import React, { useState, useEffect, useMemo, useCallback } from 'react'
import { useParams, useNavigate } from 'react-router-dom'
import { Button } from '../ui/Button'
import {
  FaArrowLeft,
  FaCalendarAlt,
  FaFileAlt,
  FaDownload,
  FaSearchPlus,
  FaSearchMinus,
} from 'react-icons/fa'
import { ReportGeneratedDto, ReportTemplateDto } from '@/proxy/reports/models'
import { useReports } from '@/utils/hooks/useReports'
import { ROUTES_ENUM } from '@/routes/route.constant'
import { useLocalization } from '@/utils/hooks/useLocalization'

export const ReportViewer: React.FC = () => {
  const { id } = useParams<{ id: string }>()
  const navigate = useNavigate()
  const [zoomLevel, setZoomLevel] = useState(100)
  const [report, setReport] = useState<ReportGeneratedDto | null>(null)
  const [template, setTemplate] = useState<ReportTemplateDto | null>(null)
  const [isLoading, setIsLoading] = useState(true)
  const [error, setError] = useState<string | null>(null)
  const { translate } = useLocalization()
  const { getReportById, getTemplateById } = useReports()

  // İçeriği sayfalara bölen fonksiyon
  const splitContentIntoPages = (content: string) => {
    // Basit olarak içeriği paragraf ve tablo bazında bölelim
    const tempDiv = document.createElement('div')
    tempDiv.innerHTML = content

    const elements = Array.from(tempDiv.children)
    const pages: string[] = []
    let currentPage = ''
    let currentPageHeight = 0
    const maxPageHeight = 257 // 297mm - 40mm padding (top+bottom)

    elements.forEach((element) => {
      const elementHtml = element.outerHTML
      // Basit yükseklik tahmini (gerçek uygulamada daha karmaşık olabilir)
      let estimatedHeight = 20 // Default height

      if (element.tagName === 'TABLE') {
        const rows = element.querySelectorAll('tr')
        estimatedHeight = rows.length * 25 // Her satır için 25mm
      } else if (element.tagName.startsWith('H')) {
        estimatedHeight = 15
      } else if (element.tagName === 'P') {
        estimatedHeight = 10
      }

      if (currentPageHeight + estimatedHeight > maxPageHeight && currentPage) {
        pages.push(currentPage)
        currentPage = elementHtml
        currentPageHeight = estimatedHeight
      } else {
        currentPage += elementHtml
        currentPageHeight += estimatedHeight
      }
    })

    if (currentPage) {
      pages.push(currentPage)
    }

    return pages.length > 0 ? pages : [content]
  }

  const preloadPdfLibs = useCallback(() => {
    // Hover’da ısıtma için (opsiyonel)
    import('jspdf')
    import('html2canvas')
  }, [])

  // YENİ: memoize edilmiş sayfalar
  const memoizedPages = useMemo(() => {
    return report ? splitContentIntoPages(report.generatedContent) : []
  }, [report])

  // Asenkron veri yükleme
  useEffect(() => {
    const loadReportData = async () => {
      if (!id) {
        setError("Rapor ID'si bulunamadı")
        setIsLoading(false)
        return
      }

      try {
        setIsLoading(true)
        setError(null)

        // Raporu yükle
        const reportData = await getReportById(id)

        if (!reportData) {
          setError('Rapor bulunamadı')
          setIsLoading(false)
          return
        }

        setReport(reportData)

        // Şablonu yükle
        if (reportData.templateId) {
          const templateData = await getTemplateById(reportData.templateId)
          setTemplate(templateData || null)
        }
      } catch (err) {
        console.error('Error loading report data:', err)
        setError('Rapor yüklenirken bir hata oluştu')
      } finally {
        setIsLoading(false)
      }
    }

    loadReportData()
  }, [id, getReportById, getTemplateById])

  // Zoom fonksiyonları
  const handleZoomIn = () => {
    setZoomLevel((prev) => Math.min(prev + 25, 200)) // Maksimum %200
  }

  const handleZoomOut = () => {
    setZoomLevel((prev) => Math.max(prev - 25, 50)) // Minimum %50
  }

