// ==UserScript==
// @name         Wiki Randomizer
// @namespace    https://script.zgc.im/
// @version      0.2
// @description  Press 'R' to navigate to Special:Random or others.
// @author       MidAutumnMoon
//
// @match https://zh.wikipedia.org/*
// @match https://en.wikipedia.org/*
// @match https://ja.wikipedia.org/*
// @match https://fr.wikipedia.org/*
// @match https://zh.moegirl.org.cn/*
// @match https://ja.moegirl.org.cn/*
// @match https://en.moegirl.org.cn/*
// @match https://tcrf.net/*
//
// @icon         https://zh.wikipedia.org/favicon.ico
// @grant        none
// @downloadURL none
// ==/UserScript==

// Almost any Mediawiki sites use /Special:Random.
const MediawikiCommon = 'Special:Random';

// The total rules
const RULES = new Map([
  // *.wikipedia.org
  [ 'wikipedia.org', 'wiki/Special:Random' ],

  // Cutting Room Floor
  [ 'tcrf.net', 'Special:RandomRootpage' ],

  // Moegirl wiki
  [ 'moegirl.org.cn', MediawikiCommon ],
]);

// Main
(function() {
  'use strict';

  // Navigate to the `location` of current site.
  const navigate_to = ( location ) => {
    window.location.href = new URL( window.location.href ).origin + '/' + location;
  };

  // Get the rule associated with current site.
  const get_rule = () => {
    let domain = new URL( window.location.href ).host;
    let rule = '';

    for (;;) {
      rule = RULES.get(domain);

      if ( rule === undefined ) {
        // If no rules were found for current domain,
        // try matching sub-domain instead.
        if ( ! validated_domain(domain) ) {
          return null;
        }
        // truncate one level of subdomain
        domain = domain.substring( domain.indexOf('.') + 1 );
      } else {
        // Otherwise just return the matched rule.
        return rule;
      }
    }

  };

  // There must be at least 2 dots in a valid domain name.
  const validated_domain = ( domain ) => {
    return ( (domain.match(/\./g) || []).length >= 2 );
  }

  // ...when press 'R'.
  document.addEventListener('keydown', ( event ) => {
    if ( event.code === 'KeyR' ) {
      const location = get_rule();

      switch ( location ) {
        case null:
          console.log( 'No rules for current site!' );
          break;
        default:
          navigate_to( location );
          break;
      }

    }
  });
})();