e-hentai retriever

e-hentai & exhentai image url retriever

You will need to install an extension such as Tampermonkey, Greasemonkey or Violentmonkey to install this script.

You will need to install an extension such as Tampermonkey or Violentmonkey to install this script.

You will need to install an extension such as Tampermonkey or Violentmonkey to install this script.

You will need to install an extension such as Tampermonkey or Userscripts to install this script.

You will need to install an extension such as Tampermonkey to install this script.

You will need to install a user script manager extension to install this script.

(I already have a user script manager, let me install it!)

You will need to install an extension such as Stylus to install this style.

You will need to install an extension such as Stylus to install this style.

You will need to install an extension such as Stylus to install this style.

You will need to install a user style manager extension to install this style.

You will need to install a user style manager extension to install this style.

You will need to install a user style manager extension to install this style.

(I already have a user style manager, let me install it!)

// ==UserScript==
// @name        e-hentai retriever
// @namespace   https://github.com/s25g5d4/e-hentai-retriever
// @description e-hentai & exhentai image url retriever
// @include     /^https?://e-hentai.org/s/.*/
// @include     /^https?://exhentai.org/s/.*/
// @version     4.4.1
// @author      s25g5d4
// @homepageURL https://github.com/s25g5d4/e-hentai-retriever
// @grant       GM_xmlhttpRequest
// @grant       unsafeWindow
// ==/UserScript==

(function () {
  'use strict';

  function styleInject(css, ref) {
    if ( ref === void 0 ) ref = {};
    var insertAt = ref.insertAt;

    if (!css || typeof document === 'undefined') { return; }

    var head = document.head || document.getElementsByTagName('head')[0];
    var style = document.createElement('style');
    style.type = 'text/css';

    if (insertAt === 'top') {
      if (head.firstChild) {
        head.insertBefore(style, head.firstChild);
      } else {
        head.appendChild(style);
      }
    } else {
      head.appendChild(style);
    }

    if (style.styleSheet) {
      style.styleSheet.cssText = css;
    } else {
      style.appendChild(document.createTextNode(css));
    }
  }

  var css_248z = "#i3 a {\n  display: inline-block;\n  position: relative;\n}\n\n#i3.force-img-full-height a img {\n\twidth:auto !important;\n\theight:100vh !important;\n}\n\n.close,\n.swap,\n.page-number {\n\tposition: absolute;\n\twidth: 32px;\n\theight: 32px;\n\tmargin: 8px;\n\tz-index: 999;\n  opacity: 0;\n  transition: opacity 0.25s;\n\tbackground-color: rgba(255, 255, 255, 0.3);\n}\n\n.close {\n\ttop: 0;\n\tright: 0;\n\tbackground-image: url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAACAAAAAgCAYAAABzenr0AAAAmElEQVRYhc2USQ6AMAwD+/9PhyuRAs3igVrqCTR2m2UtL1u8Hj3sdkjz0MOCQ5o7j+iDOsTWgwyRZhMhykxliDZLEWLMmABkr9gByfuoAsQmKQPGd8mbAW7eDYHoV/NsCFxH3/6I+h8xAZ/tgMo/mDkWogOUhZiAxiEUt2gzlHUss4hOTjPJWd6y8UXSDaFWqQyUUo1Iy3lcN6p2mB7qGCwAAAAASUVORK5CYII=);\n}\n\n.swap {\n\ttop: 0;\n\tleft: 0;\n\tbackground-image: url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAACAAAAAgCAYAAABzenr0AAAAdklEQVRYhe3TwQ0AIQhE0enA7b9JS2BPezExERb9HpiEI/KiIlUqZ2I3AFCECUaYYMQI+IXokwMjhQNCCPwGmqTHWal/IJKrtsDVlA3Y17Bwnns4/lb4TzX5161lDo9UJ4eHAZmIMGCGOB4cMCKw4IAPUalszwvTfbCPlftI4QAAAABJRU5ErkJggg==);\n}\n\n.page-number {\n\tbottom: 0;\n\tright: 0;\n\tfont-size: 16px;\n\tline-height: 32px;\n\tcolor: black;\n}\n\n.close:hover,\n.swap:hover,\n.page-number:hover {\n  opacity: 1;\n}\n\n.hidden {\n\tdisplay: none !important;\n}\n\n.show-hidden {\n\tfont-size: larger;\n\tmargin-left: 5px;\n}\n";
  styleInject(css_248z);

