hooks/useCanvasFileUtils.ts

import React, { useCallback } from 'react';
import { getBlankCanvasDataURL } from '../utils/canvasUtils';
import { CanvasHistoryHook } from './useCanvasHistory';
import { ConfirmModalHook } from './useConfirmModal';
import { ToastMessage } from './useToasts';


interface UseCanvasFileUtilsProps {
  canvasState: {
    currentDataURL: string | null;
    canvasWidth: number;
    canvasHeight: number;
  };
  historyActions: {
    updateCanvasState: CanvasHistoryHook['updateCanvasState'];
  };
  uiActions: {
    showToast: (message: string, type: ToastMessage['type']) => void;
    setZoomLevel: (zoom: number) => void;
  };
  confirmModalActions: {
    requestConfirmation: ConfirmModalHook['requestConfirmation'];
  };
}

export interface CanvasFileUtilsHook {
  handleLoadImageFile: (event: React.ChangeEvent<HTMLInputElement>) => void;
  handleExportImage: () => void;
  handleClearCanvas: () => void;
  handleCanvasSizeChange: (newWidth: number, newHeight: number) => void;
}

export const useCanvasFileUtils = ({
  canvasState,
  historyActions,
  uiActions,
  confirmModalActions,
}: UseCanvasFileUtilsProps): CanvasFileUtilsHook => {
  const { currentDataURL, canvasWidth, canvasHeight } = canvasState;
  const { updateCanvasState } = historyActions;
  const { showToast, setZoomLevel } = uiActions;
  const { requestConfirmation } = confirmModalActions;

  const handleLoadImageFile = useCallback((event: React.ChangeEvent<HTMLInputElement>) => {
    const file = event.target.files?.[0];
    if (file) {
      const reader = new FileReader();
      reader.onload = (e) => {
        const imageDataUrl = e.target?.result as string;
        if (imageDataUrl) {
          const img = new Image();
          img.onload = () => {
            let imageToDrawWidth = img.naturalWidth;
            let imageToDrawHeight = img.naturalHeight;

            if (img.naturalWidth > canvasWidth || img.naturalHeight > canvasHeight) {
                const widthRatio = canvasWidth / img.naturalWidth;
                const heightRatio = canvasHeight / img.naturalHeight;
                const scaleFactor = Math.min(widthRatio, heightRatio); 
                imageToDrawWidth = Math.max(1, Math.floor(img.naturalWidth * scaleFactor));
                imageToDrawHeight = Math.max(1, Math.floor(img.naturalHeight * scaleFactor));
            }
            
            const finalCanvasWidth = canvasWidth;
            const finalCanvasHeight = canvasHeight;

            const tempCanvas = document.createElement('canvas');
            tempCanvas.width = finalCanvasWidth;
            tempCanvas.height = finalCanvasHeight;
            const tempCtx = tempCanvas.getContext('2d');

            if (tempCtx) {
              tempCtx.fillStyle = '#FFFFFF';
              tempCtx.fillRect(0, 0, finalCanvasWidth, finalCanvasHeight);
              
              // Change: Draw image at top-left (0,0)
              const drawX = 0; 
              const drawY = 0;
              
              tempCtx.drawImage(img, drawX, drawY, imageToDrawWidth, imageToDrawHeight); 
              const compositeDataURL = tempCanvas.toDataURL('image/png');
              
              updateCanvasState(compositeDataURL, finalCanvasWidth, finalCanvasHeight);
              showToast('Image loaded successfully.', 'success');
            }
          };
          img.onerror = () => showToast("Error loading image file for processing.", 'error');
          img.src = imageDataUrl;
        }
      };
      reader.onerror = () => showToast("Error reading image file.", 'error');
      reader.readAsDataURL(file);
      if(event.target) event.target.value = ''; 
    }
  }, [canvasWidth, canvasHeight, updateCanvasState, showToast]);
  
  const handleExportImage = useCallback(() => {
    if (currentDataURL) {
      const link = document.createElement('a');
      link.href = currentDataURL;
      link.download = `paint-masterpiece-${Date.now()}.png`;
      document.body.appendChild(link);
      link.click();
      document.body.removeChild(link);
      showToast('Image exported!', 'success');
    } else {
      showToast('No image to export.', 'info');
    }
  }, [currentDataURL, showToast]);

  const handleClearCanvas = useCallback(() => {
    const blankCanvas = getBlankCanvasDataURL(canvasWidth, canvasHeight);
    updateCanvasState(blankCanvas, canvasWidth, canvasHeight);
    showToast("Canvas cleared.", "info");
  }, [canvasWidth, canvasHeight, updateCanvasState, showToast]);

  const handleCanvasSizeChange = useCallback((newWidth: number, newHeight: number) => {
    if (newWidth === canvasWidth && newHeight === canvasHeight) {
      return;
    }
    requestConfirmation(
      "Confirm Canvas Size Change",
      "Changing canvas size will clear the current drawing and history. Are you sure you want to continue?",
      () => {
        const blankCanvas = getBlankCanvasDataURL(newWidth, newHeight);
        updateCanvasState(blankCanvas, newWidth, newHeight);
        setZoomLevel(0.5);
        showToast(`Canvas resized to ${newWidth}x${newHeight}px. Drawing cleared.`, 'info');
      },
      { isDestructive: true }
    );
  }, [canvasWidth, canvasHeight, requestConfirmation, updateCanvasState, setZoomLevel, showToast]);

  return { handleLoadImageFile, handleExportImage, handleClearCanvas, handleCanvasSizeChange };
};