1 files changed, 54 insertions, 0 deletions
diff --git a/src/LivingVillage.Kernel/SimulationControl.fs b/src/LivingVillage.Kernel/SimulationControl.fs
new file mode 100644
index 0000000..83e5f36
--- /dev/null
+++ b/src/LivingVillage.Kernel/SimulationControl.fs
@@ -0,0 +1,54 @@
+namespace LivingVillage.Kernel
+
+type SimulationSpeed =
+    | OneX
+    | TwoX
+    | FiveX
+
+type SimulationControl =
+    { Paused: bool
+      Speed: SimulationSpeed }
+
+module SimulationControl =
+
+    let initial : SimulationControl =
+        { Paused = false
+          Speed = OneX }
+
+    let setSpeed (speed: SimulationSpeed) (control: SimulationControl) : SimulationControl =
+        { control with Speed = speed }
+
+    let togglePause (control: SimulationControl) : SimulationControl =
+        { control with Paused = not control.Paused }
+
+    let initialForConfiguredSteps (configuredSteps: int) : SimulationControl * int option =
+        let steps = if configuredSteps > 0 then configuredSteps else 1
+        let control =
+            match steps with
+            | 2 -> setSpeed TwoX initial
+            | 5 -> setSpeed FiveX initial
+            | _ -> initial
+        let legacySteps =
+            match steps with
+            | 1
+            | 2
+            | 5 -> None
+            | value -> Some value
+        control, legacySteps
+
+    let stepsPerFrame (control: SimulationControl) : int =
+        if control.Paused then
+            0
+        else
+            match control.Speed with
+            | OneX -> 1
+            | TwoX -> 2
+            | FiveX -> 5
+
+    let stepsPerFrameWithLegacy (legacySteps: int option) (control: SimulationControl) : int =
+        if control.Paused then
+            0
+        else
+            match legacySteps with
+            | Some steps when steps > 0 -> steps
+            | _ -> stepsPerFrame control