  class Queue {
      constructor(limit, timeout = 0, delay = 0) {
          this.limit = limit;
          this.timeout = timeout;
          this.delay = delay;
          this.slot = [];
          this.q = [];
      }
      queue(executor, name) {
          const job = new Promise((resolve, reject) => {
              this.q.push({
                  name,
                  run: executor,
                  resolve,
                  reject,
                  isTimeout: false,
                  timeoutId: undefined
              });
          });
          // console.log(`queue: job ${name} queued`);
          this.dequeue();
          return job;
      }
      dequeue() {
          const { q, slot, limit, timeout, delay } = this;
          if (slot.length < limit && q.length >= 1) {
              const job = q.shift();
              slot.push(job);
              // console.log(`queue: job ${job.name} started`);
              if (timeout) {
                  job.timeoutId = window.setTimeout(() => this.jobTimeout(job), timeout);
              }
              const onFulfilled = (data) => {
                  if (job.isTimeout) {
                      return;
                  }
                  this.removeJob(job);
                  window.setTimeout(() => this.dequeue(), delay); // force dequeue() run after current dequeue()
                  if (job.timeoutId) {
                      window.clearTimeout(job.timeoutId);
                  }
                  // console.log(`queue: job ${job.name} resolved`);
                  job.resolve(data);
              };
              const onRejected = (reason) => {
                  if (job.isTimeout) {
                      return;
                  }
                  this.removeJob(job);
                  setTimeout(() => this.dequeue(), delay);
                  if (job.timeoutId) {
                      window.clearTimeout(job.timeoutId);
                  }
                  // console.log(`queue: job ${job.name} rejected`);
                  job.reject(reason);
              };
              job.run(onFulfilled, onRejected);
          }
      }
      jobTimeout(job) {
          this.removeJob(job);
          // console.log(`queue: job ${job.name} timeout`);
          job.reject(new Error(`queue: job ${job.name} timeout`));
          job = null;
      }
      removeJob(job) {
          let index = this.slot.indexOf(job);
          if (index >= 0) {
              this.slot.splice(index, 1);
              return;
          }
          index = this.q.indexOf(job);
          if (index >= 0) {
              this.q.splice(index, 1);
          }
      }
  }

  // Origin from window.fetch polyfill
  // https://github.com/github/fetch
  // License https://github.com/github/fetch/blob/master/LICENSE
  const COFetch = (input, init = {}) => {
      let request;
      if (Request.prototype.isPrototypeOf(input) && !init) {
          request = input;
      }
      else {
          request = new Request(input, init);
      }
      const headers = Object.assign({}, request.headers);
      let anonymous = true;
      if (request.credentials === 'include') {
          anonymous = false;
      }
      const onload = (resolve, reject, gmxhr) => {
          const init = {
              url: gmxhr.finalUrl || request.url,
              status: gmxhr.status,
              statusText: gmxhr.statusText,
              headers: undefined
          };
          try {
              const rawHeaders = gmxhr.responseHeaders.trim().replace(/\r\n(\s+)/g, '$1').split('\r\n').map(e => e.split(/:/));
              const header = new Headers();
              rawHeaders.forEach(e => {
                  header.append(e[0].trim(), e[1].trim());
              });
              init.headers = header;
              const res = new Response(gmxhr.response, init);
              resolve(res);
          }
          catch (e) {
              reject(e);
          }
      };
      const onerror = (resolve, reject, gmxhr) => {
          reject(new TypeError('Network request failed'));
      };
      return new Promise((resolve, reject) => {
          GM_xmlhttpRequest({
              anonymous,
              method: request.method,
              url: request.url,
              headers: headers,
              responseType: 'blob',
              data: init.body,
              onload: onload.bind(null, resolve, reject),
              onerror: onerror.bind(null, resolve, reject)
          });
      });
  };

  var domain;

  // This constructor is used to store event handlers. Instantiating this is
  // faster than explicitly calling `Object.create(null)` to get a "clean" empty
  // object (tested with v8 v4.9).
  function EventHandlers() {}
  EventHandlers.prototype = Object.create(null);

  function EventEmitter() {
    EventEmitter.init.call(this);
  }

  // nodejs oddity
  // require('events') === require('events').EventEmitter
  EventEmitter.EventEmitter = EventEmitter;

  EventEmitter.usingDomains = false;

  EventEmitter.prototype.domain = undefined;
  EventEmitter.prototype._events = undefined;
  EventEmitter.prototype._maxListeners = undefined;

  // By default EventEmitters will print a warning if more than 10 listeners are
  // added to it. This is a useful default which helps finding memory leaks.
  EventEmitter.defaultMaxListeners = 10;

  EventEmitter.init = function() {
    this.domain = null;
    if (EventEmitter.usingDomains) {
      // if there is an active domain, then attach to it.
      if (domain.active ) ;
    }

    if (!this._events || this._events === Object.getPrototypeOf(this)._events) {
      this._events = new EventHandlers();
      this._eventsCount = 0;
    }

    this._maxListeners = this._maxListeners || undefined;
  };

