'use client';

import Image from 'next/image';
import { type ChangeEvent, useRef, useState } from 'react';
import {
  type Preloaded,
  usePreloadedQuery,
  useMutation,
  useQuery,
} from 'convex/react';
import { api } from '~/convex/_generated/api';
import {
  BasedAvatar,
  Button,
  CardContent,
  ImageCrop,
  ImageCropApply,
  ImageCropContent,
  ImageCropReset,
  Input,
} from '@/components/ui';
import { toast } from 'sonner';
import { Loader2, Pencil, Upload, XIcon } from 'lucide-react';
import { type Id } from '~/convex/_generated/dataModel';

type AvatarUploadProps = {
  preloadedUser: Preloaded<typeof api.auth.getUser>;
};

const dataUrlToBlob = async (
  dataUrl: string,
): Promise<{ blob: Blob; type: string }> => {
  const re = /^data:([^;,]+)[;,]/;
  const m = re.exec(dataUrl);
  const type = m?.[1] ?? 'image/png';

  const res = await fetch(dataUrl);
  const blob = await res.blob();
  return { blob, type };
};

export const AvatarUpload = ({ preloadedUser }: AvatarUploadProps) => {
  const user = usePreloadedQuery(preloadedUser);
  const [isUploading, setIsUploading] = useState(false);
  const [selectedFile, setSelectedFile] = useState<File | null>(null);
  const [croppedImage, setCroppedImage] = useState<string | null>(null);

  const inputRef = useRef<HTMLInputElement>(null);

  const generateUploadUrl = useMutation(api.files.generateUploadUrl);
  const updateUserImage = useMutation(api.auth.updateUserImage);

  const currentImageUrl = useQuery(
    api.files.getImageUrl,
    user?.image ? { storageId: user.image } : 'skip',
  );

  const handleFileChange = (event: ChangeEvent<HTMLInputElement>) => {
    const file = event.target.files?.[0] ?? null;
    if (!file) return;
    if (!file.type.startsWith('image/')) {
      toast.error('Please select an image file.');
      if (inputRef.current) inputRef.current.value = '';
      return;
    }
    setSelectedFile(file);
    setCroppedImage(null);
  };

  const handleReset = () => {
    setSelectedFile(null);
    setCroppedImage(null);
    if (inputRef.current) inputRef.current.value = '';
  };

  const handleSave = async () => {
    if (!croppedImage) {
      toast.error('Please apply a crop first.');
      return;
    }
    setIsUploading(true);
    try {
      const { blob, type } = await dataUrlToBlob(croppedImage);
      const postUrl = await generateUploadUrl();

      const result = await fetch(postUrl, {
        method: 'POST',
        headers: { 'Content-Type': type },
        body: blob,
      });
      if (!result.ok) {
        const msg = await result.text().catch(() => 'Upload failed.');
        throw new Error(msg);
      }

      const uploadResponse = (await result.json()) as {
        storageId: Id<'_storage'>;
      };

      await updateUserImage({ storageId: uploadResponse.storageId });

      toast.success('Profile picture updated.');
      handleReset();
    } catch (error) {
      console.error('Upload failed:', error);
      toast.error('Upload failed. Please try again.');
    } finally {
      setIsUploading(false);
    }
  };

  return (
    <CardContent>
      <div className='flex flex-col items-center gap-4'>
        {/* Current avatar + trigger (hidden when cropping) */}
        {!selectedFile && (
          <div
            className='relative group cursor-pointer'
            onClick={() => inputRef.current?.click()}
          >
            <BasedAvatar
              src={currentImageUrl ?? undefined}
              fullName={user?.name}
              className='h-32 w-32'
              fallbackProps={{ className: 'text-4xl font-semibold' }}
              userIconProps={{ size: 100 }}
            />
            <div
              className='absolute inset-0 rounded-full bg-black/0
                group-hover:bg-black/50 transition-all flex items-center
                justify-center'
            >
              <Upload
                className='text-white opacity-0 group-hover:opacity-100
                  transition-opacity'
                size={24}
              />
            </div>
            <div
              className='absolute inset-1 transition-all flex items-end
              justify-end'
            >
              <Pencil
                className='text-white opacity-100 group-hover:opacity-0
                  transition-opacity'
                size={24}
              />
            </div>
          </div>
        )}

        {/* File input (hidden) */}
        <Input
          ref={inputRef}
          id='avatar-upload'
          type='file'
          accept='image/*'
          className='hidden'
          onChange={handleFileChange}
          disabled={isUploading}
        />

        {/* Crop UI */}
        {selectedFile && !croppedImage && (
          <div className='flex flex-col items-center gap-3'>
            <ImageCrop
              aspect={1}
              circularCrop
              file={selectedFile}
              maxImageSize={3 * 1024 * 1024} // 3MB guard
              onCrop={setCroppedImage}
            >
              <ImageCropContent className='max-w-sm' />
              <div className='flex items-center gap-2'>
                <ImageCropApply />
                <ImageCropReset />
                <Button
                  onClick={handleReset}
                  size='icon'
                  type='button'
                  variant='ghost'
                >
                  <XIcon className='size-4' />
                </Button>
              </div>
            </ImageCrop>
          </div>
        )}

        {/* Cropped preview + actions */}
        {croppedImage && (
          <div className='flex flex-col items-center gap-3'>
            <Image
              alt='Cropped preview'
              className='overflow-hidden rounded-full'
              height={128}
              src={croppedImage}
              unoptimized
              width={128}
            />
            <div className='flex items-center gap-2'>
              <Button
                onClick={handleSave}
                disabled={isUploading}
                className='px-6'
              >
                {isUploading ? (
                  <span className='inline-flex items-center gap-2'>
                    <Loader2 className='h-4 w-4 animate-spin' />
                    Saving...
                  </span>
                ) : (
                  'Save Avatar'
                )}
              </Button>
              <Button
                onClick={handleReset}
                size='icon'
                type='button'
                variant='ghost'
              >
                <XIcon className='size-4' />
              </Button>
            </div>
          </div>
        )}

        {/* Uploading indicator */}
        {isUploading && !croppedImage && (
          <div className='flex items-center text-sm text-gray-500 mt-2'>
            <Loader2 className='h-4 w-4 mr-2 animate-spin' />
            Uploading...
          </div>
        )}
      </div>
    </CardContent>
  );
};