/** Interface for the options used to export a dashboard or map as a PDF */
export interface PdfExportOptions {
  page_size: "Letter" | "A4" | "A3"
  orientation: "portrait" | "landscape"

  /** The margins to use for the PDF in inches. Usually 0.5 inch by default. */
  margins: number

  /**
   * Scaling factor for the viewport width. Higher values will render the content at a larger size.
   */
  scale: number
}

export const defaultOptions: PdfExportOptions = {
  page_size: "Letter",
  orientation: "portrait",
  margins: 0.5,
  scale: 1
}

// Chrome default DPI for printing
const DPI = 144

const PAGE_DIMENSIONS_INCHES = {
  Letter: { width: 8.5, height: 11 },
  A4: { width: 8.27, height: 11.69 }, // 210mm x 297mm
  A3: { width: 11.69, height: 16.54 } // 297mm x 420mm
}

/**
 * Calculates the viewport width for a given page size and orientation
 * @param options The options to use for the calculation
 * @returns The viewport width in pixels
 */
export function calculateViewportWidth(options: PdfExportOptions): number {
  const { page_size, orientation, margins, scale } = options

  const dimensions = PAGE_DIMENSIONS_INCHES[page_size]
  if (!dimensions) {
    throw new Error(`Unknown page size: ${page_size}`)
  }

  let actualPageWidth: number
  if (orientation === "portrait") {
    actualPageWidth = dimensions.width
  } else {
    actualPageWidth = dimensions.height // In landscape, the page height becomes the effective width
  }

  const printableWidthInches = actualPageWidth - (2 * margins)
  const printableWidthPixels = printableWidthInches * DPI
  const finalWidth = printableWidthPixels

  return Math.round(finalWidth) // Return an integer value for pixels
}

/**
 * Calculates the viewport height for a given page size and orientation
 * @param options The options to use for the calculation
 * @returns The viewport height in pixels
 */
export function calculateViewportHeight(options: PdfExportOptions): number {
  const { page_size, orientation, margins, scale } = options

  const dimensions = PAGE_DIMENSIONS_INCHES[page_size]
  if (!dimensions) {
    throw new Error(`Unknown page size: ${page_size}`)
  }

  let actualPageHeight: number
  if (orientation === "portrait") {
    actualPageHeight = dimensions.height
  } else {
    actualPageHeight = dimensions.width // In landscape, the page width becomes the effective height
  }

  const printableHeightInches = actualPageHeight - (2 * margins)
  const printableHeightPixels = printableHeightInches * DPI
  const finalHeight = printableHeightPixels

  return Math.round(finalHeight) // Return an integer value for pixels
}