/**
 * PDF conversion utilities loaded on demand so headless startup
 * does not require ESM-only pdf-to-img at module load time.
 */
export async function convertPDFToImage(pdfInput, options = {}) {
  const [{ pdf }, sharp] = await Promise.all([
    import('pdf-to-img'),
    import('sharp')
  ])

  try {
    let scale = options.scale || 2

    const pdfOptions = {
      scale,
      ...options
    }

    const document = await pdf(pdfInput, pdfOptions)
    const outputImages = []

    if (
      options.page_numbers &&
      Array.isArray(options.page_numbers) &&
      options.page_numbers.length > 0
    ) {
      for (const pageNum of options.page_numbers) {
        let image = await document.getPage(pageNum)

        if (options.width || options.height) {
          const resizeOptions = {}
          if (options.width) resizeOptions.width = options.width
          if (options.height) resizeOptions.height = options.height
          image = await sharp.default(image).resize(resizeOptions).toBuffer()
        }

        outputImages.push(image)
      }
    } else {
      for await (const image of document) {
        let processedImage = image

        if (options.width || options.height) {
          const resizeOptions = {}
          if (options.width) resizeOptions.width = options.width
          if (options.height) resizeOptions.height = options.height
          processedImage = await sharp.default(image)
            .resize(resizeOptions)
            .toBuffer()
        }

        outputImages.push(processedImage)
      }
    }

    return outputImages
  } catch (error) {
    console.error('Error converting PDF to image:', error)
    throw error
  }
}