BookStack/resources/js/wysiwyg/lexical/clipboard/clipboard.ts

/**
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 */

import {$generateHtmlFromNodes, $generateNodesFromDOM} from '@lexical/html';
import {$addNodeStyle, $sliceSelectedTextNodeContent} from '@lexical/selection';
import {objectKlassEquals} from '@lexical/utils';
import {
  $cloneWithProperties,
  $createTabNode,
  $getEditor,
  $getRoot,
  $getSelection,
  $isElementNode,
  $isRangeSelection,
  $isTextNode,
  $parseSerializedNode,
  BaseSelection,
  COMMAND_PRIORITY_CRITICAL,
  COPY_COMMAND,
  isSelectionWithinEditor,
  LexicalEditor,
  LexicalNode,
  SELECTION_INSERT_CLIPBOARD_NODES_COMMAND,
  SerializedElementNode,
  SerializedTextNode,
} from 'lexical';
import {CAN_USE_DOM} from 'lexical/shared/canUseDOM';
import invariant from 'lexical/shared/invariant';

const getDOMSelection = (targetWindow: Window | null): Selection | null =>
  CAN_USE_DOM ? (targetWindow || window).getSelection() : null;

export interface LexicalClipboardData {
  'text/html'?: string | undefined;
  'application/x-lexical-editor'?: string | undefined;
  'text/plain': string;
}

/**
 * Returns the *currently selected* Lexical content as an HTML string, relying on the
 * logic defined in the exportDOM methods on the LexicalNode classes. Note that
 * this will not return the HTML content of the entire editor (unless all the content is included
 * in the current selection).
 *
 * @param editor - LexicalEditor instance to get HTML content from
 * @param selection - The selection to use (default is $getSelection())
 * @returns a string of HTML content
 */
export function $getHtmlContent(
  editor: LexicalEditor,
  selection = $getSelection(),
): string {
  if (selection == null) {
    invariant(false, 'Expected valid LexicalSelection');
  }

  // If we haven't selected anything
  if (
    ($isRangeSelection(selection) && selection.isCollapsed()) ||
    selection.getNodes().length === 0
  ) {
    return '';
  }

  return $generateHtmlFromNodes(editor, selection);
}

/**
 * Returns the *currently selected* Lexical content as a JSON string, relying on the
 * logic defined in the exportJSON methods on the LexicalNode classes. Note that
 * this will not return the JSON content of the entire editor (unless all the content is included
 * in the current selection).
 *
 * @param editor  - LexicalEditor instance to get the JSON content from
 * @param selection - The selection to use (default is $getSelection())
 * @returns
 */
export function $getLexicalContent(
  editor: LexicalEditor,
  selection = $getSelection(),
): null | string {
  if (selection == null) {
    invariant(false, 'Expected valid LexicalSelection');
  }

  // If we haven't selected anything
  if (
    ($isRangeSelection(selection) && selection.isCollapsed()) ||
    selection.getNodes().length === 0
  ) {
    return null;
  }

  return JSON.stringify($generateJSONFromSelectedNodes(editor, selection));
}

/**
 * Attempts to insert content of the mime-types text/plain or text/uri-list from
 * the provided DataTransfer object into the editor at the provided selection.
 * text/uri-list is only used if text/plain is not also provided.
 *
 * @param dataTransfer an object conforming to the [DataTransfer interface] (https://html.spec.whatwg.org/multipage/dnd.html#the-datatransfer-interface)
 * @param selection the selection to use as the insertion point for the content in the DataTransfer object
 */
export function $insertDataTransferForPlainText(
  dataTransfer: DataTransfer,
  selection: BaseSelection,
): void {
  const text =
    dataTransfer.getData('text/plain') || dataTransfer.getData('text/uri-list');

  if (text != null) {
    selection.insertRawText(text);
  }
}

/**
 * Attempts to insert content of the mime-types application/x-lexical-editor, text/html,
 * text/plain, or text/uri-list (in descending order of priority) from the provided DataTransfer
 * object into the editor at the provided selection.
 *
 * @param dataTransfer an object conforming to the [DataTransfer interface] (https://html.spec.whatwg.org/multipage/dnd.html#the-datatransfer-interface)
 * @param selection the selection to use as the insertion point for the content in the DataTransfer object
 * @param editor the LexicalEditor the content is being inserted into.
 */
export function $insertDataTransferForRichText(
  dataTransfer: DataTransfer,
  selection: BaseSelection,
  editor: LexicalEditor,
): void {
  const lexicalString = dataTransfer.getData('application/x-lexical-editor');

