import {
  useState,
  useCallback,
  useRef,
  useImperativeHandle,
  useEffect,
  forwardRef,
} from 'react';
import {
  X,
  Image as ImageIcon,
  Upload,
  ChevronRight,
  AlertCircle,
} from 'lucide-react';
import { Button } from './button';
import { Alert, AlertDescription } from './alert';
import { cn, formatFileSize } from '@/lib/utils';
import { imagesApi } from '@/lib/api';
import type { ImageResponse } from 'shared/types';

interface ImageUploadSectionProps {
  images: ImageResponse[];
  onImagesChange: (images: ImageResponse[]) => void;
  onUpload: (file: File) => Promise<ImageResponse>;
  onDelete?: (imageId: string) => Promise<void>;
  onImageUploaded?: (image: ImageResponse) => void; // Custom callback for upload success
  isUploading?: boolean;
  disabled?: boolean;
  readOnly?: boolean;
  collapsible?: boolean;
  defaultExpanded?: boolean;
  hideDropZone?: boolean; // Hide the drag and drop area
  className?: string;
}

export interface ImageUploadSectionHandle {
  addFiles: (files: FileList | File[] | null) => Promise<void>;
}

const MAX_SIZE_BYTES = 20 * 1024 * 1024; // 20MB
const VALID_TYPES = [
  'image/png',
  'image/jpeg',
  'image/jpg',
  'image/gif',
  'image/webp',
  'image/bmp',
  'image/svg+xml',
];

export const ImageUploadSection = forwardRef<
  ImageUploadSectionHandle,
  ImageUploadSectionProps
>(
  (
    {
      images,
      onImagesChange,
      onUpload,
      onDelete,
      onImageUploaded,
      isUploading = false,
      disabled = false,
      readOnly = false,
      collapsible = true,
      defaultExpanded = false,
      hideDropZone = false,
      className,
    },
    ref
  ) => {
    const [isExpanded, setIsExpanded] = useState(
      defaultExpanded || images.length > 0
    );
    const [isDragging, setIsDragging] = useState(false);
    const [uploadingFiles, setUploadingFiles] = useState<Set<string>>(
      new Set()
    );
    const [errorMessage, setErrorMessage] = useState<string | null>(null);
    const fileInputRef = useRef<HTMLInputElement>(null);
    const latestImagesRef = useRef(images);

    useEffect(() => {
      latestImagesRef.current = images;
    }, [images]);

    useEffect(() => {
      if (collapsible && images.length > 0 && !isExpanded) {
        setIsExpanded(true);
      }
    }, [collapsible, images.length, isExpanded]);

    const handleFiles = useCallback(
      async (filesInput: FileList | File[] | null) => {
        if (!filesInput || disabled || readOnly) return;

        const files = Array.isArray(filesInput)
          ? filesInput
          : Array.from(filesInput);

        setErrorMessage(null);

        const invalidFiles: string[] = [];
        const oversizedFiles: string[] = [];
        const validFiles: File[] = [];

        files.forEach((file) => {
          if (!VALID_TYPES.includes(file.type.toLowerCase())) {
            invalidFiles.push(file.name);
            return;
          }

          if (file.size > MAX_SIZE_BYTES) {
            oversizedFiles.push(
              `${file.name} (${(file.size / 1048576).toFixed(1)} MB)`
            );
            return;
          }

          validFiles.push(file);
        });

        if (invalidFiles.length > 0 || oversizedFiles.length > 0) {
          const errors: string[] = [];
          if (invalidFiles.length > 0) {
            errors.push(`Unsupported file type: ${invalidFiles.join(', ')}`);
          }
          if (oversizedFiles.length > 0) {
            errors.push(
              `Files too large (max 20 MB): ${oversizedFiles.join(', ')}`
            );
          }
          setErrorMessage(errors.join('. '));
        }

        for (const file of validFiles) {
          const tempId = `uploading-${Date.now()}-${file.name}`;
          setUploadingFiles((prev) => new Set(prev).add(tempId));

          try {
            const uploadedImage = await onUpload(file);

            // Call custom upload callback if provided, otherwise use default behavior
            if (onImageUploaded) {
              onImageUploaded(uploadedImage);
            } else {
              const nextImages = [...latestImagesRef.current, uploadedImage];
              latestImagesRef.current = nextImages;
              onImagesChange(nextImages);
            }

            setErrorMessage(null);
          } catch (error: unknown) {
            console.error('Failed to upload image:', error);
            const message =
              error instanceof Error
                ? error.message
                : 'Failed to upload image. Please try again.';
            setErrorMessage(message);
          } finally {
            setUploadingFiles((prev) => {
              const next = new Set(prev);
              next.delete(tempId);
              return next;
            });
          }
        }
      },
      [disabled, readOnly, onUpload, onImageUploaded, onImagesChange]
    );

    useImperativeHandle(
      ref,
      () => ({
        addFiles: async (files: FileList | File[] | null) => {
          await handleFiles(files);
        },
      }),
      [handleFiles]
    );

    const handleDrop = useCallback(
      (e: React.DragEvent) => {
        e.preventDefault();
        setIsDragging(false);
        void handleFiles(e.dataTransfer.files);
      },
      [handleFiles]
    );

