Simplify PresentedOfferingContextBackend creation

Add fromContext factory on PresentedOfferingContextBackend that
encapsulates the nil-check logic, removing duplication between
BackendStoredEvent and PaywallStoredEvent conversion paths.

Author: rickvdl

purchases/src/main/kotlin/com/revenuecat/purchases/common/events/BackendEvent.kt

@@ -123,7 +123,22 @@ internal sealed class BackendEvent : Event {
         val targetingRevision: Int? = null,
         @SerialName("targeting_rule_id")
         val targetingRuleId: String? = null,
-    )
+    ) {
+        companion object {
+            fun fromContext(
+                context: com.revenuecat.purchases.PresentedOfferingContext,
+            ): PresentedOfferingContextBackend? {
+                if (context.placementIdentifier == null && context.targetingContext == null) {
+                    return null
+                }
+                return PresentedOfferingContextBackend(
+                    placementIdentifier = context.placementIdentifier,
+                    targetingRevision = context.targetingContext?.revision,
+                    targetingRuleId = context.targetingContext?.ruleId,
+                )
+            }
+        }
+    }
 
     /**
      * Represents an event related to a custom paywall.

purchases/src/main/kotlin/com/revenuecat/purchases/common/events/BackendStoredEvent.kt

@@ -86,18 +86,6 @@ internal fun PaywallEvent.toBackendStoredEvent(
         // WIP: We should implement support for these events in the backend.
         return null
     }
-    val context = data.presentedOfferingContext
-    val presentedContext = if (
-        context.placementIdentifier != null || context.targetingContext != null
-    ) {
-        BackendEvent.PresentedOfferingContextBackend(
-            placementIdentifier = context.placementIdentifier,
-            targetingRevision = context.targetingContext?.revision,
-            targetingRuleId = context.targetingContext?.ruleId,
-        )
-    } else {
-        null
-    }
     return BackendStoredEvent.Paywalls(
         BackendEvent.Paywalls(
             id = creationData.id.toString(),
@@ -112,7 +100,9 @@ internal fun PaywallEvent.toBackendStoredEvent(
             displayMode = data.displayMode,
             darkMode = data.darkMode,
             localeIdentifier = data.localeIdentifier,
-            presentedOfferingContext = presentedContext,
+            presentedOfferingContext = BackendEvent.PresentedOfferingContextBackend.fromContext(
+                data.presentedOfferingContext,
+            ),
             exitOfferType = data.exitOfferType?.value,
             exitOfferingID = data.exitOfferingIdentifier,
             packageID = data.packageIdentifier,

purchases/src/main/kotlin/com/revenuecat/purchases/paywalls/events/PaywallStoredEvent.kt

@@ -22,18 +22,6 @@ internal data class PaywallStoredEvent(
 
     @OptIn(InternalRevenueCatAPI::class)
     fun toBackendEvent(): BackendEvent.Paywalls {
-        val context = event.data.presentedOfferingContext
-        val presentedContext = if (
-            context.placementIdentifier != null || context.targetingContext != null
-        ) {
-            BackendEvent.PresentedOfferingContextBackend(
-                placementIdentifier = context.placementIdentifier,
-                targetingRevision = context.targetingContext?.revision,
-                targetingRuleId = context.targetingContext?.ruleId,
-            )
-        } else {
-            null
-        }
         return BackendEvent.Paywalls(
             id = event.creationData.id.toString(),
             version = BackendEvent.PAYWALL_EVENT_SCHEMA_VERSION,
@@ -47,7 +35,9 @@ internal data class PaywallStoredEvent(
             displayMode = event.data.displayMode,
             darkMode = event.data.darkMode,
             localeIdentifier = event.data.localeIdentifier,
-            presentedOfferingContext = presentedContext,
+            presentedOfferingContext = BackendEvent.PresentedOfferingContextBackend.fromContext(
+                event.data.presentedOfferingContext,
+            ),
             exitOfferType = event.data.exitOfferType?.value,
             exitOfferingID = event.data.exitOfferingIdentifier,
         )