chore: android fix

Author: MichaelVerdon

packages/firebase_database/firebase_database/android/src/main/kotlin/io/flutter/plugins/firebase/database/TransactionHandler.kt

@@ -1,9 +1,3 @@
-/*
- * Copyright 2022, the Chromium project authors.  Please see the AUTHORS file
- * for details. All rights reserved. Use of this source code is governed by a
- * BSD-style license that can be found in the LICENSE file.
- */
-
 package io.flutter.plugins.firebase.database
 
 import android.util.Log
@@ -17,67 +11,84 @@ import com.google.firebase.database.MutableData
 import com.google.firebase.database.Transaction
 import com.google.firebase.database.Transaction.Handler
 import io.flutter.plugin.common.MethodChannel
-import java.util.*
 
 class TransactionHandler @JvmOverloads constructor(
-    @NonNull private val channel: MethodChannel,
-    private val transactionKey: Int
+  @NonNull private val channel: MethodChannel,
+  private val transactionKey: Int
 ) : Handler {
-    
-    private val transactionCompletionSource = TaskCompletionSource<Map<String, Any?>>()
 
-    fun getTask(): Task<Map<String, Any?>> {
-        return transactionCompletionSource.task
+  private val transactionCompletionSource = TaskCompletionSource<Map<String, Any?>>()
+
+  fun getTask(): Task<Map<String, Any?>> {
+    return transactionCompletionSource.task
+  }
+
+  @NonNull
+  override fun doTransaction(@NonNull currentData: MutableData): Transaction.Result {
+    val snapshotMap = mutableMapOf<String, Any?>().apply {
+      put(Constants.KEY, currentData.key ?: "")
+      put(Constants.VALUE, currentData.value)
     }
 
-    @NonNull
-    override fun doTransaction(@NonNull currentData: MutableData): Transaction.Result {
-        val snapshotMap = mutableMapOf<String, Any?>()
-        val transactionArgs = mutableMapOf<String, Any?>()
+    val transactionArgs = mutableMapOf<String, Any?>().apply {
+      put(Constants.SNAPSHOT, snapshotMap)
+      put(Constants.TRANSACTION_KEY, transactionKey)
+    }
 
-        snapshotMap[Constants.KEY] = currentData.key ?: ""
-        snapshotMap[Constants.VALUE] = currentData.value
+    return try {
+      val executor = TransactionExecutor(channel)
+      val updatedData: Any? = executor.execute(transactionArgs)
 
-        transactionArgs[Constants.SNAPSHOT] = snapshotMap
-        transactionArgs[Constants.TRANSACTION_KEY] = transactionKey
+      @Suppress("UNCHECKED_CAST")
+      val transactionHandlerResult: Map<String, Any?> = when (updatedData) {
+        is Map<*, *> -> updatedData as Map<String, Any?>
+        null -> emptyMap()
+        else -> {
+          Log.e("firebase_database", "Unexpected transaction result type: ${updatedData::class.java}")
+          emptyMap()
+        }
+      }
+
+      val aborted: Boolean = (transactionHandlerResult["aborted"] as? Boolean) ?: false
+      val exception: Boolean = (transactionHandlerResult["exception"] as? Boolean) ?: false
 
-        return try {
-            val executor = TransactionExecutor(channel)
-            val updatedData = executor.execute(transactionArgs)
-            @Suppress("UNCHECKED_CAST")
-            val transactionHandlerResult = updatedData as Map<String, Any?>
-            val aborted = transactionHandlerResult["aborted"] as Boolean
-            val exception = transactionHandlerResult["exception"] as Boolean
-            
-            if (aborted || exception) {
-                Transaction.abort()
-            } else {
-                currentData.value = transactionHandlerResult["value"]
-                Transaction.success(currentData)
-            }
-        } catch (e: Exception) {
-            Log.e("firebase_database", "An unexpected exception occurred for a transaction.", e)
-            Transaction.abort()
+      if (aborted || exception) {
+        Transaction.abort()
+      } else {
+        if (transactionHandlerResult.containsKey("value")) {
+          currentData.value = transactionHandlerResult["value"]
         }
+        Transaction.success(currentData)
+      }
+    } catch (e: Exception) {
+      Log.e("firebase_database", "An unexpected exception occurred for a transaction.", e)
+      Transaction.abort()
     }
+  }
 
-    override fun onComplete(
-        @Nullable error: DatabaseError?,
-        committed: Boolean,
-        @Nullable currentData: DataSnapshot?
-    ) {
-        when {
-            error != null -> {
-                transactionCompletionSource.setException(
-                    FlutterFirebaseDatabaseException.fromDatabaseError(error)
-                )
-            }
-            currentData != null -> {
-                val payload = FlutterDataSnapshotPayload(currentData)
-                val additionalParams = mutableMapOf<String, Any?>()
-                additionalParams[Constants.COMMITTED] = committed
-                transactionCompletionSource.setResult(payload.withAdditionalParams(additionalParams).toMap())
-            }
-        }
+  override fun onComplete(
+    @Nullable error: DatabaseError?,
+    committed: Boolean,
+    @Nullable currentData: DataSnapshot?
+  ) {
+    when {
+      error != null -> {
+        transactionCompletionSource.setException(
+          FlutterFirebaseDatabaseException.fromDatabaseError(error)
+        )
+      }
+      currentData != null -> {
+        val payload = FlutterDataSnapshotPayload(currentData)
+        val additionalParams: MutableMap<String, Any> = mutableMapOf(
+          Constants.COMMITTED to committed
+        )
+        transactionCompletionSource.setResult(
+          payload.withAdditionalParams(additionalParams).toMap()
+        )
+      }
+      else -> {
+        transactionCompletionSource.setResult(emptyMap())
+      }
     }
+  }
 }