package csvwriter

import (
	"bytes"
	"os"
)

type CsvWriter struct {
	f   *os.File
	buf bytes.Buffer
}

func NewCsvWriter(path string) (*CsvWriter, error) {
	f, err := os.Create(path)
	if err != nil {
		return nil, err
	}

	w := &CsvWriter{
		f: f,
	}
	return w, nil
}

func (c *CsvWriter) Close() error {
	c.Sync()
	return c.f.Close()
}

func (c *CsvWriter) Write(strs []string) error {

	for i, str := range strs {
		if i != 0 {
			_, err := c.buf.Write([]byte(","))
			if err != nil {
				return err
			}
		}
		_, err := c.buf.Write([]byte(str))
		if err != nil {
			return err
		}
	}
	c.buf.WriteByte('\n')

	if c.buf.Len() > 1*1024*1024 {
		err := c.Sync()
		if err != nil {
			return err
		}
	}
	return nil
}

func (c *CsvWriter) Sync() error {
	_, err := c.f.Write(c.buf.Bytes())
	if err != nil {
		return err
	}
	c.buf.Reset()
	return nil
}