Create a nice progress bar using symbols

progress_bar.go

package progress_bar

import (
	"strings"
	"text/template"
)

// Options can be used to customize look of the progress bar. DefaultProgressOptions() has pretty good defaults.
type Options struct {
	Fill  string             // The character(s) used to fill in the progress bar
	Empty string             // The character(s) used to indicate empty space at the end of progress bar
	Width int                // How many characters wide the progress bar should be. A value of 10 looks good on slack phone clients.
	Msg   *template.Template // The message template that will be sent to slack. Uses text/template for creating templates.
}

var defaultTemplate = template.Must(template.New("default_progress_msg").Parse("`{{.ProgBar}}` {{.Done}}% ({{.Pos}}/{{.Total}})"))

// DefaultProgressOptions creates an Options struct with decent defaults.
func DefaultProgressOptions() *Options {
	return &Options{
		Fill:  "🟦",
		Empty: "⬜",
		Width: 10, // Looks good on slack phone clients
		Msg:   defaultTemplate,
	}
}

type Progress struct {
	Opts *Options
}

// NewProgress creates a new progress bar. Uses default options if non were set
func NewProgress(opts *Options) *Progress {
	progress := &Progress{
		Opts: opts,
	}

	if opts == nil {
		progress.Opts = DefaultProgressOptions()
	}

	return progress
}

func (p *Progress) drawBar(pos int, total int) string {
	if pos == 0 || total == 0 {
		return strings.Repeat(p.Opts.Empty, p.Opts.Width)
	}

	done := pos * 100 / total

	bar := strings.Repeat(p.Opts.Fill, done/p.Opts.Width)
	bar += strings.Repeat(p.Opts.Empty, p.Opts.Width-len([]rune(bar)))

	return bar
}

func (p *Progress) GetProgress(pos int, total int) (string, error) {
	msg := &strings.Builder{}
	done := 0
	if total != 0 {
		done = pos * 100 / total
	}

	data := map[string]interface{}{
		"ProgBar":  p.drawBar(pos, total),
		"Done":     done,
		"Pos":      pos,
		"Total":    total,
		"Complete": pos == total,
	}

	err := p.Opts.Msg.Execute(msg, data)
	return msg.String(), err
}