import { useCallback, useState } from "react";
import { Upload, File, X } from "lucide-react";
import { Button } from "@/components/ui/button";
import { Card } from "@/components/ui/card";

type UploadedFile = {
  name: string;
  size: number;
  type: string;
};

type FileUploadZoneProps = {
  onFilesSelected: (files: File[]) => void;
  onClose?: () => void;
};

export function FileUploadZone({ onFilesSelected, onClose }: FileUploadZoneProps) {
  const [dragActive, setDragActive] = useState(false);
  const [selectedFiles, setSelectedFiles] = useState<UploadedFile[]>([]);

  const handleDrag = useCallback((e: React.DragEvent) => {
    e.preventDefault();
    e.stopPropagation();
    if (e.type === "dragenter" || e.type === "dragover") {
      setDragActive(true);
    } else if (e.type === "dragleave") {
      setDragActive(false);
    }
  }, []);

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

    const files = Array.from(e.dataTransfer.files);
    handleFiles(files);
  }, []);

  const handleFiles = (files: File[]) => {
    const uploadedFiles = files.map(f => ({
      name: f.name,
      size: f.size,
      type: f.type
    }));
    setSelectedFiles(prev => [...prev, ...uploadedFiles]);
    onFilesSelected(files);
  };

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

  const removeFile = (index: number) => {
    setSelectedFiles(prev => prev.filter((_, i) => i !== index));
  };

  const formatFileSize = (bytes: number) => {
    if (bytes < 1024) return bytes + " B";
    if (bytes < 1024 * 1024) return (bytes / 1024).toFixed(1) + " KB";
    return (bytes / (1024 * 1024)).toFixed(1) + " MB";
  };

  return (
    <Card className="p-6">
      <div className="flex items-center justify-between mb-4">
        <h3 className="text-lg font-semibold">Upload Files</h3>
        {onClose && (
          <Button variant="ghost" size="icon" onClick={onClose} data-testid="button-close-upload">
            <X className="h-5 w-5" />
          </Button>
        )}
      </div>

      <div
        className={`border-2 border-dashed rounded-xl p-8 text-center transition-colors ${
          dragActive ? "border-primary bg-primary/5" : "border-border"
        }`}
        onDragEnter={handleDrag}
        onDragLeave={handleDrag}
        onDragOver={handleDrag}
        onDrop={handleDrop}
        data-testid="dropzone"
      >
        <Upload className="h-12 w-12 mx-auto mb-4 text-muted-foreground" />
        <p className="text-sm font-medium mb-2">Drag and drop files here</p>
        <p className="text-xs text-muted-foreground mb-4">or</p>
        <label htmlFor="file-upload">
          <Button variant="outline" asChild data-testid="button-browse-files">
            <span className="cursor-pointer">Browse Files</span>
          </Button>
        </label>
        <input
          id="file-upload"
          type="file"
          multiple
          onChange={handleFileInput}
          className="hidden"
        />
        <p className="text-xs text-muted-foreground mt-4">
          Supports: .html, .js, .css, .py, .json, and more
        </p>
      </div>

      {selectedFiles.length > 0 && (
        <div className="mt-4 space-y-2">
          <p className="text-sm font-medium">Selected Files:</p>
          {selectedFiles.map((file, index) => (
            <div
              key={index}
              className="flex items-center justify-between p-3 bg-muted rounded-lg"
              data-testid={`file-item-${index}`}
            >
              <div className="flex items-center gap-3">
                <File className="h-4 w-4 text-muted-foreground" />
                <div>
                  <p className="text-sm font-medium">{file.name}</p>
                  <p className="text-xs text-muted-foreground">{formatFileSize(file.size)}</p>
                </div>
              </div>
              <Button
                variant="ghost"
                size="icon"
                className="h-8 w-8"
                onClick={() => removeFile(index)}
                data-testid={`button-remove-file-${index}`}
              >
                <X className="h-4 w-4" />
              </Button>
            </div>
          ))}
        </div>
      )}
    </Card>
  );
}