Add countdown

1 files changed, 36 insertions, 0 deletions

diff --git a/countdown.go b/countdown.go
new file mode 100644
index 0000000..1ba1999
--- /dev/null
+++ b/countdown.go
@@ -0,0 +1,36 @@
+package main
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"time"
+)
+
+type Sleeper interface {
+	Sleep()
+}
+
+type DefaultSleeper struct{}
+
+func (d *DefaultSleeper) Sleep() {
+	time.Sleep(1 * time.Second)
+}
+
+const finalWord = "Go!"
+const countdownStart = 3
+
+func Countdown(out io.Writer, sleeper Sleeper) {
+	for i := countdownStart; i > 0; i-- {
+		sleeper.Sleep()
+		fmt.Fprintln(out, i)
+	}
+
+	sleeper.Sleep()
+	fmt.Fprint(out, finalWord)
+}
+
+func main() {
+	sleeper := &DefaultSleeper{}
+	Countdown(os.Stdout, sleeper)
+}