/* eslint-disable require-jsdoc */

const Parchment = Quill.import("parchment")
const Delta = Quill.import("delta");

const getLineFormats = (context) => {
  return Object.keys(context.format).reduce(
    (formats, format) => {
      // See Parchment registry.ts => (1 << 3) | ((1 << 2) - 1) = 8 | 3 = 11
      const blockScope = 11;
      if (
        Parchment.query(format, blockScope) &&
        !Array.isArray(context.format[format])
      ) {
        formats[format] = context.format[format];
      }
      return formats;
    },
    {},
  );
}

const continueFormats = (quill, context, lineFormats) => {
  Object.keys(context.format).forEach((name) => {
    if (typeof lineFormats[name] !== "undefined" && lineFormats[name] !== null) {
      return;
    }
    if (Array.isArray(context.format[name])) {
      return;
    }
    if (name === "link") {
      return;
    }
    quill.format(name, context.format[name], Quill.sources.USER);
  });
}

const lineBreakHandler = (quill, range, context) => {
  const currentLeaf = quill.getLeaf(range.index)[0];
  const nextLeaf = quill.getLeaf(range.index + 1)[0];
  const previousChar = quill.getText(range.index - 1, 1);
  const formats = quill.getFormat(range.index);

  if (currentLeaf?.next?.domNode?.tagName === "A" || nextLeaf?.parent?.domNode?.tagName === "A") {
    quill.insertEmbed(range.index, "break", true, "user");
    quill.removeFormat(range.index, 1, Quill.sources.SILENT)
  } else {
    quill.insertEmbed(range.index, "break", true, "user");
  }

  if (nextLeaf === null) {
    quill.insertEmbed(range.index, "break", true, "user");
  } else if (context.offset === 1 && previousChar === "\n") {
    const delta = new Delta().retain(range.index).insert("\n");
    quill.updateContents(delta, Quill.sources.USER);
  }

  Object.keys(formats).forEach((format) => {
    quill.format(format, context.format[format], Quill.sources.USER);
  });
  quill.setSelection(range.index + 1, Quill.sources.SILENT);

  const lineFormats = getLineFormats(context);
  continueFormats(quill, context, lineFormats);
};

export default function addEnterBindings(quill) {
  quill.keyboard.addBinding({
    key: 13,
    shiftKey: true
  }, (range, context) => {
    lineBreakHandler(quill, range, context);
  });

  // HAX: make our SHIFT+ENTER binding the second (first is added below) in order to override Quill defaults
  quill.keyboard.bindings[13].unshift(quill.keyboard.bindings[13].pop());

  quill.keyboard.addBinding({ key: 13, shiftKey: false }, (range, context) => {
    const lineFormats = getLineFormats(context);
    const previousChar = quill.getText(range.index - 1, 1);
    const nextChar = quill.getText(range.index, 1);
    const delta = new Delta().retain(range.index).insert("\n", lineFormats);
    // const length = context.prefix.length;
    if (previousChar === "" || previousChar === "\n") {
      if (lineFormats.list && nextChar === "\n") {
        if (quill.getLength() - range.index > 2) {
          const endFormatDelta = new Delta().retain(range.index - 1).delete(1);
          quill.updateContents(endFormatDelta, Quill.sources.USER);
        } else {
          // Delete empty list item and end the list
          const endFormatDelta = new Delta().retain(range.index - 1).delete(1).retain(range.index).insert("\n");
          quill.updateContents(endFormatDelta, Quill.sources.USER);
          quill.setSelection(range.index + 1, Quill.sources.SILENT);
        }
      } else {
        quill.updateContents(delta, Quill.sources.USER);
        if (context.offset === 1 && previousChar === "\n") {
          quill.setSelection(range.index + 1, Quill.sources.SILENT);
        } else {
          quill.setSelection(range.index + 2, Quill.sources.SILENT);
        }
      }
    } else {
      quill.updateContents(delta, Quill.sources.USER);
      quill.setSelection(range.index + 1, Quill.sources.SILENT);
    }
    quill.focus();

    continueFormats(quill, context, lineFormats);
  });

  // Replace the default enter handling because we have modified the break element
  quill.keyboard.bindings[13].unshift(quill.keyboard.bindings[13].pop());
  return;
}