import lexicalComposerContext from '@lexical/react/LexicalComposerContext.js';
import lexicalUtils from '@lexical/utils';
import lexical, { type LexicalCommand } from 'lexical';
import { useEffect } from 'react';

import { $createAttachmentNode, AttachmentNode } from './node.js';

type AttachmentPayload = Readonly<{ filename: string; url: string }>;

/**
 * A command to insert an attachment. The argument is an {@link AttachmentPayload}.
 */
export const INSERT_ATTACHMENT_COMMAND: LexicalCommand<AttachmentPayload> =
  lexical.createCommand('INSERT_ATTACHMENT_COMMAND');

/**
 * A Lexical plugin to register the INSERT_ATTACHMENT_COMMAND
 */
export const AttachmentPlugin = (): JSX.Element | null => {
  const [editor] = lexicalComposerContext.useLexicalComposerContext();

  useEffect(() => {
    if (!editor.hasNodes([AttachmentNode])) {
      throw new Error('AttachmentsPlugin: AttachmentNode not registered on editor');
    }

    return lexicalUtils.mergeRegister(
      editor.registerCommand<AttachmentPayload>(
        INSERT_ATTACHMENT_COMMAND,
        (payload) => {
          editor.update(() => {
            const attachmentNode = $createAttachmentNode(payload.url, payload.filename);
            const textNode = lexical.$createTextNode(`📎 ${payload.filename}`);
            attachmentNode.append(textNode);
            const selection = lexical.$getRoot().selectEnd();
            if (
              lexical.$isRangeSelection(selection) &&
              selection.anchor.key === selection.focus.key &&
              selection.anchor.offset === selection.focus.offset
            ) {
              const node = selection.anchor.getNode();
              if (!lexical.$isParagraphNode(node) || !node.isEmpty()) {
                editor.dispatchCommand(lexical.INSERT_PARAGRAPH_COMMAND, undefined);
              }
            } else {
              editor.dispatchCommand(lexical.INSERT_PARAGRAPH_COMMAND, undefined);
            }
            lexical.$insertNodes([attachmentNode]);
          });

          return true;
        },
        lexical.COMMAND_PRIORITY_EDITOR,
      ),
    );
  }, [editor]);

  return null;
};