  // Obviously not all Emitters should be limited to 10. This function allows
  // that to be increased. Set to zero for unlimited.
  EventEmitter.prototype.setMaxListeners = function setMaxListeners(n) {
    if (typeof n !== 'number' || n < 0 || isNaN(n))
      throw new TypeError('"n" argument must be a positive number');
    this._maxListeners = n;
    return this;
  };

  function $getMaxListeners(that) {
    if (that._maxListeners === undefined)
      return EventEmitter.defaultMaxListeners;
    return that._maxListeners;
  }

  EventEmitter.prototype.getMaxListeners = function getMaxListeners() {
    return $getMaxListeners(this);
  };

  // These standalone emit* functions are used to optimize calling of event
  // handlers for fast cases because emit() itself often has a variable number of
  // arguments and can be deoptimized because of that. These functions always have
  // the same number of arguments and thus do not get deoptimized, so the code
  // inside them can execute faster.
  function emitNone(handler, isFn, self) {
    if (isFn)
      handler.call(self);
    else {
      var len = handler.length;
      var listeners = arrayClone(handler, len);
      for (var i = 0; i < len; ++i)
        listeners[i].call(self);
    }
  }
  function emitOne(handler, isFn, self, arg1) {
    if (isFn)
      handler.call(self, arg1);
    else {
      var len = handler.length;
      var listeners = arrayClone(handler, len);
      for (var i = 0; i < len; ++i)
        listeners[i].call(self, arg1);
    }
  }
  function emitTwo(handler, isFn, self, arg1, arg2) {
    if (isFn)
      handler.call(self, arg1, arg2);
    else {
      var len = handler.length;
      var listeners = arrayClone(handler, len);
      for (var i = 0; i < len; ++i)
        listeners[i].call(self, arg1, arg2);
    }
  }
  function emitThree(handler, isFn, self, arg1, arg2, arg3) {
    if (isFn)
      handler.call(self, arg1, arg2, arg3);
    else {
      var len = handler.length;
      var listeners = arrayClone(handler, len);
      for (var i = 0; i < len; ++i)
        listeners[i].call(self, arg1, arg2, arg3);
    }
  }

  function emitMany(handler, isFn, self, args) {
    if (isFn)
      handler.apply(self, args);
    else {
      var len = handler.length;
      var listeners = arrayClone(handler, len);
      for (var i = 0; i < len; ++i)
        listeners[i].apply(self, args);
    }
  }

  EventEmitter.prototype.emit = function emit(type) {
    var er, handler, len, args, i, events, domain;
    var doError = (type === 'error');

    events = this._events;
    if (events)
      doError = (doError && events.error == null);
    else if (!doError)
      return false;

    domain = this.domain;

    // If there is no 'error' event listener then throw.
    if (doError) {
      er = arguments[1];
      if (domain) {
        if (!er)
          er = new Error('Uncaught, unspecified "error" event');
        er.domainEmitter = this;
        er.domain = domain;
        er.domainThrown = false;
        domain.emit('error', er);
      } else if (er instanceof Error) {
        throw er; // Unhandled 'error' event
      } else {
        // At least give some kind of context to the user
        var err = new Error('Uncaught, unspecified "error" event. (' + er + ')');
        err.context = er;
        throw err;
      }
      return false;
    }

    handler = events[type];

    if (!handler)
      return false;

    var isFn = typeof handler === 'function';
    len = arguments.length;
    switch (len) {
      // fast cases
      case 1:
        emitNone(handler, isFn, this);
        break;
      case 2:
        emitOne(handler, isFn, this, arguments[1]);
        break;
      case 3:
        emitTwo(handler, isFn, this, arguments[1], arguments[2]);
        break;
      case 4:
        emitThree(handler, isFn, this, arguments[1], arguments[2], arguments[3]);
        break;
      // slower
      default:
        args = new Array(len - 1);
        for (i = 1; i < len; i++)
          args[i - 1] = arguments[i];
        emitMany(handler, isFn, this, args);
    }

    return true;
  };

  function _addListener(target, type, listener, prepend) {
    var m;
    var events;
    var existing;

    if (typeof listener !== 'function')
      throw new TypeError('"listener" argument must be a function');

    events = target._events;
    if (!events) {
      events = target._events = new EventHandlers();
      target._eventsCount = 0;
    } else {
      // To avoid recursion in the case that type === "newListener"! Before
      // adding it to the listeners, first emit "newListener".
      if (events.newListener) {
        target.emit('newListener', type,
                    listener.listener ? listener.listener : listener);