  // Loading durumu
  if (isLoading) {
    return (
      <div className="min-h-screen bg-gray-50 flex items-center justify-center">
        <div className="text-center">
          <div className="animate-spin rounded-full h-12 w-12 border-b-2 border-blue-600 mx-auto mb-4"></div>
          <h1 className="text-xl font-semibold text-gray-900 mb-2">
            {translate('::App.Reports.ReportViewer.LoadingTitle')}
          </h1>
          <p className="text-gray-600">{translate('::App.Reports.ReportViewer.LoadingSubtitle')}</p>
        </div>
      </div>
    )
  }

  // Error durumu
  if (error || !id) {
    return (
      <div className="min-h-screen bg-gray-50 flex items-center justify-center">
        <div className="text-center">
          <h1 className="text-2xl font-bold text-gray-900 mb-4">
            {error || translate('::App.Reports.ReportViewer.ErrorNotFound')}
          </h1>
          <Button onClick={() => navigate(ROUTES_ENUM.protected.dashboard)}>
            <FaArrowLeft className="h-4 w-4 mr-2" />
            Ana Sayfaya Dön
          </Button>
        </div>
      </div>
    )
  }

  if (!id) {
    return (
      <div className="min-h-screen bg-gray-50 flex items-center justify-center">
        <div className="text-center">
          <h1 className="text-2xl font-bold text-gray-900 mb-4">
            {translate('::App.Reports.ReportViewer.ErrorNotFound')}
          </h1>
          <Button onClick={() => navigate(ROUTES_ENUM.protected.dashboard)}>
            <FaArrowLeft className="h-4 w-4 mr-2" />
            Ana Sayfaya Dön
          </Button>
        </div>
      </div>
    )
  }

  // Report yüklenmemiş ise
  if (!report) {
    return (
      <div className="min-h-screen bg-gray-50 flex items-center justify-center">
        <div className="text-center">
          <h1 className="text-2xl font-bold text-gray-900 mb-4">
            {translate('::App.Reports.ReportViewer.ErrorNotFound')}
          </h1>
          <p className="text-gray-600 mb-6">
            {translate('::App.Reports.ReportViewer.ErrorNotFoundDescription')}
          </p>
          <Button onClick={() => navigate(ROUTES_ENUM.protected.dashboard)}>
            <FaArrowLeft className="h-4 w-4 mr-2" />
            {translate('::App.Reports.ReportViewer.BackToDashboard')}
          </Button>
        </div>
      </div>
    )
  }

  const handlePrint = () => {
    // Yazdırma sırasında zoom seviyesini geçici olarak %100'e ayarla
    const currentZoom = zoomLevel
    setZoomLevel(100)

    // DOM'un güncellenmesi için kısa bir gecikme
    setTimeout(() => {
      window.print()

      // Yazdırma işlemi tamamlandıktan sonra orijinal zoom seviyesine geri dön
      // Print dialog kapandıktan sonra zoom'u eski haline getir
      setTimeout(() => {
        setZoomLevel(currentZoom)
      }, 100)
    }, 100)
  }

  // DEĞİŞTİR: handleDownloadPdf
  const handleDownloadPdf = async () => {
    // Ağır kütüphaneleri ihtiyaç anında indir
    const [jspdfMod, h2cMod] = await Promise.all([import('jspdf'), import('html2canvas')])

    // jsPDF bazı dağıtımlarda default, bazılarında { jsPDF } olarak gelir
    const jsPDFCtor = (jspdfMod as any).default ?? (jspdfMod as any).jsPDF
    const html2canvas = (h2cMod as any).default ?? (h2cMod as any)

    const pages = memoizedPages // aşağıdaki 2. adımda tanımlayacağız

    try {
      const pdf = new jsPDFCtor({ orientation: 'portrait', unit: 'mm', format: 'a4' })

      for (let i = 0; i < pages.length; i++) {
        const elementId = i === 0 ? 'report-content' : `report-content-page-${i + 1}`
        const element = document.getElementById(elementId)
        if (!element) continue

