import { BadRequestException } from '@nestjs/common';
import ExcelJS from 'exceljs';
import JSZip from 'jszip';
import { randomUUID } from 'node:crypto';
import type { EmbeddedImage, EmbeddedImageMetadata, ReportWorkbookFormat } from './report-materials.contracts';
import { normalizeImageExtension, readEmbeddedImages } from './report-materials.helpers';

const MAX_WORKBOOK_BYTES = 100 * 1024 * 1024;
const MAX_EXPANDED_BYTES = 500 * 1024 * 1024;
const MAX_IMAGE_BYTES = 20 * 1024 * 1024;
const MAX_TOTAL_IMAGE_BYTES = 300 * 1024 * 1024;
const DISPIMG_FORMULA = /^_xlfn\.DISPIMG\(["'](ID_[A-F0-9]{32})["'],1\)$/i;

function decodeXml(value: string) {
  return value
    .replace(/"/g, '"')
    .replace(/'/g, "'")
    .replace(/&lt;/g, '<')
    .replace(/&gt;/g, '>')
    .replace(/&amp;/g, '&');
}

function attributes(source: string) {
  return Object.fromEntries(
    [...source.matchAll(/([\w:-]+)="([^"]*)"/g)].map((match) => [match[1], decodeXml(match[2])]),
  );
}

function packagePath(target: string) {
  return `xl/${target.replace(/^\/?xl\//, '').replace(/^\//, '')}`.replace(/\\/g, '/');
}

function coordinates(address: string) {
  const match = /^([A-Z]+)(\d+)$/.exec(address.toUpperCase());
  if (!match) return null;
  let column = 0;
  for (const character of match[1]) column = column * 26 + character.charCodeAt(0) - 64;
  return { row: Number(match[2]), column };
}

async function text(zip: JSZip, path: string) {
  return zip.file(path)?.async('string') ?? '';
}

function validImageSignature(extension: string, buffer: Buffer) {
  if (extension === 'png')
    return buffer.subarray(0, 8).equals(Buffer.from([0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a]));
  if (extension === 'jpeg') return buffer[0] === 0xff && buffer[1] === 0xd8 && buffer[2] === 0xff;
  if (extension === 'gif') return buffer.subarray(0, 3).toString('ascii') === 'GIF';
  return false;
}

function validateWorkbookValues(workbook: ExcelJS.Workbook, allowedWpsIds: Set<string>) {
  for (const worksheet of workbook.worksheets) {
    worksheet.eachRow((row) =>
      row.eachCell((cell) => {
        const value = cell.value;
        if (value && typeof value === 'object' && ('formula' in value || 'sharedFormula' in value)) {
          const formula =
            typeof (value as { formula?: unknown }).formula === 'string'
              ? (value as { formula: string }).formula.trim()
              : '';
          const match = DISPIMG_FORMULA.exec(formula);
          if (!match || !allowedWpsIds.has(match[1]))
            throw new BadRequestException(`工作表 ${worksheet.name} 包含不允许的公式`);
        }
        const valueText = typeof value === 'string' ? value.trimStart() : '';
        if (/^[=+@]/.test(valueText) || /^-[^\d.]/.test(valueText))
          throw new BadRequestException(`工作表 ${worksheet.name} 包含公式或可执行单元格`);
      }),
    );
  }
}

