import fs from 'fs'
import path from 'path'
import React, { useEffect, useState } from 'react'
import Image from 'next/image'
import AppContainer from './appContainer'

const shimmer = (width, height) => `
  <svg width="${width}" height="${height}" viewBox="0 0 ${width} ${height}" xmlns="http://www.w3.org/2000/svg">
    <defs>
      <linearGradient id="gradient">
        <stop stop-color="#e5e7eb" offset="20%" />
        <stop stop-color="#f9fafb" offset="50%" />
        <stop stop-color="#e5e7eb" offset="70%" />
      </linearGradient>
    </defs>
    <rect width="${width}" height="${height}" fill="#e5e7eb" />
    <rect width="${width}" height="${height}" fill="url(#gradient)" />
  </svg>
`

const toBase64 = value =>
  typeof window === 'undefined' ? Buffer.from(value).toString('base64') : window.btoa(value)

const galleryBannerLoader = () => '/resource/parallax/Gallery.jpg'

const Gallery = ({ images }) => {
  const [selectedImage, setSelectedImage] = useState(null)

  const closeLightbox = () => setSelectedImage(null)

  const showPreviousImage = () => {
    setSelectedImage(current => (current === 0 ? images.length - 1 : current - 1))
  }

  const showNextImage = () => {
    setSelectedImage(current => (current === images.length - 1 ? 0 : current + 1))
  }

  useEffect(() => {
    if (selectedImage === null) return undefined

    const handleKeyDown = event => {
      if (event.key === 'Escape') setSelectedImage(null)
      if (event.key === 'ArrowRight') {
        setSelectedImage(current => (current === images.length - 1 ? 0 : current + 1))
      }
      if (event.key === 'ArrowLeft') {
        setSelectedImage(current => (current === 0 ? images.length - 1 : current - 1))
      }
    }

    const previousOverflow = document.body.style.overflow
    document.body.style.overflow = 'hidden'
    window.addEventListener('keydown', handleKeyDown)

    return () => {
      document.body.style.overflow = previousOverflow
      window.removeEventListener('keydown', handleKeyDown)
    }
  }, [selectedImage, images.length])

  return (
    <AppContainer title='گالری بیمارستان مهر ایرانیان پرند'>
      <style jsx>{`
        .gallery-page {
          direction: rtl;
          padding: 3rem 1rem 5rem;
          background: #fff;
        }

        .gallery-header {
          max-width: 1200px;
          margin: 0 auto 2rem;
          text-align: right;
        }

        .gallery-header h2 {
          margin: 0 0 0.5rem;
          color: #263238;
          font-size: 1.75rem;
          font-weight: 700;
        }

        .gallery-header p {
          margin: 0;
          color: #6b7280;
          font-size: 0.95rem;
        }

        .gallery-header::after {
          content: '';
          display: block;
          width: 54px;
          height: 3px;
          margin-top: 0.9rem;
          border-radius: 999px;
          background: #009688;
        }

        .gallery-grid {
          display: grid;
          grid-template-columns: repeat(4, minmax(0, 1fr));
          gap: 1rem;
          max-width: 1200px;
          margin: 0 auto;
        }

        .gallery-card {
          position: relative;
          aspect-ratio: 16 / 9;
          padding: 0;
          overflow: hidden;
          border: 1px solid #e5e7eb;
          border-radius: 0.85rem;
          background: #f3f4f6;
          cursor: zoom-in;
          box-shadow: 0 4px 14px rgba(15, 23, 42, 0.07);
          transition: transform 180ms ease, box-shadow 180ms ease;
        }

        .gallery-card:hover,
        .gallery-card:focus-visible {
          transform: translateY(-3px);
          box-shadow: 0 10px 24px rgba(15, 23, 42, 0.15);
          outline: none;
        }

        .gallery-card :global(img) {
          transition: transform 250ms ease;
        }

        .gallery-card:hover :global(img) {
          transform: scale(1.035);
        }

        .lightbox {
          position: fixed;
          z-index: 1500;
          inset: 0;
          display: flex;
          align-items: center;
          justify-content: center;
          padding: 4.5rem 5rem 3rem;
          background: rgba(0, 0, 0, 0.92);
        }

        .lightbox-image {
          max-width: 100%;
          max-height: calc(100vh - 7.5rem);
          object-fit: contain;
          border-radius: 0.4rem;
        }

        .lightbox-close,
        .lightbox-navigation {
          position: absolute;
          display: flex;
          align-items: center;
          justify-content: center;
          border: 0;
          color: #fff;
          background: rgba(255, 255, 255, 0.13);
          cursor: pointer;
          transition: background 150ms ease;
        }

