import type { Advertisement } from '../api/types';
import { recordList, safeUrl, setAdClickData } from '../api/protocol';

const AGE_KEY = 'hg_age_ok';
const DISMISSED_KEY = 'dialogAdDismissed';
const PROGRESS_KEY = 'dialogAdProgress';
const GRID_DISMISSED_KEY = 'gridAdDismissed';

function advertisements(list: unknown): Advertisement[] {
  return recordList<Advertisement>(list).map(item => ({...item,
    id: String(item.advertiseCode || '').trim() || String(item.id || '').trim(),
    images: safeUrl(item.images), link: safeUrl(item.link), title: String(item.title || '').trim(),
  })).filter(item => item.images);
}

type SessionStore = Pick<Storage, 'getItem' | 'setItem' | 'removeItem'>;
export interface StartupView {
  showAge(): void;
  closeAge(): void;
  prepareAdvertisement(): void;
  loadAdvertisement(item: Advertisement, signal: AbortSignal): Promise<void>;
  showAdvertisement(item: Advertisement): void;
  hideAdvertisement(): void;
  loadGrid(items: Advertisement[], signal: AbortSignal): Promise<Advertisement[]>;
  showGrid(items: Advertisement[]): void;
  hideGrid(): void;
}

/** Session keys, signature version and resume behavior for JHA-1047. */
export class StartupDialogs {
  private accepted = false;
  private items: Advertisement[] = [];
  private signature = '';
  private index = 0;
  private readyIndex = -1;
  private visibleIndex = -1;
  private displayed = false;
  private generation = 0;
  private loading?: AbortController;
  private advertisementPending = false;
  private gridSignature = '';
  private gridItems: Advertisement[] = [];
  private gridLoading?: AbortController;
  private gridVisible = false;
  private gridDismissed = false;

  constructor(private storage: SessionStore, private view: StartupView, confirmed = false) {
    this.accepted = confirmed || this.read(AGE_KEY) === '1';
    if (this.accepted) view.closeAge(); else view.showAge();
  }

  private read(key: string) {try {return this.storage.getItem(key) || '';} catch {return '';}}
  private write(key: string, value: string) {try {this.storage.setItem(key, value);} catch {}}
  private remove(key: string) {try {this.storage.removeItem(key);} catch {}}

  confirmAge() {
    this.write(AGE_KEY, '1');
    this.accepted = true;
    this.view.closeAge();
    this.showReady();
    this.showGridReady();
  }

  setAdvertisements(list: Advertisement[], gridList: Advertisement[] = []) {
    const items = advertisements(list);
    const signature = items.length ? '2|' + items.map((item, index) => item.id || item.images || String(index)).join('|') : '';
    const changed = signature !== this.signature;
    if (changed) {
      this.generation++;
      this.loading?.abort();
      this.view.hideAdvertisement();
      this.view.hideGrid();
      this.gridVisible = false;
      this.items = items;
      this.signature = signature;
      this.readyIndex = this.visibleIndex = -1;
      this.displayed = false;
      this.advertisementPending = !!items.length && this.read(DISMISSED_KEY) !== signature;
    }
    this.setGridAdvertisements(gridList);
    if (changed && this.advertisementPending) void this.showItem(this.readProgress());
    this.showGridReady();
  }

  private setGridAdvertisements(list: Advertisement[]) {
    const items = advertisements(list);
    const signature = items.length ? JSON.stringify(items.map(item => [item.id, item.images, item.link, item.title])) : '';
    if (signature === this.gridSignature) return;
    this.gridLoading?.abort();
    this.view.hideGrid();
    this.gridVisible = false;
    this.gridItems = [];
    this.gridSignature = signature;
    this.gridDismissed = this.read(GRID_DISMISSED_KEY) === signature;
    if (!items.length || this.gridDismissed) return;
    const controller = this.gridLoading = new AbortController();
    void this.view.loadGrid(items, controller.signal).then(loaded => {
      if (controller.signal.aborted) return;
      this.gridItems = loaded;
      this.showGridReady();
    }).catch(() => { /* A failed grid must never block the page or the other dialogs. */ });
  }

  private showGridReady() {
    if (!this.accepted || this.advertisementPending || this.gridVisible || this.gridDismissed || !this.gridItems.length) return;
    this.gridVisible = true;
    this.view.showGrid(this.gridItems);
  }

