feat: add horizon provider (#4)

## Summary
- add OpenIapProtocol contract and Horizon billing implementation on top
of the generated types
- allow selecting play | horizon | auto via BuildConfig and auto-detect
hardware when in auto mode
- update the example app and docs to reflect provider selection and
Horizon configuration

Author: hyochan

Example/build.gradle.kts

@@ -17,6 +17,14 @@ android {
 
         testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
         vectorDrawables.useSupportLibrary = true
+
+        val store = (project.findProperty("EXAMPLE_OPENIAP_STORE") as String?) ?: "play"
+        buildConfigField("String", "OPENIAP_STORE", "\"${store}\"")
+
+        val appId = (project.findProperty("EXAMPLE_HORIZON_APP_ID") as String?)
+            ?: (project.findProperty("EXAMPLE_OPENIAP_APP_ID") as String?)
+            ?: ""
+        buildConfigField("String", "HORIZON_APP_ID", "\"${appId}\"")
     }
 
     buildTypes {
@@ -44,6 +52,7 @@ android {
 
     buildFeatures {
         compose = true
+        buildConfig = true
     }
 
     packaging {

Example/src/main/java/dev/hyo/martie/Constants.kt

@@ -1,14 +1,28 @@
 package dev.hyo.martie
 
 object IapConstants {
-    // App-defined SKU lists
-    val INAPP_SKUS = listOf(
+    private fun isHorizon(): Boolean =
+        dev.hyo.martie.BuildConfig.OPENIAP_STORE.equals("horizon", ignoreCase = true)
+
+    private val HORIZON_INAPP = listOf(
         "dev.hyo.martie.10bulbs",
-        "dev.hyo.martie.30bulbs"
+        "dev.hyo.martie.30bulbs",
+    )
+    private val HORIZON_SUBS = listOf(
+        "dev.hyo.martie.premium",
     )
 
-    val SUBS_SKUS = listOf(
-        "dev.hyo.martie.premium"
+    private val PLAY_INAPP = listOf(
+        "dev.hyo.martie.10bulbs",
+        "dev.hyo.martie.30bulbs",
     )
-}
+    private val PLAY_SUBS = listOf(
+        "dev.hyo.martie.premium",
+    )
+
+    val INAPP_SKUS: List<String>
+        get() = if (isHorizon()) HORIZON_INAPP else PLAY_INAPP
 
+    val SUBS_SKUS: List<String>
+        get() = if (isHorizon()) HORIZON_SUBS else PLAY_SUBS
+}

Example/src/main/java/dev/hyo/martie/screens/PurchaseFlowScreen.kt

@@ -47,7 +47,12 @@ fun PurchaseFlowScreen(
     val activity = context as? Activity
     val uiScope = rememberCoroutineScope()
     val appContext = context.applicationContext as Context
-    val iapStore = storeParam ?: remember(appContext) { OpenIapStore(appContext) }
+    val iapStore = storeParam ?: remember(appContext) {
+        val storeKey = dev.hyo.martie.BuildConfig.OPENIAP_STORE
+        val appId = dev.hyo.martie.BuildConfig.HORIZON_APP_ID
+        runCatching { OpenIapStore(appContext, storeKey, appId) }
+            .getOrElse { OpenIapStore(appContext, "auto", appId) }
+    }
     val products by iapStore.products.collectAsState()
     val purchases by iapStore.availablePurchases.collectAsState()
     val androidProducts = remember(products) { products.filterIsInstance<ProductAndroid>() }

Example/src/main/java/dev/hyo/martie/screens/SubscriptionFlowScreen.kt

@@ -59,7 +59,12 @@ fun SubscriptionFlowScreen(
     val activity = context as? Activity
     val uiScope = rememberCoroutineScope()
     val appContext = context.applicationContext as Context
-    val iapStore = storeParam ?: remember(appContext) { OpenIapStore(appContext) }
+    val iapStore = storeParam ?: remember(appContext) {
+        val storeKey = dev.hyo.martie.BuildConfig.OPENIAP_STORE
+        val appId = dev.hyo.martie.BuildConfig.HORIZON_APP_ID
+        runCatching { OpenIapStore(appContext, storeKey, appId) }
+            .getOrElse { OpenIapStore(appContext, "auto", appId) }
+    }
     val products by iapStore.products.collectAsState()
     val purchases by iapStore.availablePurchases.collectAsState()
     val androidProducts = remember(products) { products.filterIsInstance<ProductAndroid>() }

