'use client';

import * as React from 'react';
import { Upload, X } from 'lucide-react';
import { cn } from '@/lib/utils/cn';
import { formatFileSize } from '@/lib/utils/fileUtils';
import { Button } from '@/components/ui/Button';

export interface FileUploadProps {
  onFileSelect: (files: File[]) => void;
  onFileRemove: (index: number) => void;
  selectedFiles?: File[];
  accept?: string;
  maxSizeMB?: number;
  disabled?: boolean;
  inputRef?: React.RefObject<HTMLInputElement | null>;
}

export function FileUpload({
  onFileSelect,
  onFileRemove,
  selectedFiles = [],
  accept,
  maxSizeMB = 500,
  disabled = false,
  inputRef,
}: FileUploadProps) {
  const [isDragging, setIsDragging] = React.useState(false);
  const fileInputRef = inputRef || React.useRef<HTMLInputElement>(null);

  const handleDragEnter = (e: React.DragEvent) => {
    e.preventDefault();
    e.stopPropagation();
    if (!disabled) {
      setIsDragging(true);
    }
  };

  const handleDragLeave = (e: React.DragEvent) => {
    e.preventDefault();
    e.stopPropagation();
    setIsDragging(false);
  };

  const handleDragOver = (e: React.DragEvent) => {
    e.preventDefault();
    e.stopPropagation();
  };

  const handleDrop = (e: React.DragEvent) => {
    e.preventDefault();
    e.stopPropagation();
    setIsDragging(false);

    if (disabled) return;

    const files = Array.from(e.dataTransfer.files);
    if (files.length > 0) {
      handleFiles(files);
    }
  };

  const handleFileInput = (e: React.ChangeEvent<HTMLInputElement>) => {
    const files = Array.from(e.target.files || []);
    if (files.length > 0) {
      handleFiles(files);
    }
  };

  const handleFiles = (files: File[]) => {
    // Check file sizes
    const maxBytes = maxSizeMB * 1024 * 1024;
    const validFiles = files.filter(file => {
      if (file.size > maxBytes) {
        alert(`${file.name} exceeds ${maxSizeMB}MB limit and will be skipped.`);
        return false;
      }
      return true;
    });

    if (validFiles.length > 0) {
      onFileSelect(validFiles);
    }

    // Reset input
    if (fileInputRef.current) {
      fileInputRef.current.value = '';
    }
  };

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

  const handleRemove = (index: number) => (e: React.MouseEvent) => {
    e.stopPropagation();
    onFileRemove(index);
  };

  return (
    <div className="w-full space-y-3">
      <input
        ref={fileInputRef}
        type="file"
        multiple
        className="hidden"
        accept={accept}
        onChange={handleFileInput}
        disabled={disabled}
      />

      {selectedFiles.length > 0 ? (
        <div className="space-y-2">
          {selectedFiles.map((file, index) => (
            <div key={`${file.name}-${index}`} className="border-2 border-border rounded-lg p-4 bg-card">
              <div className="flex items-center justify-between">
                <div className="flex-1 min-w-0">
                  <p className="text-sm font-medium text-foreground truncate">{file.name}</p>
                  <p className="text-xs text-muted-foreground mt-1">
                    {formatFileSize(file.size)}
                  </p>
                </div>
                <Button
                  variant="ghost"
                  size="icon"
                  onClick={handleRemove(index)}
                  disabled={disabled}
                  className="ml-4"
                >
                  <X className="h-4 w-4" />
                  <span className="sr-only">Remove file</span>
                </Button>
              </div>
            </div>
          ))}

          {/* Add more files button */}
          <Button
            variant="outline"
            onClick={handleClick}
            disabled={disabled}
            className="w-full"
          >
            <Upload className="h-4 w-4 mr-2" />
            Add More Files
          </Button>
        </div>
      ) : (
        <div
          onClick={handleClick}
          onDragEnter={handleDragEnter}
          onDragOver={handleDragOver}
          onDragLeave={handleDragLeave}
          onDrop={handleDrop}
          className={cn(
            'border-2 border-dashed rounded-lg p-12 text-center cursor-pointer transition-colors',
            'hover:border-primary hover:bg-primary/5',
            {
              'border-primary bg-primary/10': isDragging,
              'border-border bg-background': !isDragging,
              'opacity-50 cursor-not-allowed': disabled,
            }
          )}
        >
          <Upload className="mx-auto h-12 w-12 text-muted-foreground mb-4" />
          <p className="text-sm font-medium text-foreground mb-1">
            Drop your files here or click to browse
          </p>
          <p className="text-xs text-muted-foreground">
            Maximum file size: {maxSizeMB}MB per file
          </p>
        </div>
      )}
    </div>
  );
}
