package mailclient

import (
	"crypto/rand"
	"fmt"
	"io"
)

type LineWriter struct {
	w      io.Writer
	length int
}

func NewLineWriter(w io.Writer, length int) *LineWriter {
	return &LineWriter{
		w:      w,
		length: length,
	}
}

func (r *LineWriter) Write(p []byte) (n int, err error) {
	for i := 0; i < len(p); i += r.length {
		end := i + r.length

		if end > len(p) {
			end = len(p) - 1
		}

		var chunk []byte
		chunk = append(chunk, p[i:end]...)

		if len(p) >= end+r.length {
			chunk = append(chunk, []byte("\r\n")...)
		}

		addN, err := r.w.Write(chunk)
		if err != nil {
			return n, err
		}
		n += addN
	}

	return n, nil
}

func (r *LineWriter) WriteString(s string) (n int, err error) {
	p := []byte(s)
	return r.Write(p)
}

func (r *LineWriter) WriteFormatString(format string, a ...any) (n int, err error) {
	p := []byte(fmt.Sprintf(format, a...))
	return r.Write(p)
}

func randomBoundary() string {
	var buf [30]byte
	_, err := io.ReadFull(rand.Reader, buf[:])
	if err != nil {
		panic(err)
	}
	return fmt.Sprintf("%x", buf[:])
}