import { useEffect, useRef } from "react";
import { api } from "../api";
import { FeedbackBanner, FreshnessBanner, LoadingState } from "../components/Feedback";
import { useAudioAnnouncements } from "../hooks/useAudioAnnouncements";
import { usePollingResource } from "../hooks/usePollingResource";
import { formatCallAnnouncement, isTimestampStale } from "../lib/format";
import type { CallBatchDto } from "../types";
import { DisplayCenter } from "./AdminPage";

function projectCurrentBatch(value: unknown): CallBatchDto | null {
  return value && typeof value === "object" ? value as CallBatchDto : null;
}

export function PublicDisplayCenterPage() {
  const { announce, audioRef } = useAudioAnnouncements();
  const resource = usePollingResource((signal) => api.displayOverview(signal), { intervalMs: 5_000 });
  const data = resource.data;
  const stale = Boolean(data) && isTimestampStale(resource.lastClientSuccessAt, 30_000);
  const lastCallsRef = useRef<Map<string, string | null> | null>(null);
  useEffect(() => {
    if (!data) return;
    const previousCalls = lastCallsRef.current;
    const nextCalls = new Map<string, string | null>();
    const announcements: string[] = [];
    for (const project of data.projects) {
      const batch = projectCurrentBatch(project.current_batch);
      const key = batch ? `${batch.batch_number}:${batch.called_at ?? ""}` : null;
      nextCalls.set(project.id, key);
      if (!previousCalls?.has(project.id) || !key || previousCalls.get(project.id) === key) continue;
      const announcement = formatCallAnnouncement(batch);
      if (announcement) announcements.push(announcement);
    }
    lastCallsRef.current = nextCalls;
    announce(announcements);
  }, [announce, data]);

  return (
    <div className="app-shell app-shell--admin app-shell--no-primary-action">
      <a className="skip-link" href="#main-content">跳到主要内容</a>
      <audio ref={audioRef} preload="auto" aria-hidden="true" />
      <header className="app-header">
        <div className="brand-lockup" aria-label="景区排队叫号系统">
          <span className="brand-logo-frame" aria-hidden="true"><img className="brand-logo" src="/xiaoqikong-logo.jpg" alt="" /></span>
          <span className="brand-lockup__text"><strong>景区排队叫号系统</strong></span>
        </div>
        <div className="account-menu"><span><strong>大屏中心</strong></span></div>
      </header>
      <main id="main-content" className="app-main">
        <section className="admin-content" aria-label="公开大屏内容">
          {resource.loading && !data ? <LoadingState label="正在汇总项目状态" /> : null}
          {resource.error && !data ? (
            <FeedbackBanner tone="danger" title="大屏数据暂时不可用" action={<button className="button button--secondary button--small" onClick={resource.refresh}>重试</button>}>
              {resource.error.message}
            </FeedbackBanner>
          ) : null}
          {data ? (
            <>
              <FreshnessBanner offline={resource.offline} stale={stale} timestamp={resource.lastClientSuccessAt} refreshing={resource.refreshing} errorMessage={resource.error?.message} onRetry={resource.refresh} />
              <DisplayCenter projects={data.projects} />
            </>
          ) : null}
        </section>
      </main>
    </div>
  );
}
