frontend/src/components/shared/FileDropZone.tsx

import { useState, useRef, useCallback } from 'react';
import { Upload } from 'lucide-react';
import { cn } from '@/lib/utils';

interface FileDropZoneProps {
  accept?: string;
  multiple?: boolean;
  onFilesSelected: (files: File[]) => void;
  description?: string;
  disabled?: boolean;
  className?: string;
}

export function FileDropZone({
  accept,
  multiple = false,
  onFilesSelected,
  description,
  disabled = false,
  className,
}: FileDropZoneProps) {
  const [isDragging, setIsDragging] = useState(false);
  const fileInputRef = useRef<HTMLInputElement>(null);

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

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

  const handleDrop = useCallback(
    (e: React.DragEvent) => {
      e.preventDefault();
      setIsDragging(false);
      if (disabled) return;

      const files = Array.from(e.dataTransfer.files);
      if (files.length > 0) {
        if (multiple) {
          onFilesSelected(files);
        } else {
          onFilesSelected([files[0]]);
        }
      }
    },
    [disabled, multiple, onFilesSelected]
  );

  const handleClick = useCallback(() => {
    if (!disabled) {
      fileInputRef.current?.click();
    }
  }, [disabled]);

  const handleFileInputChange = useCallback(
    (e: React.ChangeEvent<HTMLInputElement>) => {
      const files = Array.from(e.target.files || []);
      if (files.length > 0) {
        onFilesSelected(files);
      }
      // Reset input value to allow selecting same file again
      if (fileInputRef.current) {
        fileInputRef.current.value = '';
      }
    },
    [onFilesSelected]
  );

  return (
    <div
      className={cn(
        'relative border-2 border-dashed rounded-xl p-8 text-center cursor-pointer transition-all duration-200',
        'bg-gradient-to-b from-teal-50/30 to-cyan-50/20',
        isDragging && 'border-teal-400 bg-teal-50/50 scale-[1.02]',
        !isDragging && 'border-teal-200/50 hover:border-teal-300/70 hover:bg-teal-50/40',
        disabled && 'opacity-50 cursor-not-allowed',
        className
      )}
      onDragOver={handleDragOver}
      onDragLeave={handleDragLeave}
      onDrop={handleDrop}
      onClick={handleClick}
    >
      {/* 图标容器 */}
      <div
        className={cn(
          'mx-auto mb-4 h-12 w-12 rounded-xl flex items-center justify-center',
          'bg-gradient-to-br from-teal-500 to-cyan-600',
          'shadow-lg shadow-teal-500/20',
          'transition-transform duration-200',
          isDragging && 'scale-110'
        )}
      >
        <Upload className="h-6 w-6 text-white" />
      </div>

      {/* 主文字 */}
      <p className={cn(
        'text-sm font-medium mb-1 transition-colors',
        isDragging ? 'text-teal-700' : 'text-gray-700'
      )}>
        {isDragging ? '松开以上传文件' : '点击或拖放文件到此处'}
      </p>

      {/* 副文字 */}
      {description && (
        <p className="text-xs text-teal-600/60">{description}</p>
      )}

      {/* 隐藏的文件输入 */}
      <input
        ref={fileInputRef}
        type="file"
        accept={accept}
        multiple={multiple}
        onChange={handleFileInputChange}
        className="hidden"
        disabled={disabled}
      />
    </div>
  );
}