  if (lexicalString) {
    try {
      const payload = JSON.parse(lexicalString);
      if (
        payload.namespace === editor._config.namespace &&
        Array.isArray(payload.nodes)
      ) {
        const nodes = $generateNodesFromSerializedNodes(payload.nodes);
        return $insertGeneratedNodes(editor, nodes, selection);
      }
    } catch {
      // Fail silently.
    }
  }

  const htmlString = dataTransfer.getData('text/html');
  if (htmlString) {
    try {
      const parser = new DOMParser();
      const dom = parser.parseFromString(htmlString, 'text/html');
      const nodes = $generateNodesFromDOM(editor, dom);
      return $insertGeneratedNodes(editor, nodes, selection);
    } catch {
      // Fail silently.
    }
  }

  // Multi-line plain text in rich text mode pasted as separate paragraphs
  // instead of single paragraph with linebreaks.
  // Webkit-specific: Supports read 'text/uri-list' in clipboard.
  const text =
    dataTransfer.getData('text/plain') || dataTransfer.getData('text/uri-list');
  if (text != null) {
    if ($isRangeSelection(selection)) {
      const parts = text.split(/(\r?\n|\t)/);
      if (parts[parts.length - 1] === '') {
        parts.pop();
      }
      for (let i = 0; i < parts.length; i++) {
        const currentSelection = $getSelection();
        if ($isRangeSelection(currentSelection)) {
          const part = parts[i];
          if (part === '\n' || part === '\r\n') {
            currentSelection.insertParagraph();
          } else if (part === '\t') {
            currentSelection.insertNodes([$createTabNode()]);
          } else {
            currentSelection.insertText(part);
          }
        }
      }
    } else {
      selection.insertRawText(text);
    }
  }
}

/**
 * Inserts Lexical nodes into the editor using different strategies depending on
 * some simple selection-based heuristics. If you're looking for a generic way to
 * to insert nodes into the editor at a specific selection point, you probably want
 * {@link lexical.$insertNodes}
 *
 * @param editor LexicalEditor instance to insert the nodes into.
 * @param nodes The nodes to insert.
 * @param selection The selection to insert the nodes into.
 */
export function $insertGeneratedNodes(
  editor: LexicalEditor,
  nodes: Array<LexicalNode>,
  selection: BaseSelection,
): void {
  if (
    !editor.dispatchCommand(SELECTION_INSERT_CLIPBOARD_NODES_COMMAND, {
      nodes,
      selection,
    })
  ) {
    selection.insertNodes(nodes);
  }
  return;
}

export interface BaseSerializedNode {
  children?: Array<BaseSerializedNode>;
  type: string;
  version: number;
}

function exportNodeToJSON<T extends LexicalNode>(node: T): BaseSerializedNode {
  const serializedNode = node.exportJSON();
  const nodeClass = node.constructor;

  if (serializedNode.type !== nodeClass.getType()) {
    invariant(
      false,
      'LexicalNode: Node %s does not implement .exportJSON().',
      nodeClass.name,
    );
  }

  if ($isElementNode(node)) {
    const serializedChildren = (serializedNode as SerializedElementNode)
      .children;
    if (!Array.isArray(serializedChildren)) {
      invariant(
        false,
        'LexicalNode: Node %s is an element but .exportJSON() does not have a children array.',
        nodeClass.name,
      );
    }
  }

  return serializedNode;
}

function $appendNodesToJSON(
  editor: LexicalEditor,
  selection: BaseSelection | null,
  currentNode: LexicalNode,
  targetArray: Array<BaseSerializedNode> = [],
): boolean {
  let shouldInclude =
    selection !== null ? currentNode.isSelected(selection) : true;
  const shouldExclude =
    $isElementNode(currentNode) && currentNode.excludeFromCopy('html');
  let target = currentNode;

  if (selection !== null) {
    let clone = $cloneWithProperties(currentNode);
    clone =
      $isTextNode(clone) && selection !== null
        ? $sliceSelectedTextNodeContent(selection, clone)
        : clone;
    target = clone;
  }
  const children = $isElementNode(target) ? target.getChildren() : [];

  const serializedNode = exportNodeToJSON(target);