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

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

    const handleRemoveImage = useCallback(
      async (imageId: string) => {
        if (onDelete) {
          try {
            await onDelete(imageId);
          } catch (error) {
            console.error('Failed to delete image:', error);
          }
        }
        onImagesChange(images.filter((img) => img.id !== imageId));
      },
      [images, onImagesChange, onDelete]
    );

    const content = (
      <div className={cn('space-y-3', className)}>
        {/* Error message */}
        {errorMessage && (
          <Alert variant="destructive">
            <AlertCircle className="h-4 w-4" />
            <AlertDescription>{errorMessage}</AlertDescription>
          </Alert>
        )}

        {/* Read-only message */}
        {readOnly && images.length === 0 && (
          <p className="text-sm text-muted-foreground">No images attached</p>
        )}

        {/* Drop zone - only show when not read-only and not hidden */}
        {!readOnly && !hideDropZone && (
          <div
            className={cn(
              'border-2 border-dashed rounded-lg p-6 text-center transition-colors',
              isDragging
                ? 'border-primary bg-primary/5'
                : 'border-muted-foreground/25 hover:border-muted-foreground/50',
              disabled && 'opacity-50 cursor-not-allowed'
            )}
            onDrop={handleDrop}
            onDragOver={handleDragOver}
            onDragLeave={handleDragLeave}
          >
            <Upload className="h-8 w-8 mx-auto mb-3 text-muted-foreground" />
            <p className="text-sm text-muted-foreground mb-1">
              Drag and drop images here, or click to select
            </p>
            <Button
              variant="secondary"
              size="sm"
              onClick={() => fileInputRef.current?.click()}
              disabled={disabled || isUploading}
            >
              Select Images
            </Button>
            <input
              ref={fileInputRef}
              type="file"
              accept="image/*"
              multiple
              className="hidden"
              onChange={(e) => {
                void handleFiles(e.target.files);
              }}
              disabled={disabled}
            />
          </div>
        )}

        {/* Image previews */}
        {images.length > 0 && (
          <div className="grid grid-cols-2 gap-2">
            {images.map((image) => (
              <div
                key={image.id}
                className="relative group border rounded-lg p-2 bg-background"
              >
                <div className="flex items-center gap-2">
                  <img
                    src={imagesApi.getImageUrl(image.id)}
                    alt={image.original_name}
                    className="h-16 w-16 object-cover rounded"
                  />
                  <div className="flex-1 min-w-0">
                    <p className="text-xs font-medium truncate">
                      {image.original_name}
                    </p>
                    <p className="text-xs text-muted-foreground">
                      {formatFileSize(image.size_bytes)}
                    </p>
                  </div>
                </div>
                {!disabled && !readOnly && (
                  <Button
                    variant="ghost"
                    size="icon"
                    className="absolute top-1 right-1 h-6 w-6 opacity-0 group-hover:opacity-100 transition-opacity"
                    onClick={() => handleRemoveImage(image.id)}
                  >
                    <X className="h-3 w-3" />
                  </Button>
                )}
              </div>
            ))}
          </div>
        )}

        {/* Uploading indicators */}
        {uploadingFiles.size > 0 && (
          <div className="space-y-1">
            {Array.from(uploadingFiles).map((tempId) => (
              <div
                key={tempId}
                className="flex items-center gap-2 text-xs text-muted-foreground"
              >
                <div className="h-3 w-3 border-2 border-primary border-t-transparent rounded-full animate-spin" />
                <span>Uploading...</span>
              </div>
            ))}
          </div>
        )}
      </div>
    );

    if (!collapsible) {
      return content;
    }

    return (
      <div className="space-y-2">
        <button
          type="button"
          onClick={() => setIsExpanded(!isExpanded)}
          className="flex items-center gap-2 text-sm text-muted-foreground hover:text-foreground transition-colors"
        >
          <ChevronRight
            className={cn(
              'h-3 w-3 transition-transform',
              isExpanded && 'rotate-90'
            )}
          />
          <ImageIcon className="h-4 w-4" />
          <span>Images {images.length > 0 && `(${images.length})`}</span>
        </button>
        {isExpanded && content}
      </div>
    );
  }
);

ImageUploadSection.displayName = 'ImageUploadSection';