'use client';

import Link from 'next/link';
import useSWR from 'swr';
import { sortFeed, type FeedItemDTO, type ProfileDTO } from '@musicshare/shared';
import { NowPlayingCard } from '@/components/NowPlayingCard';
import { SharingControls } from '@/components/SharingControls';
import { UserSearch } from '@/components/UserSearch';
import { api, fetcher, useMe } from '@/lib/api';
import { useRealtime } from '@/lib/useRealtime';

export default function Home() {
  const { me, isLoading, loggedOut } = useMe();
  if (isLoading) return null;
  if (loggedOut || !me) return <Landing />;
  return <Feed />;
}

function Feed() {
  const { me } = useMe();
  const { data: feed, mutate } = useSWR<FeedItemDTO[]>('/feed', fetcher);
  // Your own profile, for the "You" card. Loading it also marks you as watched, so your updates arrive quickly.
  const { data: mine, mutate: mutateMine } = useSWR<ProfileDTO>(me ? `/users/${me.username}` : null, fetcher);

  useRealtime(true, (msg) => {
    if (msg.type !== 'now_playing') return;
    if (msg.data.user.id === me?.id) {
      if (mine) mutateMine({ ...mine, nowPlaying: msg.data }, { revalidate: false });
      return;
    }
    mutate(
      (current = []) => {
        const existing = current.find((n) => n.user.id === msg.data.user.id);
        const item = { ...msg.data, pinnedAt: existing?.pinnedAt ?? null };
        return sortFeed([item, ...current.filter((n) => n.user.id !== msg.data.user.id)]);
      },
      { revalidate: false },
    );
  });

  const togglePin = async (item: FeedItemDTO) => {
    const pinnedAt = item.pinnedAt ? null : new Date().toISOString();
    // optimistic: reorder immediately, roll back if the server refuses (e.g. pin limit)
    const previous = feed;
    mutate(sortFeed((feed ?? []).map((n) => (n.user.id === item.user.id ? { ...n, pinnedAt } : n))), { revalidate: false });
    try {
      await api(`/users/${item.user.username}/pin`, { method: pinnedAt ? 'PUT' : 'DELETE', body: pinnedAt ? {} : undefined });
    } catch (err) {
      mutate(previous, { revalidate: false });
      alert((err as Error).message);
    }
  };

  return (
    <div className="stack">
      <UserSearch />
      <SharingControls compact />
      {mine?.nowPlaying && (
        <section className="stack">
          <h2 className="section-label">You</h2>
          <NowPlayingCard np={mine.nowPlaying} preferred={me?.preferredService} showUser={false} />
        </section>
      )}
      <h1>Friends listening</h1>
      {!me?.preferredService && (
        <p className="notice">
          Pick your streaming service in <Link href="/settings">Settings</Link> so songs open in the right app.
        </p>
      )}
      {feed?.length === 0 && (
        <p className="muted">Nothing yet. Follow some friends and their music will show up here live.</p>
      )}
      {feed?.map((np) => (
        <NowPlayingCard
          key={np.user.id}
          np={np}
          preferred={me?.preferredService}
          pinned={Boolean(np.pinnedAt)}
          onTogglePin={() => togglePin(np)}
        />
      ))}
    </div>
  );
}

function Landing() {
  return (
    <section className="hero">
      <h1>See what your friends are playing.</h1>
      <p>
        Connect Spotify, Last.fm, ListenBrainz and more. When a friend on Apple Music is playing something you like,
        one tap opens it in your app.
      </p>
      <div className="row">
        <Link href="/register" className="btn btn-primary">
          Create account
        </Link>
        <Link href="/login" className="btn">
          Log in
        </Link>
      </div>
    </section>
  );
}