package main

import (
	"bufio"
	"encoding/csv"
	"fmt"
	"os"
	"time"
)

// Экспорт в CSV
type CsvExporter struct {
	Encoding Encoding
}

func (c *CsvExporter) FileExt() string {
	return ".csv"
}

func (c *CsvExporter) Convert(filePath string, rows chan []any) error {
	f, err := os.Create(filePath + c.FileExt())
	if err != nil {
		return err
	}

	buf := bufio.NewWriterSize(f, 4*1024*1024)

	enc, err := c.Encoding.Encoder()
	if err != nil {
		return err
	}

	w := csv.NewWriter(enc.Writer(buf))
	w.Comma = ';'

	rowNum := 0
	for row := range rows {
		rowNum++
		rowsStr := make([]string, len(row))
		for i := range row {
			rowsStr[i] = toCsvField(row[i])
		}

		err = w.Write(rowsStr)
		if err != nil {
			f.Close()
			return err
		}
	}

	w.Flush()
	if err = w.Error(); err != nil {
		f.Close()
		return err
	}

	err = buf.Flush()
	if err != nil {
		f.Close()
		return err
	}

	err = f.Close()
	if err != nil {
		return err
	}

	return nil
}

func toCsvField(a any) string {
	if a == nil {
		return ""
	}

	switch v := a.(type) {
	case time.Time:
		return v.Format("02.01.2006 15:04:05")
	}

	return fmt.Sprint(a)
}