README.md

@@ -29,6 +29,7 @@ OpenIAP GMS is a modern, type-safe Kotlin library that simplifies Google Play in
 - 🔐 **Google Play Billing v8** - Latest billing library with enhanced security
 - ⚡ **Kotlin Coroutines** - Modern async/await API
 - 🎯 **Type Safe** - Full Kotlin type safety with sealed classes
+- 🥽 **Meta Horizon OS Support** - Optional compatibility SDK integration alongside Play Billing
 - 🔄 **Real-time Events** - Purchase update and error listeners
 - 🧵 **Thread Safe** - Concurrent operations with proper synchronization
 - 📱 **Easy Integration** - Simple singleton pattern with context management
@@ -52,6 +53,21 @@ dependencies {
 }
 ```
 
+### Optional provider configuration
+
+Set the target billing provider via `BuildConfig` fields (default is `play`). The library will also auto-detect Horizon hardware when `auto` is supplied.
+
+```kotlin
+android {
+    defaultConfig {
+        buildConfigField("String", "OPENIAP_STORE", "\"auto\"") // play | horizon | auto
+        buildConfigField("String", "HORIZON_APP_ID", "\"YOUR_APP_ID\"")
+    }
+}
+```
+
+The example app reads the same values via `EXAMPLE_OPENIAP_STORE` / `EXAMPLE_HORIZON_APP_ID` Gradle properties for quick testing.
+
 Or `build.gradle`:
 
 ```groovy

openiap/build.gradle.kts

@@ -20,6 +20,8 @@ android {
 
         testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
         consumerProguardFiles("consumer-rules.pro")
+        buildConfigField("String", "OPENIAP_STORE", "\"play\"")
+        buildConfigField("String", "HORIZON_APP_ID", "\"\"")
     }
 
     buildTypes {
@@ -44,6 +46,7 @@ android {
     // Enable Compose for composables in this library (IapContext)
     buildFeatures {
         compose = true
+        buildConfig = true
     }
 }
 
@@ -53,6 +56,10 @@ dependencies {
 
     // Google Play Billing Library (align with app/lib v8)
     api("com.android.billingclient:billing-ktx:8.0.0")
+
+    // Meta Horizon Billing Compatibility SDK (optional provider)
+    implementation("com.meta.horizon.billingclient.api:horizon-billing-compatibility:1.1.1")
+    implementation("com.meta.horizon.platform.ovr:android-platform-sdk:72")
 
     // Kotlin Coroutines
     implementation("org.jetbrains.kotlinx:kotlinx-coroutines-core:1.9.0")

openiap/src/main/java/dev/hyo/openiap/OpenIapModule.kt

@@ -68,7 +68,7 @@ import java.lang.ref.WeakReference
 /**
  * Main OpenIapModule implementation for Android
  */
-class OpenIapModule(private val context: Context) : PurchasesUpdatedListener {
+class OpenIapModule(private val context: Context) : OpenIapProtocol, PurchasesUpdatedListener {
 
     companion object {
         private const val TAG = "OpenIapModule"
@@ -83,7 +83,7 @@ class OpenIapModule(private val context: Context) : PurchasesUpdatedListener {
     private val purchaseErrorListeners = mutableSetOf<OpenIapPurchaseErrorListener>()
     private var currentPurchaseCallback: ((Result<List<Purchase>>) -> Unit)? = null
 
-    val initConnection: MutationInitConnectionHandler = {
+    override val initConnection: MutationInitConnectionHandler = {
         withContext(Dispatchers.IO) {
             suspendCancellableCoroutine<Boolean> { continuation ->
                 initBillingClient(
@@ -97,7 +97,7 @@ class OpenIapModule(private val context: Context) : PurchasesUpdatedListener {
         }
     }
 
-    val endConnection: MutationEndConnectionHandler = {
+    override val endConnection: MutationEndConnectionHandler = {
         withContext(Dispatchers.IO) {
             runCatching {
                 billingClient?.endConnection()
@@ -107,7 +107,7 @@ class OpenIapModule(private val context: Context) : PurchasesUpdatedListener {
         }
     }
 
-    val fetchProducts: QueryFetchProductsHandler = { params ->
+    override val fetchProducts: QueryFetchProductsHandler = { params ->
         withContext(Dispatchers.IO) {
             val client = billingClient ?: throw OpenIapError.NotPrepared
             if (!client.isReady) throw OpenIapError.NotPrepared
@@ -140,11 +140,11 @@ class OpenIapModule(private val context: Context) : PurchasesUpdatedListener {
             }
         }
     }
-    val getAvailablePurchases: QueryGetAvailablePurchasesHandler = { _ ->
+    override val getAvailablePurchases: QueryGetAvailablePurchasesHandler = { _ ->
         withContext(Dispatchers.IO) { restorePurchasesHelper(billingClient) }
     }
 
