feat(android): add foss flavor build without gms services (#3666)

apps/readest-app/src-tauri/plugins/tauri-plugin-native-bridge/android/build.gradle.kts

@@ -30,10 +30,21 @@ android {
     kotlinOptions {
         jvmTarget = "1.8"
     }
+
+    flavorDimensions += "store"
+    productFlavors {
+        create("foss") {
+            dimension = "store"
+        }
+        create("googleplay") {
+            dimension = "store"
+        }
+    }
 }
 
 dependencies {
-    implementation("com.android.billingclient:billing-ktx:7.1.1")
+    "googleplayImplementation"("com.android.billingclient:billing-ktx:7.1.1")
+    "googleplayImplementation"("com.google.android.gms:play-services-base:18.5.0")
     implementation("androidx.core:core-ktx:1.12.0")
     implementation("androidx.appcompat:appcompat:1.6.1")
     implementation("androidx.browser:browser:1.8.0")

apps/readest-app/src-tauri/plugins/tauri-plugin-native-bridge/android/src/foss/java/com/readest/native_bridge/BillingManager.kt

@@ -0,0 +1,31 @@
+package com.readest.native_bridge
+
+import android.app.Activity
+import android.util.Log
+
+class BillingManager(private val activity: Activity) {
+    companion object {
+        private const val TAG = "BillingManager"
+    }
+
+    fun isBillingAvailable(): Boolean {
+        return false
+    }
+
+    fun initialize(callback: (Boolean) -> Unit) {
+        Log.d(TAG, "Google Play billing not available in this build")
+        callback(false)
+    }
+
+    fun fetchProducts(productIds: List<String>, callback: (List<ProductData>) -> Unit) {
+        callback(emptyList())
+    }
+
+    fun purchaseProduct(productId: String, callback: (PurchaseData?) -> Unit) {
+        callback(null)
+    }
+
+    fun restorePurchases(callback: (List<PurchaseData>) -> Unit) {
+        callback(emptyList())
+    }
+}