async function inspectWpsImages(zip: JSZip, includeImageData: boolean) {
  const cellImagesXml = await text(zip, 'xl/cellimages.xml');
  if (!cellImagesXml)
    return {
      allowedIds: new Set<string>(),
      imagesBySheet: new Map<string, Array<EmbeddedImage | EmbeddedImageMetadata>>(),
      mediaTargets: new Set<string>(),
    };
  const relXml = await text(zip, 'xl/_rels/cellimages.xml.rels');
  const relTargets = new Map<string, string>();
  const seenRelations = new Set<string>();
  for (const match of relXml.matchAll(/<Relationship\b([^>]*)\/?>(?:<\/Relationship>)?/g)) {
    const attrs = attributes(match[1]);
    if (seenRelations.has(attrs.Id)) {
      relTargets.delete(attrs.Id);
      continue;
    }
    seenRelations.add(attrs.Id);
    if (attrs.Id && attrs.Target && attrs.TargetMode !== 'External' && /\/image$/.test(attrs.Type ?? ''))
      relTargets.set(attrs.Id, packagePath(attrs.Target));
  }
  const imageTargets = new Map<string, string>();
  const seenImageIds = new Set<string>();
  const duplicateImageIds = new Set<string>();
  // Bound every lookup to one node: a damaged node must never consume its neighbour's blip.
  for (const match of cellImagesXml.matchAll(/<etc:cellImage\b[^>]*?(?:\/>|>([\s\S]*?)<\/etc:cellImage>)/g)) {
    const node = match[1] ?? '';
    const id = attributes(node.match(/<xdr:cNvPr\b([^>]*)>/)?.[1] ?? '').name;
    if (!id) continue;
    if (seenImageIds.has(id)) {
      duplicateImageIds.add(id);
      imageTargets.delete(id);
      continue;
    }
    seenImageIds.add(id);
    const target = relTargets.get(attributes(node.match(/<a:blip\b([^>]*)>/)?.[1] ?? '')['r:embed']);
    if (id && target) imageTargets.set(id, target);
  }
  const workbookXml = await text(zip, 'xl/workbook.xml');
  const workbookRelsXml = await text(zip, 'xl/_rels/workbook.xml.rels');
  const sheetRelTargets = new Map<string, string>();
  for (const match of workbookRelsXml.matchAll(/<Relationship\b([^>]*)\/?>(?:<\/Relationship>)?/g)) {
    const attrs = attributes(match[1]);
    if (attrs.Id && attrs.Target && /\/worksheet$/.test(attrs.Type ?? ''))
      sheetRelTargets.set(attrs.Id, packagePath(attrs.Target));
  }
  const allowedIds = new Set<string>();
  const imagesBySheet = new Map<string, Array<EmbeddedImage | EmbeddedImageMetadata>>();
  let totalImageBytes = 0;
  for (const match of workbookXml.matchAll(/<sheet\b([^>]*)\/?>(?:<\/sheet>)?/g)) {
    const attrs = attributes(match[1]);
    const path = sheetRelTargets.get(attrs['r:id']);
    if (!attrs.name || !path) continue;
    const sheetXml = await text(zip, path);
    const images: Array<EmbeddedImage | EmbeddedImageMetadata> = [];
    for (const cell of sheetXml.matchAll(/<c\b([^>]*?)(?:\/>|>([\s\S]*?)<\/c>)/g)) {
      const formulaText = decodeXml((cell[2] ?? '').match(/<f(?:\s[^>]*)?>([\s\S]*?)<\/f>/)?.[1]?.trim() ?? '');
      if (!formulaText) continue;
      const formula = DISPIMG_FORMULA.exec(formulaText);
      if (!formula) throw new BadRequestException(`工作簿包含不允许的公式：${formulaText.slice(0, 80)}`);
      const target = imageTargets.get(formula[1]);
      const address = attributes(cell[1]).r ?? '';
      const cellPosition = coordinates(address);
      const location = `工作表【${attrs.name}】${cellPosition ? address : '未知单元格'}`;
      if (duplicateImageIds.has(formula[1]))
        throw new BadRequestException(`${location}的WPS图片ID重复，无法确定对应图片，请重新插入图片`);
      if (!cellPosition) throw new BadRequestException(`${location}的WPS图片单元格地址无效`);
      if (!target) throw new BadRequestException(`${location}的WPS图片引用缺失或不唯一，请重新插入图片或清空该单元格`);
      const imageEntry = zip.file(target);
      if (!imageEntry) throw new BadRequestException(`${location}的WPS图片文件缺失，请重新插入图片或清空该单元格`);
      const extension = normalizeImageExtension(target.split('.').pop() ?? 'png');
      if (!['png', 'jpeg', 'gif'].includes(extension)) throw new BadRequestException('WPS单元格图片格式不受支持');
      const size = Number(
        (imageEntry as unknown as { _data?: { uncompressedSize?: number } })._data?.uncompressedSize ?? 0,
      );
      if (size > MAX_IMAGE_BYTES) throw new BadRequestException('单张WPS图片不能超过20MB');
      totalImageBytes += size;
      if (includeImageData) {
        const imageBuffer = await imageEntry.async('nodebuffer');
        if (!validImageSignature(extension, imageBuffer))
          throw new BadRequestException('WPS单元格图片内容与格式不匹配');
        images.push({ ...cellPosition, extension, buffer: imageBuffer });
      } else {
        images.push({ ...cellPosition, extension, size, target });
      }
      allowedIds.add(formula[1]);
    }
    imagesBySheet.set(attrs.name, images);
  }
  if (totalImageBytes > MAX_TOTAL_IMAGE_BYTES) throw new BadRequestException('WPS图片总量不能超过300MB');
  return { allowedIds, imagesBySheet, mediaTargets: new Set(imageTargets.values()) };
}

