Fix connection lifecycle and undefined method issues (#518)

## Summary

This PR fixes critical issues with IAP connection lifecycle management
and undefined method errors in the Flutter InApp Purchase plugin.

### Changes

1. **Fix undefined method error in getAvailablePurchases** 
   - Replace direct method calls with proper channel invocations
   - Fix getAvailableItemsByType calls for Android platform
   - Use extractPurchased helper to process results correctly

2. **Fix connection check in subscription flow screen**
   - Change connection result comparison from string to boolean
   - Match the pattern used in purchase flow screen
   - Resolves "Not connected" issue in subscription flow

3. **Add proper connection lifecycle management**
   - Add endConnection calls to dispose methods in all screens
   - Ensure connections are properly closed when leaving screens
   - Prevent connection issues when re-entering screens

4. **Remove hook and provider implementations**
   - Completely remove use_iap hook implementation
   - Remove IapProvider from the example app
   - Simplify API to use direct FlutterInappPurchase.instance calls
   - Remove flutter_hooks dependency from example app and main package

5. **Update to version 6.0.0-rc.4**
   - Add new errors and events modules for better error handling
   - Update example app with improved screen structure
   - Clean up deprecated methods and imports
   - Restructure documentation to align with simplified API

## Breaking Changes

- Removed useIap hook - use FlutterInappPurchase.instance directly
instead
- Removed IapProvider - no longer needed with simplified API
- Removed flutter_hooks dependency

## Test Plan

- [x] Test purchase flow screen - connections properly initialized and
closed
- [x] Test subscription flow screen - connections properly initialized
and closed
- [x] Test available purchases screen - connections properly initialized
and closed
- [x] Verify no connection issues when navigating between screens
- [x] Confirm purchases and subscriptions work correctly on both iOS and
Android
- [x] Verify all screens work without hooks/provider

## Related Issues

Fixes connection lifecycle issues reported in the example app where
screens would show "Not connected" after navigating back and forth.

Author: hyochan

README.md

@@ -1,10 +1,15 @@
 # flutter_inapp_purchase
 
-<img src="https://flutter-inapp-purchase.hyo.dev/img/logo.png" width="200" alt="flutter_inapp_purchase logo" />
+<div align="center">
+  <img src="https://flutter-inapp-purchase.hyo.dev/img/logo.png" width="200" alt="flutter_inapp_purchase logo" />
+  
+  [![Pub Version](https://img.shields.io/pub/v/flutter_inapp_purchase.svg?style=flat-square)](https://pub.dartlang.org/packages/flutter_inapp_purchase) [![Flutter CI](https://github.com/hyochan/flutter_inapp_purchase/actions/workflows/ci.yml/badge.svg)](https://github.com/hyochan/flutter_inapp_purchase/actions/workflows/ci.yml) [![Coverage Status](https://codecov.io/gh/hyochan/flutter_inapp_purchase/branch/main/graph/badge.svg?token=WXBlKvRB2G)](https://codecov.io/gh/hyochan/flutter_inapp_purchase) ![License](https://img.shields.io/badge/license-MIT-blue.svg)
+  
+  A comprehensive Flutter plugin for implementing in-app purchases that conforms to the [Open IAP specification](https://openiap.dev)
 
-[![Pub Version](https://img.shields.io/pub/v/flutter_inapp_purchase.svg?style=flat-square)](https://pub.dartlang.org/packages/flutter_inapp_purchase) [![Flutter CI](https://github.com/hyochan/flutter_inapp_purchase/actions/workflows/ci.yml/badge.svg)](https://github.com/hyochan/flutter_inapp_purchase/actions/workflows/ci.yml) [![Coverage Status](https://codecov.io/gh/hyochan/flutter_inapp_purchase/branch/main/graph/badge.svg?token=WXBlKvRB2G)](https://codecov.io/gh/hyochan/flutter_inapp_purchase) ![License](https://img.shields.io/badge/license-MIT-blue.svg)
+<a href="https://openiap.dev"><img src="https://openiap.dev/logo.png" alt="Open IAP" height="40" /></a>
 
-A comprehensive Flutter plugin for implementing in-app purchases that conforms to the [Open IAP specification](https://openiap.dev)
+</div>
 
 ## 📚 Documentation
 
@@ -14,22 +19,27 @@ A comprehensive Flutter plugin for implementing in-app purchases that conforms t
 
 ```yaml
 dependencies:
-  flutter_inapp_purchase: ^6.0.0-rc.3
+  flutter_inapp_purchase: ^6.0.0-rc.4
 ```
 
