'use client';

import * as React from 'react';
import { Button } from '@/components/ui/button';
import { cn } from '@/lib/utils';

interface ImageFile {
  file: File;
  preview: string;
}

interface ImageUploadProps {
  images: ImageFile[];
  onChange: (images: ImageFile[]) => void;
  maxFiles?: number;
  className?: string;
}

export function ImageUpload({ images, onChange, maxFiles = 20, className }: ImageUploadProps) {
  const inputRef = React.useRef<HTMLInputElement>(null);
  const [isDragging, setIsDragging] = React.useState(false);

  const addFiles = React.useCallback(
    (files: FileList | File[]) => {
      const newImages: ImageFile[] = [];
      const allowedTypes = ['image/jpeg', 'image/png', 'image/webp'];
      const maxSize = 10 * 1024 * 1024; // 10MB

      Array.from(files).forEach((file) => {
        if (!allowedTypes.includes(file.type)) return;
        if (file.size > maxSize) return;
        if (images.length + newImages.length >= maxFiles) return;

        newImages.push({
          file,
          preview: URL.createObjectURL(file),
        });
      });

      if (newImages.length > 0) {
        onChange([...images, ...newImages]);
      }
    },
    [images, onChange, maxFiles],
  );

  const removeImage = React.useCallback(
    (index: number) => {
      const updated = [...images];
      URL.revokeObjectURL(updated[index]!.preview);
      updated.splice(index, 1);
      onChange(updated);
    },
    [images, onChange],
  );

  const handleDragOver = React.useCallback((e: React.DragEvent) => {
    e.preventDefault();
    setIsDragging(true);
  }, []);

  const handleDragLeave = React.useCallback((e: React.DragEvent) => {
    e.preventDefault();
    setIsDragging(false);
  }, []);

  const handleDrop = React.useCallback(
    (e: React.DragEvent) => {
      e.preventDefault();
      setIsDragging(false);
      if (e.dataTransfer.files.length > 0) {
        addFiles(e.dataTransfer.files);
      }
    },
    [addFiles],
  );

  React.useEffect(() => {
    return () => {
      images.forEach((img) => URL.revokeObjectURL(img.preview));
    };
  }, []); // intentionally empty: runs only on unmount to revoke object URLs

  return (
    <div className={cn('space-y-4', className)}>
      <div
        role="button"
        tabIndex={0}
        onDragOver={handleDragOver}
        onDragLeave={handleDragLeave}
        onDrop={handleDrop}
        onClick={() => inputRef.current?.click()}
        onKeyDown={(e) => {
          if (e.key === 'Enter' || e.key === ' ') {
            e.preventDefault();
            inputRef.current?.click();
          }
        }}
        aria-label="Tải ảnh lên. Kéo thả ảnh vào đây hoặc nhấn để chọn"
        className={cn(
          'flex cursor-pointer flex-col items-center justify-center rounded-lg border-2 border-dashed p-8 transition-colors focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-primary',
          isDragging
            ? 'border-primary bg-primary/5'
            : 'border-muted-foreground/25 hover:border-primary/50',
        )}
      >
        <svg
          xmlns="http://www.w3.org/2000/svg"
          width="40"
          height="40"
          viewBox="0 0 24 24"
          fill="none"
          stroke="currentColor"
          strokeWidth="1.5"
          strokeLinecap="round"
          strokeLinejoin="round"
          className="mb-3 text-muted-foreground"
        >
          <rect width="18" height="18" x="3" y="3" rx="2" ry="2" />
          <circle cx="9" cy="9" r="2" />
          <path d="m21 15-3.086-3.086a2 2 0 0 0-2.828 0L6 21" />
        </svg>
        <p className="text-sm font-medium">Kéo thả ảnh vào đây hoặc nhấp để chọn</p>
        <p className="mt-1 text-xs text-muted-foreground">
          JPG, PNG, WebP - Tối đa {maxFiles} ảnh, mỗi ảnh 10MB
        </p>
        <input
          ref={inputRef}
          type="file"
          accept="image/jpeg,image/png,image/webp"
          multiple
          className="hidden"
          onChange={(e) => {
            if (e.target.files) addFiles(e.target.files);
            e.target.value = '';
          }}
        />
      </div>

      {images.length > 0 && (
        <div className="grid grid-cols-2 gap-3 sm:grid-cols-3 md:grid-cols-4">
          {images.map((img, index) => (
            <div key={img.preview} className="group relative aspect-square overflow-hidden rounded-lg border">
              <img
                src={img.preview}
                alt={`Ảnh ${index + 1}`}
                className="h-full w-full object-cover"
              />
              <div className="absolute inset-0 flex items-center justify-center bg-black/40 opacity-0 transition-opacity group-hover:opacity-100">
                <Button
                  type="button"
                  variant="destructive"
                  size="sm"
                  onClick={(e) => {
                    e.stopPropagation();
                    removeImage(index);
                  }}
                >
                  Xóa
                </Button>
              </div>
              {index === 0 && (
                <span className="absolute left-1.5 top-1.5 rounded bg-primary px-1.5 py-0.5 text-[10px] font-semibold text-primary-foreground">
                  Ảnh bìa
                </span>
              )}
            </div>
          ))}
        </div>
      )}
    </div>
  );
}

export type { ImageFile };