        // Re-assign `events` because a newListener handler could have caused the
        // this._events to be assigned to a new object
        events = target._events;
      }
      existing = events[type];
    }

    if (!existing) {
      // Optimize the case of one listener. Don't need the extra array object.
      existing = events[type] = listener;
      ++target._eventsCount;
    } else {
      if (typeof existing === 'function') {
        // Adding the second element, need to change to array.
        existing = events[type] = prepend ? [listener, existing] :
                                            [existing, listener];
      } else {
        // If we've already got an array, just append.
        if (prepend) {
          existing.unshift(listener);
        } else {
          existing.push(listener);
        }
      }

      // Check for listener leak
      if (!existing.warned) {
        m = $getMaxListeners(target);
        if (m && m > 0 && existing.length > m) {
          existing.warned = true;
          var w = new Error('Possible EventEmitter memory leak detected. ' +
                              existing.length + ' ' + type + ' listeners added. ' +
                              'Use emitter.setMaxListeners() to increase limit');
          w.name = 'MaxListenersExceededWarning';
          w.emitter = target;
          w.type = type;
          w.count = existing.length;
          emitWarning(w);
        }
      }
    }

    return target;
  }
  function emitWarning(e) {
    typeof console.warn === 'function' ? console.warn(e) : console.log(e);
  }
  EventEmitter.prototype.addListener = function addListener(type, listener) {
    return _addListener(this, type, listener, false);
  };

  EventEmitter.prototype.on = EventEmitter.prototype.addListener;

  EventEmitter.prototype.prependListener =
      function prependListener(type, listener) {
        return _addListener(this, type, listener, true);
      };

  function _onceWrap(target, type, listener) {
    var fired = false;
    function g() {
      target.removeListener(type, g);
      if (!fired) {
        fired = true;
        listener.apply(target, arguments);
      }
    }
    g.listener = listener;
    return g;
  }

  EventEmitter.prototype.once = function once(type, listener) {
    if (typeof listener !== 'function')
      throw new TypeError('"listener" argument must be a function');
    this.on(type, _onceWrap(this, type, listener));
    return this;
  };

  EventEmitter.prototype.prependOnceListener =
      function prependOnceListener(type, listener) {
        if (typeof listener !== 'function')
          throw new TypeError('"listener" argument must be a function');
        this.prependListener(type, _onceWrap(this, type, listener));
        return this;
      };

  // emits a 'removeListener' event iff the listener was removed
  EventEmitter.prototype.removeListener =
      function removeListener(type, listener) {
        var list, events, position, i, originalListener;

        if (typeof listener !== 'function')
          throw new TypeError('"listener" argument must be a function');

        events = this._events;
        if (!events)
          return this;

        list = events[type];
        if (!list)
          return this;

        if (list === listener || (list.listener && list.listener === listener)) {
          if (--this._eventsCount === 0)
            this._events = new EventHandlers();
          else {
            delete events[type];
            if (events.removeListener)
              this.emit('removeListener', type, list.listener || listener);
          }
        } else if (typeof list !== 'function') {
          position = -1;

          for (i = list.length; i-- > 0;) {
            if (list[i] === listener ||
                (list[i].listener && list[i].listener === listener)) {
              originalListener = list[i].listener;
              position = i;
              break;
            }
          }

          if (position < 0)
            return this;

          if (list.length === 1) {
            list[0] = undefined;
            if (--this._eventsCount === 0) {
              this._events = new EventHandlers();
              return this;
            } else {
              delete events[type];
            }
          } else {
            spliceOne(list, position);
          }

          if (events.removeListener)
            this.emit('removeListener', type, originalListener || listener);
        }

        return this;
      };
      
  // Alias for removeListener added in NodeJS 10.0
  // https://nodejs.org/api/events.html#events_emitter_off_eventname_listener
  EventEmitter.prototype.off = function(type, listener){
      return this.removeListener(type, listener);
  };

  EventEmitter.prototype.removeAllListeners =
      function removeAllListeners(type) {
        var listeners, events;

        events = this._events;
        if (!events)
          return this;

        // not listening for removeListener, no need to emit
        if (!events.removeListener) {
          if (arguments.length === 0) {
            this._events = new EventHandlers();
            this._eventsCount = 0;
          } else if (events[type]) {
            if (--this._eventsCount === 0)
              this._events = new EventHandlers();
            else
              delete events[type];
          }
          return this;
        }

