Add half baked countdown utility

countdown.go

@@ -0,0 +1,99 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"strings"
+	"time"
+)
+
+var (
+	formats = []string{
+		"2006-01-02",
+		"Monday",
+		"2/1",
+		"15:04",
+		time.Kitchen,
+		time.RFC1123,
+		time.RFC1123Z,
+		time.RFC3339,
+		time.RFC3339Nano,
+		time.RFC822,
+		time.RFC822Z,
+		time.RFC850,
+	}
+)
+
+func main() {
+	var target time.Time
+
+	input := os.Args[1]
+
+	d, err := time.ParseDuration(input)
+	if err == nil {
+		target = time.Now().Add(-d)
+	}
+
+	for _, format := range formats {
+		t, err := time.Parse(format, input)
+		if err == nil {
+			target = t
+			break
+		}
+	}
+
+	if target.Unix() == new(time.Time).Unix() {
+		fmt.Printf("Could not parse date: %q\n", input)
+		os.Exit(1)
+	}
+
+	fmt.Println(target)
+
+	// Assume year was not given and add the target to current time.
+	if target.Year() == 0 {
+		epoch := time.Now().Truncate(24 * time.Hour)
+		diff := target.Sub(epoch)
+		fmt.Println(diff)
+
+		target = time.Now().Add(diff)
+	}
+
+	fmt.Println(target)
+
+	for {
+		diff := target.Sub(time.Now())
+		days := int(diff.Hours() / 24)
+		hours := int(diff.Hours()) % 24
+		minutes := int(diff.Minutes()) % 60
+		seconds := int(diff.Minutes()*60) % 60
+
+		postfix := "left"
+		scale := 1
+
+		if target.Before(time.Now()) {
+			postfix = "ago"
+			scale = -1
+		}
+
+		var parts []string
+
+		if diff.Hours() > 24 {
+			parts = append(parts, fmt.Sprintf("%v days", scale*days))
+		}
+
+		if diff.Hours() > 0 {
+			parts = append(parts, fmt.Sprintf("%v hours", scale*hours))
+		}
+
+		if diff.Minutes() > 0 {
+			parts = append(parts, fmt.Sprintf("%v minutes", scale*minutes))
+		}
+
+		parts = append(parts, fmt.Sprintf("%v seconds", scale*seconds))
+		parts = append(parts, postfix)
+
+		fmt.Printf("\r%v", strings.Join(parts, " "))
+
+		time.Sleep(1 * time.Second)
+	}
+}