        .lightbox-close:hover,
        .lightbox-navigation:hover {
          background: rgba(255, 255, 255, 0.25);
        }

        .lightbox-close {
          top: 1.25rem;
          right: 1.25rem;
          width: 44px;
          height: 44px;
          border-radius: 50%;
          font-size: 1.9rem;
          line-height: 1;
        }

        .lightbox-navigation {
          top: 50%;
          width: 46px;
          height: 58px;
          border-radius: 0.5rem;
          font-size: 2rem;
          transform: translateY(-50%);
        }

        .lightbox-previous {
          left: 1.25rem;
        }

        .lightbox-next {
          right: 1.25rem;
        }

        .lightbox-counter {
          position: absolute;
          bottom: 1rem;
          left: 50%;
          margin: 0;
          color: #fff;
          font-size: 0.9rem;
          transform: translateX(-50%);
        }

        @media (max-width: 992px) {
          .gallery-grid {
            grid-template-columns: repeat(3, minmax(0, 1fr));
          }
        }

        @media (max-width: 768px) {
          .gallery-page {
            padding: 2rem 1rem 4rem;
          }

          .gallery-grid {
            grid-template-columns: repeat(2, minmax(0, 1fr));
            gap: 0.75rem;
          }

          .lightbox {
            padding: 4rem 1rem;
          }

          .lightbox-navigation {
            top: auto;
            bottom: 0.8rem;
            transform: none;
          }

          .lightbox-previous {
            left: 1rem;
          }

          .lightbox-next {
            right: 1rem;
          }
        }

        @media (max-width: 480px) {
          .gallery-header h2 {
            font-size: 1.4rem;
          }

          .gallery-grid {
            grid-template-columns: 1fr;
          }
        }
      `}</style>

      <div className='parallax-container'>
        <h1 className='center-align text-white header_back service-text dana font-weight-bold'>گالری بیمارستان</h1>
        <Image
          loader={galleryBannerLoader}
          src='gallery-banner.jpg'
          className='responsive-img shadow-5'
          alt='گالری بیمارستان مهر ایرانیان پرند'
          width={3000}
          height={1300}
          priority
        />
      </div>

      <main className='gallery-page'>
        <header className='gallery-header'>
          <h2>گالری تصاویر</h2>
          <p>تصاویر بیمارستان مهر ایرانیان پرند</p>
        </header>

        <section className='gallery-grid' aria-label='تصاویر گالری بیمارستان'>
          {images.map((image, index) => (
            <button
              type='button'
              className='gallery-card'
              key={image.id}
              aria-label={`نمایش تصویر ${index + 1} از گالری`}
              onClick={() => setSelectedImage(index)}
            >
              <Image
                src={image.image}
                alt={image.title}
                layout='fill'
                objectFit='cover'
                placeholder='blur'
                blurDataURL={`data:image/svg+xml;base64,${toBase64(shimmer(640, 360))}`}
              />
            </button>
          ))}
        </section>
      </main>

      {selectedImage !== null && (
        <div className='lightbox' role='dialog' aria-modal='true' aria-label='نمایش تصویر گالری' onClick={closeLightbox}>
          <button type='button' className='lightbox-close' aria-label='بستن تصویر' onClick={closeLightbox}>
            &times;
          </button>
          <button
            type='button'
            className='lightbox-navigation lightbox-previous'
            aria-label='تصویر قبلی'
            onClick={event => {
              event.stopPropagation()
              showPreviousImage()
            }}
          >
            &#8249;
          </button>
          <img
            className='lightbox-image'
            src={images[selectedImage].image}
            alt={images[selectedImage].title}
            onClick={event => event.stopPropagation()}
          />
          <button
            type='button'
            className='lightbox-navigation lightbox-next'
            aria-label='تصویر بعدی'
            onClick={event => {
              event.stopPropagation()
              showNextImage()
            }}
          >
            &#8250;
          </button>
          <p className='lightbox-counter'>
            {selectedImage + 1} از {images.length}
          </p>
        </div>
      )}
    </AppContainer>
  )
}

export async function getStaticProps() {
  const galleryDirectory = path.join(process.cwd(), 'public', 'resource', 'images', 'gallery')
  const fileNames = fs
    .readdirSync(galleryDirectory)
    .filter(fileName => /\.(jpe?g|png|webp)$/i.test(fileName))
    .sort((first, second) => first.localeCompare(second, undefined, { numeric: true }))

  const images = fileNames.map((fileName, index) => ({
    id: fileName,
    image: `/resource/images/gallery/${encodeURIComponent(fileName)}`,
    title: `تصویر ${index + 1} از بیمارستان مهر ایرانیان پرند`
  }))

  return {
    props: { images }
  }
}

export default Gallery