  // TODO: TextNode calls getTextContent() (NOT node.__text) within its exportJSON method
  // which uses getLatest() to get the text from the original node with the same key.
  // This is a deeper issue with the word "clone" here, it's still a reference to the
  // same node as far as the LexicalEditor is concerned since it shares a key.
  // We need a way to create a clone of a Node in memory with its own key, but
  // until then this hack will work for the selected text extract use case.
  if ($isTextNode(target)) {
    const text = target.__text;
    // If an uncollapsed selection ends or starts at the end of a line of specialized,
    // TextNodes, such as code tokens, we will get a 'blank' TextNode here, i.e., one
    // with text of length 0. We don't want this, it makes a confusing mess. Reset!
    if (text.length > 0) {
      (serializedNode as SerializedTextNode).text = text;
    } else {
      shouldInclude = false;
    }
  }

  for (let i = 0; i < children.length; i++) {
    const childNode = children[i];
    const shouldIncludeChild = $appendNodesToJSON(
      editor,
      selection,
      childNode,
      serializedNode.children,
    );

    if (
      !shouldInclude &&
      $isElementNode(currentNode) &&
      shouldIncludeChild &&
      currentNode.extractWithChild(childNode, selection, 'clone')
    ) {
      shouldInclude = true;
    }
  }

  if (shouldInclude && !shouldExclude) {
    targetArray.push(serializedNode);
  } else if (Array.isArray(serializedNode.children)) {
    for (let i = 0; i < serializedNode.children.length; i++) {
      const serializedChildNode = serializedNode.children[i];
      targetArray.push(serializedChildNode);
    }
  }

  return shouldInclude;
}

// TODO why $ function with Editor instance?
/**
 * Gets the Lexical JSON of the nodes inside the provided Selection.
 *
 * @param editor LexicalEditor to get the JSON content from.
 * @param selection Selection to get the JSON content from.
 * @returns an object with the editor namespace and a list of serializable nodes as JavaScript objects.
 */
export function $generateJSONFromSelectedNodes<
  SerializedNode extends BaseSerializedNode,
>(
  editor: LexicalEditor,
  selection: BaseSelection | null,
): {
  namespace: string;
  nodes: Array<SerializedNode>;
} {
  const nodes: Array<SerializedNode> = [];
  const root = $getRoot();
  const topLevelChildren = root.getChildren();
  for (let i = 0; i < topLevelChildren.length; i++) {
    const topLevelNode = topLevelChildren[i];
    $appendNodesToJSON(editor, selection, topLevelNode, nodes);
  }
  return {
    namespace: editor._config.namespace,
    nodes,
  };
}

/**
 * This method takes an array of objects conforming to the BaseSeralizedNode interface and returns
 * an Array containing instances of the corresponding LexicalNode classes registered on the editor.
 * Normally, you'd get an Array of BaseSerialized nodes from {@link $generateJSONFromSelectedNodes}
 *
 * @param serializedNodes an Array of objects conforming to the BaseSerializedNode interface.
 * @returns an Array of Lexical Node objects.
 */
export function $generateNodesFromSerializedNodes(
  serializedNodes: Array<BaseSerializedNode>,
): Array<LexicalNode> {
  const nodes = [];
  for (let i = 0; i < serializedNodes.length; i++) {
    const serializedNode = serializedNodes[i];
    const node = $parseSerializedNode(serializedNode);
    if ($isTextNode(node)) {
      $addNodeStyle(node);
    }
    nodes.push(node);
  }
  return nodes;
}

const EVENT_LATENCY = 50;
let clipboardEventTimeout: null | number = null;

// TODO custom selection
// TODO potentially have a node customizable version for plain text
/**
 * Copies the content of the current selection to the clipboard in
 * text/plain, text/html, and application/x-lexical-editor (Lexical JSON)
 * formats.
 *
 * @param editor the LexicalEditor instance to copy content from
 * @param event the native browser ClipboardEvent to add the content to.
 * @returns
 */
export async function copyToClipboard(
  editor: LexicalEditor,
  event: null | ClipboardEvent,
  data?: LexicalClipboardData,
): Promise<boolean> {
  if (clipboardEventTimeout !== null) {
    // Prevent weird race conditions that can happen when this function is run multiple times
    // synchronously. In the future, we can do better, we can cancel/override the previously running job.
    return false;
  }
  if (event !== null) {
    return new Promise((resolve, reject) => {
      editor.update(() => {
        resolve($copyToClipboardEvent(editor, event, data));
      });
    });
  }

