"use client";

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

type Props = {
  images: string[];
  title?: string;
  autoPlay?: boolean;
  intervalMs?: number;
};

export default function GalleryCarousel({
  images,
  title = "Gallery",
  autoPlay = true,
  intervalMs = 4500,
}: Props) {
  const containerRef = useRef<HTMLDivElement | null>(null);
  const itemRefs = useRef<(HTMLButtonElement | null)[]>([]);
  const [active, setActive] = useState(0);
  const [paused, setPaused] = useState(false);

  const safeImages = useMemo(() => images.filter(Boolean), [images]);

  function clampIndex(i: number) {
    const n = safeImages.length;
    if (n === 0) return 0;
    return (i + n) % n;
  }

  function scrollToIndex(i: number) {
  const idx = clampIndex(i);
  setActive(idx);

  const track = containerRef.current;
  const el = itemRefs.current[idx];
  if (!track || !el) return;

  const trackRect = track.getBoundingClientRect();
  const elRect = el.getBoundingClientRect();

  const target =
    track.scrollLeft +
    (elRect.left + elRect.width / 2) -
    (trackRect.left + trackRect.width / 2);

  track.scrollTo({ left: target, behavior: "smooth" });
}


  // Auto-advance
  useEffect(() => {
    if (!autoPlay || paused || safeImages.length <= 1) return;
    const t = setInterval(() => scrollToIndex(active + 1), intervalMs);
    return () => clearInterval(t);
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [autoPlay, paused, active, intervalMs, safeImages.length]);

  // Keep active in sync when user swipes/scrolls
  useEffect(() => {
    const el = containerRef.current;
    if (!el || safeImages.length <= 1) return;

    let raf = 0;

    const onScroll = () => {
      cancelAnimationFrame(raf);
      raf = requestAnimationFrame(() => {
        const rect = el.getBoundingClientRect();
        const centerX = rect.left + rect.width / 2;

        let bestIdx = active;
        let bestDist = Number.POSITIVE_INFINITY;

        for (let i = 0; i < safeImages.length; i++) {
          const item = itemRefs.current[i];
          if (!item) continue;
          const r = item.getBoundingClientRect();
          const itemCenter = r.left + r.width / 2;
          const d = Math.abs(itemCenter - centerX);
          if (d < bestDist) {
            bestDist = d;
            bestIdx = i;
          }
        }

        if (bestIdx !== active) setActive(bestIdx);
      });
    };

    el.addEventListener("scroll", onScroll, { passive: true });
    return () => {
      el.removeEventListener("scroll", onScroll);
      cancelAnimationFrame(raf);
    };
  }, [active, safeImages.length]);

  if (safeImages.length === 0) return null;

  return (
    <section className="mt-10">
      <div className="flex items-center justify-between gap-4">
        <h2 className="text-xl font-semibold tracking-tight text-black/90">
          {title}
        </h2>

        <div className="flex items-center gap-2">
          <button
            type="button"
            onClick={() => scrollToIndex(active - 1)}
            className="rounded-full border border-black/10 bg-white/70 px-3 py-2 text-sm text-black/70 hover:text-black hover:border-black/25 transition"
            aria-label="Previous"
          >
            ←
          </button>
          <button
            type="button"
            onClick={() => scrollToIndex(active + 1)}
            className="rounded-full border border-black/10 bg-white/70 px-3 py-2 text-sm text-black/70 hover:text-black hover:border-black/25 transition"
            aria-label="Next"
          >
            →
          </button>
        </div>
      </div>

      {/* Track */}
      <div
        ref={containerRef}
        onMouseEnter={() => setPaused(true)}
        onMouseLeave={() => setPaused(false)}
        className="mt-4 flex w-full max-w-full gap-4 overflow-x-auto overflow-y-hidden overscroll-x-contain pb-3 scrollbar-hide px-2"
        style={{ scrollSnapType: "x mandatory" }}
      >
        {safeImages.map((img, i) => (
          <button
            key={`${img}-${i}`}
            ref={(el) => {
              itemRefs.current[i] = el;
            }}
            type="button"
            onClick={() => scrollToIndex(i)}
            className={[
              "relative shrink-0 rounded-3xl glass-strong specular overflow-hidden",
              "min-w-[320px] md:min-w-[520px] h-[220px] md:h-[320px]",
              "transition will-change-transform",
              "focus:outline-none focus:ring-2 focus:ring-black/20",
              i === active ? "scale-[1.00]" : "scale-[0.97] opacity-90 hover:opacity-100",
            ].join(" ")}
            style={{ scrollSnapAlign: "center" }}
            aria-label={`Select image ${i + 1}`}
          >
            <Image
              src={img}
              alt={`Gallery image ${i + 1}`}
              fill
              className="object-cover"
              priority={i === 0}
            />
            <div className="absolute inset-0 bg-gradient-to-t from-black/10 to-transparent pointer-events-none" />
          </button>
        ))}
      </div>

      {/* Dots */}
      {safeImages.length > 1 && (
        <div className="mt-3 flex items-center justify-center gap-2">
          {safeImages.map((_, i) => (
            <button
              key={i}
              type="button"
              onClick={() => scrollToIndex(i)}
              className={[
                "h-2.5 w-2.5 rounded-full transition",
                i === active ? "bg-black/50" : "bg-black/15 hover:bg-black/30",
              ].join(" ")}
              aria-label={`Go to slide ${i + 1}`}
            />
          ))}
        </div>
      )}
    </section>
  );
}