package csv

import (
	"encoding/csv"
	"io"
	"os"

	"go.uber.org/zap"
)

func InitializeHeader(logger *zap.Logger) {
	csvFile, err := os.OpenFile("mqtt-logs.csv", os.O_CREATE|os.O_RDWR|os.O_APPEND, 0644)
	if err != nil {
		logger.Fatal("error opening csv file", zap.Error(err))
	}
	defer csvFile.Close()

	r := csv.NewReader(csvFile)
	w := csv.NewWriter(csvFile)
	record, err := r.Read()

	if err == io.EOF {
		w.Write([]string{"Date (UTC)", "Topic", "Message"})
		w.Flush()
	} else if err != nil {
		logger.Fatal("error initializing csv file", zap.Error(err))
	} else if record[0] == "Date (UTC)" && record[1] == "Topic" && record[2] == "Message" {
		return
	} else {
		logger.Fatal("First row of csv file is not as expected. Please make sure the file is in the correct format.")
	}

}