        // emit removeListener for all listeners on all events
        if (arguments.length === 0) {
          var keys = Object.keys(events);
          for (var i = 0, key; i < keys.length; ++i) {
            key = keys[i];
            if (key === 'removeListener') continue;
            this.removeAllListeners(key);
          }
          this.removeAllListeners('removeListener');
          this._events = new EventHandlers();
          this._eventsCount = 0;
          return this;
        }

        listeners = events[type];

        if (typeof listeners === 'function') {
          this.removeListener(type, listeners);
        } else if (listeners) {
          // LIFO order
          do {
            this.removeListener(type, listeners[listeners.length - 1]);
          } while (listeners[0]);
        }

        return this;
      };

  EventEmitter.prototype.listeners = function listeners(type) {
    var evlistener;
    var ret;
    var events = this._events;

    if (!events)
      ret = [];
    else {
      evlistener = events[type];
      if (!evlistener)
        ret = [];
      else if (typeof evlistener === 'function')
        ret = [evlistener.listener || evlistener];
      else
        ret = unwrapListeners(evlistener);
    }

    return ret;
  };

  EventEmitter.listenerCount = function(emitter, type) {
    if (typeof emitter.listenerCount === 'function') {
      return emitter.listenerCount(type);
    } else {
      return listenerCount.call(emitter, type);
    }
  };

  EventEmitter.prototype.listenerCount = listenerCount;
  function listenerCount(type) {
    var events = this._events;

    if (events) {
      var evlistener = events[type];

      if (typeof evlistener === 'function') {
        return 1;
      } else if (evlistener) {
        return evlistener.length;
      }
    }

    return 0;
  }

  EventEmitter.prototype.eventNames = function eventNames() {
    return this._eventsCount > 0 ? Reflect.ownKeys(this._events) : [];
  };

  // About 1.5x faster than the two-arg version of Array#splice().
  function spliceOne(list, index) {
    for (var i = index, k = i + 1, n = list.length; k < n; i += 1, k += 1)
      list[i] = list[k];
    list.pop();
  }

  function arrayClone(arr, i) {
    var copy = new Array(i);
    while (i--)
      copy[i] = arr[i];
    return copy;
  }

  function unwrapListeners(arr) {
    var ret = new Array(arr.length);
    for (var i = 0; i < ret.length; ++i) {
      ret[i] = arr[i].listener || arr[i];
    }
    return ret;
  }

