1 files changed, 76 insertions, 0 deletions
diff --git a/progress-bar.go b/progress-bar.go
new file mode 100644
index 0000000..0b1cefe
--- /dev/null
+++ b/progress-bar.go
@@ -0,0 +1,76 @@
+package main
+
+import (
+	"bytes"
+	"errors"
+	"flag"
+	"fmt"
+	"os"
+	"os/exec"
+	"strconv"
+	"strings"
+	"time"
+
+	"golang.org/x/term"
+)
+
+var n = flag.Duration("n", 2*time.Minute, "polling interval")
+
+func run() error {
+	cols, _, err := term.GetSize(int(os.Stdout.Fd()))
+	if err != nil {
+		return err
+	}
+	args := flag.Args()
+	if len(args) < 2 {
+		return errors.New("usage error")
+	}
+	maxStr := args[0]
+	maxVal, err := strconv.Atoi(maxStr)
+	if err != nil {
+		return fmt.Errorf("max: %s", err)
+	}
+	cmd := args[1:]
+	type measurement struct {
+		t time.Time
+		i int
+	}
+	var measurements []measurement
+	for i := 0; ; i++ {
+		outputBytes, err := exec.Command(cmd[0], cmd[1:]...).Output()
+		if err != nil {
+			fmt.Println(err)
+			continue
+		}
+		output, err := strconv.Atoi(string(bytes.TrimSuffix(outputBytes, []byte("\n"))))
+		if err != nil {
+			fmt.Println(err)
+			continue
+		}
+		p := output * cols / maxVal
+		if i > 0 {
+			fmt.Print("\033[2F\033[J")
+		}
+		fmt.Printf("%s>\n", strings.Repeat("=", max(p-1, 0)))
+		measurements = append(measurements, measurement{time.Now(), output})
+		if len(measurements) > 20 {
+			measurements = measurements[1:]
+		}
+		deltaT := measurements[len(measurements)-1].t.Sub(measurements[0].t)
+		delta := measurements[len(measurements)-1].i - measurements[0].i
+		if delta == 0 {
+			fmt.Println()
+		} else {
+			fmt.Printf("ETA: %s\n", time.Duration(float64(maxVal-output)/float64(delta)*float64(deltaT)).Round(time.Second))
+		}
+		time.Sleep(*n)
+	}
+}
+
+func main() {
+	flag.Parse()
+	if err := run(); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+}