-    val getActiveSubscriptions: QueryGetActiveSubscriptionsHandler = { subscriptionIds ->
+    override val getActiveSubscriptions: QueryGetActiveSubscriptionsHandler = { subscriptionIds ->
         withContext(Dispatchers.IO) {
             val purchases = queryPurchases(billingClient, BillingClient.ProductType.SUBS)
             val filtered = if (subscriptionIds.isNullOrEmpty()) {
@@ -158,11 +158,11 @@ class OpenIapModule(private val context: Context) : PurchasesUpdatedListener {
         }
     }
 
-    val hasActiveSubscriptions: QueryHasActiveSubscriptionsHandler = { subscriptionIds ->
+    override val hasActiveSubscriptions: QueryHasActiveSubscriptionsHandler = { subscriptionIds ->
         getActiveSubscriptions(subscriptionIds).isNotEmpty()
     }
 
-    val requestPurchase: MutationRequestPurchaseHandler = { props ->
+    override val requestPurchase: MutationRequestPurchaseHandler = { props ->
         val purchases = withContext(Dispatchers.IO) {
             val androidArgs = props.toAndroidPurchaseArgs()
             val activity = currentActivityRef?.get() ?: (context as? Activity)
@@ -313,7 +313,7 @@ class OpenIapModule(private val context: Context) : PurchasesUpdatedListener {
         queryPurchases(billingClient, billingType)
     }
 
-    val finishTransaction: MutationFinishTransactionHandler = { purchase, isConsumable ->
+    override val finishTransaction: MutationFinishTransactionHandler = { purchase, isConsumable ->
         withContext(Dispatchers.IO) {
             val client = billingClient ?: throw OpenIapError.NotPrepared
             if (!client.isReady) throw OpenIapError.NotPrepared
@@ -344,7 +344,7 @@ class OpenIapModule(private val context: Context) : PurchasesUpdatedListener {
         }
     }
 
-    val acknowledgePurchaseAndroid: MutationAcknowledgePurchaseAndroidHandler = { purchaseToken ->
+    override val acknowledgePurchaseAndroid: MutationAcknowledgePurchaseAndroidHandler = { purchaseToken ->
         withContext(Dispatchers.IO) {
             val client = billingClient ?: throw OpenIapError.NotPrepared
             val params = AcknowledgePurchaseParams.newBuilder().setPurchaseToken(purchaseToken).build()
@@ -361,7 +361,7 @@ class OpenIapModule(private val context: Context) : PurchasesUpdatedListener {
         }
     }
 
-    val consumePurchaseAndroid: MutationConsumePurchaseAndroidHandler = { purchaseToken ->
+    override val consumePurchaseAndroid: MutationConsumePurchaseAndroidHandler = { purchaseToken ->
         withContext(Dispatchers.IO) {
             val client = billingClient ?: throw OpenIapError.NotPrepared
             val params = ConsumeParams.newBuilder().setPurchaseToken(purchaseToken).build()
@@ -378,7 +378,7 @@ class OpenIapModule(private val context: Context) : PurchasesUpdatedListener {
         }
     }
 
-    val deepLinkToSubscriptions: MutationDeepLinkToSubscriptionsHandler = { options ->
+    override val deepLinkToSubscriptions: MutationDeepLinkToSubscriptionsHandler = { options ->
         val pkg = options?.packageNameAndroid ?: context.packageName
         val uri = if (!options?.skuAndroid.isNullOrBlank()) {
             Uri.parse("https://play.google.com/store/account/subscriptions?sku=${options!!.skuAndroid}&package=$pkg")
@@ -389,14 +389,14 @@ class OpenIapModule(private val context: Context) : PurchasesUpdatedListener {
         context.startActivity(intent)
     }
 
-    val restorePurchases: MutationRestorePurchasesHandler = {
+    override val restorePurchases: MutationRestorePurchasesHandler = {
         withContext(Dispatchers.IO) {
             restorePurchasesHelper(billingClient)
             Unit
         }
     }
 
-    val validateReceipt: MutationValidateReceiptHandler = { throw OpenIapError.NotSupported }
+    override val validateReceipt: MutationValidateReceiptHandler = { throw OpenIapError.NotSupported }
 
     private val purchaseError: SubscriptionPurchaseErrorHandler = {
         onPurchaseError(this::addPurchaseErrorListener, this::removePurchaseErrorListener)
@@ -406,15 +406,15 @@ class OpenIapModule(private val context: Context) : PurchasesUpdatedListener {
         onPurchaseUpdated(this::addPurchaseUpdateListener, this::removePurchaseUpdateListener)
     }
 
