progress output for cli go applications

progress.go

func PrintProgress(completed_files, statuses, finished chan string) {
	last_status := ""
	last_len := 0
	for {
		select {
		case completed_file := <-completed_files:
			fmt.Printf("\r")
			line := "completed: " + completed_file
			fmt.Print(line)
			print_len := len(line)
			trail_len := last_len - print_len
			if trail_len > 0 {
				for i := 0; i < trail_len; i++ {
					fmt.Print(" ")
				}
			}
			fmt.Print("\n" + last_status)
		case status := <-statuses:
			last_status = status
			fmt.Printf("\r")
			fmt.Print(status)
			print_len := len(status)
			trail_len := last_len - print_len
			if trail_len > 0 {
				for i := 0; i < trail_len; i++ {
					fmt.Print(" ")
				}
			}
			last_len = print_len
		case elapsed := <-finished:
			fmt.Println("\n" + elapsed)
			return
		}
	}
}