  const rootElement = editor.getRootElement();
  const windowDocument =
    editor._window == null ? window.document : editor._window.document;
  const domSelection = getDOMSelection(editor._window);
  if (rootElement === null || domSelection === null) {
    return false;
  }
  const element = windowDocument.createElement('span');
  element.style.cssText = 'position: fixed; top: -1000px;';
  element.append(windowDocument.createTextNode('#'));
  rootElement.append(element);
  const range = new Range();
  range.setStart(element, 0);
  range.setEnd(element, 1);
  domSelection.removeAllRanges();
  domSelection.addRange(range);
  return new Promise((resolve, reject) => {
    const removeListener = editor.registerCommand(
      COPY_COMMAND,
      (secondEvent) => {
        if (objectKlassEquals(secondEvent, ClipboardEvent)) {
          removeListener();
          if (clipboardEventTimeout !== null) {
            window.clearTimeout(clipboardEventTimeout);
            clipboardEventTimeout = null;
          }
          resolve(
            $copyToClipboardEvent(editor, secondEvent as ClipboardEvent, data),
          );
        }
        // Block the entire copy flow while we wait for the next ClipboardEvent
        return true;
      },
      COMMAND_PRIORITY_CRITICAL,
    );
    // If the above hack execCommand hack works, this timeout code should never fire. Otherwise,
    // the listener will be quickly freed so that the user can reuse it again
    clipboardEventTimeout = window.setTimeout(() => {
      removeListener();
      clipboardEventTimeout = null;
      resolve(false);
    }, EVENT_LATENCY);
    windowDocument.execCommand('copy');
    element.remove();
  });
}

// TODO shouldn't pass editor (pass namespace directly)
function $copyToClipboardEvent(
  editor: LexicalEditor,
  event: ClipboardEvent,
  data?: LexicalClipboardData,
): boolean {
  if (data === undefined) {
    const domSelection = getDOMSelection(editor._window);
    if (!domSelection) {
      return false;
    }
    const anchorDOM = domSelection.anchorNode;
    const focusDOM = domSelection.focusNode;
    if (
      anchorDOM !== null &&
      focusDOM !== null &&
      !isSelectionWithinEditor(editor, anchorDOM, focusDOM)
    ) {
      return false;
    }
    const selection = $getSelection();
    if (selection === null) {
      return false;
    }
    data = $getClipboardDataFromSelection(selection);
  }
  event.preventDefault();
  const clipboardData = event.clipboardData;
  if (clipboardData === null) {
    return false;
  }
  setLexicalClipboardDataTransfer(clipboardData, data);
  return true;
}

const clipboardDataFunctions = [
  ['text/html', $getHtmlContent],
  ['application/x-lexical-editor', $getLexicalContent],
] as const;

/**
 * Serialize the content of the current selection to strings in
 * text/plain, text/html, and application/x-lexical-editor (Lexical JSON)
 * formats (as available).
 *
 * @param selection the selection to serialize (defaults to $getSelection())
 * @returns LexicalClipboardData
 */
export function $getClipboardDataFromSelection(
  selection: BaseSelection | null = $getSelection(),
): LexicalClipboardData {
  const clipboardData: LexicalClipboardData = {
    'text/plain': selection ? selection.getTextContent() : '',
  };
  if (selection) {
    const editor = $getEditor();
    for (const [mimeType, $editorFn] of clipboardDataFunctions) {
      const v = $editorFn(editor, selection);
      if (v !== null) {
        clipboardData[mimeType] = v;
      }
    }
  }
  return clipboardData;
}

/**
 * Call setData on the given clipboardData for each MIME type present
 * in the given data (from {@link $getClipboardDataFromSelection})
 *
 * @param clipboardData the event.clipboardData to populate from data
 * @param data The lexical data
 */
export function setLexicalClipboardDataTransfer(
  clipboardData: DataTransfer,
  data: LexicalClipboardData,
) {
  for (const k in data) {
    const v = data[k as keyof LexicalClipboardData];
    if (v !== undefined) {
      clipboardData.setData(k, v);
    }
  }
}