export async function loadCompatibleWorkbook(
  buffer: Buffer,
  options: { includeImageData?: boolean; onProgress?: (progress: number, stage: string) => void | Promise<void> } = {},
) {
  if (buffer.length > MAX_WORKBOOK_BYTES) throw new BadRequestException('导入文件不能超过100MB');
  let zip: JSZip;
  try {
    zip = await JSZip.loadAsync(buffer);
  } catch {
    throw new BadRequestException('仅支持有效的 XLSX 文件');
  }
  await options.onProgress?.(35, '已读取工作簿压缩包');
  const expandedBytes = Object.values(zip.files).reduce(
    (sum, entry) =>
      sum + Number((entry as unknown as { _data?: { uncompressedSize?: number } })._data?.uncompressedSize ?? 0),
    0,
  );
  if (Object.keys(zip.files).length > 3000) throw new BadRequestException('工作簿ZIP条目数量超过安全限制');
  if (expandedBytes > MAX_EXPANDED_BYTES) throw new BadRequestException('工作簿解压后超过500MB安全限制');
  if (Object.keys(zip.files).some((name) => /(^|\/)(vbaProject|externalLinks|embeddings|activeX)(\/|\.)/i.test(name)))
    throw new BadRequestException('工作簿包含不允许的外部对象或宏');
  const wps = await inspectWpsImages(zip, options.includeImageData !== false);
  await options.onProgress?.(55, '已定位WPS单元格图片');
  let excelJsInput = buffer;
  if (options.includeImageData === false && wps.mediaTargets.size) {
    for (const target of wps.mediaTargets) zip.remove(target);
    zip.remove('xl/cellimages.xml');
    zip.remove('xl/_rels/cellimages.xml.rels');
    excelJsInput = await zip.generateAsync({
      type: 'nodebuffer',
      compression: 'DEFLATE',
      compressionOptions: { level: 1 },
    });
    await options.onProgress?.(70, '已剥离解析阶段无需加载的WPS图片数据');
  }
  const workbook = new ExcelJS.Workbook();
  await workbook.xlsx.load(excelJsInput as never);
  await options.onProgress?.(80, '已解析工作表内容');
  validateWorkbookValues(workbook, wps.allowedIds);
  await options.onProgress?.(90, '已完成工作簿安全校验');
  return { workbook, wpsImagesBySheet: wps.imagesBySheet };
}

export function compatibleImages(
  workbook: ExcelJS.Workbook,
  worksheet: ExcelJS.Worksheet,
  wpsImagesBySheet: Map<string, Array<EmbeddedImage | EmbeddedImageMetadata>>,
) {
  const merged = new Map<string, EmbeddedImage>();
  const wpsImages = wpsImagesBySheet.get(worksheet.name) ?? [];
  for (const image of readEmbeddedImages(workbook, worksheet)) {
    if (wpsImages.length && image.buffer.length <= 128) continue;
    const extension = normalizeImageExtension(image.extension);
    if (image.buffer.length > MAX_IMAGE_BYTES) throw new BadRequestException('单张工作簿图片不能超过20MB');
    if (!validImageSignature(extension, image.buffer)) throw new BadRequestException('工作簿图片内容与格式不匹配');
    merged.set(`${image.row}:${image.column}`, image);
  }
  for (const image of wpsImages) {
    if (!('buffer' in image)) throw new BadRequestException('图片元数据不能用于提交导入');
    merged.set(`${image.row}:${image.column}`, image);
  }
  return [...merged.values()];
}

