'use client';

import { Download, Loader2 } from 'lucide-react';
import { useCallback, useState } from 'react';
import { Button } from '@/components/ui/button';

interface ExportPdfButtonProps {
  /** CSS selector for the DOM element to capture */
  targetSelector: string;
  /** Filename without extension */
  filename?: string;
}

export function ExportPdfButton({
  targetSelector,
  filename = 'dinh-gia-bat-dong-san',
}: ExportPdfButtonProps) {
  const [isExporting, setIsExporting] = useState(false);

  const handleExport = useCallback(async () => {
    setIsExporting(true);
    try {
      const element = document.querySelector(targetSelector);
      if (!element) {
        console.error('Export target not found:', targetSelector);
        return;
      }

      // Dynamic imports for client-only PDF libraries
      const [html2canvasModule, jsPDFModule] = await Promise.all([
        import('html2canvas'),
        import('jspdf'),
      ]);
      const html2canvas = html2canvasModule.default;
      const { jsPDF } = jsPDFModule;

      const canvas = await html2canvas(element as HTMLElement, {
        scale: 2,
        useCORS: true,
        logging: false,
        backgroundColor: '#ffffff',
      });

      const imgData = canvas.toDataURL('image/png');
      const imgWidth = canvas.width;
      const imgHeight = canvas.height;

      // A4 dimensions in mm
      const pdfWidth = 210;
      const pdfMargin = 10;
      const contentWidth = pdfWidth - 2 * pdfMargin;
      const contentHeight = (imgHeight / imgWidth) * contentWidth;

      const pdf = new jsPDF({
        orientation: contentHeight > 297 - 2 * pdfMargin ? 'portrait' : 'portrait',
        unit: 'mm',
        format: 'a4',
      });

      // Add header
      pdf.setFontSize(16);
      pdf.setTextColor(34, 139, 34); // Green
      pdf.text('GoodGo — Báo cáo định giá', pdfMargin, pdfMargin + 5);
      pdf.setFontSize(10);
      pdf.setTextColor(128, 128, 128);
      pdf.text(
        `Ngày: ${new Date().toLocaleDateString('vi-VN')}`,
        pdfMargin,
        pdfMargin + 12,
      );

      const headerHeight = 20;
      const availableHeight = 297 - 2 * pdfMargin - headerHeight;

      if (contentHeight <= availableHeight) {
        // Fits on one page
        pdf.addImage(
          imgData,
          'PNG',
          pdfMargin,
          pdfMargin + headerHeight,
          contentWidth,
          contentHeight,
        );
      } else {
        // Multi-page: split the image
        let yOffset = 0;
        let isFirstPage = true;

        while (yOffset < contentHeight) {
          if (!isFirstPage) {
            pdf.addPage();
          }

          const pageContentHeight = isFirstPage
            ? availableHeight
            : 297 - 2 * pdfMargin;
          const pageTopMargin = isFirstPage
            ? pdfMargin + headerHeight
            : pdfMargin;

          // Calculate source rectangle in image coordinates
          const srcY = (yOffset / contentHeight) * imgHeight;
          const srcHeight = (pageContentHeight / contentHeight) * imgHeight;

          // Create a temporary canvas for this page slice
          const pageCanvas = document.createElement('canvas');
          pageCanvas.width = imgWidth;
          pageCanvas.height = Math.min(srcHeight, imgHeight - srcY);

          const ctx = pageCanvas.getContext('2d');
          if (ctx) {
            ctx.drawImage(
              canvas,
              0,
              srcY,
              imgWidth,
              pageCanvas.height,
              0,
              0,
              imgWidth,
              pageCanvas.height,
            );
          }

          const pageImgData = pageCanvas.toDataURL('image/png');
          const sliceHeight =
            (pageCanvas.height / imgWidth) * contentWidth;

          pdf.addImage(
            pageImgData,
            'PNG',
            pdfMargin,
            pageTopMargin,
            contentWidth,
            sliceHeight,
          );

          yOffset += pageContentHeight;
          isFirstPage = false;
        }
      }

      // Footer on last page
      pdf.setFontSize(8);
      pdf.setTextColor(180, 180, 180);
      pdf.text(
        'Được tạo bởi GoodGo AI Valuation — goodgo.vn',
        pdfMargin,
        297 - pdfMargin,
      );

      pdf.save(`${filename}.pdf`);
    } catch (error) {
      console.error('PDF export failed:', error);
    } finally {
      setIsExporting(false);
    }
  }, [targetSelector, filename]);

  return (
    <Button
      variant="outline"
      size="sm"
      onClick={handleExport}
      disabled={isExporting}
    >
      {isExporting ? (
        <Loader2 className="mr-2 h-4 w-4 animate-spin" />
      ) : (
        <Download className="mr-2 h-4 w-4" />
      )}
      {isExporting ? 'Đang xuất...' : 'Xuất PDF'}
    </Button>
  );
}