export const getBlankCanvasDataURL = (width: number, height: number): string => {
  const tempCanvas = document.createElement('canvas');
  tempCanvas.width = width;
  tempCanvas.height = height;
  const ctx = tempCanvas.getContext('2d');
  if (ctx) {
    ctx.fillStyle = '#FFFFFF'; // Ensure blank canvas is white
    ctx.fillRect(0, 0, width, height);
  }
  return tempCanvas.toDataURL('image/png');
};

export const dataURLtoBlob = async (dataurl: string): Promise<Blob> => {
  const res = await fetch(dataurl);
  return res.blob();
};

export const calculateSHA256 = async (blob: Blob): Promise<string> => {
  const buffer = await blob.arrayBuffer();
  const hashBuffer = await crypto.subtle.digest('SHA-256', buffer);
  const hashArray = Array.from(new Uint8Array(hashBuffer));
  return hashArray.map(b => b.toString(16).padStart(2, '0')).join('');
};

export const copyToClipboard = async (
    text: string,
    showInfoToast: (message: string, type: 'info' | 'error') => void // Callback for toast
): Promise<boolean> => {
  if (!navigator.clipboard) {
    showInfoToast('Clipboard API not available.', 'info');
    return false;
  }
  try {
    await navigator.clipboard.writeText(text);
    return true;
  } catch (err) {
    console.error('Failed to copy text: ', err);
    showInfoToast('Failed to copy URL to clipboard.', 'error');
    return false;
  }
};