        // Yakalama öncesi zoom’u etkisizleştir (transform varsa kalite düşmesin)
        const container = element.parentElement as HTMLElement | null
        const prevTransform = container?.style.transform
        if (container) container.style.transform = 'none'

        const canvas = await html2canvas(element, {
          scale: 2,
          useCORS: true,
          allowTaint: true,
          backgroundColor: '#ffffff',
        })

        if (container) container.style.transform = prevTransform ?? ''

        const imgData = canvas.toDataURL('image/png')
        const imgWidth = 210
        const imgHeight = 297
        if (i > 0) pdf.addPage()
        pdf.addImage(imgData, 'PNG', 0, 0, imgWidth, imgHeight)
      }

      pdf.save(
        `${report!.templateName}_${new Date(report!.generatedAt).toLocaleDateString('tr-TR')}.pdf`,
      )
    } catch (error) {
      console.error('PDF oluşturma hatası:', error)
      alert('PDF oluşturulurken bir hata oluştu.')
    }
  }

  return (
    <div className="min-h-screen bg-gray-50">
      {/* Header - Print edilmeyecek */}
      <div className="print:hidden bg-white shadow-sm border-b border-gray-200 sticky top-0 z-10">
        <div className="w-full px-4">
          <div className="flex items-center justify-between h-16">
            <div className="flex items-center space-x-4 flex-1">
              <div className="flex-1">
                <h1 className="text-lg font-semibold text-gray-900">{report.templateName}</h1>
                <div className="flex items-center space-x-4 text-sm text-gray-500">
                  <span className="flex items-center">
                    <FaCalendarAlt className="h-4 w-4 mr-1" />
                    {new Date(report.generatedAt).toLocaleDateString('tr-TR', {
                      year: 'numeric',
                      month: 'long',
                      day: 'numeric',
                      hour: '2-digit',
                      minute: '2-digit',
                    })}
                  </span>
                  {template && (
                    <span className="flex items-center">
                      <FaFileAlt className="h-4 w-4 mr-1" />
                      {template.categoryName}
                    </span>
                  )}
                </div>
              </div>
            </div>

            <div className="flex items-center space-x-2 flex-shrink-0">
              <Button variant="solid" onClick={handleZoomOut} disabled={zoomLevel <= 50} size="sm">
                <FaSearchMinus className="h-4 w-4" />
              </Button>
              <span className="text-sm text-gray-600 px-2 min-w-[4rem] text-center">
                {zoomLevel}%
              </span>
              <Button variant="solid" onClick={handleZoomIn} disabled={zoomLevel >= 200} size="sm">
                <FaSearchPlus className="h-4 w-4" />
              </Button>
              <div className="w-px h-6 bg-gray-300 mx-2"></div>
              <Button
                onMouseEnter={preloadPdfLibs} // ← opsiyonel prefetch
                onClick={handleDownloadPdf}
                className="bg-white-600 hover:bg-white-700 font-medium px-2 sm:px-3 py-1.5 rounded text-xs flex items-center gap-1"
              >
                <FaDownload className="h-4 w-4 mr-2" />
                {translate('::App.Reports.ReportViewer.DownloadPDF')}
              </Button>
              <Button variant="solid" onClick={handlePrint}>
                {translate('::App.Reports.ReportViewer.Print')}
              </Button>
            </div>
          </div>
        </div>
      </div>

      {/* Rapor İçeriği */}
      <div className="flex justify-center bg-gray-200 py-8 print:bg-white print:py-0">
        <div
          className="space-y-8 print:space-y-0 transition-transform duration-300 ease-in-out"
          style={{
            transform: `scale(${zoomLevel / 100})`,
            transformOrigin: 'top center',
          }}
        >
          {memoizedPages.map((pageContent, index) => (
            <div
              key={index}
              id={index === 0 ? 'report-content' : `report-content-page-${index + 1}`}
              className="bg-white shadow-lg print:shadow-none page-container"
              style={{
                width: '210mm',
                minHeight: '297mm',
                padding: '0',
                boxSizing: 'border-box',
                position: 'relative',
                display: 'flex',
                flexDirection: 'column',
              }}
            >
              {index === 0 && (
                <style>
                  {`
                    /* Sayfa kırılması için CSS */
                    .page-container {
                      page-break-after: always;
                      margin-bottom: 20px;
                    }
                    
