import html2canvas from 'html2canvas';
import { jsPDF } from 'jspdf';

export interface ExportPdfOptions {
  filename?: string;
  pageSize?: 'A4' | 'A5' | 'Letter';
  pageMargin?: { bottom: number; left: number; right: number; top: number };
  quality?: number;
}

// 页面尺寸（单位：mm）
const PAGE_SIZES_MM = {
  A4: { width: 210, height: 297 },
  A5: { width: 148, height: 210 },
  Letter: { width: 216, height: 279 },
};

// 页面尺寸（单位：px，96dpi）
const PAGE_SIZES_PX = {
  A4: { width: 794, height: 1123 },
  A5: { width: 559, height: 794 },
  Letter: { width: 816, height: 1056 },
};

/**
 * 将多个页面元素导出为 PDF
 * @param pages 页面元素数组
 * @param options 导出选项
 */
export async function exportPagesToPdf(
  pages: HTMLElement[],
  options: ExportPdfOptions = {},
): Promise<void> {
  const {
    filename = `contract-${Date.now()}.pdf`,
    pageSize = 'A4',
    quality = 4, // 提高默认分辨率，3 = 3倍缩放
  } = options;

  const pageConfig = PAGE_SIZES_MM[pageSize];

  // 创建 PDF
  const pdf = new jsPDF({
    orientation: 'portrait',
    unit: 'mm',
    format: [pageConfig.width, pageConfig.height],
  });

  // 逐页渲染
  for (const [i, page] of pages.entries()) {
    // 导出前隐藏不需要的元素（如已签署徽章）
    const hiddenElements: HTMLElement[] = [];
    page.querySelectorAll('.signed-badge').forEach((el) => {
      const htmlEl = el as HTMLElement;
      hiddenElements.push(htmlEl);
      htmlEl.style.display = 'none';
    });

    // 导出前移除签名区域的边框和背景样式
    const signedElements: { el: HTMLElement; originalStyle: string }[] = [];
    page
      .querySelectorAll('.signature-display.signed, .seal-display.signed')
      .forEach((el) => {
        const htmlEl = el as HTMLElement;
        signedElements.push({
          el: htmlEl,
          originalStyle: htmlEl.getAttribute('style') || '',
        });
        htmlEl.style.border = 'none';
        htmlEl.style.background = 'transparent';
        htmlEl.style.padding = '0';
      });

    // 使用 html2canvas 将元素转换为 canvas
    const canvas = await html2canvas(page, {
      scale: quality,
      useCORS: true,
      allowTaint: true,
      backgroundColor: '#ffffff',
      logging: false,
    });

    // 导出后恢复隐藏的元素
    hiddenElements.forEach((el) => {
      el.style.display = '';
    });

    // 导出后恢复签名区域的样式
    signedElements.forEach(({ el, originalStyle }) => {
      el.setAttribute('style', originalStyle);
    });

    // 计算图片尺寸（填满整页）
    const imgData = canvas.toDataURL('image/jpeg', 0.95);

    if (i > 0) {
      pdf.addPage();
    }

    // 添加图片，填满整页
    pdf.addImage(imgData, 'JPEG', 0, 0, pageConfig.width, pageConfig.height);
  }

  // 下载 PDF
  pdf.save(filename);
}

/**
 * 将 HTML 元素导出为 PDF
 * @param element 要导出的 HTML 元素
 * @param options 导出选项
 */
export async function exportToPdf(
  element: HTMLElement,
  options: ExportPdfOptions = {},
): Promise<void> {
  const {
    filename = `contract-${Date.now()}.pdf`,
    pageSize = 'A4',
    pageMargin = { top: 10, right: 10, bottom: 10, left: 10 },
    quality = 2,
  } = options;

  const pageConfig = PAGE_SIZES_MM[pageSize];

  // 导出前隐藏不需要的元素（如已签署徽章）
  const hiddenElements: HTMLElement[] = [];
  element.querySelectorAll('.signed-badge').forEach((el) => {
    const htmlEl = el as HTMLElement;
    hiddenElements.push(htmlEl);
    htmlEl.style.display = 'none';
  });

