import { nextTick, computed } from 'vue';
import { useMainStore } from '@/store';
import { ElLoading } from 'element-plus';
import html2canvas from 'html2canvas';
import jsPDF from 'jspdf';
import { showMessage } from './common';
import { uploadFile } from '@/utils/http';
import { savePdf } from '@/utils/api';

const mainStore = useMainStore();
const expanded = computed(() => mainStore.getExpanded);
const phone = computed(() => mainStore.getPhone);
const recordId = computed(() => mainStore.getRecordId);
const isLoadOver = computed(() => mainStore.getIsLoadOver);

/**
 * 生成 PDF Blob
 */
async function generatePDFBlob(
  pdfContent?: HTMLElement,
  showLoading = false
): Promise<Blob | null> {
  if (!isLoadOver.value) {
    showMessage({ type: 'warning', message: '数据加载中，请稍后再试' });
    return null;
  }
  let loading: any = null;

  if (showLoading) {
    loading = ElLoading.service({
      lock: true,
      text: '生成报告中...',
      background: 'rgba(0,0,0,0.7)'
    });
  }

  try {
    if (!pdfContent) pdfContent = document.getElementById('Record') as HTMLElement;
    if (!expanded.value) {
      mainStore.setExpanded(true);
      await nextTick();
    }
    await nextTick();

    const canvas = await html2canvas(pdfContent, {
      scale: 2,
      useCORS: true,
      backgroundColor: '#fff'
    });

    const canvasWidth = canvas.width;
    const canvasHeight = canvas.height;

    const pdf = new jsPDF('p', 'mm', 'a4');
    const pageWidth = pdf.internal.pageSize.getWidth();
    const pageHeight = pdf.internal.pageSize.getHeight();
    const ratio = pageWidth / canvasWidth;
    const pagePixelHeight = pageHeight / ratio;

    // 页边距（像素）
    const marginTop = 20;    // 仅作用于非第一页
    const marginBottom = 40; // 所有页生效

    let positionY = 0;
    let pageIndex = 0;

    while (positionY < canvasHeight) {
      // 判断是否第一页
      const topMargin = pageIndex === 0 ? 0 : marginTop;

      // 每页实际可容纳的内容高度
      const h = Math.min(
        pagePixelHeight - topMargin - marginBottom,
        canvasHeight - positionY
      );

      const pageCanvas = document.createElement('canvas');
      pageCanvas.width = canvasWidth;
      pageCanvas.height = h;
      const ctx = pageCanvas.getContext('2d');
      ctx?.drawImage(canvas, 0, positionY, canvasWidth, h, 0, 0, canvasWidth, h);

      const imgData = pageCanvas.toDataURL('image/jpeg', 0.95);

      // 添加到 PDF 时，整体往下偏移 topMargin
      pdf.addImage(imgData, 'JPEG', 0, topMargin * ratio, pageWidth, h * ratio);

      positionY += h;
      pageIndex++;

      if (positionY < canvasHeight) pdf.addPage();
    }

    return pdf.output('blob');
  } catch (error) {
    console.error(error);
    showMessage({ type: 'error', message: '生成失败，请稍后再试' });
    return null;
  } finally {
    mainStore.setExpanded(false);
    setTimeout(() => loading && loading.close(), 500);
  }
}

/**
 * 下载文件
 */
function triggerDownload(blob: Blob, filename = 'analysis.pdf') {
  const url = URL.createObjectURL(blob);
  const a = document.createElement('a');
  a.href = url;
  a.download = filename;
  a.click();
  URL.revokeObjectURL(url);
}

/**
 * 上传文件
 */
async function uploadPDFFile(blob: Blob) {
  const file = new File([blob], 'analysis.pdf', { type: 'application/pdf' });
  const uploadRes = await uploadFile(file, { source: 'media', mediaType: 'file' });
  const pdfUrl = uploadRes.data.url;

  await savePdf({
    phone: phone.value,
    id: recordId.value,
    pdfUrl
  });

  return pdfUrl;
}

/**
 * 统一入口：生成 PDF
 * @param pdfContent - PDF内容DOM
 * @param mode - "manual" 手动下载 | "auto" 自动下载并上传
 */
export async function handlePDF(pdfContent?: HTMLElement, mode: 'manual' | 'auto' = 'manual') {
  const blob = await generatePDFBlob(pdfContent, true);
  if (!blob) return;

  // 下载
  triggerDownload(blob);

  // 自动模式下再上传
  if (mode === 'auto') {
    try {
      await uploadPDFFile(blob);
      // showMessage({ type: 'success', message: '报告已下载并上传成功' });
    } catch (err) {
      // showMessage({ type: 'error', message: '报告上传失败' });
      throw err;
    }
  }
}