import html2Canvas from 'html2canvas'
import JsPDF from 'jspdf'

class PDF {
  /**
   * 从 HTML 中生成 PDF
   * @param element HTML 元素
   */
  public static generate(element: HTMLElement): Promise<JsPDF> {
    return new Promise<JsPDF>((resolve: any) => {
      html2Canvas(element, {
        y: 280,
      }).then((canvas: any) => {
        const contentWidth = canvas.width
        const contentHeight = canvas.height
        const pageHeight = (contentWidth / 592.28) * 841.89

        const imgWidth = 595.28
        const imgHeight = (592.28 / contentWidth) * contentHeight
        const pageData = canvas.toDataURL('image/jpeg', 1.0)
        const pdf = new JsPDF('portrait', 'pt', 'a4')

        let leftHeight = contentHeight - 280
        let position = 0

        if (leftHeight < pageHeight) {
          pdf.addImage(pageData, 'JPEG', 0, 0, imgWidth, imgHeight)
        } else {
          while (leftHeight > 0) {
            pdf.addImage(pageData, 'JPEG', 0, position, imgWidth, imgHeight)
            leftHeight -= pageHeight
            position -= 841.89

            if (leftHeight > 0) {
              pdf.addPage()
            }
          }
        }

        resolve(pdf)
      })
    })
  }
}

// eslint-disable-next-line import/no-unused-modules
export { PDF }