 ## 🔧 Quick Start
 
+### Basic Usage
+
 ```dart
 import 'package:flutter_inapp_purchase/flutter_inapp_purchase.dart';
 
+// Create instance
+final iap = FlutterInappPurchase();
+
 // Initialize connection
-await FlutterInappPurchase.instance.initConnection();
+await iap.initConnection();
 
 // Get products
-final products = await FlutterInappPurchase.instance.getProducts(['product_id']);
+final products = await iap.getProducts(['product_id']);
 
 // Request purchase
-await FlutterInappPurchase.instance.requestPurchase(
+await iap.requestPurchase(
   RequestPurchase(
     ios: RequestPurchaseIosProps(sku: 'product_id'),
     android: RequestPurchaseAndroidProps(skus: ['product_id']),
@@ -38,6 +48,30 @@ await FlutterInappPurchase.instance.requestPurchase(
 );
 ```
 
+### Singleton Usage
+
+For global state management or when you need a shared instance:
+
+```dart
+// Use singleton instance
+final iap = FlutterInappPurchase.instance;
+await iap.initConnection();
+
+// The instance is shared across your app
+final sameIap = FlutterInappPurchase.instance; // Same instance
+```
+
+### With Flutter Hooks
+
+```dart
+// useIAP hook automatically uses singleton
+final iapState = useIAP();
+
+// Access products, purchases, etc.
+final products = iapState.products;
+final currentPurchase = iapState.currentPurchase;
+```
+
 ## Sponsors
 
 💼 **[View Our Sponsors](https://openiap.dev/sponsors)**

android/src/main/kotlin/dev/hyo/flutterinapppurchase/AmazonInappPurchasePlugin.kt

@@ -63,10 +63,6 @@ class AmazonInappPurchasePlugin : MethodCallHandler {
             "showInAppMessages" -> {
                 safeResult!!.success("in app messages not supported for amazon")
             }
-            "consumeAllItems" -> {
-                // consumable is a separate type in amazon
-                safeResult!!.success("no-ops in amazon")
-            }
             "getProducts",
             "getSubscriptions" -> {
                 Log.d(TAG, call.method)

android/src/main/kotlin/dev/hyo/flutterinapppurchase/AndroidInappPurchasePlugin.kt

@@ -34,9 +34,11 @@ class AndroidInappPurchasePlugin internal constructor() : MethodCallHandler,
     }
     fun setActivity(activity: Activity?) {
         this.activity = activity
+        Log.d(TAG, "Activity set: ${if (activity != null) "not null" else "null"}")
     }
     fun setChannel(channel: MethodChannel?) {
         this.channel = channel
+        Log.d(TAG, "Channel set: ${if (channel != null) "not null" else "null"}")
     }
     fun onDetachedFromActivity() {
         endBillingClientConnection()
@@ -79,6 +81,7 @@ class AndroidInappPurchasePlugin internal constructor() : MethodCallHandler,
                 return
             }
 
+            Log.d(TAG, "Creating BillingClient with PurchasesUpdatedListener")
             billingClient = BillingClient.newBuilder(context ?: return)
                 .setListener(purchasesUpdatedListener)
                 .enablePendingPurchases(
@@ -87,6 +90,7 @@ class AndroidInappPurchasePlugin internal constructor() : MethodCallHandler,
                         .build()
                 )
                 .build()
+            Log.d(TAG, "BillingClient created successfully")
 
             billingClient?.startConnection(object : BillingClientStateListener {
                 private var alreadyFinished = false
@@ -162,7 +166,6 @@ class AndroidInappPurchasePlugin internal constructor() : MethodCallHandler,
 
         when(call.method){
             "showInAppMessages" -> showInAppMessages(safeChannel)
-            "consumeAllItems" -> consumeAllItems(safeChannel, call)
             "getProducts" -> getProductsByType(BillingClient.ProductType.INAPP, call, safeChannel)
             "getSubscriptions" -> getProductsByType(BillingClient.ProductType.SUBS, call, safeChannel)
             "getAvailableItemsByType" -> getAvailableItemsByType(call, safeChannel)
@@ -212,53 +215,6 @@ class AndroidInappPurchasePlugin internal constructor() : MethodCallHandler,
         safeChannel.success("show in app messages ready")
     }
 