  dismissGrid() {
    if (!this.gridVisible) return;
    this.gridDismissed = true;
    this.gridVisible = false;
    this.write(GRID_DISMISSED_KEY, this.gridSignature);
    this.view.hideGrid();
  }

  private readProgress() {
    try {
      const progress = JSON.parse(this.read(PROGRESS_KEY));
      const value = Number(progress?.index);
      return progress?.signature === this.signature && Number.isFinite(value) && value >= 0 ? Math.floor(value) : 0;
    } catch {return 0;}
  }

  private async showItem(index: number) {
    const generation = ++this.generation;
    this.loading?.abort();
    this.readyIndex = this.visibleIndex = -1;
    this.index = index;
    if (index >= this.items.length) {this.finish(); return;}
    this.write(PROGRESS_KEY, JSON.stringify({signature: this.signature, index}));
    this.view.prepareAdvertisement();
    const controller = this.loading = new AbortController();
    try {
      await this.view.loadAdvertisement(this.items[index], controller.signal);
      if (controller.signal.aborted || generation !== this.generation) return;
      this.readyIndex = index;
      this.showReady();
    } catch {
      if (!controller.signal.aborted && generation === this.generation) void this.showItem(index + 1);
    }
  }

  private showReady() {
    if (!this.accepted || this.readyIndex < 0 || this.visibleIndex === this.readyIndex) return;
    this.visibleIndex = this.readyIndex;
    this.displayed = true;
    this.view.showAdvertisement(this.items[this.readyIndex]);
  }

  nextAdvertisement() {
    if (!this.accepted || this.visibleIndex < 0) return;
    void this.showItem(this.visibleIndex + 1);
  }

  private finish() {
    if (this.displayed) this.write(DISMISSED_KEY, this.signature); else this.remove(DISMISSED_KEY);
    this.remove(PROGRESS_KEY);
    this.view.hideAdvertisement();
    this.readyIndex = this.visibleIndex = -1;
    this.advertisementPending = false;
    this.showGridReady();
  }
}

export function loadStartupImage(image: HTMLImageElement, source: string, signal: AbortSignal, timeoutMs = 12000): Promise<void> {
  return new Promise((resolve, reject) => {
    let settled = false;
    const timer = setTimeout(() => finish(new Error('广告图片加载超时')), timeoutMs);
    function finish(error?: Error) {
      if (settled) return;
      settled = true;
      clearTimeout(timer);
      image.removeEventListener('load', loaded);
      image.removeEventListener('error', failed);
      signal.removeEventListener('abort', aborted);
      if (error) reject(error); else resolve();
    }
    function loaded() {finish(image.naturalWidth > 0 ? undefined : new Error('广告图片无法解码'));}
    function failed() {finish(new Error('广告图片加载失败'));}
    function aborted() {finish(new DOMException('Aborted', 'AbortError'));}
    function check() {if (image.complete) loaded();}
    image.addEventListener('load', loaded);
    image.addEventListener('error', failed);
    signal.addEventListener('abort', aborted, {once: true});
    if (signal.aborted) {aborted(); return;}
    try {
      if (window.processImage) {
        Promise.resolve(window.processImage(source, image)).then(result => {
          if (!result) finish(new Error('广告图片解码失败')); else check();
        }).catch(error => finish(error instanceof Error ? error : new Error('广告图片解码失败')));
      } else {image.src = source; check();}
    } catch (error) {finish(error instanceof Error ? error : new Error('广告图片加载失败'));}
  });
}

