Improve library usability

library/src/main/java/com/billing/BillingService.kt

@@ -0,0 +1,99 @@
+package com.billing
+
+import android.app.Activity
+import android.os.Handler
+import android.os.Looper
+import androidx.annotation.CallSuper
+
+abstract class BillingService {
+
+    private val purchaseServiceListeners: MutableList<PurchaseServiceListener> = mutableListOf()
+    private val subscriptionServiceListeners: MutableList<SubscriptionServiceListener> = mutableListOf()
+
+    fun addPurchaseListener(purchaseServiceListener: PurchaseServiceListener) {
+        purchaseServiceListeners.add(purchaseServiceListener)
+    }
+
+    fun removePurchaseListener(purchaseServiceListener: PurchaseServiceListener) {
+        purchaseServiceListeners.remove(purchaseServiceListener)
+    }
+
+    fun addSubscriptionListener(subscriptionServiceListener: SubscriptionServiceListener) {
+        subscriptionServiceListeners.add(subscriptionServiceListener)
+    }
+
+    fun removeSubscriptionListener(subscriptionServiceListener: SubscriptionServiceListener) {
+        subscriptionServiceListeners.remove(subscriptionServiceListener)
+    }
+
+    /**
+     * @param sku       - product specificator
+     * @param isRestore - a flag indicating whether it's a fresh purchase or restored product
+     */
+    fun productOwned(sku: String?, isRestore: Boolean) {
+        findUiHandler().post {
+            productOwnedInternal(sku, isRestore)
+        }
+    }
+
+    fun productOwnedInternal(sku: String?, isRestore: Boolean) {
+        for (purchaseServiceListener in purchaseServiceListeners) {
+            if (isRestore) {
+                purchaseServiceListener.onProductRestored(sku)
+            } else {
+                purchaseServiceListener.onProductPurchased(sku)
+            }
+        }
+    }
+
+    /**
+     * @param sku       - subscription specificator
+     * @param isRestore - a flag indicating whether it's a fresh purchase or restored subscription
+     */
+    fun subscriptionOwned(sku: String, isRestore: Boolean) {
+        findUiHandler().post {
+            subscriptionOwnedInternal(sku, isRestore)
+        }
+    }
+
+    fun subscriptionOwnedInternal(sku: String, isRestore: Boolean) {
+        for (subscriptionServiceListener in subscriptionServiceListeners) {
+            if (isRestore) {
+                subscriptionServiceListener.onSubscriptionRestored(sku)
+            } else {
+                subscriptionServiceListener.onSubscriptionPurchased(sku)
+            }
+        }
+    }
+
+    fun updatePrices(iapkeyPrices: Map<String, String>) {
+        findUiHandler().post {
+            updatePricesInternal(iapkeyPrices)
+        }
+    }
+
+    fun updatePricesInternal(iapkeyPrices: Map<String, String>) {
+        for (billingServiceListener in purchaseServiceListeners) {
+            billingServiceListener.onPricesUpdated(iapkeyPrices)
+        }
+        for (billingServiceListener in subscriptionServiceListeners) {
+            billingServiceListener.onPricesUpdated(iapkeyPrices)
+        }
+    }
+
+    abstract fun init(key: String?)
+    abstract fun buy(activity: Activity, sku: String)
+    abstract fun subscribe(activity: Activity, sku: String)
+    abstract fun unsubscribe(activity: Activity, sku: String)
+    abstract fun enableDebugLogging(enable: Boolean)
+
+    @CallSuper
+    open fun close() {
+        subscriptionServiceListeners.clear()
+        purchaseServiceListeners.clear()
+    }
+}
+
+fun findUiHandler(): Handler {
+    return Handler(Looper.getMainLooper())
+}

library/src/main/java/com/billing/amazon/AmazonBillingService.kt

@@ -11,7 +11,7 @@ class AmazonBillingService(val context: Context, private val iapKeys: List<Strin
 
     private var mAmazonBillingListener: AmazonBillingListener? = null
 
-    override fun init(key: String) {
+    override fun init(key: String?) {
         mAmazonBillingListener = AmazonBillingListener(this)
         PurchasingService.registerListener(context, mAmazonBillingListener)
 
@@ -22,15 +22,15 @@ class AmazonBillingService(val context: Context, private val iapKeys: List<Strin
         PurchasingService.getPurchaseUpdates(true)
     }
 
-    override fun buy(activity: Activity, sku: String, id: Int) {
+    override fun buy(activity: Activity, sku: String) {
         PurchasingService.purchase(sku)
     }
 
-    override fun subscribe(activity: Activity, sku: String, id: Int) {
+    override fun subscribe(activity: Activity, sku: String) {
         PurchasingService.purchase(sku)
     }
 
-    override fun unsubscribe(activity: Activity, sku: String, id: Int) {
+    override fun unsubscribe(activity: Activity, sku: String) {
         try {
             val intent = Intent()
             intent.action = Intent.ACTION_VIEW

library/src/main/java/com/billing/google/GoogleBillingService2.kt

@@ -12,13 +12,13 @@ class GoogleBillingService2(val context: Context, private val inAppSkuKeys: List
     : BillingService(), PurchasesUpdatedListener, BillingClientStateListener, AcknowledgePurchaseResponseListener {
 
     private lateinit var mBillingClient: BillingClient
-    private lateinit var decodedKey: String
+    private var decodedKey: String? = null
 
     private var enableDebug: Boolean = false
 
     private val skusDetails = mutableMapOf<String, SkuDetails?>()
 
-    override fun init(key: String) {
+    override fun init(key: String?) {
         decodedKey = key
 
         mBillingClient = BillingClient.newBuilder(context).setListener(this).enablePendingPurchases().build()
@@ -51,7 +51,7 @@ class GoogleBillingService2(val context: Context, private val inAppSkuKeys: List
         }
     }
 
-    override fun buy(activity: Activity, sku: String, id: Int) {
+    override fun buy(activity: Activity, sku: String) {
         if (!sku.isSkuReady()) {
             log("buy. Google billing service is not ready yet.")
             return
@@ -60,7 +60,7 @@ class GoogleBillingService2(val context: Context, private val inAppSkuKeys: List
         launchBillingFlow(activity, sku, BillingClient.SkuType.INAPP)
     }
 
-    override fun subscribe(activity: Activity, sku: String, id: Int) {
+    override fun subscribe(activity: Activity, sku: String) {
         if (!sku.isSkuReady()) {
             log("buy. Google billing service is not ready yet.")
             return
@@ -77,7 +77,7 @@ class GoogleBillingService2(val context: Context, private val inAppSkuKeys: List
         }
     }
 
-    override fun unsubscribe(activity: Activity, sku: String, id: Int) {
+    override fun unsubscribe(activity: Activity, sku: String) {
         try {
             val intent = Intent()
             intent.action = Intent.ACTION_VIEW
@@ -165,7 +165,8 @@ class GoogleBillingService2(val context: Context, private val inAppSkuKeys: List
     }
 
     private fun isSignatureValid(purchase: Purchase): Boolean {
-        return Security.verifyPurchase(decodedKey, purchase.originalJson, purchase.signature)
+        val key = decodedKey ?: return true
+        return Security.verifyPurchase(key, purchase.originalJson, purchase.signature)
     }
 
     /**