Add simple time passed guard

src/main/java/de/w665/pr/statemachine/trafficlight/MinimumTimePassedGuard.java

@@ -0,0 +1,27 @@
+package de.w665.pr.statemachine.trafficlight;
+
+import lombok.RequiredArgsConstructor;
+import org.springframework.statemachine.StateContext;
+import org.springframework.statemachine.guard.Guard;
+import org.springframework.stereotype.Component;
+
+@RequiredArgsConstructor
+@Component
+public class MinimumTimePassedGuard implements Guard<TrafficLightStates, TrafficLightEvents> {
+
+    private static final long MIN_TIME_BETWEEN_TRANSITIONS = 1000 * 2; // 2 Seconds
+
+    private final TimingContext timingContext;
+
+    @Override
+    public boolean evaluate(StateContext<TrafficLightStates, TrafficLightEvents> context) {
+        long currentTime = System.currentTimeMillis();
+        long lastTransitionTime = timingContext.getLastTransitionTime();
+
+        if(lastTransitionTime == 0) {
+            return true;
+        }
+
+        return (currentTime - lastTransitionTime) >= MIN_TIME_BETWEEN_TRANSITIONS;
+    }
+}

src/main/java/de/w665/pr/statemachine/trafficlight/TimingContext.java

@@ -0,0 +1,19 @@
+package de.w665.pr.statemachine.trafficlight;
+
+import org.springframework.stereotype.Component;
+
+/**
+ * Tracks the time, when a light switch is triggered
+ */
+@Component
+public class TimingContext {
+    private volatile long lastTransitionTime = 0;
+
+    public void recordTransition() {
+        this.lastTransitionTime = System.currentTimeMillis();
+    }
+
+    public long getLastTransitionTime() {
+        return lastTransitionTime;
+    }
+}

src/main/java/de/w665/pr/statemachine/trafficlight/TrafficLightStateMachineConfig.java

@@ -1,5 +1,6 @@
 package de.w665.pr.statemachine.trafficlight;
 
+import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
@@ -12,10 +13,14 @@ import org.springframework.statemachine.config.builders.StateMachineTransitionCo
 import java.util.EnumSet;
 
 @Slf4j
+@RequiredArgsConstructor
 @Configuration
 @EnableStateMachine
 public class TrafficLightStateMachineConfig extends StateMachineConfigurerAdapter<TrafficLightStates, TrafficLightEvents> {
 
+    private final MinimumTimePassedGuard minimumTimePassedGuard;
+    private final TimingContext timingContext;
+
     @Override
     public void configure(StateMachineStateConfigurer<TrafficLightStates, TrafficLightEvents> states) throws Exception{
         states
@@ -23,8 +28,8 @@ public class TrafficLightStateMachineConfig extends StateMachineConfigurerAdapte
                 .initial(TrafficLightStates.RED)
                 .state(TrafficLightStates.RED, redEntryAction(), redExitAction())
                 .state(TrafficLightStates.YELLOW, yellowEntryAction(), yellowExitAction())
-                .state(TrafficLightStates.GREEN, greenEntryAction(), greenExitAction())
+                .state(TrafficLightStates.GREEN, greenEntryAction(), greenExitAction());
-                .states(EnumSet.allOf(TrafficLightStates.class)); // Do I need this line? Aren't all the states configured in the line above?
+                /*.states(EnumSet.allOf(TrafficLightStates.class));*/ // Redundant -> Only used when all enum values should be added as states | We're defining them above already
     }
 
     @Override
@@ -34,16 +39,27 @@ public class TrafficLightStateMachineConfig extends StateMachineConfigurerAdapte
                     .source(TrafficLightStates.RED)
                     .target(TrafficLightStates.GREEN)
                     .event(TrafficLightEvents.TIMER)
+                    .guard(minimumTimePassedGuard)
+                    .action(recordTransitionAction())
                 .and()
                 .withExternal()
                     .source(TrafficLightStates.GREEN)
                     .target(TrafficLightStates.YELLOW)
                     .event(TrafficLightEvents.TIMER)
+                    .guard(minimumTimePassedGuard)
+                    .action(recordTransitionAction())
                 .and()
                 .withExternal()
                     .source(TrafficLightStates.YELLOW)
                     .target(TrafficLightStates.RED)
-                    .event(TrafficLightEvents.TIMER);
+                    .event(TrafficLightEvents.TIMER)
+                    .guard(minimumTimePassedGuard)
+                    .action(recordTransitionAction());
+    }
+
+    @Bean
+    public Action<TrafficLightStates, TrafficLightEvents> recordTransitionAction() {
+        return context -> timingContext.recordTransition();
     }
 
     @Bean