apex/up

// Package progressreader provides an io.Reader progress bar.
package progressreader

import (
    "io"
    "sync"

    "github.com/apex/up/internal/util"
    "github.com/tj/go-progress"
    "github.com/tj/go/term"
)

// reader wrapping a progress bar.
type reader struct {
    io.ReadCloser
    p       *progress.Bar
    render  func(string)
    written int
    sync.Once
}

// Read implementation.
func (r *reader) Read(b []byte) (int, error) {
    r.Do(term.ClearAll)
    n, err := r.ReadCloser.Read(b)
    r.written += n
    r.p.ValueInt(r.written)
    r.render(term.CenterLine(r.p.String()))
    return n, err
}

// New returns a progress bar reader.
func New(size int, r io.ReadCloser) io.ReadCloser {
    return &reader{
        ReadCloser: r,
        p:          util.NewProgressInt(size),
        render:     term.Renderer(),
    }
}