outline/shared/editor/nodes/MathBlock.ts

import {
  makeBlockMathInputRule,
  mathSchemaSpec,
} from "@benrbray/prosemirror-math";
import type { PluginSimple } from "markdown-it";
import type {
  NodeSpec,
  NodeType,
  Node as ProsemirrorNode,
} from "prosemirror-model";
import type { Command } from "prosemirror-state";
import { TextSelection } from "prosemirror-state";
import type { MarkdownSerializerState } from "../lib/markdown/serializer";
import mathRule, { REGEX_BLOCK_MATH_DOLLARS } from "../rules/math";
import Node from "./Node";

export default class MathBlock extends Node {
  get name() {
    return "math_block";
  }

  get schema(): NodeSpec {
    return mathSchemaSpec.nodes.math_display;
  }

  get rulePlugins(): PluginSimple[] {
    return [mathRule];
  }

  commands({ type }: { type: NodeType }) {
    return (): Command => (state, dispatch) => {
      const tr = state.tr.replaceSelectionWith(type.create());
      dispatch?.(
        tr
          .setSelection(
            TextSelection.near(tr.doc.resolve(state.selection.from - 1))
          )
          .scrollIntoView()
      );
      return true;
    };
  }

  inputRules({ type }: { type: NodeType }) {
    return [makeBlockMathInputRule(REGEX_BLOCK_MATH_DOLLARS, type)];
  }

  toMarkdown(state: MarkdownSerializerState, node: ProsemirrorNode) {
    // Inside table cells literal newlines break the row structure, so encode
    // the block on a single line using <br> for line breaks. Backslashes and
    // pipes are escaped so the cell content cannot break out of the column.
    if (state.inTable) {
      const math = node.textContent
        .replace(/[\\|]/g, "\\$&")
        .replace(/\n/g, "<br>");
      state.write("$$<br>" + math + "<br>$$");
      return;
    }

    state.write("$$\n");
    state.text(node.textContent, false);
    state.ensureNewLine();
    state.write("$$");
    state.closeBlock(node);
  }

  parseMarkdown() {
    return {
      node: "math_block",
      block: "math_block",
      noCloseToken: true,
    };
  }
}