import { useCallback, useState } from 'react';
import { useDataContext } from './DataTable';

const headerStyle = {
  fill: {
      patternType: 'solid',
      fgColor: { rgb: "FBF6D900" }
  },
  font: {
      bold: true
  }
};

const extraStyle = {
  fill: {
      patternType: 'solid',
      fgColor: { rgb: "E5E4E200" }
  },
  alignment: {
    horizontal: 'right'
  },
  font: {
      bold: true
  }
};

export default function useExporter(header: any[], params: any, map: Function, extra: any = null, transform: Function | null = null): any {
  const [loading, setLoading] = useState(false);
  const fetchData = useDataContext();

  const handleExport = useCallback(async function (name) {
    const _XLSX = await import('sheetjs-style-v2');
    const XLSX = _XLSX?.default || _XLSX;
    
    setLoading(true);
    try {
        const data = await fetchData({itemPerPage: -1, ...(params || {})});

        const array = (extra && extra.length > 0 ? extra.concat([[]]) : [])
        .concat([header])
        .concat((transform ? transform(data.data) : data.data).map(map));

        const headerStart = (((extra && extra.length && (extra.length + 1)) || 0) + 1).toString();

        const ws = XLSX.utils.aoa_to_sheet(array);

        for (let i = 0; i < (((extra && extra.length && (extra.length)) || 0)); ++i) {
          ws["A" + (i+1).toString()].s = extraStyle;
        }

        ws['!cols'] = formatExcelCols([header].concat(data.data.map(map)));
        for (let i = 0; i < header.length; ++i) {
            ws[String.fromCharCode(65 + i) + headerStart].s = headerStyle;
        }

        ws['!autofilter'] = { ref: "A" + headerStart + ":" + String.fromCharCode(65 + header.length - 1) + array.length };

        const new_workbook = XLSX.utils.book_new();
        const finalName = name || 'Report';
        XLSX.utils.book_append_sheet(new_workbook, ws, finalName.length > 30 ? 'Report' : finalName);
        XLSX.writeFile(new_workbook, (name || 'Report') + '.xlsx');
    } finally {
        setLoading(false);
    }
  }, [fetchData, header, map, params, setLoading]);

  return [ handleExport, loading ];
}

function formatExcelCols(json: any[]) {
  let widthArr = json[0].map(key => {
      return {width: (key || '').toString().length + 2} // plus 2 to account for short object keys
  });

  for (let i = 0; i < json.length; i++) {
      let value = json[i];
      for (let j = 0; j < value.length; j++) {
          if (value[j]?.length > widthArr[j].width) {
              widthArr[j].width = value[j].length;
          }
      }
  }
  return widthArr;
}