import React, { useState, useRef, DragEvent, ChangeEvent } from 'react';
import { Upload, Image as ImageIcon, X, AlertCircle } from 'lucide-react';

interface ImageDropzoneProps {
  value: string;
  onChange: (base64Url: string) => void;
  onClear: () => void;
  label?: string;
  className?: string;
}

export default function ImageDropzone({
  value,
  onChange,
  onClear,
  label = '상품 대표 이미지 업로드',
  className = ''
}: ImageDropzoneProps) {
  const [isDragActive, setIsDragActive] = useState(false);
  const [error, setError] = useState<string | null>(null);
  const fileInputRef = useRef<HTMLInputElement>(null);

  const processFile = (file: File) => {
    setError(null);
    
    // Validate file type
    if (!file.type.startsWith('image/')) {
      setError('이미지 파일(*.png, *.jpg, *.jpeg, *.gif)만 업로드할 수 있습니다.');
      return;
    }

    // Validate size (e.g., max 4MB for high-fidelity base64 storage)
    const maxSize = 4 * 1024 * 1024;
    if (file.size > maxSize) {
      setError('이미지 최댓값은 4MB입니다. 더 작고 최적화된 이미지를 권장합니다.');
      return;
    }

    const reader = new FileReader();
    reader.onload = (e) => {
      if (e.target?.result && typeof e.target.result === 'string') {
        onChange(e.target.result);
      } else {
        setError('이미지 해독 과정에 이상이 발생했습니다.');
      }
    };
    reader.onerror = () => {
      setError('파일을 수집하지 못했습니다.');
    };
    reader.readAsDataURL(file);
  };

  const handleDragOver = (e: DragEvent<HTMLDivElement>) => {
    e.preventDefault();
    e.stopPropagation();
    setIsDragActive(true);
  };

  const handleDragLeave = (e: DragEvent<HTMLDivElement>) => {
    e.preventDefault();
    e.stopPropagation();
    setIsDragActive(false);
  };

  const handleDrop = (e: DragEvent<HTMLDivElement>) => {
    e.preventDefault();
    e.stopPropagation();
    setIsDragActive(false);

    if (e.dataTransfer.files && e.dataTransfer.files[0]) {
      processFile(e.dataTransfer.files[0]);
    }
  };

  const handleFileChange = (e: ChangeEvent<HTMLInputElement>) => {
    if (e.target.files && e.target.files[0]) {
      processFile(e.target.files[0]);
    }
  };

  const handleButtonClick = () => {
    fileInputRef.current?.click();
  };

  return (
    <div className={`space-y-1.5 font-mono text-xs ${className}`}>
      <label className="font-semibold text-foreground flex items-center gap-1.5">
        <span className="h-1.5 w-1.5 rounded-full bg-primary" />
        {label}
      </label>

      {value ? (
        // Preview Mode with image loaded
        <div className="relative group border border-border rounded-lg overflow-hidden bg-background h-44 flex items-center justify-center">
          <img
            src={value}
            alt="Uploaded preview"
            referrerPolicy="no-referrer"
            className="h-full w-full object-contain"
          />
          {/* Hover overlay control */}
          <div className="absolute inset-0 bg-black/50 opacity-0 group-hover:opacity-100 transition-opacity flex flex-col items-center justify-center gap-2">
            <button
              type="button"
              onClick={handleButtonClick}
              className="px-3 py-1.5 bg-background text-foreground hover:bg-muted font-bold rounded text-[11px] cursor-pointer"
            >
              다른 이미지로 교체
            </button>
            <button
              type="button"
              onClick={onClear}
              className="px-3 py-1.5 bg-destructive text-destructive-foreground hover:opacity-90 font-bold rounded text-[11px] cursor-pointer flex items-center gap-1"
            >
              <X size={12} />
              이미지 제거
            </button>
          </div>
        </div>
      ) : (
        // Active Dropzone Area
        <div
          onDragOver={handleDragOver}
          onDragLeave={handleDragLeave}
          onDrop={handleDrop}
          onClick={handleButtonClick}
          className={`border-2 border-dashed rounded-lg p-6 flex flex-col items-center justify-center text-center cursor-pointer min-h-44 transition-all ${
            isDragActive 
              ? 'border-primary bg-primary/5' 
              : 'border-border hover:border-foreground/30 bg-muted/20'
          }`}
        >
          <input
            type="file"
            ref={fileInputRef}
            onChange={handleFileChange}
            accept="image/*"
            className="hidden"
          />
          
          <div className="p-2.5 bg-background border border-border rounded-full shadow-xs mb-3 text-muted-foreground">
            {isDragActive ? (
              <Upload size={22} className="animate-bounce text-primary" />
            ) : (
              <ImageIcon size={22} />
            )}
          </div>

          <div className="space-y-1">
            <p className="font-semibold text-foreground text-xs">
              {isDragActive ? '여기에 드롭하여 업로드' : '이지지 드래그 앤 드롭 또는 파일 탐색'}
            </p>
            <p className="text-[10px] text-muted-foreground max-w-[280px] leading-relaxed">
              PNG, JPG, JPEG, GIF 파일 지원 (최대 4MB)
            </p>
          </div>
        </div>
      )}

      {error && (
        <div className="flex items-center gap-1.5 text-[10px] text-destructive mt-1">
          <AlertCircle size={12} />
          <span>{error}</span>
        </div>
      )}
    </div>
  );
}