import { Extension } from "@tiptap/core";
import { Fragment, Node } from "prosemirror-model";
import { NodeSelection, Plugin } from "prosemirror-state";
import { CellSelection } from "prosemirror-tables";
import type { EditorView } from "prosemirror-view";

import type { BlockNoteEditor } from "../../../editor/BlockNoteEditor.js";
import {
  BlockSchema,
  InlineContentSchema,
  StyleSchema,
} from "../../../schema/index.js";
import { createExternalHTMLExporter } from "../../exporters/html/externalHTMLExporter.js";
import { cleanHTMLToMarkdown } from "../../exporters/markdown/markdownExporter.js";
import { fragmentToBlocks } from "../../nodeConversions/fragmentToBlocks.js";
import {
  contentNodeToInlineContent,
  contentNodeToTableContent,
} from "../../nodeConversions/nodeToBlock.js";

function fragmentToExternalHTML<
  BSchema extends BlockSchema,
  I extends InlineContentSchema,
  S extends StyleSchema,
>(
  view: EditorView,
  selectedFragment: Fragment,
  editor: BlockNoteEditor<BSchema, I, S>,
) {
  let isWithinBlockContent = false;
  const isWithinTable = view.state.selection instanceof CellSelection;

  if (!isWithinTable) {
    // Checks whether block ancestry should be included when creating external
    // HTML. If the selection is within a block content node, the block ancestry
    // is excluded as we only care about the inline content.
    const fragmentWithoutParents = view.state.doc.slice(
      view.state.selection.from,
      view.state.selection.to,
      false,
    ).content;

    const children = [];
    for (let i = 0; i < fragmentWithoutParents.childCount; i++) {
      children.push(fragmentWithoutParents.child(i));
    }

    isWithinBlockContent =
      children.find(
        (child) =>
          child.type.isInGroup("bnBlock") ||
          child.type.name === "blockGroup" ||
          child.type.spec.group === "blockContent",
      ) === undefined;
    if (isWithinBlockContent) {
      selectedFragment = fragmentWithoutParents;
    }
  }

  let externalHTML: string;

  const externalHTMLExporter = createExternalHTMLExporter(
    view.state.schema,
    editor,
  );

  if (isWithinTable) {
    if (selectedFragment.firstChild?.type.name === "table") {
      // contentNodeToTableContent expects the fragment of the content of a table, not the table node itself
      // but cellselection.content() returns the table node itself if all cells and columns are selected
      selectedFragment = selectedFragment.firstChild.content;
    }

    // first convert selection to blocknote-style table content, and then
    // pass this to the exporter
    const ic = contentNodeToTableContent(
      selectedFragment as any,
      editor.schema.inlineContentSchema,
      editor.schema.styleSchema,
    );

    // Wrap in table to ensure correct parsing by spreadsheet applications
    externalHTML = `<table>${externalHTMLExporter.exportInlineContent(
      ic as any,
      {},
    )}</table>`;
  } else if (isWithinBlockContent) {
    // first convert selection to blocknote-style inline content, and then
    // pass this to the exporter
    const ic = contentNodeToInlineContent(
      selectedFragment as any,
      editor.schema.inlineContentSchema,
      editor.schema.styleSchema,
    );
    externalHTML = externalHTMLExporter.exportInlineContent(ic, {});
  } else {
    const blocks = fragmentToBlocks(selectedFragment);
    externalHTML = externalHTMLExporter.exportBlocks(blocks, {});
  }
  return externalHTML;
}

export function selectedFragmentToHTML<
  BSchema extends BlockSchema,
  I extends InlineContentSchema,
  S extends StyleSchema,
>(
  view: EditorView,
  editor: BlockNoteEditor<BSchema, I, S>,
): {
  clipboardHTML: string;
  externalHTML: string;
  markdown: string;
} {
  // Checks if a `blockContent` node is being copied and expands
  // the selection to the parent `blockContainer` node. This is
  // for the use-case in which only a block without content is
  // selected, e.g. an image block.
  if (
    "node" in view.state.selection &&
    (view.state.selection.node as Node).type.spec.group === "blockContent"
  ) {
    editor.transact((tr) =>
      tr.setSelection(
        new NodeSelection(tr.doc.resolve(view.state.selection.from - 1)),
      ),
    );
  }

