/*
syncer -- stateful file/device data syncer.
Copyright (C) 2015-2020 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, version 3 of the License.

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 main

import (
	"fmt"
	"strconv"
)

const (
	BufLine       = 80
	CharChanged   = byte('%')
	CharUnchanged = byte('.')
)

type Printer struct {
	i       int64
	total   int64
	changed int64
	frmt    string
	bufSize int
	outBuf  []byte
}

func NewPrinter(total int64) *Printer {
	p := Printer{total: total}
	maxLen := len(fmt.Sprintf("%d", total))
	p.frmt = "%" + strconv.Itoa(maxLen) + "d/%d %02d%% %s\n"
	p.bufSize = BufLine - (2*maxLen + 6)
	p.outBuf = make([]byte, 0, p.bufSize)
	return &p
}

func (p *Printer) Changed() {
	p.i++
	p.changed++
	p.outBuf = append(p.outBuf, CharChanged)
	p.Output()
}

func (p *Printer) Unchanged() {
	p.i++
	p.outBuf = append(p.outBuf, CharUnchanged)
	p.Output()
}

func (p *Printer) Output() {
	if !(len(p.outBuf) == p.bufSize || p.i == p.total) {
		return
	}
	fmt.Printf(p.frmt, p.i, p.total, 100*p.changed/p.i, string(p.outBuf))
	p.outBuf = p.outBuf[:0]
}