'use client';

import { AnimatePresence, motion } from 'motion/react';
import Link from 'next/link';
import useSWR from 'swr';
import { sortFeed, type FeedItemDTO, type FollowListDTO, type ProfileDTO } from '@musicshare/shared';
import { Avatar } from '@/components/Avatar';
import { Equalizer } from '@/components/Equalizer';
import { NowPlayingCard } from '@/components/NowPlayingCard';
import { SharingControls } from '@/components/SharingControls';
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/${me.username}` : null, fetcher);
  // Everyone you follow; the feed only has the ones who've played something.
  const { data: following } = useSWR<FollowListDTO>(me ? `/users/${me.username}/following` : null, fetcher);
  const inFeed = new Set(feed?.map((n) => n.user.id));
  const quiet = following?.users.filter((u) => !inFeed.has(u.id)) ?? [];

  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">
      <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 &&
        (following?.users.length ? (
          <p className="muted">Nobody you follow has played anything yet. Their music will show up here live.</p>
        ) : (
          <p className="muted">Nothing yet. <Link href="/friends">Find friends</Link>, and their music will show up here live.</p>
        ))}
      {/* Cards rise in on load and glide to new positions when someone pins or starts playing. */}
      <AnimatePresence initial={true}>
        {feed?.map((np, i) => (
          <motion.div
            key={np.user.id}
            layout
            initial={{ opacity: 0, y: 24, scale: 0.98 }}
            animate={{ opacity: 1, y: 0, scale: 1 }}
            exit={{ opacity: 0, scale: 0.96 }}
            transition={{ type: 'spring', stiffness: 380, damping: 32, delay: Math.min(i, 8) * 0.05 }}
          >
            <NowPlayingCard
              np={np}
              preferred={me?.preferredService}
              pinned={Boolean(np.pinnedAt)}
              onTogglePin={() => togglePin(np)}
            />
          </motion.div>
        ))}
      </AnimatePresence>

      {quiet.length > 0 && (
        <section className="stack">
          <h2 className="section-label">Following · nothing played yet</h2>
          <div className="card quiet-list">
            {quiet.map((u) => (
              <Link key={u.id} href={`/u/${u.username}`} className="quiet-person" title={`@${u.username}`}>
                <Avatar user={u} size={44} />
                <span>{u.displayName ?? u.username}</span>
              </Link>
            ))}
            {following?.nextCursor && me && (
              <Link href={`/u/${me.username}/following`} className="quiet-person quiet-more">
                See all
              </Link>
            )}
          </div>
        </section>
      )}
    </div>
  );
}

function Landing() {
  return (
    <motion.section
      className="hero"
      initial={{ opacity: 0, y: 20 }}
      animate={{ opacity: 1, y: 0 }}
      transition={{ duration: 0.6, ease: [0.22, 1, 0.36, 1] }}
    >
      <Equalizer playing />
      <h1>
        See what your friends are <span className="gradient-text">playing.</span>
      </h1>
      <p>
        Share what you play on Spotify, Apple Music, YouTube Music, Plex 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>
    </motion.section>
  );
}