feat: Improved event observation API

Signed-off-by: Fabrizio Demaria <[email protected]>

Author: fabriziodemaria

android/src/main/java/dev/openfeature/sdk/OpenFeatureAPI.kt

@@ -1,15 +1,21 @@
 package dev.openfeature.sdk
 
+import kotlinx.coroutines.flow.MutableSharedFlow
+import kotlinx.coroutines.flow.SharedFlow
+
 @Suppress("TooManyFunctions")
 object OpenFeatureAPI {
     private var provider: FeatureProvider? = null
     private var context: EvaluationContext? = null
+    private val providersFlow: MutableSharedFlow<FeatureProvider> = MutableSharedFlow(replay = 1)
+    internal val sharedProvidersFlow: SharedFlow<FeatureProvider> get() = providersFlow
 
     var hooks: List<Hook<*>> = listOf()
         private set
 
     fun setProvider(provider: FeatureProvider, initialContext: EvaluationContext? = null) {
         this@OpenFeatureAPI.provider = provider
+        providersFlow.tryEmit(provider)
         if (initialContext != null) context = initialContext
         try {
             provider.initialize(context)

android/src/main/java/dev/openfeature/sdk/async/Extensions.kt

@@ -9,8 +9,11 @@ import dev.openfeature.sdk.events.observe
 import kotlinx.coroutines.CoroutineDispatcher
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.cancel
 import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.distinctUntilChanged
+import kotlinx.coroutines.flow.flatMapLatest
 import kotlinx.coroutines.flow.onStart
 import kotlinx.coroutines.flow.take
 import kotlinx.coroutines.launch
@@ -42,6 +45,17 @@ internal fun FeatureProvider.observeProviderReady() = observe<OpenFeatureEvents.
         }
     }
 
+/*
+Observe events from currently configured Provider.
+The most recent event prior to starting the observation is collected on start.
+ */
+@OptIn(ExperimentalCoroutinesApi::class)
+fun OpenFeatureAPI.observeEvents(): Flow<OpenFeatureEvents> {
+    return sharedProvidersFlow.flatMapLatest { provider ->
+        provider.observe().distinctUntilChanged()
+    }
+}
+
 internal fun FeatureProvider.observeProviderError() = observe<OpenFeatureEvents.ProviderError>()
     .onStart {
         val status = getProviderStatus()
@@ -50,10 +64,6 @@ internal fun FeatureProvider.observeProviderError() = observe<OpenFeatureEvents.
         }
     }
 
-inline fun <reified T : OpenFeatureEvents> OpenFeatureAPI.observeEvents(): Flow<T>? {
-    return getProvider()?.observe<T>()
-}
-
 suspend fun FeatureProvider.awaitReadyOrError(
     dispatcher: CoroutineDispatcher = Dispatchers.IO
 ) = suspendCancellableCoroutine { continuation ->