import React, { useEffect, useRef, useState } from 'react';
import { useNavigate } from 'react-router-dom';
import { useTranslation } from 'react-i18next';
import {
  Headphones, Zap, Music2, Music, Cpu, Mic, Radio, Cloud,
  Leaf, Heart, Sun, Flame, Film, Globe, BookOpen, Podcast, Star,
  Tags, type LucideIcon,
} from 'lucide-react';
import { getGenres, SubsonicGenre } from '../api/subsonic';
import { useAuthStore } from '../store/authStore';

function getGenreIcon(name: string): LucideIcon {
  const n = name.toLowerCase();
  if (/ambient|drone|new age/.test(n)) return Cloud;
  if (/metal|hardcore|thrash|death|grind|doom/.test(n)) return Zap;
  if (/rock/.test(n)) return Radio;
  if (/jazz/.test(n)) return Music2;
  if (/classical|orchestra|chamber|baroque|opera|symphon/.test(n)) return Music;
  if (/electronic|techno|edm|house|trance|electro|synth/.test(n)) return Cpu;
  if (/hip.?hop|rap/.test(n)) return Mic;
  if (/pop/.test(n)) return Star;
  if (/folk|country|bluegrass|americana/.test(n)) return Leaf;
  if (/blues/.test(n)) return Music2;
  if (/soul|r.?b|funk|gospel/.test(n)) return Heart;
  if (/reggae|ska|dub/.test(n)) return Sun;
  if (/punk/.test(n)) return Flame;
  if (/soundtrack|score|ost|film|movie|cinema/.test(n)) return Film;
  if (/world|latin|afro|celtic|tribal|traditional/.test(n)) return Globe;
  if (/audiobook|spoken|hörbuch|speech|comedy/.test(n)) return BookOpen;
  if (/podcast/.test(n)) return Podcast;
  return Headphones;
}

const CTP_COLORS = [
  'var(--ctp-rosewater)', 'var(--ctp-flamingo)', 'var(--ctp-pink)', 'var(--ctp-mauve)',
  'var(--ctp-red)', 'var(--ctp-maroon)', 'var(--ctp-peach)', 'var(--ctp-yellow)',
  'var(--ctp-green)', 'var(--ctp-teal)', 'var(--ctp-sky)', 'var(--ctp-sapphire)',
  'var(--ctp-blue)', 'var(--ctp-lavender)',
];

function genreColor(name: string): string {
  let h = 0;
  for (let i = 0; i < name.length; i++) h = (h * 31 + name.charCodeAt(i)) >>> 0;
  return CTP_COLORS[h % CTP_COLORS.length];
}

const SCROLL_KEY = 'genres-scroll';

export default function Genres() {
  const { t } = useTranslation();
  const navigate = useNavigate();
  const [genres, setGenres] = useState<SubsonicGenre[]>([]);
  const [loading, setLoading] = useState(true);
  const containerRef = useRef<HTMLDivElement>(null);

  useEffect(() => {
    getGenres()
      .then(data => {
        const sorted = [...data].sort((a, b) => b.albumCount - a.albumCount);
        setGenres(sorted);
      })
      .finally(() => setLoading(false));
  }, []); // getGenres is not folder-scoped — no dep on musicLibraryFilterVersion

  // Restore scroll position after genres are rendered
  useEffect(() => {
    if (loading || genres.length === 0) return;
    const saved = sessionStorage.getItem(SCROLL_KEY);
    if (!saved) return;
    const pos = parseInt(saved, 10);
    sessionStorage.removeItem(SCROLL_KEY);
    requestAnimationFrame(() => {
      if (containerRef.current) containerRef.current.scrollTop = pos;
    });
  }, [loading, genres.length]);

  const handleGenreClick = (genreValue: string) => {
    if (containerRef.current) {
      sessionStorage.setItem(SCROLL_KEY, String(containerRef.current.scrollTop));
    }
    navigate(`/genres/${encodeURIComponent(genreValue)}`);
  };

  return (
    <div ref={containerRef} className="content-body animate-fade-in">
      <div style={{ display: 'flex', alignItems: 'center', gap: '1rem', marginBottom: '1.5rem', flexWrap: 'wrap' }}>
        <h1 className="page-title" style={{ marginBottom: 0 }}>{t('genres.title')}</h1>
        {!loading && genres.length > 0 && (
          <span style={{ display: 'flex', alignItems: 'center', gap: '0.4rem', color: 'var(--text-secondary)', fontSize: '0.9rem', fontWeight: 500 }}>
            <Tags size={14} style={{ color: 'var(--accent)' }} />
            {genres.length} {t('genres.genreCount')}
          </span>
        )}
      </div>

      {loading && <p className="loading-text">{t('genres.loading')}</p>}
      {!loading && genres.length === 0 && <p className="loading-text">{t('genres.empty')}</p>}

      {!loading && genres.length > 0 && (
        <div className="album-grid-wrap">
          {genres.map(genre => {
            const Icon = getGenreIcon(genre.value);
            const color = genreColor(genre.value);
            return (
              <div
                key={genre.value}
                className="genre-card"
                style={{ '--genre-color': color } as React.CSSProperties}
                onClick={() => handleGenreClick(genre.value)}
                role="button"
                tabIndex={0}
                onKeyDown={e => e.key === 'Enter' && handleGenreClick(genre.value)}
                data-tooltip={genre.value}
              >
                <div className="genre-card-watermark">
                  <Icon size={80} strokeWidth={1.2} />
                </div>
                <p className="genre-card-name">{genre.value}</p>
                <p className="genre-card-count">
                  {t('genres.albumCount', { count: genre.albumCount })}
                </p>
              </div>
            );
          })}
        </div>
      )}
    </div>
  );
}