import { Injectable } from '@angular/core';
import { saveAs } from 'file-saver';
import * as XLSX from 'xlsx';
import { EXCEL_FILE_EXTENSION, EXCEL_FILE_TYPE } from '../../utils/app.constants';

@Injectable({
  providedIn: 'root'
})
export class ExcelExportService {

  constructor() { }

  private fileType = EXCEL_FILE_TYPE;
   private fileExtension = EXCEL_FILE_EXTENSION;

  public exportExcel(jsonData: any[], fileName: string): void {

    const ws: XLSX.WorkSheet = XLSX.utils.json_to_sheet(jsonData);
    const wb: XLSX.WorkBook = { Sheets: { 'data': ws }, SheetNames: ['data'] };
    const excelBuffer: any = XLSX.write(wb, { bookType: 'xlsx', type: 'array' });
    this.saveExcelFile(excelBuffer, fileName);
  }

  private saveExcelFile(buffer: any, fileName: string): void {
    const data: Blob = new Blob([buffer], {type: this.fileType});
    saveAs.saveAs(data, fileName + this.fileExtension);
  }
}