chore: added screen processor

posthog-android/src/main/java/com/posthog/android/PostHogAndroid.kt

@@ -11,6 +11,7 @@ import com.posthog.android.internal.PostHogAndroidLogger
 import com.posthog.android.internal.PostHogAndroidNetworkStatus
 import com.posthog.android.internal.PostHogAppInstallIntegration
 import com.posthog.android.internal.PostHogLifecycleObserverIntegration
+import com.posthog.android.internal.PostHogScreenProcessor
 import com.posthog.android.internal.PostHogSharedPreferences
 import com.posthog.android.internal.appContext
 import com.posthog.android.replay.PostHogReplayIntegration
@@ -88,6 +89,10 @@ public class PostHogAndroid private constructor() {
                 if (config.captureDeepLinks || config.captureScreenViews || config.sessionReplay) {
                     config.addIntegration(PostHogActivityLifecycleCallbackIntegration(context, config))
                 }
+                // if the processor depends on captureScreenViews, only adds if its enabled
+                if (config.captureScreenViews) {
+                    config.addProcessor(PostHogScreenProcessor())
+                }
             }
             if (config.captureApplicationLifecycleEvents) {
                 config.addIntegration(PostHogAppInstallIntegration(context, config))

posthog-android/src/main/java/com/posthog/android/internal/PostHogActivityLifecycleCallbackIntegration.kt

@@ -47,6 +47,7 @@ internal class PostHogActivityLifecycleCallbackIntegration(
 
             if (!screenName.isNullOrEmpty()) {
                 PostHog.screen(screenName)
+                ScreenTracker.setCurrentScreen(screenName)
             }
         }
     }

posthog-android/src/main/java/com/posthog/android/internal/PostHogScreenProcessor.kt

@@ -0,0 +1,17 @@
+package com.posthog.android.internal
+
+import com.posthog.PostHogPropertiesProcessor
+
+internal class PostHogScreenProcessor : PostHogPropertiesProcessor {
+    override fun process(properties: MutableMap<String, Any>): Map<String, Any> {
+        if (properties.containsKey("\$screen_name")) {
+            return properties
+        }
+
+        val currentScreen = ScreenTracker.getCurrentScreenName()
+
+        properties["\$screen_name"] = currentScreen
+
+        return properties
+    }
+}

posthog-android/src/main/java/com/posthog/android/internal/ScreenTracker.kt

@@ -0,0 +1,13 @@
+package com.posthog.android.internal
+
+public object ScreenTracker {
+    @Volatile private lateinit var currentScreen: String
+
+    public fun setCurrentScreen(screenName: String) {
+        currentScreen = screenName
+    }
+
+    public fun getCurrentScreenName(): String {
+        return currentScreen
+    }
+}

posthog/src/main/java/com/posthog/PostHog.kt

@@ -68,8 +68,6 @@ public class PostHog private constructor(
     private var isIdentifiedLoaded: Boolean = false
     private var isPersonProcessingLoaded: Boolean = false
 
-    private lateinit var currentScreen: String
-
     public override fun <T : PostHogConfig> setup(config: T) {
         synchronized(setupLock) {
             try {
@@ -319,10 +317,6 @@ public class PostHog private constructor(
                 }
             }
 
-            currentScreen.let {
-                props["\$screen_name"] = currentScreen
-            }
-
             userProperties?.let {
                 props["\$set"] = it
             }
@@ -447,8 +441,14 @@ public class PostHog private constructor(
                     appendGroups = !groupIdentify,
                 )
 
+            var currentProperties = mergedProperties
+            // has to run before the sanitizer so people can remove stuff processors add
+            config?.processors?.forEach {
+                currentProperties = it.process(currentProperties.toMutableMap())
+            }
+
             // sanitize the properties or fallback to the original properties
-            val sanitizedProperties = config?.propertiesSanitizer?.sanitize(mergedProperties.toMutableMap()) ?: mergedProperties
+            val sanitizedProperties = config?.propertiesSanitizer?.sanitize(currentProperties.toMutableMap()) ?: currentProperties
 
             val postHogEvent =
                 PostHogEvent(
@@ -512,8 +512,6 @@ public class PostHog private constructor(
         val props = mutableMapOf<String, Any>()
         props["\$screen_name"] = screenTitle
 
-        currentScreen = screenTitle
-
         properties?.let {
             props.putAll(it)
         }

posthog/src/main/java/com/posthog/PostHogConfig.kt

@@ -156,6 +156,9 @@ public open class PostHogConfig(
     private val integrationsList: MutableList<PostHogIntegration> = mutableListOf()
     private val integrationLock = Any()
 
+    private val processorsList: MutableList<PostHogPropertiesProcessor> = mutableListOf()
+    private val processorsLock = Any()
+
     /**
      * The integrations list
      */
@@ -188,6 +191,21 @@ public open class PostHogConfig(
         }
     }
 
+    public val processors: List<PostHogPropertiesProcessor>
+        get() {
+            val list: List<PostHogPropertiesProcessor>
+            synchronized(processorsLock) {
+                list = processorsList.toList()
+            }
+            return list
+        }
+
+    public fun addProcessor(processor: PostHogPropertiesProcessor) {
+        synchronized(processorsLock) {
+            processorsList.add(processor)
+        }
+    }
+
     public companion object {
         public const val DEFAULT_HOST: String = "https://us.i.posthog.com"
     }

posthog/src/main/java/com/posthog/PostHogPropertiesProcessor.kt

@@ -0,0 +1,5 @@
+package com.posthog
+
+public fun interface PostHogPropertiesProcessor {
+    public fun process(properties: MutableMap<String, Any>): Map<String, Any>
+}