export function startStartupDialogs(): StartupDialogs {
  const age = document.getElementById('startup-age') as HTMLDialogElement;
  const ad = document.getElementById('startup-ad') as HTMLDialogElement;
  const grid = document.getElementById('startup-grid') as HTMLDialogElement;
  const promotions = grid.querySelector<HTMLElement>('.startup-promotions')!;
  let gridLinks = new Map<Advertisement, HTMLAnchorElement>();
  let image = ad.querySelector<HTMLImageElement>('.startup-ad-image')!;
  const media = ad.querySelector<HTMLAnchorElement>('.startup-ad-media')!;
  const loading = ad.querySelector<HTMLElement>('.startup-ad-loading')!;
  const close = ad.querySelector<HTMLButtonElement>('.startup-close')!;
  const view: StartupView = {
    showAge() {if (!age.open) age.showModal();},
    closeAge() {
      const wasOpen = age.open;
      if (wasOpen) age.close();
      document.documentElement.classList.add('eighteen-ok');
      if (wasOpen) document.dispatchEvent(new CustomEvent('eighteen:closed'));
    },
    prepareAdvertisement() {media.hidden = true; loading.hidden = false; close.disabled = true; ad.setAttribute('aria-busy', 'true');},
    async loadAdvertisement(item, signal) {
      const pending = image.cloneNode(false) as HTMLImageElement;
      pending.removeAttribute('src');
      pending.setAttribute('fetchpriority', 'high');
      await loadStartupImage(pending, item.images, signal);
      if (signal.aborted) return;
      image.replaceWith(pending);
      image = pending;
    },
    showAdvertisement(item) {
      image.alt = image.title = item.title?.trim() || '推荐广告';
      media.setAttribute('aria-label', item.title || '查看广告');
      if (item.link) media.href = item.link; else media.removeAttribute('href');
      setAdClickData(media, item.id, item.location);
      media.hidden = false; loading.hidden = true; close.disabled = false;
      ad.removeAttribute('aria-busy');
      ad.setAttribute('aria-label', item.title || '广告推荐');
      if (!ad.open) ad.showModal();
    },
    hideAdvertisement() {if (ad.open) ad.close(); media.hidden = true; loading.hidden = true; ad.removeAttribute('aria-busy');},
    async loadGrid(items, signal) {
      const links = new Map<Advertisement, HTMLAnchorElement>();
      const loaded = await Promise.all(items.map(async item => {
        const link = document.createElement('a');
        link.className = 'startup-promotion';
        link.target = '_blank';
        link.rel = 'sponsored nofollow noopener noreferrer';
        link.setAttribute('aria-label', item.title || '查看推荐应用');
        if (item.link) link.href = item.link;
        setAdClickData(link, item.id, item.location);
        const icon = document.createElement('img');
        icon.width = icon.height = 80;
        icon.alt = item.title || '推荐应用';
        icon.decoding = 'async';
        const name = document.createElement('span');
        name.textContent = item.title || '推荐应用';
        link.append(icon, name);
        try {
          await loadStartupImage(icon, item.images, signal);
          links.set(item, link);
          return item;
        } catch {return null;}
      }));
      if (signal.aborted) return [];
      gridLinks = links;
      return loaded.filter((item): item is Advertisement => item !== null);
    },
    showGrid(items) {
      promotions.replaceChildren(...items.map(item => gridLinks.get(item)!));
      promotions.scrollTop = 0;
      if (!grid.open) grid.showModal();
    },
    hideGrid() {if (grid.open) grid.close();},
  };
  const storage: SessionStore = {
    getItem: key => window.sessionStorage.getItem(key),
    setItem: (key, value) => window.sessionStorage.setItem(key, value),
    removeItem: key => window.sessionStorage.removeItem(key),
  };
  const startup = new StartupDialogs(storage, view, document.documentElement.classList.contains('eighteen-ok'));
  age.addEventListener('cancel', event => event.preventDefault());
  age.querySelector('.startup-age-confirm')!.addEventListener('click', () => startup.confirmAge());
  age.querySelectorAll('.startup-age-leave,.startup-close').forEach(button => button.addEventListener('click', () => location.assign('https://www.google.com')));
  function nextAdvertisement() {startup.nextAdvertisement();}
  close.addEventListener('click', nextAdvertisement);
  ad.addEventListener('cancel', event => {event.preventDefault(); nextAdvertisement();});
  grid.querySelector('.startup-close')!.addEventListener('click', () => startup.dismissGrid());
  grid.addEventListener('cancel', event => {event.preventDefault(); startup.dismissGrid();});
  promotions.addEventListener('click', event => {
    const target = event.target instanceof Element ? event.target : null;
    if (target?.closest('.startup-promotion[href]')) startup.dismissGrid();
  });
  [age, ad, grid].forEach(dialog => {
    dialog.addEventListener('keydown', event => {if (event.key === 'Tab') dialog.classList.add('startup-keyboard-focus');});
    dialog.addEventListener('pointerdown', () => dialog.classList.remove('startup-keyboard-focus'));
    dialog.addEventListener('close', () => dialog.classList.remove('startup-keyboard-focus'));
  });
  return startup;
}