github.com/Code-Hex/battery@v1.0.0/battery.go

package battery

import (
	"bytes"
	"errors"
	"fmt"
	"math"
	"strconv"

	"github.com/fatih/color"
)

// LENGTH: 8
var chars = []string{
	"▏",
	"▎",
	"▍",
	"▌",
	"▋",
	"▊",
	"▉",
	"█",
}

// Icons of battery
var icons = []string{
	"   ",
	"   ",
	"   ",
	"   ",
	"   ",
	"   ",
}

type Bar struct {
	buffer      bytes.Buffer
	gauge       string
	gaugeWidth  int
	width       int
	nowVal      int
	elapsed     int
	totalVal    int
	charLen     int
	format      string
	prefix      string
	postfix     string
	charge      string
	ShowPercent bool
	ShowCounter bool
	Showthunder bool
	ShowElapsed bool
	ShowIcon    bool
	EnableColor bool
	EnableTmux  bool
}

func digit(num int) string {
	return strconv.Itoa(int(math.Log10(float64(num))) + 1)
}

func New(total int) *Bar {
	if total <= 0 {
		panic(errors.New("Please specify total size that is greater than zero"))
	}
	bar := &Bar{
		buffer:      bytes.Buffer{},
		totalVal:    total,
		nowVal:      -1,
		charLen:     len(chars),
		format:      "%s",
		prefix:      "|",
		postfix:     "|",
		charge:      "ϟ",
		ShowPercent: true,
		ShowCounter: true,
		Showthunder: false,
		ShowElapsed: false,
		ShowIcon:    false,
		EnableColor: false,
		EnableTmux:  true,
	}
	return bar.SetWidth(3)
}

func (bar *Bar) SetPrefix(char rune) *Bar {
	bar.prefix = string(char)
	return bar
}

func (bar *Bar) SetPostfix(char rune) *Bar {
	bar.postfix = string(char)
	return bar
}

func (bar *Bar) SetWidth(width int) *Bar {
	bar.width = width
	// +1 for postfix
	bar.gaugeWidth = width + 1

	return bar
}

func (bar *Bar) Set(percent, elapsed int) *Bar {
	bar.nowVal = percent
	bar.elapsed = elapsed
	return bar
}

func (bar *Bar) Run() {
	bar.writer()
}

func (bar *Bar) writer() {
	if bar.ShowPercent {
		bar.format = "%3d%%" + bar.format
	}

	if bar.ShowCounter {
		digit := digit(bar.totalVal)
		bar.format += " %" + digit + "d/%" + digit + "d"
	}

	if bar.ShowElapsed {
		bar.format += "%s"
	}

	if bar.nowVal <= bar.totalVal {
		bar.print()
	}

}

func (bar *Bar) print() {
	frac := float64(bar.nowVal) / float64(bar.totalVal)

	if bar.Showthunder {
		// append prefix
		bar.gauge += bar.prefix
		mid := int(math.Ceil(float64(bar.gaugeWidth / 2)))
		for i := 1; i < mid; i++ {
			bar.gauge += " "
		}
		// Middle
		bar.gauge += bar.charge
		for i := mid + 1; i < bar.gaugeWidth; i++ {
			bar.gauge += " "
		}
		// append postfix
		bar.gauge += bar.postfix
		bar.write(frac)

		return
	}

	if bar.ShowIcon {
		// append an icon
		bar.gauge += icons[bar.nowVal / 20]
	} else {
		barLen, fracBarLen := bar.divmod(frac)

		// append prefix
		bar.gauge += bar.prefix

		// append full block
		for i := 1; i < barLen; i++ {
			bar.gauge += chars[bar.charLen-1]
		}

		// append lower block
		bar.gauge += chars[fracBarLen]

		// padding with whitespace
		for i := barLen + 1; i < bar.gaugeWidth; i++ {
			bar.gauge += " "
		}
		// append postfix
		bar.gauge += bar.postfix
	}

	bar.write(frac)
}

func (bar *Bar) write(frac float64) {
	var args []interface{}
	percent := int(frac * 100)

	if bar.ShowPercent {
		args = append(args, percent)
	}

	args = append(args, string(bar.gauge))

	if bar.ShowCounter {
		args = append(args, bar.nowVal)
		args = append(args, bar.totalVal)
	}

	if bar.ShowElapsed {
		if bar.elapsed > 0 {
			args = append(args, fmt.Sprintf(" %d:%02d", bar.elapsed/60, bar.elapsed%60))
		} else {
			args = append(args, "")
		}
	}

	if bar.EnableColor {
		if bar.EnableTmux {
			bar.colorTmuxPrint(percent, args...)
		} else {
			bar.colorPrint(percent, args...)
		}
	} else {
		fmt.Fprintf(&bar.buffer, bar.format, args...)
	}
	color.Output.Write(bar.buffer.Bytes())
}

func (bar *Bar) colorTmuxPrint(percent int, args ...interface{}) {
	if percent >= 60 {
		bar.format = "#[fg=green]" + bar.format
	} else if 20 <= percent && percent < 60 {
		bar.format = "#[fg=yellow]" + bar.format
	} else {
		bar.format = "#[fg=red]" + bar.format
	}
	fmt.Fprintf(&bar.buffer, bar.format+"#[default]", args...)
}

func (bar *Bar) colorPrint(percent int, args ...interface{}) {
	if percent >= 60 {
		bar.buffer.WriteString(color.GreenString(bar.format, args...))
	} else if 20 <= percent && percent < 60 {
		bar.buffer.WriteString(color.YellowString(bar.format, args...))
	} else {
		bar.buffer.WriteString(color.RedString(bar.format, args...))
	}
}

func (bar *Bar) divmod(frac float64) (int, int) {
	// Over 100%
	if frac >= 1.0 {
		return bar.width, bar.charLen - 1
	}
	pre := int(frac * float64(bar.width) * float64(bar.charLen))
	return pre/bar.charLen + 1, pre % bar.charLen
}