/**
 * @license
 *
 * Copyright (c) 2011-2014, Christopher Jeffrey. (MIT Licensed)
 * https://github.com/chjj/marked
 *
 * Copyright (c) 2018, Костя Третяк. (MIT Licensed)
 * https://github.com/ts-stack/markdown
 */

import type { Replacements } from "./interfaces.ts";

const escapeTest = /[&<>"']/;
const escapeReplace = /[&<>"']/g;
const replacements: Replacements = {
  "&": "&amp;",
  "<": "&lt;",
  ">": "&gt;",
  '"': "&quot;",
  // tslint:disable-next-line:quotemark
  "'": "&#39;",
};

const escapeTestNoEncode = /[<>"']|&(?!#?\w+;)/;
const escapeReplaceNoEncode = /[<>"']|&(?!#?\w+;)/g;

export function escape(html: string, encode?: boolean) {
  if (encode) {
    if (escapeTest.test(html)) {
      return html.replace(escapeReplace, (ch: string) => replacements[ch]);
    }
  } else {
    if (escapeTestNoEncode.test(html)) {
      return html.replace(
        escapeReplaceNoEncode,
        (ch: string) => replacements[ch]
      );
    }
  }

  return html;
}

export function unescape(html: string) {
  // Explicitly match decimal, hex, and named HTML entities
  return html.replace(/&(#(?:\d+)|(?:#x[0-9A-Fa-f]+)|(?:\w+));?/gi, function (
    _,
    n
  ) {
    n = n.toLowerCase();

    if (n === "colon") {
      return ":";
    }

    if (n.charAt(0) === "#") {
      return n.charAt(1) === "x"
        ? String.fromCharCode(parseInt(n.substring(2), 16))
        : String.fromCharCode(+n.substring(1));
    }

    return "";
  });
}