works

go.mod

@@ -0,0 +1,3 @@
+module git.schreifuchs.ch/schreifuchs/worktime
+
+go 1.22.5

main.go

@@ -0,0 +1,47 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"time"
+)
+
+const (
+	defaultFormat = "15:04"
+	defaultGoal   = "8.3h"
+)
+
+func main() {
+	format := flag.String("f", defaultFormat, "Set the input time format ")
+	goalS := flag.String("g", defaultGoal, "Set the duration goal ")
+	flag.Parse()
+
+	goal, err := time.ParseDuration(*goalS)
+	if err != nil {
+		fmt.Printf("Error parsing \"%s\": %v", *goalS, err)
+		eight := 8.3 * float64(time.Hour)
+		goal = time.Duration(eight)
+	}
+
+	acc := time.Second * 0
+	for i, arg := range flag.Args() {
+		t, err := time.Parse(*format, arg)
+		if err != nil {
+			fmt.Printf("Error parsing \"%s\": %v", arg, err)
+			continue
+		}
+		dur := time.Hour*time.Duration(t.Hour()) + time.Minute*time.Duration(t.Minute())
+
+		if i%2 == 0 {
+			acc -= dur
+		} else {
+			acc += dur
+		}
+	}
+	if len(flag.Args())%2 != 0 {
+		diff := goal - acc
+		fmt.Printf("You reached your goal of %v at: %s\n", goal, time.Time{}.Add(diff).Format(*format))
+	} else {
+		fmt.Printf("With these hour's you have worked: %v\n", acc)
+	}
+}