                    .page-container:last-child {
                      page-break-after: auto;
                      margin-bottom: 0;
                    }
                    
                    /* Header ve Footer stilleri */
                    .page-header {
                      height: 15mm;
                      width: 100%;
                      display: flex;
                      align-items: center;
                      justify-content: right;
                      background-color: transparent;
                      color: #666;
                      font-size: 10px;
                      padding: 0 20mm;
                      box-sizing: border-box;
                    }
                    
                    .page-footer {
                      height: 15mm;
                      width: 100%;
                      display: flex;
                      align-items: center;
                      justify-content: flex-end;
                      background-color: transparent;
                      color: #666;
                      font-size: 10px;
                      padding: 0 20mm;
                      box-sizing: border-box;
                      margin-top: auto;
                    }
                    
                    .page-content-area {
                      flex: 1;
                      padding: 0 20mm;
                      min-height: 267mm; /* 297mm - 15mm header - 15mm footer */
                      box-sizing: border-box;
                    }
                    
                    /* İçerik için sayfa kırılması kuralları */
                    .page-container h1, .page-container h2, .page-container h3 {
                      page-break-after: avoid;
                    }
                    
                    .page-container table {
                      page-break-inside: avoid;
                      border-collapse: collapse;
                      width: 100%;
                      margin: 0;
                    }
                    
                    .page-container table td,
                    .page-container table th {
                      border: 1px solid #ddd;
                      text-align: left;
                      vertical-align: top;
                    }
                
                    /* Print specific styles */
                    @media print {
                      body { 
                        margin: 0 !important; 
                        padding: 0 !important; 
                      }
                      
                      .page-container {
                        width: 210mm !important;
                        min-height: 297mm !important;
                        margin: 0 !important;
                        padding: 0 !important;
                        box-shadow: none !important;
                        page-break-after: always !important;
                      }
                      
                      .page-container:last-child {
                        page-break-after: auto !important;
                      }
                      
                      .page-header {
                        height: 15mm !important;
                        color: #666 !important;
                        -webkit-print-color-adjust: exact !important;
                      }
                      
                      .page-footer {
                        height: 15mm !important;
                        color: #666 !important;
                        -webkit-print-color-adjust: exact !important;
                      }
                      
                      .page-content-area {
                        padding: 0 20mm !important;
                        min-height: 267mm !important;
                      }
                      
                      .print\\:hidden { 
                        display: none !important; 
                      }
                      
                      /* Table print styles */
                      .page-container table {
                        border-collapse: collapse !important;
                        page-break-inside: avoid !important;
                      }
                      
                      .page-container table th,
                      .page-container table td {
                        border: 1px solid #000 !important;
                        page-break-inside: avoid !important;
                      }
                      
                      .page-container table th {
                        background-color: #f0f0f0 !important;
                        -webkit-print-color-adjust: exact !important;
                        color-adjust: exact !important;
                      }
                      
                      .page-container table tr:nth-child(even) {
                        background-color: #f5f5f5 !important;
                        -webkit-print-color-adjust: exact !important;
                        color-adjust: exact !important;
                      }
                    }
                  `}
                </style>
              )}

              {/* Sayfa Header - Tarih ve Saat */}
              <div className="page-header">
                {new Date().toLocaleDateString('tr-TR', {
                  year: 'numeric',
                  month: 'long',
                  day: 'numeric',
                  hour: '2-digit',
                  minute: '2-digit',
                })}
              </div>

              {/* Sayfa İçeriği */}
              <div className="page-content-area">
                <div dangerouslySetInnerHTML={{ __html: pageContent }} />
              </div>

              {/* Sayfa Footer - Sayfa Numarası */}
              <div className="page-footer">
                {translate('::App.Reports.ReportViewer.Page')} {index + 1} / {memoizedPages.length}
              </div>
            </div>
          ))}
        </div>
      </div>
    </div>
  )
}