"use client";

import * as React from "react";
import { motion } from "framer-motion";
import { CalendarDays, Compass, Sparkles, User } from "lucide-react";

import { api, bytes, type Discover as DiscoverData, type Recap } from "@/lib/api";
import { Skeletons } from "@/components/skeletons";

/**
 * Recommendations and a personal recap, both derived from muse's OWN request
 * history plus Deezer's related-artists graph.
 *
 * Deliberately not built on listening data: Navidrome owns play counts,
 * favourites and history, and a second source of truth for those would
 * disagree with the one the user actually listens through.
 */
export function DiscoverPanel({ onArtist }: { onArtist: (name: string) => void }) {
  const [d, setD] = React.useState<DiscoverData | null>(null);
  const [r, setR] = React.useState<Recap | null>(null);

  React.useEffect(() => {
    api.discover().then(setD).catch(() => setD({ seeds: [], artists: [] }));
    api.recap().then(setR).catch(() => undefined);
  }, []);

  if (!d) return <Skeletons n={4} />;

  const empty = d.artists.length === 0 && (!r || r.tracks === 0);
  if (empty)
    return (
      <motion.div
        initial={{ opacity: 0, y: 10 }}
        animate={{ opacity: 1, y: 0 }}
        className="px-5 py-16 text-center"
      >
        <div
          className="mx-auto mb-4 grid h-14 w-14 place-items-center rounded-[18px]
                     border border-accent-line bg-accent-soft text-accent"
        >
          <Compass className="h-6 w-6" />
        </div>
        <h2 className="text-title">Nothing to go on yet</h2>
        <p className="mx-auto mt-1.5 max-w-[46ch] text-callout text-dim">
          Recommendations are built from what you&rsquo;ve actually added. Request a few
          tracks and this fills in.
        </p>
      </motion.div>
    );

  return (
    <div className="flex flex-col gap-5">
      {r && r.tracks > 0 && <RecapPanel r={r} />}

      {d.artists.length > 0 && (
        <section>
          <SectionHead
            icon={<Sparkles className="h-3.5 w-3.5" />}
            title="Because you added"
            sub={d.seeds.slice(0, 3).join(" · ")}
          />
          <div className="grid grid-cols-2 gap-2.5 sm:grid-cols-3 lg:grid-cols-6">
            {d.artists.map((a, i) => (
              <motion.button
                key={a.id}
                initial={{ opacity: 0, y: 10 }}
                animate={{ opacity: 1, y: 0 }}
                transition={{ delay: Math.min(i * 0.03, 0.3) }}
                onClick={() => onArtist(a.name)}
                className="glass lift ring group cursor-pointer rounded-panel p-3 text-center"
              >
                {a.picture ? (
                  /* eslint-disable-next-line @next/next/no-img-element */
                  <img
                    src={a.picture}
                    alt=""
                    className="mx-auto mb-2.5 h-20 w-20 rounded-full border border-edge object-cover"
                  />
                ) : (
                  <div className="mx-auto mb-2.5 grid h-20 w-20 place-items-center rounded-full bg-faint text-dim">
                    <User className="h-7 w-7" />
                  </div>
                )}
                <div className="text-callout font-semibold clamp1">{a.name}</div>
                {a.fans ? (
                  <div className="text-caption text-dim nums">
                    {a.fans.toLocaleString()} fans
                  </div>
                ) : null}
              </motion.button>
            ))}
          </div>
        </section>
      )}
    </div>
  );
}

function RecapPanel({ r }: { r: Recap }) {
  const maxDecade = Math.max(1, ...r.decades.map((d) => d.n));
  return (
    <section>
      <SectionHead
        icon={<CalendarDays className="h-3.5 w-3.5" />}
        title="Your year in muse"
        sub={`${r.tracks} tracks · ${bytes(r.bytes)}`}
      />
      <div className="grid gap-2.5 md:grid-cols-3">
        <Card title="Most requested">
          {r.artists.slice(0, 5).map((a, i) => (
            <Row key={a.name} i={i} label={a.name} n={a.n} />
          ))}
        </Card>
        <Card title="Genres">
          {r.genres.slice(0, 5).map((g, i) => (
            <Row key={g.name} i={i} label={g.name} n={g.n} />
          ))}
          {r.genres.length === 0 && <Muted>No genre data yet.</Muted>}
        </Card>
        <Card title="Decades">
          {r.decades.length === 0 && <Muted>No release years yet.</Muted>}
          {r.decades.map((d, i) => (
            <motion.div
              key={d.decade}
              initial={{ opacity: 0, x: -6 }}
              animate={{ opacity: 1, x: 0 }}
              transition={{ delay: i * 0.04 }}
              className="flex items-center gap-2.5"
            >
              <span className="w-12 shrink-0 text-callout text-dim nums">{d.decade}</span>
              <div className="h-1.5 flex-1 overflow-hidden rounded-pill bg-faint">
                <motion.i
                  className="block h-full rounded-pill bg-accent"
                  initial={{ width: 0 }}
                  animate={{ width: `${(d.n / maxDecade) * 100}%` }}
                  transition={{ delay: i * 0.04, duration: 0.5, ease: "easeOut" }}
                />
              </div>
              <span className="w-6 shrink-0 text-right text-caption text-dim nums">
                {d.n}
              </span>
            </motion.div>
          ))}
          {r.busiest_day && (
            <div className="mt-1 border-t border-edge pt-2 text-caption text-dim">
              Busiest day {r.busiest_day.date} — {r.busiest_day.n} tracks
            </div>
          )}
        </Card>
      </div>
    </section>
  );
}

function SectionHead({
  icon,
  title,
  sub,
}: {
  icon: React.ReactNode;
  title: string;
  sub?: string;
}) {
  return (
    <div className="mb-2.5 flex items-baseline gap-2">
      <span className="translate-y-[1px] text-accent">{icon}</span>
      <h2 className="text-headline">{title}</h2>
      {sub && <span className="text-caption text-dim clamp1">{sub}</span>}
    </div>
  );
}

function Card({ title, children }: { title: string; children: React.ReactNode }) {
  return (
    <motion.div
      initial={{ opacity: 0, y: 10 }}
      animate={{ opacity: 1, y: 0 }}
      className="glass rounded-panel p-4"
    >
      <h3 className="mb-2.5 text-caption font-bold uppercase tracking-[0.9px] text-dim">
        {title}
      </h3>
      <div className="flex flex-col gap-2">{children}</div>
    </motion.div>
  );
}

function Row({ i, label, n }: { i: number; label: string; n: number }) {
  return (
    <motion.div
      initial={{ opacity: 0, x: -6 }}
      animate={{ opacity: 1, x: 0 }}
      transition={{ delay: i * 0.04 }}
      className="flex items-center gap-2"
    >
      <span
        className="grid h-5 w-5 shrink-0 place-items-center rounded-md bg-faint
                   text-caption text-dim nums"
      >
        {i + 1}
      </span>
      <span className="min-w-0 flex-1 text-callout clamp1">{label}</span>
      <span className="text-caption text-dim nums">{n}</span>
    </motion.div>
  );
}

function Muted({ children }: { children: React.ReactNode }) {
  return <span className="text-callout text-dim">{children}</span>;
}