export function compatibleImagePositions(
  workbook: ExcelJS.Workbook,
  worksheet: ExcelJS.Worksheet,
  wpsImagesBySheet: Map<string, Array<EmbeddedImage | EmbeddedImageMetadata>>,
) {
  const wpsImages = wpsImagesBySheet.get(worksheet.name) ?? [];
  const positions = new Map<string, { row: number; column: number }>();
  for (const image of readEmbeddedImages(workbook, worksheet)) {
    if (wpsImages.length && image.buffer.length <= 128) continue;
    positions.set(`${image.row}:${image.column}`, { row: image.row, column: image.column });
  }
  for (const image of wpsImages)
    positions.set(`${image.row}:${image.column}`, { row: image.row, column: image.column });
  return [...positions.values()];
}

export async function convertWorkbookOutput(content: Buffer, outputFormat: ReportWorkbookFormat = 'excel_drawing') {
  if (outputFormat === 'excel_drawing') return content;
  if (outputFormat !== 'wps_cell_image') throw new BadRequestException('不支持的报备文件格式');
  const workbook = new ExcelJS.Workbook();
  await workbook.xlsx.load(content as never);
  const pictures: Array<{
    sheetName: string;
    address: string;
    extension: string;
    buffer: Buffer;
    id: string;
    relId: string;
    mediaPath: string;
  }> = [];
  for (const sheet of workbook.worksheets) {
    for (const image of readEmbeddedImages(workbook, sheet)) {
      const extension = normalizeImageExtension(image.extension);
      pictures.push({
        sheetName: sheet.name,
        address: `${sheet.getColumn(image.column).letter}${image.row}`,
        extension,
        buffer: image.buffer,
        id: `ID_${randomUUID().replace(/-/g, '').toUpperCase()}`,
        relId: `rId${pictures.length + 1}`,
        mediaPath: `xl/media/wps-cell-image-${pictures.length + 1}.${extension === 'jpeg' ? 'jpg' : extension}`,
      });
    }
  }
  if (!pictures.length) return content;
  const zip = await JSZip.loadAsync(content);
  Object.keys(zip.files)
    .filter((name) => /^xl\/media\//.test(name))
    .forEach((name) => zip.remove(name));
  const workbookXml = await text(zip, 'xl/workbook.xml');
  let workbookRels = await text(zip, 'xl/_rels/workbook.xml.rels');
  const relTargets = new Map<string, string>();
  for (const match of workbookRels.matchAll(/<Relationship\b([^>]*)\/?>(?:<\/Relationship>)?/g)) {
    const attrs = attributes(match[1]);
    if (attrs.Id && attrs.Target && /\/worksheet$/.test(attrs.Type ?? ''))
      relTargets.set(attrs.Id, packagePath(attrs.Target));
  }
  const sheetTargets = new Map<string, string>();
  for (const match of workbookXml.matchAll(/<sheet\b([^>]*)\/?>(?:<\/sheet>)?/g)) {
    const attrs = attributes(match[1]);
    const target = relTargets.get(attrs['r:id']);
    if (attrs.name && target) sheetTargets.set(attrs.name, target);
  }
  for (const [sheetName, path] of sheetTargets) {
    const sheetPictures = pictures.filter((picture) => picture.sheetName === sheetName);
    if (!sheetPictures.length) continue;
    let sheetXml = await text(zip, path);
    sheetXml = sheetXml.replace(/<drawing\b[^>]*\/?>(?:<\/drawing>)?/g, '');
    for (const picture of sheetPictures) {
      const fullCell = new RegExp(`<c\\b([^>]*\\br="${picture.address}"[^>]*)>[\\s\\S]*?<\\/c>`);
      const emptyCell = new RegExp(`<c\\b([^>]*\\br="${picture.address}"[^>]*)\\/>`);
      const replaceCell = (opening: string) =>
