Database transactions

firebase-common/src/jsMain/kotlin/dev/gitlive/firebase/externals.kt

@@ -317,6 +317,11 @@ external object firebase {
             fun update(value: Any?): Promise<Unit>
             fun set(value: Any?): Promise<Unit>
             fun push(): ThenableReference
+            fun <T> runTransaction(
+                transactionUpdate: (currentData: T) -> T,
+                onComplete: (error: Error?, committed: Boolean, snapshot: DataSnapshot?) -> Unit,
+                applyLocally: Boolean?
+            ): Promise<T>
         }
 
         open class DataSnapshot {

firebase-database/build.gradle.kts

@@ -10,6 +10,7 @@ version = project.property("firebase-database.version") as String
 plugins {
     id("com.android.library")
     kotlin("multiplatform")
+    kotlin("plugin.serialization") version "1.5.10"
 }
 
 repositories {

firebase-database/src/androidMain/kotlin/dev/gitlive/firebase/database/database.kt

@@ -5,26 +5,27 @@
 package dev.gitlive.firebase.database
 
 import com.google.android.gms.tasks.Task
-import com.google.firebase.database.ChildEventListener
-import com.google.firebase.database.Logger
+import com.google.firebase.database.*
 import com.google.firebase.database.ServerValue
-import com.google.firebase.database.ValueEventListener
 import dev.gitlive.firebase.Firebase
 import dev.gitlive.firebase.FirebaseApp
 import dev.gitlive.firebase.database.ChildEvent.Type
 import dev.gitlive.firebase.decode
 import dev.gitlive.firebase.safeOffer
+import kotlinx.coroutines.CompletableDeferred
 import kotlinx.coroutines.FlowPreview
 import kotlinx.coroutines.channels.awaitClose
 import kotlinx.coroutines.coroutineScope
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.callbackFlow
 import kotlinx.coroutines.flow.filter
 import kotlinx.coroutines.flow.produceIn
+import kotlinx.coroutines.runBlocking
 import kotlinx.coroutines.selects.select
 import kotlinx.coroutines.tasks.asDeferred
 import kotlinx.coroutines.tasks.await
 import kotlinx.serialization.DeserializationStrategy
+import kotlinx.serialization.KSerializer
 import kotlinx.serialization.SerializationStrategy
 
 @PublishedApi
@@ -188,8 +189,30 @@ actual class DatabaseReference internal constructor(
     actual suspend fun removeValue() = android.removeValue()
         .run { if(persistenceEnabled) await() else awaitWhileOnline() }
         .run { Unit }
-}
 
+    actual suspend fun <T> runTransaction(strategy: KSerializer<T>, transactionUpdate: (currentData: T) -> T): DataSnapshot {
+        val deferred = CompletableDeferred<Result<DataSnapshot>>()
+        android.runTransaction(object : Transaction.Handler {
+
+            override fun doTransaction(currentData: MutableData) =
+                Transaction.success(transactionUpdate(decode(strategy, currentData)) as MutableData)
+
+            override fun onComplete(
+                error: DatabaseError?,
+                committed: Boolean,
+                snapshot: com.google.firebase.database.DataSnapshot?
+            ) {
+                if(error != null) {
+                    throw error.toException()
+                } else {
+                    deferred.complete(Result.success(DataSnapshot(snapshot!!)))
+                }
+            }
+
+        })
+        return deferred.await().getOrThrow()
+    }
+}
 @Suppress("UNCHECKED_CAST")
 actual class DataSnapshot internal constructor(val android: com.google.firebase.database.DataSnapshot) {
 

firebase-database/src/commonMain/kotlin/dev/gitlive/firebase/database/database.kt

@@ -9,6 +9,7 @@ import dev.gitlive.firebase.FirebaseApp
 import dev.gitlive.firebase.database.ChildEvent.Type.*
 import kotlinx.coroutines.flow.Flow
 import kotlinx.serialization.DeserializationStrategy
+import kotlinx.serialization.KSerializer
 import kotlinx.serialization.SerializationStrategy
 
 /** Returns the [FirebaseDatabase] instance of the default [FirebaseApp]. */
@@ -71,6 +72,8 @@ expect class DatabaseReference : Query {
     suspend fun <T> setValue(strategy: SerializationStrategy<T>, value: T, encodeDefaults: Boolean = true)
     suspend fun updateChildren(update: Map<String, Any?>, encodeDefaults: Boolean = true)
     suspend fun removeValue()
+
+    suspend fun <T> runTransaction(strategy: KSerializer<T>, transactionUpdate: (currentData: T) -> T): DataSnapshot
 }
 
 expect class DataSnapshot {

firebase-database/src/iosMain/kotlin/dev/gitlive/firebase/database/database.kt

@@ -22,6 +22,7 @@ import kotlinx.coroutines.flow.filter
 import kotlinx.coroutines.flow.produceIn
 import kotlinx.coroutines.selects.select
 import kotlinx.serialization.DeserializationStrategy
+import kotlinx.serialization.KSerializer
 import kotlinx.serialization.SerializationStrategy
 import platform.Foundation.*
 import kotlin.collections.component1
@@ -156,6 +157,24 @@ actual class DatabaseReference internal constructor(
     actual suspend fun removeValue() {
         ios.await(persistenceEnabled) { removeValueWithCompletionBlock(it) }
     }
+
+    actual suspend fun <T> runTransaction(strategy: KSerializer<T>, transactionUpdate: (currentData: T) -> T): DataSnapshot {
+        val deferred = CompletableDeferred<Result<DataSnapshot>>()
+        ios.runTransactionBlock(
+            block = { firMutableData ->
+                FIRTransactionResult.successWithValue(transactionUpdate(decode(strategy, firMutableData)) as FIRMutableData)
+            },
+            andCompletionBlock = { error, _, snapshot ->
+                if (error != null) {
+                    throw DatabaseException(error.toString(), null)
+                } else {
+                    deferred.complete(Result.success(DataSnapshot(snapshot!!)))
+                }
+            },
+            withLocalEvents = false
+        )
+        return deferred.await().getOrThrow()
+    }
 }
 
 @Suppress("UNCHECKED_CAST")

firebase-database/src/jsMain/kotlin/dev/gitlive/firebase/database/database.kt

@@ -12,6 +12,7 @@ import kotlinx.coroutines.flow.filter
 import kotlinx.coroutines.flow.produceIn
 import kotlinx.coroutines.selects.select
 import kotlinx.serialization.DeserializationStrategy
+import kotlinx.serialization.KSerializer
 import kotlinx.serialization.SerializationStrategy
 import kotlin.js.Promise
 
@@ -127,6 +128,23 @@ actual class DatabaseReference internal constructor(override val js: firebase.da
 
     actual suspend fun <T> setValue(strategy: SerializationStrategy<T>, value: T, encodeDefaults: Boolean) =
         rethrow { js.set(encode(strategy, value, encodeDefaults)).awaitWhileOnline() }
+
+    actual suspend fun <T> runTransaction(strategy: KSerializer<T>, transactionUpdate: (currentData: T) -> T): DataSnapshot {
+        val deferred = CompletableDeferred<Result<DataSnapshot>>()
+        js.runTransaction(
+            transactionUpdate,
+            { error, _, snapshot ->
+                if (error != null) {
+                    throw error
+                } else {
+                    deferred.complete(Result.success(DataSnapshot(snapshot!!)))
+                }
+            },
+            applyLocally = false
+        ).await()
+        return deferred.await().getOrThrow()
+    }
+
 }
 
 actual class DataSnapshot internal constructor(val js: firebase.database.DataSnapshot) {