script/output_csv.go

package script

import (
	"encoding/csv"
	"errors"
	"os"
)

// CSV creates csv.Writer writing to underlying file.
// Do not forget to call Close method once you are done.
func NewCSVWriter(filename string) (*CSVWriter, error) {
	return newCSVwriter(filename)
}

type CSVWriter struct {
	f   *os.File
	wr  *csv.Writer
	err error
}

// Write writer row to csv. Writes are buffered
func (c *CSVWriter) Write(record []string) error {
	err := c.wr.Write(record)
	c.err = err

	return err
}

// Close flushes underlying csv.Writer and closes
// file.
func (c *CSVWriter) Close() error {
	c.wr.Flush()
	flushErr := c.wr.Error()
	closeErr := c.f.Close()

	err := errors.Join(flushErr, closeErr)
	c.err = err

	if err != nil {
		return err
	}

	return nil
}

// Error return last encountered error.
func (c *CSVWriter) Error() error {
	return c.err
}

func newCSVwriter(name string) (*CSVWriter, error) {
	var (
		f   *os.File
		err error
	)

	if _, err = os.Stat(name); err == nil {
		f, err = os.OpenFile(name, os.O_APPEND|os.O_WRONLY, 0664)
	} else {
		f, err = os.Create(name)
	}

	if err != nil {
		return nil, err
	}

	csvwr := csv.NewWriter(f)

	return &CSVWriter{f: f, wr: csvwr}, nil
}