import { useState, useEffect, useRef } from 'react';

interface LazyImageProps {
  src: string;
  alt: string;
  className?: string;
  width?: number;
  height?: number;
  placeholder?: string;
}

/**
 * Lazy-loaded image component with intersection observer
 * Only loads images when they're about to enter the viewport
 */
export function LazyImage({ 
  src, 
  alt, 
  className = '', 
  width, 
  height,
  placeholder = 'data:image/svg+xml,%3Csvg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 400 300"%3E%3Crect fill="%23e5e7eb" width="400" height="300"/%3E%3C/svg%3E'
}: LazyImageProps) {
  const [imageSrc, setImageSrc] = useState<string>(placeholder);
  const [isLoaded, setIsLoaded] = useState(false);
  const imgRef = useRef<HTMLImageElement>(null);

  useEffect(() => {
    // Check if IntersectionObserver is supported
    if (!('IntersectionObserver' in window)) {
      // Fallback: load image immediately
      setImageSrc(src);
      return;
    }

    const observer = new IntersectionObserver(
      (entries) => {
        entries.forEach((entry) => {
          if (entry.isIntersecting) {
            setImageSrc(src);
            if (imgRef.current) {
              observer.unobserve(imgRef.current);
            }
          }
        });
      },
      {
        rootMargin: '50px', // Start loading 50px before entering viewport
      }
    );

    if (imgRef.current) {
      observer.observe(imgRef.current);
    }

    return () => {
      if (imgRef.current) {
        observer.unobserve(imgRef.current);
      }
    };
  }, [src]);

  return (
    <img
      ref={imgRef}
      src={imageSrc}
      alt={alt}
      className={`${className} ${isLoaded ? 'opacity-100' : 'opacity-0'} transition-opacity duration-300`}
      width={width}
      height={height}
      loading="lazy"
      onLoad={() => setIsLoaded(true)}
    />
  );
}

export default LazyImage;