"use client";

import Image from "next/image";
import { useEffect, useRef, useState } from "react";

export function Gallery({ images, alt }: { images: string[]; alt: string }) {
  const [open, setOpen] = useState<number | null>(null);
  const touchStartX = useRef<number | null>(null);
  const thumbsRef = useRef<HTMLDivElement>(null);

  // Keyboard + scroll lock
  useEffect(() => {
    if (open === null) return;
    const prev = document.body.style.overflow;
    document.body.style.overflow = "hidden";

    const onKey = (e: KeyboardEvent) => {
      if (e.key === "Escape") setOpen(null);
      if (e.key === "ArrowRight") setOpen((i) => (i === null ? null : (i + 1) % images.length));
      if (e.key === "ArrowLeft")  setOpen((i) => (i === null ? null : (i - 1 + images.length) % images.length));
    };
    window.addEventListener("keydown", onKey);
    return () => {
      window.removeEventListener("keydown", onKey);
      document.body.style.overflow = prev;
    };
  }, [open, images.length]);

  // Scroll active thumbnail into view
  useEffect(() => {
    if (open === null || !thumbsRef.current) return;
    const btn = thumbsRef.current.children[open] as HTMLElement | undefined;
    btn?.scrollIntoView({ block: "nearest", inline: "center", behavior: "smooth" });
  }, [open]);

  if (images.length === 0) return null;
  const [hero, ...rest] = images;

  const go = (dir: 1 | -1) =>
    setOpen((i) => (i === null ? null : (i + dir + images.length) % images.length));

  return (
    <>
      {/* Grid */}
      <div className="grid md:grid-cols-5 gap-2 md:gap-3">
        <button
          onClick={() => setOpen(0)}
          className="md:col-span-3 relative aspect-[4/3] overflow-hidden rounded-sm group"
        >
          <Image
            src={hero}
            alt={`${alt} — Ansicht 1`}
            fill
            priority
            sizes="(max-width: 768px) 100vw, 60vw"
            className="object-cover transition-transform duration-700 group-hover:scale-[1.02]"
          />
          <div className="absolute inset-0 flex items-center justify-center opacity-0 group-hover:opacity-100 transition-opacity duration-300">
            <span className="bg-ink/70 text-parchment text-xs px-3 py-1.5 rounded-full backdrop-blur-sm">
              Alle {images.length} Fotos
            </span>
          </div>
        </button>

        <div className="md:col-span-2 grid grid-cols-2 gap-2 md:gap-3">
          {rest.slice(0, 4).map((src, idx) => (
            <button
              key={src}
              onClick={() => setOpen(idx + 1)}
              className="relative aspect-[4/3] overflow-hidden rounded-sm group"
            >
              <Image
                src={src}
                alt={`${alt} — Ansicht ${idx + 2}`}
                fill
                sizes="(max-width: 768px) 50vw, 25vw"
                className="object-cover transition-transform duration-700 group-hover:scale-[1.03]"
              />
              {idx === 3 && images.length > 5 && (
                <div className="absolute inset-0 bg-ink/55 text-parchment flex items-center justify-center text-sm font-medium">
                  +{images.length - 5}
                </div>
              )}
            </button>
          ))}
        </div>
      </div>

      {/* Lightbox */}
      {open !== null && (
        <div
          className="fixed inset-0 z-50 bg-ink/95 flex flex-col"
          onClick={() => setOpen(null)}
          role="dialog"
          aria-modal="true"
          onTouchStart={(e) => { touchStartX.current = e.touches[0].clientX; }}
          onTouchEnd={(e) => {
            if (touchStartX.current === null) return;
            const dx = e.changedTouches[0].clientX - (touchStartX.current as number);
            if (Math.abs(dx) > 50) go(dx < 0 ? 1 : -1);
            touchStartX.current = null;
          }}
        >
          {/* Top bar */}
          <div className="shrink-0 flex items-center justify-between px-5 py-4" onClick={(e) => e.stopPropagation()}>
            <span className="text-parchment/50 text-sm tabular-nums">{open + 1} / {images.length}</span>
            <button
              onClick={() => setOpen(null)}
              className="text-parchment/70 hover:text-parchment transition-colors text-xl leading-none px-2 py-1"
              aria-label="Galerie schließen"
            >
              ✕
            </button>
          </div>

          {/* Image */}
          <div
            className="flex-1 flex items-center justify-center relative px-14 md:px-20 min-h-0"
            onClick={(e) => e.stopPropagation()}
          >
            <button
              onClick={(e) => { e.stopPropagation(); go(-1); }}
              className="absolute left-2 md:left-4 top-1/2 -translate-y-1/2 text-parchment/60 hover:text-parchment text-5xl px-3 py-4 transition-colors select-none z-10"
              aria-label="Vorheriges Bild"
            >‹</button>

            <div className="relative w-full max-w-5xl aspect-[4/3]">
              <Image
                key={open}
                src={images[open]}
                alt={`${alt} — Ansicht ${open + 1}`}
                fill
                sizes="90vw"
                className="object-contain"
              />
            </div>

            <button
              onClick={(e) => { e.stopPropagation(); go(1); }}
              className="absolute right-2 md:right-4 top-1/2 -translate-y-1/2 text-parchment/60 hover:text-parchment text-5xl px-3 py-4 transition-colors select-none z-10"
              aria-label="Nächstes Bild"
            >›</button>
          </div>

          {/* Thumbnail strip */}
          <div
            className="shrink-0 py-3 px-4"
            onClick={(e) => e.stopPropagation()}
          >
            <div ref={thumbsRef} className="flex gap-2 overflow-x-auto" style={{ scrollbarWidth: "none" }}>
              {images.map((src, idx) => (
                <button
                  key={src}
                  onClick={() => setOpen(idx)}
                  className={`relative shrink-0 w-14 h-10 rounded overflow-hidden transition-all duration-200 ${
                    idx === open ? "ring-2 ring-parchment opacity-100" : "opacity-35 hover:opacity-65"
                  }`}
                >
                  <Image src={src} alt="" fill sizes="56px" className="object-cover" />
                </button>
              ))}
            </div>
          </div>
        </div>
      )}
    </>
  );
}