// apps/dm/app/(landing)/reuse/_components/ImageSlider.tsx
"use client";

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

type Slide = { src: string; alt?: string };

type Props = {
  slides: Slide[];
  className?: string;
  maxWidthClassName?: string; // 예: "max-w-[760px]"
};

export default function CaseImageSlider({
  slides,
  className = "",
  maxWidthClassName = "max-w-[760px]",
}: Props) {
  const safeSlides = useMemo(() => slides.filter(Boolean), [slides]);
  const [idx, setIdx] = useState(0);
  const [dragging, setDragging] = useState(false);

  const startX = useRef(0);
  const deltaX = useRef(0);

  const total = safeSlides.length;
  const canSlide = total > 1;

  const go = (dir: number) => {
    if (!canSlide) return;
    setIdx((prev) => {
      const next = prev + dir;
      if (next < 0) return total - 1;
      if (next >= total) return 0;
      return next;
    });
  };

  // ← → 키보드 지원(선택)
  useEffect(() => {
    const onKey = (e: KeyboardEvent) => {
      if (!canSlide) return;
      if (e.key === "ArrowLeft") go(-1);
      if (e.key === "ArrowRight") go(1);
    };
    window.addEventListener("keydown", onKey);
    return () => window.removeEventListener("keydown", onKey);
  }, [canSlide, total]);

  // 드래그(마우스/터치)로 넘기기
  const onPointerDown = (e: React.PointerEvent) => {
    if (!canSlide) return;
    setDragging(true);
    startX.current = e.clientX;
    deltaX.current = 0;
    (e.currentTarget as HTMLElement).setPointerCapture(e.pointerId);
  };

  const onPointerMove = (e: React.PointerEvent) => {
    if (!dragging) return;
    deltaX.current = e.clientX - startX.current;
  };

  const onPointerUp = () => {
    if (!dragging) return;
    setDragging(false);

    const threshold = 60; // 넘김 감도
    if (deltaX.current > threshold) go(-1);
    else if (deltaX.current < -threshold) go(1);

    deltaX.current = 0;
  };

  if (!total) return null;

  return (
    <section className={className}>
      <div className={`mx-auto ${maxWidthClassName}`}>
        <div className="relative">
          {/* 좌측 버튼 */}
          <button
            type="button"
            onClick={() => go(-1)}
            className="absolute left-[-60px] top-1/2 -translate-y-1/2 z-10
                        w-[80px] h-[80px] rounded-full border border-black/20 bg-white
                        grid place-items-center shadow-sm hover:bg-black/[0.03]"
            >
            <Image
              src="/images/landing/icon_left_arrow.png"
              alt="이전"
              width={12}
              height={22}
              className="w-[12px] h-[22px]"
            />
          </button>


          {/* 우측 버튼 */}
          <button
            type="button"
            onClick={() => go(1)}
            className="absolute right-[-60px] top-1/2 -translate-y-1/2 z-10
                        w-[80px] h-[80px] rounded-full border border-black/20 bg-white
                        grid place-items-center shadow-sm hover:bg-black/[0.03]"
            >
            <Image
              src="/images/landing/icon_right_arrow.png"
              alt="다음"
              width={12}
              height={22}
              className="w-[12px] h-[22px]"
            />
          </button>


          {/* 뷰포트 */}
          <div
            className={[
              "overflow-hidden",
              "select-none touch-pan-y",
              "cursor-grab active:cursor-grabbing",
              "w-[583px] h-[400px] mx-auto",
            ].join(" ")}
            onPointerDown={onPointerDown}
            onPointerMove={onPointerMove}
            onPointerUp={onPointerUp}
            onPointerCancel={onPointerUp}
          >
            <div
              className="flex transition-transform duration-300 ease-out"
              style={{ transform: `translateX(-${idx * 100}%)` }}
            >
              {safeSlides.map((s, i) => (
                <div key={`${s.src}-${i}`} className="min-w-full">
                  <Image
                    src={s.src}
                    alt={s.alt ?? `slide-${i + 1}`}
                    width={583}
                    height={400}
                    className="w-full h-full object-contain"
                    style={{ width: "100%", height: "100%" }}
                    draggable={false}
                  />
                </div>
              ))}
            </div>
          </div>
        </div>

        {/* 도트 */}
        {canSlide && (
          <div className="mt-3 flex items-center justify-center gap-2">
            {safeSlides.map((_, i) => {
              const active = i === idx;
              return (
                <button
                  key={i}
                  type="button"
                  onClick={() => setIdx(i)}
                  aria-label={`${i + 1}번 슬라이드`}
                  className={[
                    "h-2 w-2 rounded-full",
                    active ? "bg-black/70" : "bg-black/20 hover:bg-black/35",
                  ].join(" ")}
                />
              );
            })}
          </div>
        )}
      </div>
    </section>
  );
}