  class EhRetriever extends EventEmitter {
      constructor(url, html) {
          super();
          const testEXHentaiUrl = /^https?:\/\/(?:e-|ex)hentai\.org\//;
          if (typeof url !== 'string') {
              throw new TypeError('invalid `url`, expected a string');
          }
          if (!testEXHentaiUrl.test(url)) {
              throw new TypeError(`invalid url: ${url}`);
          }
          this.url = url;
          this.html = html;
          this.gallery = { gid: '', token: '' };
          this.referer = url;
          this.showkey = '';
          this.ehentaiHost = testEXHentaiUrl.exec(url)[0].slice(0, -1);
          this.q = new Queue(3, 3000, 1000);
          this.pages = this.init();
          this.pages.then(() => this.emit('ready'));
      }
      async init() {
          if (!this.html) {
              this.html = await this.fetch(this.url).then(res => res.text());
          }
          const galleryURL = this.html.match(/hentai\.org\/g\/(\d+)\/([a-z0-9]+)/i);
          const showkey = this.html.match(/showkey="([^"]+)"/i);
          if (galleryURL) {
              this.gallery.gid = galleryURL[1];
              this.gallery.token = galleryURL[2];
          }
          else {
              throw new Error("Can't get gallery URL");
          }
          if (showkey) {
              this.showkey = showkey[1];
          }
          else {
              throw new Error("Can't get showkey");
          }
          return await this.getAllPageURL();
      }
      async getAllPageURL() {
          const { ehentaiHost, gallery: { gid, token } } = this;
          const firstPage = await this.fetch(`${ehentaiHost}/g/${gid}/${token}`).then(res => res.text());
          let pageNum;
          const pageLinksTable = firstPage.match(/<table[^>]*class="ptt"[^>]*>((?:[^<]*)(?:<(?!\/table>)[^<]*)*)<\/table>/);
          if (pageLinksTable) {
              const pageLinks = pageLinksTable[1].match(/g\/[^/]+\/[^/]+\/\?p=\d+/g);
              if (pageLinks) {
                  pageNum = Math.max.apply(null, pageLinks.map(e => parseInt(/\d+$/.exec(e)[0], 10)));
              }
              else {
                  pageNum = 0;
              }
          }
          else {
              throw new Error('Cant get page numbers');
          }
          const allPages = await Promise.all(Array(pageNum).fill(undefined).map((e, i) => {
              return this.fetch(`${ehentaiHost}/g/${gid}/${token}/?p=${i + 1}`).then(res => res.text());
          }));
          allPages.unshift(firstPage);
          return allPages
              .map(p => this.parsePage(p))
              .reduce((p, c) => p.concat(c), []); // 2d array to 1d
      }
      parsePage(page) {
          const gdtMatcher = /<div[^>]*id="gdt"[^>]*>/g;
          gdtMatcher.exec(page);
          const gtbMatcher = /<div[^>]*class="gtb"[^>]*>/g;
          gtbMatcher.lastIndex = gdtMatcher.lastIndex;
          gtbMatcher.exec(page);
          const gdtContent = page.substring(gdtMatcher.lastIndex, gtbMatcher.lastIndex);
          return Array.from(gdtContent.matchAll(/s\/(\w+)\/\d+-(\d+)/g)).map(([, imgkey, page]) => ({ imgkey, page: parseInt(page, 10) }));
      }
      fetch(url, options = {}) {
          if (typeof url !== 'string') {
              return Promise.reject(new TypeError('invalid `url`, expected a string'));
          }
          if (url.search(/^https?:\/\//) < 0) {
              return Promise.reject(new TypeError(`invalid url: ${url}`));
          }
          const cofetchOptions = {
              method: 'GET',
              credentials: 'include',
              headers: {
                  'User-Agent': navigator.userAgent,
                  Referer: this.referer
              }
          };
          for (const key of Object.keys(options)) {
              if (key === 'headers') {
                  Object.assign(cofetchOptions.headers, options.headers);
              }
              else {
                  cofetchOptions[key] = options[key];
              }
          }
          return this.q.queue((resolve, reject) => {
              COFetch(url, cofetchOptions).then(resolve).catch(reject);
          }, `Fetch ${url} ${JSON.stringify(cofetchOptions)}`);
      }
      async retrieve(start = 0, stop = -1) {
          const pages = await this.pages;
          if (start < 0 || start >= pages.length || isNaN(start)) {
              throw new RangeError(`invalid start number: ${start}`);
          }
          if (stop < 0) {
              stop = pages.length - 1;
          }
          else if (stop < start || stop >= pages.length || isNaN(stop)) {
              throw new RangeError(`invalid stop number: ${stop}, start: ${start}`);
          }
          const retrievePages = pages.slice(start, stop + 1);
          const loadPage = async (e) => {
              if (e.imgsrc && e.filename) {
                  return Promise.resolve(e);
              }
              const fetchPage = await this.fetch(`${this.ehentaiHost}/api.php`, {
                  method: 'POST',
                  headers: { 'Content-Type': 'application/json' },
                  // assign e = {'imgkey': ..., 'page': ...} to object literal {'method': ..., 'gid': ..., 'showkey': ...}
                  // does not modify e
                  body: JSON.stringify(Object.assign({
                      method: 'showpage',
                      gid: this.gallery.gid,
                      showkey: this.showkey
                  }, e))
              }).then(res => res.json());
              this.emit('load', {
                  current: e.page - start,
                  total: stop - start + 1
              });
              return fetchPage;
          };
          const imagePages = await Promise.all(retrievePages.map(loadPage));
          imagePages.forEach((e, i) => {
              retrievePages[i].filename = e.i.match(/>([^:]+):/)[1].trim();
              retrievePages[i].imgsrc = e.i3.match(/src="([^"]+)"/)[1];
              retrievePages[i].failnl = new Set([e.i6.match(/nl\('([^']+)'/)[1]]);
              retrievePages[i].style = e.i3.match(/style="([^"]+)"/)[1];
              retrievePages[i].url = e.s;
          });
          return retrievePages;
      }
      async fail(index) {
          const pages = await this.pages;
          const failPage = pages[index - 1];
          const failnl = [...failPage.failnl.values()].map(e => `nl=${e}`).join('&');
          const res = await this.fetch(`${this.ehentaiHost}/${failPage.url}?${failnl}`).then(res => res.text());
          const parsed = res.match(/<img[^>]*id="img"[^>]*src="([^"]+)"[^>]*.*onclick="return nl\('([^']+)'\)/i);
          if (parsed) {
              failPage.imgsrc = parsed[1];
              failPage.failnl.add(parsed[2]);
              return failPage;
          }
          return null;
      }
  }

