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

var noTableHeight = 0 //table外的元素高度

export const htmlPdf = (title, html, fileList, type) => {
  return new Promise((resolve, reject) => {
    if (fileList) {
      const pageHeight = Math.floor(277 * html.scrollWidth / 190) + 20 // 计算pdf高度
      for (let i = 0; i < fileList.length; i++) { // 循环获取的元素
        const multiple = Math.ceil((fileList[i].offsetTop + fileList[i].offsetHeight) / pageHeight) // 元素的高度
        if (isSplit(fileList, i, multiple * pageHeight)) { // 计算是否超出一页
          var _H = '' // 向pdf插入空白块的内容高度
          if (fileList[i].localName !== 'tr') { // 判断是不是表格里的内容
            _H = multiple * pageHeight - (fileList[i].offsetTop + fileList[i].offsetHeight)
          } else {
            _H = multiple * pageHeight - (fileList[i].offsetTop + fileList[i].offsetHeight + noTableHeight) + 20
          }
          var newNode = getFooterElement(_H)  // 向pdf插入空白块的内容
          const divParent = fileList[i].parentNode // 获取该div的父节点
          const next = fileList[i].nextSibling // 获取div的下一个兄弟节点
          // 判断兄弟节点是否存在
          if (next) {
            // 存在则将新节点插入到div的下一个兄弟节点之前，即div之后
            divParent.insertBefore(newNode, next)
          } else {
            // 否则向节点添加最后一个子节点
            divParent.appendChild(newNode)
          }
        }
      }
    }

    html2Canvas(html, {
      allowTaint: false,
      taintTest: false,
      logging: false,
      useCORS: true,
      dpi: window.devicePixelRatio * 1,
      scale: 1 // 按比例增加分辨率
    }).then(canvas => {
      var pdf = new JsPDF('l', 'mm', 'a4') // A4纸，横向或纵向
      var ctx = canvas.getContext('2d')
      var a4w = type ? 277 : 190; var a4h = type ? 190 : 277 // A4大小
      var imgHeight = Math.floor(a4h * canvas.width / a4w) // 按A4显示比例换算一页图像的像素高度
      var renderedHeight = 0

      while (renderedHeight < canvas.height) {
        var page = document.createElement('canvas')
        page.width = canvas.width
        page.height = Math.min(imgHeight, canvas.height - renderedHeight)// 可能内容不足一页

        // 用getImageData剪裁指定区域，并画到前面创建的canvas对象中
        page.getContext('2d').putImageData(ctx.getImageData(0, renderedHeight, canvas.width, Math.min(imgHeight, canvas.height - renderedHeight)), 0, 0)
        pdf.addImage(page.toDataURL('image/jpeg', 1.0), 'JPEG', 10, 10, a4w, Math.min(a4h, a4w * page.height / page.width)) // 添加图像到页面

        renderedHeight += imgHeight
        if (renderedHeight < canvas.height) {
          pdf.addPage()// 如果后面还有内容，添加一个空页
        }
      }

      // 返回Blob对象而不是直接下载文件
      const pdfBlob = pdf.output('blob');
      resolve(pdfBlob);
    }).catch(error => {
      reject(error);
    });
  });
}

// pdf截断需要一个空白位置来补充
const getFooterElement = (remainingHeight, fillingHeight = 0) => {
  const newNode = document.createElement('div')
  newNode.style.background = '#ffffff'
  newNode.style.width = 'calc(100% + 8px)'
  newNode.style.marginLeft = '-4px'
  newNode.style.marginBottom = '0px'
  newNode.classList.add('divRemove')
  newNode.style.height = (remainingHeight + fillingHeight) + 'px'
  return newNode
}

const isSplit = (nodes, index, pageHeight) => {
  if (nodes[index].localName !== 'tr') {  // 判断元素是不是tr
    noTableHeight += nodes[index].clientHeight
  }

  if (nodes[index].localName !== 'tr') {
    return nodes[index].offsetTop + nodes[index].offsetHeight < pageHeight && nodes[index + 1] && nodes[index + 1].offsetTop + nodes[index + 1].offsetHeight > pageHeight
  } else {
    return nodes[index].offsetTop + nodes[index].offsetHeight + noTableHeight < pageHeight && nodes[index + 1] && nodes[index + 1].offsetTop + nodes[index + 1].offsetHeight + noTableHeight > pageHeight
  }
}