Restore the ad removal from Play purchases

app/build.gradle

@@ -162,9 +162,10 @@ dependencies {
     // odrcore's JNI bindings, java and native in one AAR (see settings.gradle)
     implementation libs.odr.core.android
 
-    // Only Lite links the ad and consent SDKs; Foss links no Play SDKs.
+    // Only Lite links the ad, consent, and billing SDKs; Foss links no Play SDKs.
     liteImplementation libs.play.services.ads
     liteImplementation libs.user.messaging.platform
+    liteImplementation libs.play.billing
     liteImplementation libs.play.review
     proImplementation libs.play.review
 

app/src/ads/java/app/opendocument/droid/nonfree/OwnedPurchases.kt

@@ -0,0 +1,90 @@
+package app.opendocument.droid.nonfree
+
+import android.content.Context
+import android.os.Handler
+import android.os.Looper
+import com.android.billingclient.api.BillingClient
+import com.android.billingclient.api.BillingClientStateListener
+import com.android.billingclient.api.BillingResult
+import com.android.billingclient.api.PendingPurchasesParams
+import com.android.billingclient.api.Purchase
+import com.android.billingclient.api.QueryPurchasesParams
+
+/**
+ * Asks play whether the account owns the ad removal that lite sold until 2023: a one-time product,
+ * and before 2022 a subscription. Nothing sells it any more, but a buyer who reinstalls or changes
+ * device has only this to restore it from.
+ */
+object OwnedPurchases {
+
+    private val PRODUCT_TYPES =
+        listOf(BillingClient.ProductType.INAPP, BillingClient.ProductType.SUBS)
+
+    /** Calls [onOwned] on the main thread if any purchase is owned; says nothing otherwise. */
+    fun query(context: Context, crashManager: CrashManager, onOwned: () -> Unit) {
+        val mainThread = Handler(Looper.getMainLooper())
+
+        val client =
+            BillingClient.newBuilder(context.applicationContext)
+                .setListener { _, _ -> }
+                .enablePendingPurchases(
+                    PendingPurchasesParams.newBuilder().enableOneTimeProducts().build()
+                )
+                .build()
+
+        client.startConnection(
+            object : BillingClientStateListener {
+                override fun onBillingSetupFinished(result: BillingResult) {
+                    if (result.responseCode != BillingClient.BillingResponseCode.OK) {
+                        crashManager.log("billing setup failed: " + result.responseCode)
+
+                        client.endConnection()
+
+                        return
+                    }
+
+                    var pending = PRODUCT_TYPES.size
+                    var owned = false
+
+                    for (type in PRODUCT_TYPES) {
+                        val params = QueryPurchasesParams.newBuilder().setProductType(type).build()
+
+                        client.queryPurchasesAsync(params) { queryResult, purchases ->
+                            mainThread.post {
+                                if (
+                                    queryResult.responseCode != BillingClient.BillingResponseCode.OK
+                                ) {
+                                    crashManager.log(
+                                        "billing query failed: " +
+                                            type +
+                                            "/" +
+                                            queryResult.responseCode
+                                    )
+                                }
+
+                                owned =
+                                    owned ||
+                                        purchases.any {
+                                            it.purchaseState == Purchase.PurchaseState.PURCHASED
+                                        }
+
+                                pending--
+                                if (pending == 0) {
+                                    client.endConnection()
+
+                                    if (owned) {
+                                        onOwned()
+                                    }
+                                }
+                            }
+                        }
+                    }
+                }
+
+                override fun onBillingServiceDisconnected() {
+                    // the next launch asks again
+                }
+            }
+        )
+    }
+}

app/src/main/java/app/opendocument/droid/nonfree/BillingManager.kt

@@ -10,7 +10,14 @@ class BillingManager {
     private var adManager: AdManager? = null
     private var billingPreferences: BillingPreferences? = null
 
-    fun initialize(context: Context, adManager: AdManager) {
+    private var onPurchaseRestored: (() -> Unit)? = null
+
+    /** Fires once play reports a purchase that the preferences did not know about. */
+    fun setRestoreListener(listener: () -> Unit) {
+        onPurchaseRestored = listener
+    }
+
+    fun initialize(context: Context, adManager: AdManager, crashManager: CrashManager) {
         this.adManager = adManager
 
         val preferences = BillingPreferences(context)
@@ -27,16 +34,32 @@ class BillingManager {
         }
 
         if (hasPurchased()) {
-            adManager.removeAds()
-
-            // no banner to gate, but withdrawal has to survive the purchase, and only an
-            // update tells us whether the sdk wants a way back out
-            adManager.updateConsentInfo()
+            removeAds(adManager)
         } else {
             adManager.showGoogleAds()
+
+            // the flag lives only on this device, so a reinstall or a new device loses it. the
+            // ads show until play answers; a purchase is never revoked, as before
+            OwnedPurchases.query(context, crashManager) {
+                crashManager.log("purchase restored")
+
+                preferences.setPurchased(true)
+
+                removeAds(adManager)
+
+                onPurchaseRestored?.invoke()
+            }
         }
     }
 
+    private fun removeAds(adManager: AdManager) {
+        adManager.removeAds()
+
+        // no banner to gate, but withdrawal has to survive the purchase, and only an
+        // update tells us whether the sdk wants a way back out
+        adManager.updateConsentInfo()
+    }
+
     fun hasPurchased(): Boolean {
         if (!enabled) {
             return true

app/src/main/java/app/opendocument/droid/ui/activity/MainActivity.kt

@@ -440,7 +440,9 @@ class MainActivity : AppCompatActivity() {
 
         billingManager = BillingManager()
         billingManager.setEnabled(adsAvailable)
-        billingManager.initialize(this, adManager)
+        // the remove ads row goes once play has restored a purchase
+        billingManager.setRestoreListener { landingFragment?.refresh() }
+        billingManager.initialize(this, adManager, crashManager)
     }
 
     override fun onNewIntent(intent: Intent) {

app/src/noAds/java/app/opendocument/droid/nonfree/OwnedPurchases.kt

@@ -0,0 +1,9 @@
+package app.opendocument.droid.nonfree
+
+import android.content.Context
+
+/** Purchases, in a build that sells none and has no ads to remove. */
+object OwnedPurchases {
+
+    fun query(context: Context, crashManager: CrashManager, onOwned: () -> Unit) {}
+}

gradle/libs.versions.toml

@@ -18,6 +18,7 @@ androidxRecyclerview = "1.4.0"
 androidxLifecycle = "2.9.4"
 material = "1.14.0"
 
+playBilling = "9.1.0"
 playServicesAds = "25.5.0"
 playReview = "2.0.2"
 userMessagingPlatform = "4.0.0"
@@ -42,6 +43,7 @@ androidx-lifecycle-viewmodel = { module = "androidx.lifecycle:lifecycle-viewmode
 androidx-lifecycle-livedata = { module = "androidx.lifecycle:lifecycle-livedata", version.ref = "androidxLifecycle" }
 material = { module = "com.google.android.material:material", version.ref = "material" }
 
+play-billing = { module = "com.android.billingclient:billing", version.ref = "playBilling" }
 play-services-ads = { module = "com.google.android.gms:play-services-ads", version.ref = "playServicesAds" }
 play-review = { module = "com.google.android.play:review", version.ref = "playReview" }
 user-messaging-platform = { module = "com.google.android.ump:user-messaging-platform", version.ref = "userMessagingPlatform" }