  const LoadTimeout = 10000;
  // helper functions
  const $ = (selector) => document.querySelector(selector);
  const $$ = (selector) => Array.from(document.querySelectorAll(selector));
  const buttonsFragment = document.createDocumentFragment();
  const buttonReverse = document.createElement('button');
  const buttonDoubleFrame = document.createElement('button');
  const buttonRetrieve = document.createElement('button');
  const buttonRange = document.createElement('button');
  const buttonFullHeight = document.createElement('button');
  buttonsFragment.appendChild(buttonReverse);
  buttonsFragment.appendChild(buttonDoubleFrame);
  buttonsFragment.appendChild(buttonFullHeight);
  buttonsFragment.appendChild(buttonRetrieve);
  buttonsFragment.appendChild(buttonRange);
  buttonReverse.textContent = 'Reverse';
  buttonDoubleFrame.textContent = 'Double Frame';
  buttonRetrieve.textContent = 'Retrieve!';
  buttonRange.textContent = 'Set Range';
  buttonFullHeight.textContent = 'View Height';
  $('#i1').insertBefore(buttonsFragment, $('#i2'));
  let ehentaiResize;
  let originalWidth;
  let ehr;
  let showHiddenImageLink = false;
  const reload = (event) => {
      event.stopPropagation();
      event.preventDefault();
      const target = event.target;
      if (target.dataset.locked === 'true') {
          return;
      }
      target.dataset.locked = 'true';
      ehr.fail(parseInt(target.dataset.page, 10)).then(imgInfo => {
          target.src = imgInfo.imgsrc;
          target.parentElement.href = imgInfo.imgsrc;
          target.dataset.locked = 'false';
      });
  };
  const showImage = (event) => {
      event.stopPropagation();
      event.preventDefault();
      $$('#i3 a').forEach(e => {
          e.classList.remove('hidden');
      });
      event.target.remove();
      showHiddenImageLink = false;
  };
  const hideImage = (event) => {
      event.stopPropagation();
      event.preventDefault();
      event.target.parentElement.classList.add('hidden');
      if (!showHiddenImageLink) {
          const showHiddenImage = document.createElement('a');
          showHiddenImage.href = '';
          showHiddenImage.textContent = 'show hidden image';
          showHiddenImage.classList.add('show-hidden');
          showHiddenImage.addEventListener('click', showImage);
          buttonRetrieve.insertAdjacentElement('afterend', showHiddenImage);
          showHiddenImageLink = true;
      }
  };
  const swapImage = (event) => {
      event.stopPropagation();
      event.preventDefault();
      const right = event.target.parentElement;
      const left = right.previousElementSibling;
      if (left) {
          left.parentElement.insertBefore(right, left);
      }
  };
  const scrollNextImage = (event) => {
      if (event.keyCode !== 9) {
          return;
      }
      event.preventDefault();
      const bodyOffset = document.body.getBoundingClientRect().top;
      const pageY = window.pageYOffset;
      const imgs = Array.from($$('#i3 a img'));
      const isLast = !imgs.some((e, i) => {
          const imgOffset = e.getBoundingClientRect().top - bodyOffset;
          if (pageY - imgOffset < -1) {
              window.scrollTo(0, imgOffset);
              return true;
          }
      });
      if (isLast) {
          window.scrollTo(0, imgs[0].getBoundingClientRect().top - bodyOffset);
      }
  };
  buttonReverse.addEventListener('click', event => {
      const i3 = $('#i3');
      const imgs = $$('#i3 > a[data-page]');
      if (buttonReverse.textContent === 'Reverse') {
          buttonReverse.textContent = 'Original Order';
          imgs
              .sort((a, b) => a.offsetTop - b.offsetTop)
              .reduce((p, c) => {
              const l = p.at(-1);
              if (!l || l.at(-1).offsetTop !== c.offsetTop) {
                  return [...p, [c]];
              }
              l.push(c);
              return p;
          }, [])
              .flatMap(e => e.reverse())
              .forEach(e => i3.appendChild(e));
      }
      else {
          buttonReverse.textContent = 'Reverse';
          imgs
              .sort((a, b) => parseInt(a.dataset.page, 10) - parseInt(b.dataset.page, 10))
              .forEach(e => i3.appendChild(e));
      }
  });
  buttonDoubleFrame.addEventListener('click', event => {
      if (!ehentaiResize) {
          try {
              ehentaiResize = unsafeWindow.onresize;
          }
          catch (e) {
              console.log(e);
          }
      }
      const imgWidths = $$('#i3 a:not(.hidden) img').map(e => e.getBoundingClientRect().width);
      const avg = imgWidths.reduce((p, c) => p + c) / imgWidths.length;
      const filtered = imgWidths.filter(v => (v < avg * 1.5 && v > avg * 0.5));
      const filteredMax = Math.max.apply(null, filtered);
      if (!originalWidth) {
          originalWidth = parseInt($('#i1').style.width, 10);
      }
      if (buttonDoubleFrame.textContent === 'Double Frame') {
          buttonDoubleFrame.textContent = 'Reset Frame';
