and
+  // perform a forward seach as if looking for the next newline.
+  const beginningOfNode = $pos.pos - $pos.parentOffset;
+  const startOfLine = $pos.parent.textContent
+    .split("")
+    .reverse()
+    .join("")
+    .indexOf("\n", $pos.parent.nodeSize - $pos.parentOffset - 2);
+
+  if (startOfLine === -1) {
+    return false;
+  }
+
+  dispatch(
+    state.tr.setSelection(
+      TextSelection.create(
+        state.doc,
+        beginningOfNode + ($pos.parent.nodeSize - startOfLine - 2)
+      )
+    )
+  );
+
+  return true;
+};
+
+/**
+ * Moves the current selection to the next newline, this is used inside code
+ * fences only, prosemirror handles this functionality fine in other nodes.
+ *
+ * @returns A prosemirror command.
+ */
+export const moveToNextNewline = (state: EditorState, dispatch: Dispatch) => {
+  if (!isInCode(state)) {
+    return false;
+  }
+
+  const $pos = state.selection.$to;
+  if (!$pos.parent.type.isTextblock) {
+    return false;
+  }
+
+  // find next newline
+  const beginningOfNode = $pos.pos - $pos.parentOffset;
+  const endOfLine = $pos.parent.textContent.indexOf("\n", $pos.parentOffset);
+  if (endOfLine === -1) {
+    return false;
+  }
+
+  dispatch(
+    state.tr.setSelection(
+      TextSelection.create(state.doc, beginningOfNode + endOfLine)
+    )
+  );
+
+  return true;
+};
+
+/**
+ * Replace the selection with a newline character preceeded by a number of
+ * spaces to have the new line align with the code on the previous. This is
+ * standard code editor behavior.
+ *
+ * @returns A prosemirror command
+ */
+export const newlineInCode = (state: EditorState, dispatch: Dispatch) => {
+  if (!isInCode(state)) {
+    return false;
+  }
+  const { tr, selection } = state;
+  const text = selection?.$anchor?.nodeBefore?.text;
+
+  let newText = "\n";
+
+  if (text) {
+    const splitByNewLine = text.split("\n");
+    const numOfSpaces = splitByNewLine[splitByNewLine.length - 1].search(
+      /\S|$/
+    );
+    newText += " ".repeat(numOfSpaces);
+  }
+
+  dispatch(tr.insertText(newText, selection.from, selection.to));
+  return true;
+};
+
+/**
+ * Insert two spaces to simulate the tab key.
+ *
+ * @returns A prosemirror command
+ */
+export const insertSpaceTab = (state: EditorState, dispatch: Dispatch) => {
+  if (!isInCode(state)) {
+    return false;
+  }
+
+  const { tr, selection } = state;
+  dispatch(tr.insertText("  ", selection.from, selection.to));
+  return true;
+};