  // 导出前移除签名区域的边框和背景样式
  const signedElements: { el: HTMLElement; originalStyle: string }[] = [];
  element
    .querySelectorAll('.signature-display.signed, .seal-display.signed')
    .forEach((el) => {
      const htmlEl = el as HTMLElement;
      signedElements.push({
        el: htmlEl,
        originalStyle: htmlEl.getAttribute('style') || '',
      });
      htmlEl.style.border = 'none';
      htmlEl.style.background = 'transparent';
      htmlEl.style.padding = '0';
    });

  // 使用 html2canvas 将元素转换为 canvas
  const canvas = await html2canvas(element, {
    scale: quality,
    useCORS: true,
    allowTaint: true,
    backgroundColor: '#ffffff',
    logging: false,
  });

  // 导出后恢复隐藏的元素
  hiddenElements.forEach((el) => {
    el.style.display = '';
  });

  // 导出后恢复签名区域的样式
  signedElements.forEach(({ el, originalStyle }) => {
    el.setAttribute('style', originalStyle);
  });

  // 创建 PDF
  const pdf = new jsPDF({
    orientation: 'portrait',
    unit: 'mm',
    format: [pageConfig.width, pageConfig.height],
  });

  // 计算可用区域（减去边距）
  const contentWidth = pageConfig.width - pageMargin.left - pageMargin.right;
  const contentHeight = pageConfig.height - pageMargin.top - pageMargin.bottom;

  // 计算图片尺寸（按宽度缩放）
  const imgWidth = contentWidth;
  const imgHeight = (canvas.height * imgWidth) / canvas.width;

  // 将 canvas 转换为图片数据
  const imgData = canvas.toDataURL('image/jpeg', 0.95);

  // 如果内容高度小于等于一页可用高度，直接添加
  if (imgHeight <= contentHeight) {
    pdf.addImage(
      imgData,
      'JPEG',
      pageMargin.left,
      pageMargin.top,
      imgWidth,
      imgHeight,
    );
  } else {
    // 需要分页
    let remainingHeight = imgHeight;
    let sourceY = 0;
    let pageIndex = 0;

    while (remainingHeight > 0) {
      if (pageIndex > 0) {
        pdf.addPage();
      }

      // 计算当前页显示的内容高度
      const currentPageContentHeight = Math.min(remainingHeight, contentHeight);

      // 计算源图片中对应的像素高度
      const sourceHeight =
        (currentPageContentHeight / imgHeight) * canvas.height;

      // 创建临时 canvas 来裁剪当前页的内容
      const tempCanvas = document.createElement('canvas');
      tempCanvas.width = canvas.width;
      tempCanvas.height = sourceHeight;
      const tempCtx = tempCanvas.getContext('2d');

      if (tempCtx) {
        tempCtx.drawImage(
          canvas,
          0,
          sourceY,
          canvas.width,
          sourceHeight, // 源区域
          0,
          0,
          canvas.width,
          sourceHeight, // 目标区域
        );

        const pageImgData = tempCanvas.toDataURL('image/jpeg', 0.95);
        pdf.addImage(
          pageImgData,
          'JPEG',
          pageMargin.left,
          pageMargin.top,
          imgWidth,
          currentPageContentHeight,
        );
      }

      sourceY += sourceHeight;
      remainingHeight -= contentHeight;
      pageIndex++;
    }
  }

  // 下载 PDF
  pdf.save(filename);
}

/**
 * 将合同渲染器导出为 PDF
 * @param containerSelector 容器选择器
 * @param options 导出选项
 */
export async function exportContractToPdf(
  containerSelector: string,
  options: ExportPdfOptions = {},
): Promise<boolean> {
  const container = document.querySelector(containerSelector) as HTMLElement;
  if (!container) {
    console.error('Container not found:', containerSelector);
    return false;
  }

  // 查找合同纸张元素
  const paper = container.querySelector('.contract-paper') as HTMLElement;
  if (!paper) {
    console.error('Contract paper not found');
    return false;
  }

  try {
    await exportToPdf(paper, options);
    return true;
  } catch (error) {
    console.error('Export PDF failed:', error);
    return false;
  }
}