-    private fun consumeAllItems(
-        safeChannel: MethodResultWrapper,
-        call: MethodCall
-    ) {
-        try {
-            val array = ArrayList<String>()
-            val params = QueryPurchasesParams.newBuilder().apply { setProductType(BillingClient.ProductType.INAPP) }.build()
-            billingClient!!.queryPurchasesAsync(params)
-            { billingResult, productDetailsList ->
-                if (billingResult.responseCode == BillingClient.BillingResponseCode.OK) {
-                    if (productDetailsList.size == 0) {
-                        safeChannel.error(
-                            call.method,
-                            "refreshItem",
-                            "No purchases found"
-                        )
-                        return@queryPurchasesAsync
-                    }
-
-                    for (purchase in productDetailsList) {
-                        val consumeParams = ConsumeParams.newBuilder()
-                            .setPurchaseToken(purchase.purchaseToken)
-                            .build()
-                        billingClient!!.consumeAsync(consumeParams) { _, outToken ->
-                            array.add(outToken)
-                            if (productDetailsList.size == array.size) {
-                                try {
-                                    safeChannel.success(array.toString())
-                                    return@consumeAsync
-                                } catch (e: FlutterException) {
-                                    Log.e(TAG, e.message!!)
-                                }
-                            }
-                        }
-                    }
-                } else {
-                    safeChannel.error(
-                        call.method, "refreshItem",
-                        "No results for query"
-                    )
-                }
-            }
-
-        } catch (err: Error) {
-            safeChannel.error(call.method, err.message, "")
-        }
-    }
 
     private fun getAvailableItemsByType(
         call: MethodCall,
@@ -618,7 +574,9 @@ class AndroidInappPurchasePlugin internal constructor() : MethodCallHandler,
                     val errorData = BillingError.getErrorFromResponseData(responseCode.responseCode)
                     safeChannel.error(TAG, errorData.code, "Failed to launch billing flow: ${errorData.message}")
                 } else {
+                    // Return success immediately - purchase result will come via purchasesUpdatedListener
                     safeChannel.success("Billing flow launched successfully")
+                    Log.d(TAG, "Billing flow launched, purchase result will be sent via purchase-updated event")
                 }
             } else {
                 Log.e(TAG, "Activity is null, cannot launch billing flow")
@@ -631,19 +589,33 @@ class AndroidInappPurchasePlugin internal constructor() : MethodCallHandler,
     }
 
     private val purchasesUpdatedListener = PurchasesUpdatedListener { billingResult, purchases ->
+        Log.d(TAG, "PurchasesUpdatedListener triggered!")
+        Log.d(TAG, "BillingResult responseCode: ${billingResult.responseCode}")
+        Log.d(TAG, "Purchases: ${purchases?.size ?: 0} items")
+        
         try {
             if (billingResult.responseCode != BillingClient.BillingResponseCode.OK) {
+                Log.d(TAG, "Purchase failed with response code: ${billingResult.responseCode}")
                 val json = JSONObject()
                 json.put("responseCode", billingResult.responseCode)
                 json.put("debugMessage", billingResult.debugMessage)
                 val errorData = BillingError.getErrorFromResponseData(billingResult.responseCode)
                 json.put("code", errorData.code)
                 json.put("message", errorData.message)
-                safeResult!!.invokeMethod("purchase-error", json.toString())
+                Log.d(TAG, "Sending purchase-error event to Flutter, channel is ${if (channel != null) "not null" else "null"}")
+                Log.d(TAG, "Error data: ${json.toString()}")
+                if (channel != null) {
+                    channel!!.invokeMethod("purchase-error", json.toString())
+                    Log.d(TAG, "Successfully sent purchase-error event")
+                } else {
+                    Log.e(TAG, "Cannot send purchase-error event: channel is null!")
+                }
                 return@PurchasesUpdatedListener
             }
             if (purchases != null) {
+                Log.d(TAG, "Processing ${purchases.size} successful purchases")
                 for (purchase in purchases) {
+                    Log.d(TAG, "Processing purchase: productId=${purchase.products[0]}, orderId=${purchase.orderId}")
                     val item = JSONObject()
                     item.put("productId", purchase.products[0])
                     item.put("transactionId", purchase.orderId)
@@ -662,7 +634,14 @@ class AndroidInappPurchasePlugin internal constructor() : MethodCallHandler,
                         item.put("obfuscatedAccountIdAndroid", accountIdentifiers.obfuscatedAccountId)
                         item.put("obfuscatedProfileIdAndroid", accountIdentifiers.obfuscatedProfileId)
                     }
-                    safeResult!!.invokeMethod("purchase-updated", item.toString())
+                    Log.d(TAG, "Sending purchase-updated event to Flutter, channel is ${if (channel != null) "not null" else "null"}")
+                    Log.d(TAG, "Purchase data: ${item.toString()}")
+                    if (channel != null) {
+                        channel!!.invokeMethod("purchase-updated", item.toString())
+                        Log.d(TAG, "Successfully sent purchase-updated event")
+                    } else {
+                        Log.e(TAG, "Cannot send purchase-updated event: channel is null!")
+                    }
                     return@PurchasesUpdatedListener
                 }
             } else {
@@ -672,11 +651,18 @@ class AndroidInappPurchasePlugin internal constructor() : MethodCallHandler,
                 val errorData = BillingError.getErrorFromResponseData(billingResult.responseCode)
                 json.put("code", errorData.code)
                 json.put("message", "purchases returns null.")
-                safeResult!!.invokeMethod("purchase-error", json.toString())
+                Log.d(TAG, "Sending purchase-error event to Flutter, channel is ${if (channel != null) "not null" else "null"}")
+                Log.d(TAG, "Error data: ${json.toString()}")
+                if (channel != null) {
+                    channel!!.invokeMethod("purchase-error", json.toString())
+                    Log.d(TAG, "Successfully sent purchase-error event")
+                } else {
+                    Log.e(TAG, "Cannot send purchase-error event: channel is null!")
+                }
                 return@PurchasesUpdatedListener
             }
         } catch (je: JSONException) {
-            safeResult!!.invokeMethod("purchase-error", je.message)
+            channel?.invokeMethod("purchase-error", je.message)
             return@PurchasesUpdatedListener
         }
     }