        `<c${opening.replace(/\s+t="[^"]*"/g, '')} t="str"><f>_xlfn.DISPIMG(&quot;${picture.id}&quot;,1)</f><v>=DISPIMG(&quot;${picture.id}&quot;,1)</v></c>`;
      if (fullCell.test(sheetXml))
        sheetXml = sheetXml.replace(fullCell, (_match, opening: string) => replaceCell(opening));
      else if (emptyCell.test(sheetXml))
        sheetXml = sheetXml.replace(emptyCell, (_match, opening: string) => replaceCell(opening));
      else throw new BadRequestException(`无法生成WPS单元格图片：${sheetName}!${picture.address}`);
      zip.file(picture.mediaPath, picture.buffer);
    }
    zip.file(path, sheetXml);
    const sheetRelsPath = path.replace(/\/([^/]+)$/, '/_rels/$1.rels');
    const sheetRels = await text(zip, sheetRelsPath);
    if (sheetRels)
      zip.file(
        sheetRelsPath,
        sheetRels.replace(/<Relationship\b[^>]*Type="[^"]*\/drawing"[^>]*\/?>(?:<\/Relationship>)?/g, ''),
      );
  }
  Object.keys(zip.files)
    .filter((name) => /^xl\/drawings\//.test(name))
    .forEach((name) => zip.remove(name));
  const cellImages = pictures
    .map(
      (picture, index) =>
        `<etc:cellImage><xdr:pic><xdr:nvPicPr><xdr:cNvPr id="${index + 1}" name="${picture.id}"/><xdr:cNvPicPr><a:picLocks noChangeAspect="1"/></xdr:cNvPicPr></xdr:nvPicPr><xdr:blipFill><a:blip r:embed="${picture.relId}"/><a:stretch><a:fillRect/></a:stretch></xdr:blipFill><xdr:spPr><a:xfrm><a:off x="0" y="0"/><a:ext cx="914400" cy="914400"/></a:xfrm><a:prstGeom prst="rect"><a:avLst/></a:prstGeom><a:noFill/><a:ln w="9525"><a:noFill/></a:ln></xdr:spPr></xdr:pic></etc:cellImage>`,
    )
    .join('');
  zip.file(
    'xl/cellimages.xml',
    `<?xml version="1.0" encoding="UTF-8" standalone="yes"?><etc:cellImages xmlns:xdr="http://schemas.openxmlformats.org/drawingml/2006/spreadsheetDrawing" xmlns:r="http://schemas.openxmlformats.org/officeDocument/2006/relationships" xmlns:a="http://schemas.openxmlformats.org/drawingml/2006/main" xmlns:etc="http://www.wps.cn/officeDocument/2017/etCustomData">${cellImages}</etc:cellImages>`,
  );
  zip.file(
    'xl/_rels/cellimages.xml.rels',
    `<?xml version="1.0" encoding="UTF-8" standalone="yes"?><Relationships xmlns="http://schemas.openxmlformats.org/package/2006/relationships">${pictures.map((picture) => `<Relationship Id="${picture.relId}" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/image" Target="${picture.mediaPath.replace(/^xl\//, '')}"/>`).join('')}</Relationships>`,
  );
  const nextRel = Math.max(0, ...[...workbookRels.matchAll(/Id="rId(\d+)"/g)].map((match) => Number(match[1]))) + 1;
  workbookRels = workbookRels.replace(
    '</Relationships>',
    `<Relationship Id="rId${nextRel}" Type="http://www.wps.cn/officeDocument/2020/cellImage" Target="cellimages.xml"/></Relationships>`,
  );
  zip.file('xl/_rels/workbook.xml.rels', workbookRels);
  let contentTypes = await text(zip, '[Content_Types].xml');
  contentTypes = contentTypes.replace(
    /<Override\b[^>]*PartName="\/xl\/drawings\/[^"]+"[^>]*\/?>(?:<\/Override>)?/g,
    '',
  );
  if (!contentTypes.includes('/xl/cellimages.xml'))
    contentTypes = contentTypes.replace(
      '</Types>',
      '<Override PartName="/xl/cellimages.xml" ContentType="application/vnd.wps-officedocument.cellimage+xml"/></Types>',
    );
  zip.file('[Content_Types].xml', contentTypes);
  return zip.generateAsync({ type: 'nodebuffer', compression: 'DEFLATE', compressionOptions: { level: 6 } });
}