          try {
              unsafeWindow.onresize = null;
          }
          catch (e) {
              console.log(e);
          }
          $('#i1').style.maxWidth = (filteredMax * 2 + 20) + 'px';
          $('#i1').style.width = (filteredMax * 2 + 20) + 'px';
      }
      else {
          buttonDoubleFrame.textContent = 'Double Frame';
          try {
              unsafeWindow.onresize = ehentaiResize;
              ehentaiResize();
          }
          catch (e) {
              console.log(e);
              $('#i1').style.maxWidth = originalWidth + 'px';
              $('#i1').style.width = originalWidth + 'px';
          }
      }
  });
  buttonRetrieve.addEventListener('click', event => {
      buttonRetrieve.setAttribute('disabled', '');
      buttonRange.setAttribute('disabled', '');
      buttonRetrieve.textContent = 'Initializing...';
      if (!ehr) {
          ehr = new EhRetriever(location.href, document.body.innerHTML);
      }
      ehr.on('ready', () => {
          buttonRetrieve.textContent = `Ready to retrieve`;
      });
      ehr.on('load', (progress) => {
          buttonRetrieve.textContent = `Retrieving ${progress.current}/${progress.total}`;
      });
      let retrieve;
      if ($('#ehrstart')) {
          const start = parseInt($('#ehrstart').value, 10);
          const stop = parseInt($('#ehrstop').value, 10);
          const pageNumMax = parseInt($('div.sn').textContent.match(/\/\s*(\d+)/)[1], 10);
          if (stop < start || start <= 0 || start > pageNumMax || stop > pageNumMax) {
              window.alert(`invalid range: ${start} - ${stop}, accepted range: 1 - ${pageNumMax}`);
              buttonRetrieve.textContent = 'Retrieve!';
              buttonRetrieve.removeAttribute('disabled');
              return;
          }
          retrieve = ehr.retrieve(start - 1, stop - 1);
          $('#ehrsetrange').remove();
      }
      else {
          retrieve = ehr.retrieve();
          buttonRange.remove();
      }
      retrieve.then(pages => {
          $('#i3 a').remove();
          const template = document.createElement('template');
          template.innerHTML = pages
              .map(e => `
        <a href="${e.imgsrc}" data-page="${e.page}">
          <img src="${e.imgsrc}" style="${e.style}" data-page="${e.page}" data-locked="false" />
          <div class="close"></div>
          <div class="swap"></div>
          <div class="page-number">${e.page}</div>
        </a>`)
              .join('');
          template.content.querySelectorAll('img').forEach(e => {
              e.addEventListener('error', function onError(event) {
                  e.removeEventListener('error', onError);
                  reload(event);
              });
              let timeout;
              {
                  timeout = window.setTimeout(() => {
                      console.log(`timeout: page ${e.dataset.page}`);
                      const clickEvent = new MouseEvent('click', {
                          bubbles: true,
                          cancelable: true,
                          view: window
                      });
                      e.dispatchEvent(clickEvent);
                  }, LoadTimeout);
                  e.addEventListener('load', function onload() {
                      e.removeEventListener('load', onload);
                      clearTimeout(timeout);
                  });
              }
          });
          $('#i3').appendChild(template.content);
          $('#i3').addEventListener('click', event => {
              if (event.target.nodeName === 'IMG') {
                  reload(event);
              }
              else if (event.target.classList.contains('close')) {
                  hideImage(event);
              }
              else if (event.target.classList.contains('swap')) {
                  swapImage(event);
              }
              else if (event.target.classList.contains('page-number')) {
                  event.preventDefault();
                  event.stopPropagation();
              }
          });
          buttonRetrieve.textContent = 'Done!';
          buttonDoubleFrame.removeAttribute('disabled');
          buttonFullHeight.removeAttribute('disabled');
          document.onkeydown = null;
          document.addEventListener('keydown', scrollNextImage);
      }).catch(e => { console.log(e); });
  });
  buttonRange.addEventListener('click', event => {
      // override e-hentai's viewing shortcut
      document.onkeydown = undefined;
      const pageNum = $('div.sn').textContent.match(/(\d+)\s*\/\s*(\d+)/).slice(1);
      buttonRange.insertAdjacentHTML('afterend', `<span id="ehrsetrange"><input type="number" id="ehrstart" value="${pageNum[0]}" min="1" max="${pageNum[1]}"> - <input type="number" id="ehrstop" value="${pageNum[1]}" min="1" max="${pageNum[1]}"></span>`);
      buttonRange.remove();
  });
  buttonFullHeight.addEventListener('click', event => {
      $('#i3').classList.toggle('force-img-full-height');
  });

})();