/*
netstring -- netstring format serialization library
Copyright (C) 2015 Sergey Matveev <stargrave@stargrave.org>

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

package netstring

import (
	"bufio"
	"io"
	"strconv"
)

type Writer struct {
	writer *bufio.Writer
	prefix []byte
	err    error
}

func NewWriter(w io.Writer) *Writer {
	return &Writer{
		writer: bufio.NewWriter(w),
		prefix: make([]byte, 0, MaxPrefixSize),
	}
}

// Write serialized representation of data to the underlying writer.
// It returns number of serialized data bytes written.
func (self *Writer) Write(data []byte) (bytesWritten int, err error) {
	self.prefix = strconv.AppendUint(self.prefix[:0], uint64(len(data)), 10)
	self.prefix = append(self.prefix, ':')
	if _, self.err = self.writer.Write(self.prefix); self.err != nil {
		return 0, self.err
	}
	if _, self.err = self.writer.Write(data); self.err != nil {
		return 0, self.err
	}
	if _, self.err = self.writer.Write([]byte{','}); self.err != nil {
		return 0, self.err
	}
	if self.err = self.writer.Flush(); self.err != nil {
		return 0, self.err
	}
	return len(self.prefix) + len(data) + 1, nil
}