/*
Copyright (c) Uber Technologies, Inc.

This source code is licensed under the MIT license found in the
LICENSE file in the root directory of this source tree.
*/

import * as React from "react";
import { useStyletron } from "baseui";
import slugify from "../helpers/slugify";

function getPadding(componentType) {
  const multiplier = Number(componentType.replace("h", ""));

  return `${multiplier * 8}px`;
}

const TableOfContents = (props) => {
  const [css, theme] = useStyletron();
  const TOC = [];
  const content = props.content[0].props.children;
  content &&
    content.forEach &&
    content.forEach((element) => {
      if (
        element.props &&
        element.props.name &&
        element.props.name.startsWith("h") &&
        element.props.children &&
        element.props.children.toLowerCase
      ) {
        TOC.push({
          name: element.props.children,
          anchor: `#${slugify(element.props.children)}`,
          component: element.props.name,
        });
      }

      if (element.props && element.props.title) {
        TOC.push({
          name: element.props.title,
          anchor: `#${slugify(element.props.title)}`,
          component: "h3",
        });
      }

      if (element.props && element.props.api && element.props.heading) {
        TOC.push({
          name: element.props.heading,
          anchor: `#${slugify(element.props.heading)}`,
          component: "h3",
        });
      }
    });

  if (TOC.length === 1) {
    return null;
  }

  return (
    <ul
      className={css({
        [theme.direction === "rtl" ? "borderRight" : "borderLeft"]:
          `1px solid ${theme.colors.mono400}`,
        listStyle: "none",
        [theme.direction === "rtl" ? "marginRight" : "marginLeft"]:
          theme.sizing.scale400,
        paddingLeft: 0,
        paddingRight: 0,
        // to make sure we align vertically with the edit on github button
        marginTop: "-10px",
        marginBottom: 0,
        // set predictable width to avoid page relayout when table of content changes
        width: "160px",
        position: "fixed",
        top: "100px",
      })}
    >
      {TOC.map((header) => (
        <li
          key={header.name}
          className={css({
            ...theme.typography.font100,
            [theme.direction === "rtl" ? "paddingRight" : "paddingLeft"]:
              getPadding(header.component),
          })}
        >
          <a
            className={css({ color: theme.colors.contentSecondary })}
            href={header.anchor}
          >
            {header.name}
          </a>
        </li>
      ))}
    </ul>
  );
};

export default TableOfContents;