import { toPng } from 'html-to-image'
import jsPDF from 'jspdf'

export interface ExportPDFOptions {
  elementId: string
  filename?: string
  title?: string
  subtitle?: string
}

/**
 * Create a temporary header element for PDF
 */
function createPDFHeader(title: string, subtitle: string): HTMLDivElement {
  const header = document.createElement('div')
  header.style.cssText = `
    padding: 24px 32px;
    background: #ffffff;
    border-bottom: 1px solid #e5e7eb;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Helvetica, Arial, sans-serif;
  `

  const titleEl = document.createElement('h1')
  titleEl.textContent = title
  titleEl.style.cssText = `
    margin: 0 0 8px 0;
    font-size: 24px;
    font-weight: 600;
    color: #1f2328;
    line-height: 1.3;
  `

  const subtitleEl = document.createElement('p')
  subtitleEl.textContent = subtitle
  subtitleEl.style.cssText = `
    margin: 0 0 8px 0;
    font-size: 14px;
    color: #6b7280;
    line-height: 1.5;
  `

  const timestampEl = document.createElement('p')
  const timestamp = new Date().toLocaleString('zh-CN', {
    year: 'numeric',
    month: '2-digit',
    day: '2-digit',
    hour: '2-digit',
    minute: '2-digit',
  })
  timestampEl.textContent = `生成时间: ${timestamp}`
  timestampEl.style.cssText = `
    margin: 0;
    font-size: 12px;
    color: #9ca3af;
    line-height: 1.5;
  `

  header.appendChild(titleEl)
  if (subtitle)
    header.appendChild(subtitleEl)
  header.appendChild(timestampEl)

  return header
}

/**
 * Export DOM element to PDF
 * @param options Export options
 */
export async function exportToPDF(options: ExportPDFOptions): Promise<void> {
  const {
    elementId,
    filename = 'report.pdf',
    title = 'Performance Report',
    subtitle = '',
  } = options

  try {
    const element = document.getElementById(elementId)
    if (!element) {
      throw new Error(`Element with id "${elementId}" not found`)
    }

    // Create header element (separate from content)
    const header = createPDFHeader(title, subtitle)
    header.style.width = `${element.offsetWidth}px`
    header.style.position = 'fixed'
    header.style.left = '-9999px'
    header.style.top = '0'
    document.body.appendChild(header)

    // Wait a bit for header to render
    await new Promise(resolve => setTimeout(resolve, 100))

    // Capture header
    const headerDataUrl = await toPng(header, {
      quality: 0.95,
      pixelRatio: 2,
      backgroundColor: '#ffffff',
    })

    // Remove header
    document.body.removeChild(header)

    // Capture content directly (no cloning to preserve Canvas/SVG)
    const contentDataUrl = await toPng(element, {
      quality: 0.95,
      pixelRatio: 2,
      backgroundColor: '#ffffff',
      cacheBust: true,
    })

    // Load header image
    const headerImg = new Image()
    headerImg.src = headerDataUrl
    await new Promise((resolve) => {
      headerImg.onload = resolve
    })

    // Load content image
    const contentImg = new Image()
    contentImg.src = contentDataUrl
    await new Promise((resolve) => {
      contentImg.onload = resolve
    })

    // A4 size: 210mm x 297mm
    const pdfWidth = 210
    const pdfHeight = 297
    const margin = 10

    // Calculate scaling based on content width
    const ratio = (pdfWidth - margin * 2) / contentImg.width

    const headerHeight = headerImg.height * ratio
    const contentHeight = contentImg.height * ratio

    // Create PDF
    const pdf = new jsPDF({
      orientation: 'portrait',
      unit: 'mm',
      format: 'a4',
    })

    const pageWidth = pdf.internal.pageSize.getWidth()
    const pageHeight = pdf.internal.pageSize.getHeight()
    const availableHeight = pageHeight - margin * 2

    let currentY = margin

    // Add header on first page
    pdf.addImage(
      headerDataUrl,
      'PNG',
      margin,
      currentY,
      pdfWidth - margin * 2,
      headerHeight,
    )
    currentY += headerHeight

    // Check if content needs pagination
    const remainingHeight = availableHeight - headerHeight
    if (contentHeight <= remainingHeight) {
      // Content fits on first page
      pdf.addImage(
        contentDataUrl,
        'PNG',
        margin,
        currentY,
        pdfWidth - margin * 2,
        contentHeight,
      )
    }
    else {
      // Content needs multiple pages
      const totalPages = Math.ceil((headerHeight + contentHeight) / availableHeight)

      // First page: remaining space after header
      const firstPageContentHeight = remainingHeight
      const sourceHeightRatio = firstPageContentHeight / contentHeight
      const sourcePixelHeight = contentImg.height * sourceHeightRatio

      let canvas = document.createElement('canvas')
      canvas.width = contentImg.width
      canvas.height = sourcePixelHeight
      let ctx = canvas.getContext('2d')

      if (ctx) {
        ctx.fillStyle = '#ffffff'
        ctx.fillRect(0, 0, canvas.width, canvas.height)
        ctx.drawImage(
          contentImg,
          0, 0, contentImg.width, sourcePixelHeight,
          0, 0, canvas.width, canvas.height,
        )
        pdf.addImage(canvas.toDataURL('image/png', 0.95), 'PNG', margin, currentY, pdfWidth - margin * 2, firstPageContentHeight)
      }

      // Subsequent pages
      let remainingContentHeight = contentHeight - firstPageContentHeight
      let sourceY = sourcePixelHeight

      let pageNum = 2
      while (remainingContentHeight > 0) {
        pdf.addPage()

        const pageContentHeight = Math.min(availableHeight, remainingContentHeight)
        const pageSourceHeightRatio = pageContentHeight / contentHeight
        const pageSourcePixelHeight = contentImg.height * pageSourceHeightRatio

        canvas = document.createElement('canvas')
        canvas.width = contentImg.width
        canvas.height = pageSourcePixelHeight
        ctx = canvas.getContext('2d')

        if (ctx) {
          ctx.fillStyle = '#ffffff'
          ctx.fillRect(0, 0, canvas.width, canvas.height)
          ctx.drawImage(
            contentImg,
            0, sourceY, contentImg.width, pageSourcePixelHeight,
            0, 0, canvas.width, canvas.height,
          )
          pdf.addImage(canvas.toDataURL('image/png', 0.95), 'PNG', margin, margin, pdfWidth - margin * 2, pageContentHeight)
        }

        sourceY += pageSourcePixelHeight
        remainingContentHeight -= pageContentHeight
        pageNum++
      }

      // Add page numbers
      const totalPagesCount = pdf.getNumberOfPages()
      for (let i = 1; i <= totalPagesCount; i++) {
        pdf.setPage(i)
        pdf.setFontSize(9)
        pdf.setTextColor(156, 163, 175)
        pdf.text(
          `${i} / ${totalPagesCount}`,
          pageWidth / 2,
          pageHeight - 5,
          { align: 'center' },
        )
      }
    }

    // Save PDF
    pdf.save(filename)
  }
  catch (error) {
    console.error('Failed to export PDF:', error)
    throw error
  }
}