docs/docs/api/index.md

@@ -27,10 +27,11 @@ Access iOS and Android specific features and capabilities.
 - **iOS Features**: Offer code redemption, subscription management, StoreKit 2 support
 - **Android Features**: Billing client state, pending purchases, deep links
 
-### 🎧 Event Listeners
+### 🎧 Event Listeners (Open IAP Spec)
 Real-time streams for monitoring purchase events and connection states.
 
-- **Purchase Events**: Success, errors, and state changes
+- **purchaseUpdatedListener**: Stream for successful purchase updates
+- **purchaseErrorListener**: Stream for purchase errors
 - **Connection Events**: Store connection status updates
 
 ### 🔧 Types & Enums
@@ -42,37 +43,51 @@ Comprehensive type definitions for type-safe development.
 
 ## Quick Start
 
+### Instance Management
+
+flutter_inapp_purchase provides flexible instance management:
+
+```dart
+// Option 1: Create your own instance (recommended for most cases)
+final iap = FlutterInappPurchase();
+
+// Option 2: Use singleton for global state management
+final iap = FlutterInappPurchase.instance;
+
+// Option 3: Use with IapProvider (recommended for Flutter apps)
+final iapProvider = IapProvider.of(context);
+```
+
+### Basic Implementation
+
 ```dart
 import 'package:flutter_inapp_purchase/flutter_inapp_purchase.dart';
 
 class PurchaseManager {
-  StreamSubscription<PurchasedItem?>? _purchaseSubscription;
-  StreamSubscription<PurchaseResult?>? _errorSubscription;
+  final FlutterInappPurchase iap = FlutterInappPurchase();
+  StreamSubscription<Purchase>? _purchaseSubscription;
+  StreamSubscription<PurchaseError>? _errorSubscription;
 
   Future<void> initializePurchases() async {
     // Initialize connection
-    await FlutterInappPurchase.instance.initConnection();
+    await iap.initConnection();
     
-    // Set up listeners
-    _purchaseSubscription = FlutterInappPurchase.purchaseUpdated.listen(
+    // Set up listeners (Open IAP spec)
+    _purchaseSubscription = iap.purchaseUpdatedListener.listen(
       (purchase) {
-        if (purchase != null) {
-          handlePurchaseSuccess(purchase);
-        }
+        handlePurchaseSuccess(purchase);
       },
     );
     
-    _errorSubscription = FlutterInappPurchase.purchaseError.listen(
+    _errorSubscription = iap.purchaseErrorListener.listen(
       (error) {
-        if (error != null) {
-          handlePurchaseError(error);
-        }
+        handlePurchaseError(error);
       },
     );
   }
   
   Future<void> makePurchase(String productId) async {
-    await FlutterInappPurchase.instance.requestPurchase(
+    await iap.requestPurchase(
       request: RequestPurchase(
         ios: RequestPurchaseIOS(sku: productId, quantity: 1),
         android: RequestPurchaseAndroid(skus: [productId]),
@@ -83,7 +98,7 @@ class PurchaseManager {
 }
 ```
 
-## TypeScript Support
+## Dart Type Safety
 
 flutter_inapp_purchase provides full type safety with comprehensive type definitions for all methods, parameters, and return values.