-    val queryHandlers: QueryHandlers = QueryHandlers(
+    override val queryHandlers: QueryHandlers = QueryHandlers(
         fetchProducts = fetchProducts,
         getActiveSubscriptions = getActiveSubscriptions,
         getAvailablePurchases = getAvailablePurchases,
         getStorefrontIOS = { getStorefront() },
         hasActiveSubscriptions = hasActiveSubscriptions
     )
 
-    val mutationHandlers: MutationHandlers = MutationHandlers(
+    override val mutationHandlers: MutationHandlers = MutationHandlers(
         acknowledgePurchaseAndroid = acknowledgePurchaseAndroid,
         consumePurchaseAndroid = consumePurchaseAndroid,
         deepLinkToSubscriptions = deepLinkToSubscriptions,
@@ -426,7 +426,7 @@ class OpenIapModule(private val context: Context) : PurchasesUpdatedListener {
         validateReceipt = validateReceipt
     )
 
-    val subscriptionHandlers: SubscriptionHandlers = SubscriptionHandlers(
+    override val subscriptionHandlers: SubscriptionHandlers = SubscriptionHandlers(
         purchaseError = purchaseError,
         purchaseUpdated = purchaseUpdated
     )
@@ -455,19 +455,19 @@ class OpenIapModule(private val context: Context) : PurchasesUpdatedListener {
         }
     }
 
-    fun addPurchaseUpdateListener(listener: OpenIapPurchaseUpdateListener) {
+    override fun addPurchaseUpdateListener(listener: OpenIapPurchaseUpdateListener) {
         purchaseUpdateListeners.add(listener)
     }
 
-    fun removePurchaseUpdateListener(listener: OpenIapPurchaseUpdateListener) {
+    override fun removePurchaseUpdateListener(listener: OpenIapPurchaseUpdateListener) {
         purchaseUpdateListeners.remove(listener)
     }
 
-    fun addPurchaseErrorListener(listener: OpenIapPurchaseErrorListener) {
+    override fun addPurchaseErrorListener(listener: OpenIapPurchaseErrorListener) {
         purchaseErrorListeners.add(listener)
     }
 
-    fun removePurchaseErrorListener(listener: OpenIapPurchaseErrorListener) {
+    override fun removePurchaseErrorListener(listener: OpenIapPurchaseErrorListener) {
         purchaseErrorListeners.remove(listener)
     }
 
@@ -557,7 +557,7 @@ class OpenIapModule(private val context: Context) : PurchasesUpdatedListener {
         })
     }
 
-    fun setActivity(activity: Activity?) {
+    override fun setActivity(activity: Activity?) {
         currentActivityRef = activity?.let { WeakReference(it) }
     }
 }

openiap/src/main/java/dev/hyo/openiap/OpenIapProtocol.kt

@@ -0,0 +1,38 @@
+package dev.hyo.openiap
+
+import android.app.Activity
+import dev.hyo.openiap.listener.OpenIapPurchaseErrorListener
+import dev.hyo.openiap.listener.OpenIapPurchaseUpdateListener
+
+/**
+ * Shared contract implemented by platform-specific OpenIAP billing modules.
+ * Provides access to generated handler typealiases so the store can remain provider-agnostic.
+ */
+interface OpenIapProtocol {
+    val initConnection: MutationInitConnectionHandler
+    val endConnection: MutationEndConnectionHandler
+
+    val fetchProducts: QueryFetchProductsHandler
+    val getAvailablePurchases: QueryGetAvailablePurchasesHandler
+    val getActiveSubscriptions: QueryGetActiveSubscriptionsHandler
+    val hasActiveSubscriptions: QueryHasActiveSubscriptionsHandler
+
+    val requestPurchase: MutationRequestPurchaseHandler
+    val finishTransaction: MutationFinishTransactionHandler
+    val acknowledgePurchaseAndroid: MutationAcknowledgePurchaseAndroidHandler
+    val consumePurchaseAndroid: MutationConsumePurchaseAndroidHandler
+    val restorePurchases: MutationRestorePurchasesHandler
+    val deepLinkToSubscriptions: MutationDeepLinkToSubscriptionsHandler
+    val validateReceipt: MutationValidateReceiptHandler
+
+    val queryHandlers: QueryHandlers
+    val mutationHandlers: MutationHandlers
+    val subscriptionHandlers: SubscriptionHandlers
+
+    fun setActivity(activity: Activity?)
+
+    fun addPurchaseUpdateListener(listener: OpenIapPurchaseUpdateListener)
+    fun removePurchaseUpdateListener(listener: OpenIapPurchaseUpdateListener)
+    fun addPurchaseErrorListener(listener: OpenIapPurchaseErrorListener)
+    fun removePurchaseErrorListener(listener: OpenIapPurchaseErrorListener)
+}