import { Button, message, Modal, Spin } from "antd";
import ExcelJS from "exceljs";
import { useEffect, useRef, useState } from "react";
import Spreadsheet from "x-data-spreadsheet";
import useDownloadFile from "../../hooks/useDownloadFile";
import { getFileUrl } from "../../utils";
import "x-data-spreadsheet/dist/xspreadsheet.css";

/**
 * Excel 查看组件。
 * 使用 exceljs 解析 xlsx，再通过 x-data-spreadsheet 渲染表格预览。
 */
function Excel(props) {
  const {
    visible = false,
    onCancel,
    file,
    name,
    inline = false,
    title = "Excel预览",
    style = {},
    extraButtons,
  } = props;

  const containerRef = useRef(null);
  const fullscreenRef = useRef(null);
  const unmountedRef = useRef(false);
  const fileUrl = getFileUrl();
  const [loading, setLoading] = useState(false);
  const { downloadFile } = useDownloadFile();

  const renderExcel = async () => {
    setLoading(true);
    containerRef.current.innerHTML = "";
    try {
      const response = await fetch(!file.includes(fileUrl) ? fileUrl + file : file);
      if (!response.ok)
        throw new Error("加载 Excel 文件失败");
      const data = await response.arrayBuffer();
      const workbook = new ExcelJS.Workbook();
      await workbook.xlsx.load(data);
      if (unmountedRef.current)
        return;
      new Spreadsheet(containerRef.current, {
        mode: "read",
        showToolbar: false,
        showContextmenu: false,
        view: {
          height: () => containerRef.current?.clientHeight || 520,
          width: () => containerRef.current?.clientWidth || 800,
        },
      }).loadData(convertWorkbookToSpreadsheet(workbook));
    }
    catch {
      message.error("加载 Excel 文件失败");
      if (!inline && onCancel)
        onCancel();
    }
    finally {
      if (!unmountedRef.current)
        setLoading(false);
    }
  };

  useEffect(() => {
    if ((!visible && !inline) || !file)
      return;

    unmountedRef.current = false;
    const initTimer = setTimeout(() => {
      renderExcel();
    }, 100);

    return () => {
      unmountedRef.current = true;
      if (containerRef.current)
        containerRef.current.innerHTML = "";
      if (initTimer)
        clearTimeout(initTimer);
    };
  }, [visible, inline, file]);

  const renderExcelContent = () => (
    <Spin spinning={loading}>
      <div
        style={{ height: "72vh", overflow: "hidden", ...style }}
      >
        <div ref={containerRef} style={{ width: "100%", height: "100%" }} />
      </div>
    </Spin>
  );

  if (inline)
    return renderExcelContent();

  const onDownloadFile = () => {
    downloadFile({
      url: file,
      name,
    });
  };

  return (
    <div ref={fullscreenRef}>
      <Modal
        style={{ top: 100, maxWidth: "calc(100vw - 32px)", paddingBottom: 24 }}
        open={visible}
        mask={{ closable: false }}
        width={1000}
        title={title}
        onCancel={() => {
          onCancel();
        }}
        getContainer={false}
        footer={[
          <Button
            key="cancel"
            onClick={() => {
              onCancel();
            }}
          >
            关闭
          </Button>,
          <Button key="download" type="primary" onClick={onDownloadFile}>下载</Button>,
          ...(extraButtons || []),
        ]}
      >
        {renderExcelContent()}
      </Modal>
    </div>
  );
}

function convertWorkbookToSpreadsheet(workbook) {
  const sheets = [];
  workbook.worksheets.forEach((worksheet) => {
    sheets.push(convertWorksheetToSheetData(worksheet));
  });
  return sheets.length > 0 ? sheets : [{ name: "Sheet1", rows: {} }];
}

function convertWorksheetToSheetData(worksheet) {
  const sheetData = {
    name: worksheet.name,
    rows: {},
    cols: { len: worksheet.columnCount || 26 },
    merges: worksheet.model?.merges || [],
  };

  worksheet.columns.forEach((column, index) => {
    if (column.width)
      sheetData.cols[index] = { width: Math.round(column.width * 8) };
  });

  // x-data-spreadsheet 使用 0 起始下标，exceljs 使用 1 起始下标，这里统一转换。
  worksheet.eachRow({ includeEmpty: true }, (row, rowIndex) => {
    const rowData = { cells: {} };
    if (row.height)
      rowData.height = Math.round(row.height * 1.4);
    row.eachCell({ includeEmpty: true }, (cell, colIndex) => {
      rowData.cells[colIndex - 1] = {
        text: getCellText(cell),
      };
    });
    sheetData.rows[rowIndex - 1] = rowData;
  });

  (sheetData.merges || []).forEach((merge) => {
    const range = parseExcelRange(merge);
    const cell = sheetData.rows[range.sri]?.cells?.[range.sci];
    if (cell)
      cell.merge = [range.eri - range.sri, range.eci - range.sci];
  });

  return sheetData;
}

function getCellText(cell) {
  if (cell.value === null || cell.value === undefined)
    return "";
  if (cell.formula)
    return cell.result === null || cell.result === undefined ? `=${cell.formula}` : String(cell.result);
  if (cell.text)
    return cell.text;
  if (cell.value instanceof Date)
    return cell.value.toLocaleDateString();
  if (typeof cell.value === "object") {
    if (cell.value.text)
      return cell.value.text;
    if (cell.value.richText)
      return cell.value.richText.map(item => item.text).join("");
    if (cell.value.result !== undefined)
      return String(cell.value.result);
  }
  return String(cell.value);
}

function parseExcelRange(range) {
  const [start, end = start] = range.split(":");
  const startCell = parseExcelCell(start);
  const endCell = parseExcelCell(end);
  return {
    sri: startCell.rowIndex,
    sci: startCell.colIndex,
    eri: endCell.rowIndex,
    eci: endCell.colIndex,
  };
}

function parseExcelCell(cell) {
  const match = /^([A-Z]+)(\d+)$/i.exec(cell);
  if (!match)
    return { rowIndex: 0, colIndex: 0 };
  return {
    rowIndex: Number(match[2]) - 1,
    colIndex: getColumnIndex(match[1]),
  };
}

function getColumnIndex(columnName) {
  return columnName.toUpperCase().split("").reduce((total, char) => {
    return total * 26 + char.charCodeAt(0) - 64;
  }, 0) - 1;
}

Excel.displayName = "Excel";

export default Excel;