const XLSX = require("xlsx");
const fs = require("fs");
const { splitFilepath } = require("./util");

// do export for excel to json output or data json object
function _internalExport(props = {}) {
  const NAME = process.env.APP_NAME || "excel2json";
  console.log("Name =>", NAME, "\n");

  // load from env
  const INPUT_FILE = props.inputFile || process.env.INPUT_FILE;
  const OUTPUT_PATH =
    props.outputPath || process.env.OUTPUT_PATH || "./data/outputs";
  const MAPPER_FILE =
    props.mapperFile || process.env.MAPPER_FILE || "./data/mapper.json";
  const SHEET_NAME = props.sheetName || process.env.SHEET_NAME || "Sheet1";
  const ENCODING = props.encoding || process.env.ENCODING || "utf-8";

  // get mapper in string
  var mapperString = undefined;
  try {
    mapperString = fs.readFileSync(
      MAPPER_FILE,
      { encoding: ENCODING },
      (err) => {
        if (err) {
          console.error(err);
        }
        console.log("Load file suceed =>", MAPPER_FILE);
      }
    );
  } catch (err) {
    // console.error("read file error", err);
  }

  // convert mapper from string to json object
  const mapperJson = mapperString ? JSON.parse(mapperString) : {};
  const configs = { ...mapperJson.configs, ...props };
  const columsData = props.mappings || mapperJson.data || undefined;
  const inFile = configs.inputFile || INPUT_FILE;

  if (!inFile) {
    throw Error("Input file is required!");
  }

  // read workbook from excel file
  const wb = XLSX.readFile(inFile);
  const xlData = XLSX.utils.sheet_to_json(
    wb.Sheets[configs.sheetName || SHEET_NAME]
  );

  // mapping the data from read excel file
  const data = xlData.map((row) => {
    if (columsData == undefined || !columsData) {
      return row;
    }

    var _r = {};

    columsData.map((col) => {
      _r[col.label] = row[col.dataIndex];
    });

    return _r;
  });

  // able to save to output or not (default is true)
  if (configs.saveToOutputput || configs.outputFile) {
    var outputPath = undefined;
    const filePath = splitFilepath(configs.outputFile);

    // validate path and filename
    if (filePath && filePath.path) {
      outputPath = filePath.path;
    }

    if (filePath.path) {
      // parse a new path
      outputPath = outputPath || configs.outputPath || OUTPUT_PATH;

      // check directory and create it if not exist
      if (!fs.existsSync(outputPath)) {
        fs.mkdirSync(outputPath, { recursive: true });
      }
    }

    // json data output
    const jsonStringData = JSON.stringify(data);

    try {
      var outFile = undefined;
      if (configs.outputFile) {
        outFile = configs.outputFile;
      } else {
        outFile = `${outputPath}/${
          configs.outputName || "exported"
        }_${new Date().getTime()}.json`;
      }

      // write to file
      fs.writeFileSync(outFile, jsonStringData, (err) => {
        if (err) throw err;
      });

      console.log("Exported excel to json to output =>", outFile);
    } catch (err) {
      console.error(err);
    } 
  }

  return data;
}

/**
 * excel2json
 * Allow to export data from excel to json object or output of json.
 *
 * @returns JSON Object of result
 */
module.exports.excel2json = excel2json = (props = {}) => {
  return _internalExport(props);
};