  // Uses default ProseMirror clipboard serialization.
  const clipboardHTML: string = view.serializeForClipboard(
    view.state.selection.content(),
  ).dom.innerHTML;

  const selectedFragment = view.state.selection.content().content;

  const externalHTML = fragmentToExternalHTML<BSchema, I, S>(
    view,
    selectedFragment,
    editor,
  );

  const markdown = cleanHTMLToMarkdown(externalHTML);

  return { clipboardHTML, externalHTML, markdown };
}

const checkIfSelectionInNonEditableBlock = () => {
  // Let browser handle event if selection is empty (nothing
  // happens).
  const selection = window.getSelection();
  if (!selection || selection.isCollapsed) {
    return true;
  }

  // Let browser handle event if it's within a non-editable
  // "island". This means it's in selectable content within a
  // non-editable block. We only need to check one node as it's
  // not possible for the browser selection to start in an
  // editable block and end in a non-editable one.
  let node = selection.focusNode;
  while (node) {
    if (
      node instanceof HTMLElement &&
      node.getAttribute("contenteditable") === "false"
    ) {
      return true;
    }

    node = node.parentElement;
  }

  return false;
};

const copyToClipboard = <
  BSchema extends BlockSchema,
  I extends InlineContentSchema,
  S extends StyleSchema,
>(
  editor: BlockNoteEditor<BSchema, I, S>,
  view: EditorView,
  event: ClipboardEvent,
) => {
  // Stops the default browser copy behaviour.
  event.preventDefault();
  event.clipboardData!.clearData();

  const { clipboardHTML, externalHTML, markdown } = selectedFragmentToHTML(
    view,
    editor,
  );

  // TODO: Writing to other MIME types not working in Safari for
  //  some reason.
  event.clipboardData!.setData("blocknote/html", clipboardHTML);
  event.clipboardData!.setData("text/html", externalHTML);
  event.clipboardData!.setData("text/plain", markdown);
};

export const createCopyToClipboardExtension = <
  BSchema extends BlockSchema,
  I extends InlineContentSchema,
  S extends StyleSchema,
>(
  editor: BlockNoteEditor<BSchema, I, S>,
) =>
  Extension.create<{ editor: BlockNoteEditor<BSchema, I, S> }, undefined>({
    name: "copyToClipboard",
    addProseMirrorPlugins() {
      return [
        new Plugin({
          props: {
            handleDOMEvents: {
              copy(view, event) {
                if (checkIfSelectionInNonEditableBlock()) {
                  return true;
                }

                copyToClipboard(editor, view, event);
                // Prevent default PM handler to be called
                return true;
              },
              cut(view, event) {
                if (checkIfSelectionInNonEditableBlock()) {
                  return true;
                }

                copyToClipboard(editor, view, event);
                if (view.editable) {
                  view.dispatch(view.state.tr.deleteSelection());
                }
                // Prevent default PM handler to be called
                return true;
              },
              // This is for the use-case in which only a block without content
              // is selected, e.g. an image block, and dragged (not using the
              // drag handle).
              dragstart(view, event) {
                // Checks if a `NodeSelection` is active.
                if (!("node" in view.state.selection)) {
                  return;
                }

                // Checks if a `blockContent` node is being dragged.
                if (
                  (view.state.selection.node as Node).type.spec.group !==
                  "blockContent"
                ) {
                  return;
                }

                // Expands the selection to the parent `blockContainer` node.
                editor.transact((tr) =>
                  tr.setSelection(
                    new NodeSelection(
                      tr.doc.resolve(view.state.selection.from - 1),
                    ),
                  ),
                );

                // Stops the default browser drag start behaviour.
                event.preventDefault();
                event.dataTransfer!.clearData();

                const { clipboardHTML, externalHTML, markdown } =
                  selectedFragmentToHTML(view, editor);

                // TODO: Writing to other MIME types not working in Safari for
                //  some reason.
                event.dataTransfer!.setData("blocknote/html", clipboardHTML);
                event.dataTransfer!.setData("text/html", externalHTML);
                event.dataTransfer!.setData("text/plain", markdown);

                // Prevent default PM handler to be called
                return true;
              },
            },
          },
        }),
      ];
    },
  });