// ==UserScript==
// @name         TabulaBili Userscript
// @namespace    https://github.com/tjsky/TabulaBili
// @homepageURL  https://github.com/Unintendedz/tabulabili-userscript
// @supportURL   https://github.com/Unintendedz/tabulabili-userscript/issues
// @updateURL    https://raw.githubusercontent.com/Unintendedz/tabulabili-userscript/main/TabulaBili.user.js
// @downloadURL  https://raw.githubusercontent.com/Unintendedz/tabulabili-userscript/main/TabulaBili.user.js
// @version      1.1.4-userscript.1
// @description  让 B 站首页推荐接口尽量以无 Cookie 方式请求，并自动点击首页“换一换”以替换首屏个性化推荐。
// @author       wangdaodao, tjsky; userscript conversion by Codex
// @license      MIT
// @match        *://www.bilibili.com/*
// @run-at       document-start
// @grant        GM_getValue
// @grant        GM_setValue
// @grant        GM_registerMenuCommand
// @grant        unsafeWindow
// ==/UserScript==

(function () {
  'use strict';

  const STORAGE_KEY = 'tabulaBiliEnabled';
  const enabled = GM_getValue(STORAGE_KEY, true);

  GM_registerMenuCommand(enabled ? '关闭 TabulaBili' : '开启 TabulaBili', () => {
    GM_setValue(STORAGE_KEY, !enabled);
    location.reload();
  });

  GM_registerMenuCommand('立即换一换', () => {
    clickRollButton(true);
  });

  if (!enabled) {
    return;
  }

  injectNetworkPatch();

  if (document.readyState === 'loading') {
    document.addEventListener('DOMContentLoaded', startAutoRoll, { once: true });
  } else {
    startAutoRoll();
  }

  function injectNetworkPatch() {
    const pageWindow = typeof unsafeWindow === 'object' ? unsafeWindow : null;
    if (pageWindow) {
      try {
        pagePatch(pageWindow);
        return;
      } catch (error) {
        console.warn('[TabulaBili] unsafeWindow patch failed; falling back to script injection.', error);
      }
    }

    const script = document.createElement('script');
    script.textContent = `(${pagePatch.toString()})(window);`;
    const root = document.documentElement || document.head || document.body;
    if (root) {
      root.appendChild(script);
      script.remove();
    }
  }

  function pagePatch(win) {
    'use strict';

    const TAG = '[TabulaBili]';
    if (!win || win.__tabulaBiliPatched) {
      return;
    }

    const nativeFetch = win.fetch;
    const XHR = win.XMLHttpRequest;
    const RequestCtor = win.Request;
    const nativeOpen = XHR.prototype.open;
    const nativeSend = XHR.prototype.send;
    win.__tabulaBiliPatched = true;

    function isTargetUrl(input) {
      try {
        const url = new win.URL(String(input), win.location.href);
        if (url.hostname !== 'api.bilibili.com') {
          return false;
        }

        const path = url.pathname;
        return (
          path.includes('/x/web-interface') &&
          path.includes('/index/top') &&
          path.includes('/rcmd')
        );
      } catch (_) {
        return false;
      }
    }

    function requestUrl(input) {
      if (input && typeof input === 'object' && 'url' in input) {
        return input.url;
      }
      return input;
    }

    if (typeof nativeFetch === 'function') {
      win.fetch = function tabulaBiliFetch(input, init) {
        if (!isTargetUrl(requestUrl(input))) {
          return nativeFetch.apply(this, arguments);
        }

        try {
          if (RequestCtor && input instanceof RequestCtor) {
            return nativeFetch.call(this, new RequestCtor(input, Object.assign({}, init, {
              credentials: 'omit'
            })));
          }

          return nativeFetch.call(this, input, Object.assign({}, init, {
            credentials: 'omit'
          }));
        } catch (error) {
          win.console.warn(TAG, 'fetch patch failed; falling back to original request.', error);
          return nativeFetch.apply(this, arguments);
        }
      };
    }

    XHR.prototype.open = function tabulaBiliOpen(method, url) {
      this.__tabulaBiliTarget = isTargetUrl(url);
      return nativeOpen.apply(this, arguments);
    };

    XHR.prototype.send = function tabulaBiliSend() {
      if (this.__tabulaBiliTarget) {
        try {
          this.withCredentials = false;
        } catch (_) {}
      }

      return nativeSend.apply(this, arguments);
    };

    win.console.info(TAG, 'recommendation feed requests will omit credentials.');
  }

  function startAutoRoll() {
    if (!isHomePage()) {
      return;
    }

    if (clickRollButton(false)) {
      return;
    }

    const root = document.body || document.documentElement;
    const observer = new MutationObserver((_, obs) => {
      if (clickRollButton(false)) {
        obs.disconnect();
      }
    });

    observer.observe(root, { childList: true, subtree: true });
    window.setTimeout(() => observer.disconnect(), 8000);
  }

  function isHomePage() {
    return location.hostname === 'www.bilibili.com' && (
      location.pathname === '/' ||
      location.pathname === '/index.html'
    );
  }

  function clickRollButton(force) {
    const rollButton = document.querySelector('.roll-btn');
    if (!rollButton) {
      return false;
    }

    if (!force && window.scrollY >= 100) {
      console.info('[TabulaBili] roll button loaded after scrolling; skip auto click.');
      return true;
    }

    rollButton.click();
    window.scrollTo({ top: 0, behavior: 'smooth' });
    return true;
  }
})();