import React, { useState, useEffect, useRef } from 'react';
import ImageFlex from './ImageFlex.jsx';

export default function ImageSlider({ images, projectTitle }) {
  const [currentIndex, setCurrentIndex] = useState(0);
  const [isFullscreen, setIsFullscreen] = useState(false);
  const intervalRef = useRef(null);

  // Auto-advance every 4 seconds
  useEffect(() => {
    if (images.length <= 1) return;
    if (intervalRef.current) clearInterval(intervalRef.current);
    intervalRef.current = setInterval(() => {
      setCurrentIndex((prev) => (prev + 1) % images.length);
    }, 4000);
    return () => {
      if (intervalRef.current) clearInterval(intervalRef.current);
    };
  }, [images.length]);

  // Pause on hover/focus
  const pauseAutoPlay = () => {
    if (intervalRef.current) clearInterval(intervalRef.current);
  };
  const resumeAutoPlay = () => {
    if (images.length <= 1) return;
    if (intervalRef.current) clearInterval(intervalRef.current);
    intervalRef.current = setInterval(() => {
      setCurrentIndex((prev) => (prev + 1) % images.length);
    }, 4000);
  };

  const goToNext = () => {
    pauseAutoPlay();
    setCurrentIndex((prev) => (prev + 1) % images.length);
    resumeAutoPlay();
  };

  const goToPrev = () => {
    pauseAutoPlay();
    setCurrentIndex((prev) => (prev - 1 + images.length) % images.length);
    resumeAutoPlay();
  };

  const goToSlide = (index) => {
    pauseAutoPlay();
    setCurrentIndex(index);
    resumeAutoPlay();
  };

  const openFullscreen = () => {
    setIsFullscreen(true);
    pauseAutoPlay();
  };

  const closeFullscreen = () => {
    setIsFullscreen(false);
    resumeAutoPlay();
  };

  // Keyboard navigation in fullscreen (auto-play stays paused in fullscreen)
  useEffect(() => {
    if (!isFullscreen) return;

    const handleKeyDown = (e) => {
      if (e.key === 'Escape') {
        setIsFullscreen(false);
        resumeAutoPlay();
      } else if (e.key === 'ArrowLeft') {
        setCurrentIndex((prev) => (prev - 1 + images.length) % images.length);
      } else if (e.key === 'ArrowRight') {
        setCurrentIndex((prev) => (prev + 1) % images.length);
      }
    };

    window.addEventListener('keydown', handleKeyDown);
    return () => window.removeEventListener('keydown', handleKeyDown);
  }, [isFullscreen, images.length]);

  if (!images || images.length === 0) return null;

  const currentImage = images[currentIndex];

  return (
    <>
      <div
        className="relative group overflow-hidden rounded-xl bg-slate-100"
        onMouseEnter={pauseAutoPlay}
        onMouseLeave={resumeAutoPlay}
      >
        <div className="aspect-video relative">
          <ImageFlex
            base={currentImage}
            alt={`${projectTitle} - Image ${currentIndex + 1}`}
            className="w-full h-full object-cover"
          />
          {/* Click-to-fullscreen overlay */}
          <button
            type="button"
            onClick={openFullscreen}
            aria-label="View fullscreen"
            className="absolute inset-0 cursor-zoom-in focus:outline-none"
          />
          {/* Navigation arrows */}
          {images.length > 1 && (
            <>
              <button
                type="button"
                onClick={goToPrev}
                className="absolute left-4 top-1/2 -translate-y-1/2 bg-white/80 hover:bg-white rounded-full p-2
                         transition opacity-0 group-hover:opacity-100 focus:opacity-100"
                aria-label="Previous image"
              >
                <svg width="20" height="20" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2">
                  <path d="M15 18l-6-6 6-6" />
                </svg>
              </button>
              <button
                type="button"
                onClick={goToNext}
                className="absolute right-4 top-1/2 -translate-y-1/2 bg-white/80 hover:bg-white rounded-full p-2
                         transition opacity-0 group-hover:opacity-100 focus:opacity-100"
                aria-label="Next image"
              >
                <svg width="20" height="20" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2">
                  <path d="M9 18l6-6-6-6" />
                </svg>
              </button>
            </>
          )}
          {/* Fullscreen button */}
          <button
            type="button"
            onClick={openFullscreen}
            className="absolute bottom-4 right-4 bg-white/80 hover:bg-white rounded-full p-2
                     transition opacity-0 group-hover:opacity-100 focus:opacity-100"
            aria-label="View fullscreen"
          >
            <svg width="20" height="20" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2">
              <path d="M8 3H5a2 2 0 00-2 2v3m18 0V5a2 2 0 00-2-2h-3m0 18h3a2 2 0 002-2v-3M3 16v3a2 2 0 002 2h3" />
            </svg>
          </button>
          {/* Slide indicators */}
          {images.length > 1 && (
            <div className="absolute bottom-4 left-1/2 -translate-x-1/2 flex gap-2">
              {images.map((_, i) => (
                <button
                  key={i}
                  type="button"
                  onClick={() => goToSlide(i)}
                  className={`h-2 rounded-full transition ${
                    i === currentIndex ? 'w-8 bg-white' : 'w-2 bg-white/50 hover:bg-white/75'
                  }`}
                  aria-label={`Go to slide ${i + 1}`}
                />
              ))}
            </div>
          )}
        </div>
      </div>

      {/* Fullscreen modal */}
      {isFullscreen && (
        <div
          className="fixed inset-0 z-[100] bg-black/95 flex items-center justify-center p-4"
          onClick={closeFullscreen}
        >
          <button
            type="button"
            onClick={closeFullscreen}
            className="absolute top-4 right-4 text-white hover:text-gray-300 p-2"
            aria-label="Close fullscreen"
          >
            <svg width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2">
              <path d="M18 6L6 18M6 6l12 12" />
            </svg>
          </button>
          <div className="relative max-w-7xl w-full h-full flex items-center" onClick={(e) => e.stopPropagation()}>
            <button
              type="button"
              onClick={goToPrev}
              className="absolute left-4 bg-white/20 hover:bg-white/30 text-white rounded-full p-3 z-10"
              aria-label="Previous image"
            >
              <svg width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2">
                <path d="M15 18l-6-6 6-6" />
              </svg>
            </button>
            <div className="w-full h-full flex items-center justify-center">
              <ImageFlex
                base={currentImage}
                alt={`${projectTitle} - Image ${currentIndex + 1}`}
                className="max-w-full max-h-full object-contain"
              />
            </div>
            <button
              type="button"
              onClick={goToNext}
              className="absolute right-4 bg-white/20 hover:bg-white/30 text-white rounded-full p-3 z-10"
              aria-label="Next image"
            >
              <svg width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2">
                <path d="M9 18l6-6-6-6" />
              </svg>
            </button>
            {/* Fullscreen indicators */}
            {images.length > 1 && (
              <div className="absolute bottom-8 left-1/2 -translate-x-1/2 flex gap-2">
                {images.map((_, i) => (
                  <button
                    key={i}
                    type="button"
                    onClick={() => goToSlide(i)}
                    className={`h-2 rounded-full transition ${
                      i === currentIndex ? 'w-8 bg-white' : 'w-2 bg-white/50 hover:bg-white/75'
                    }`}
                    aria-label={`Go to slide ${i + 1}`}
                  />
                ))}
              </div>
            )}
          </div>
        </div>
      )}
    </>
  );
}