[Case 1] Proposed solution

case-1/src/main/java/com/company/app/pvmodulelayouts/DefaultPvModuleLayouts.java

@@ -4,18 +4,23 @@
 import com.company.app.PvModuleLayouts;
 import com.company.app.PvModulePosition;
 import com.company.app.RoofFace;
-import com.company.app.pvmodulelayouts.layoutspecification.PvModulesMountedOnRoofFacePlaneLayoutSpecification;
-import com.company.app.pvmodulelayouts.layoutspecification.PvModulesMountedOnTiltedRacksLayoutSpecification;
 
 import java.util.List;
+import java.util.function.BiFunction;
 import java.util.stream.Stream;
 
 public class DefaultPvModuleLayouts implements PvModuleLayouts {
+    private final BiFunction<RoofFace, PvModuleDefinition, LayoutSpecification> layoutSpecificationConstructor;
+
+    public DefaultPvModuleLayouts(
+            BiFunction<RoofFace, PvModuleDefinition, LayoutSpecification> layoutSpecificationConstructor
+    ) {
+        this.layoutSpecificationConstructor = layoutSpecificationConstructor;
+    }
+
     @Override
     public List<PvModulePosition> optimalLayoutFor(RoofFace roofFace, PvModuleDefinition pvModuleDefinition) {
-        var layoutSpecification = roofFace.slopeAngleInDegrees() < 10
-                ? new PvModulesMountedOnRoofFacePlaneLayoutSpecification(pvModuleDefinition)
-                : new PvModulesMountedOnTiltedRacksLayoutSpecification(pvModuleDefinition);
+        var layoutSpecification = layoutSpecificationConstructor.apply(roofFace, pvModuleDefinition);
 
         return optimalLayoutTiles(roofFace, layoutSpecification)
                 .flatMap(layoutTile -> layoutSpecification.splitIntoPvModulePositions(layoutTile))

case-1/src/main/java/com/company/app/pvmodulelayouts/layoutspecification/PvModulesMountedOnRoofFacePlaneLayoutSpecification.java

@@ -13,10 +13,10 @@
  * Let's assume the logic is that PV modules are always mounted individually and in portrait orientation.
  * (i.e. the unit of placement (layout tile) is a single PV module in portrait orientation)
  */
-public class PvModulesMountedOnRoofFacePlaneLayoutSpecification implements LayoutSpecification {
+class PvModulesMountedOnRoofFacePlaneLayoutSpecification implements LayoutSpecification {
     private final PvModuleDefinition pvModuleDefinition;
 
-    public PvModulesMountedOnRoofFacePlaneLayoutSpecification(PvModuleDefinition pvModuleDefinition) {
+    PvModulesMountedOnRoofFacePlaneLayoutSpecification(PvModuleDefinition pvModuleDefinition) {
         this.pvModuleDefinition = pvModuleDefinition;
     }
 

case-1/src/main/java/com/company/app/pvmodulelayouts/layoutspecification/PvModulesMountedOnTiltedRacksLayoutSpecification.java

@@ -13,10 +13,10 @@
  * Let's assume the logic is that PV modules are always mounted in rows of 3 in landscape orientation
  * (i.e. the unit of placement (layout tile) is a group of 3 PV modules in landscape orientation)
  */
-public class PvModulesMountedOnTiltedRacksLayoutSpecification implements LayoutSpecification {
+class PvModulesMountedOnTiltedRacksLayoutSpecification implements LayoutSpecification {
     private final PvModuleDefinition pvModuleDefinition;
 
-    public PvModulesMountedOnTiltedRacksLayoutSpecification(PvModuleDefinition pvModuleDefinition) {
+    PvModulesMountedOnTiltedRacksLayoutSpecification(PvModuleDefinition pvModuleDefinition) {
         this.pvModuleDefinition = pvModuleDefinition;
     }
 

case-1/src/main/java/com/company/app/pvmodulelayouts/layoutspecification/RoofSlopeDependentLayoutSpecification.java

@@ -0,0 +1,34 @@
+package com.company.app.pvmodulelayouts.layoutspecification;
+
+import com.company.app.PvModuleDefinition;
+import com.company.app.PvModulePosition;
+import com.company.app.RoofFace;
+import com.company.app.pvmodulelayouts.LayoutSpecification;
+import com.company.app.pvmodulelayouts.LayoutTile;
+
+import java.util.stream.Stream;
+
+public class RoofSlopeDependentLayoutSpecification implements LayoutSpecification {
+    private final LayoutSpecification delegate;
+
+    public RoofSlopeDependentLayoutSpecification(RoofFace roofFace, PvModuleDefinition pvModuleDefinition) {
+        this.delegate = roofFace.slopeAngleInDegrees() < 10
+                ? new PvModulesMountedOnRoofFacePlaneLayoutSpecification(pvModuleDefinition)
+                : new PvModulesMountedOnTiltedRacksLayoutSpecification(pvModuleDefinition);
+    }
+
+    @Override
+    public double tileWidth() {
+        return delegate.tileWidth();
+    }
+
+    @Override
+    public double tileLength() {
+        return delegate.tileLength();
+    }
+
+    @Override
+    public Stream<PvModulePosition> splitIntoPvModulePositions(LayoutTile layoutTile) {
+        return delegate.splitIntoPvModulePositions(layoutTile);
+    }
+}

case-1/src/main/java/com/company/appconfig/Main.java

@@ -0,0 +1,13 @@
+package com.company.appconfig;
+
+import com.company.app.PvModuleLayouts;
+import com.company.app.pvmodulelayouts.DefaultPvModuleLayouts;
+import com.company.app.pvmodulelayouts.layoutspecification.RoofSlopeDependentLayoutSpecification;
+
+// @Configuration
+public class Main {
+    // @Bean
+    public PvModuleLayouts pvModuleLayouts() {
+        return new DefaultPvModuleLayouts(RoofSlopeDependentLayoutSpecification::new);
+    }
+}