Add stateflow for shopping cart (#137)

Author: Fabtron

core/src/main/java/io/snabble/sdk/Project.kt

@@ -21,6 +21,9 @@ import io.snabble.sdk.utils.getIntOpt
 import io.snabble.sdk.utils.getString
 import io.snabble.sdk.utils.getStringListOpt
 import io.snabble.sdk.utils.getStringOpt
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.asStateFlow
 import okhttp3.OkHttpClient
 import okhttp3.Request
 import org.apache.commons.lang3.LocaleUtils
@@ -290,11 +293,18 @@ class Project internal constructor(jsonObject: JsonObject) {
     private lateinit var shoppingCartStorage: ShoppingCartStorage
         private set
 
+    private val _shoppingCart = MutableStateFlow(ShoppingCart())
+
+    /**
+     * Flow to observe the current users shopping cart
+     */
+    val shoppingCartFlow: StateFlow<ShoppingCart> = _shoppingCart.asStateFlow()
+
     /**
      * The users shopping cart
      */
-    lateinit var shoppingCart: ShoppingCart
-        private set
+    val shoppingCart: ShoppingCart
+        get() = shoppingCartFlow.value
 
     /**
      * Provides a list of active coupons
@@ -496,15 +506,15 @@ class Project internal constructor(jsonObject: JsonObject) {
             .addInterceptor(AcceptedLanguageInterceptor())
             .build()
 
-        shoppingCart = ShoppingCart(this)
+        _shoppingCart.tryEmit(ShoppingCart(this))
 
         shoppingCartStorage = ShoppingCartStorage(this)
 
-        checkout = Checkout(this, shoppingCart)
+        checkout = Checkout(this, shoppingCartFlow.value)
 
-        productDatabase = ProductDatabase(this, shoppingCart, "$id.sqlite3", Snabble.config.generateSearchIndex)
+        productDatabase = ProductDatabase(this, shoppingCartFlow.value, "$id.sqlite3", Snabble.config.generateSearchIndex)
 
-        events = Events(this, shoppingCart)
+        events = Events(this, shoppingCartFlow.value)
 
         assets = Assets(this)
 

ui/src/main/java/io/snabble/sdk/ui/cart/PaymentSelectionHelper.java

@@ -147,17 +147,21 @@ private void setProject(Project project) {
         if (project != null) {
             PaymentSelectionHelper.this.project = project;
 
-            if (cart != null) {
-                cart.removeListener(shoppingCartListener);
-            }
-
-            cart = project.getShoppingCart();
-            cart.addListener(shoppingCartListener);
-
+            updateShoppingCart();
             update();
         }
     }
 
+    public void updateShoppingCart() {
+        if (cart != null) {
+            cart.removeListener(shoppingCartListener);
+        }
+
+        cart = project.getShoppingCart();
+        cart.addListener(shoppingCartListener);
+        update();
+    }
+
     private void update() {
         updateGooglePayIsReadyToPay();