From e7173043a9897c2fc5fdbc4f716cf6400b6cda72 Mon Sep 17 00:00:00 2001
From: Jan Seeger <seeger@sipgate.de>
Date: Thu, 14 Mar 2024 18:10:41 +0100
Subject: [PATCH] Help the polymorphic decoder determine the Serializer to use
 by always putting the type discriminator first

---
 .../common/StringMapToObjectDecoder.kt        |  2 +-
 .../federmappe/realtimedb/DataSnapshotExt.kt  | 24 ++++++++++++++++---
 2 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/common/src/main/kotlin/de/sipgate/federmappe/common/StringMapToObjectDecoder.kt b/common/src/main/kotlin/de/sipgate/federmappe/common/StringMapToObjectDecoder.kt
index df3c374..7b80f6c 100644
--- a/common/src/main/kotlin/de/sipgate/federmappe/common/StringMapToObjectDecoder.kt
+++ b/common/src/main/kotlin/de/sipgate/federmappe/common/StringMapToObjectDecoder.kt
@@ -100,8 +100,8 @@ class StringMapToObjectDecoder(
         super.endStructure(descriptor)
     }
 
+    @Suppress("UNCHECKED_CAST")
     override fun <T> decodeType(typeKey: String): T? {
-        @Suppress("UNCHECKED_CAST")
         val currentData = (data[key] as? Map<String, Any>) ?: return null
         return (currentData[typeKey] as? T)
     }
diff --git a/realtimedb/src/main/kotlin/de/sipgate/federmappe/realtimedb/DataSnapshotExt.kt b/realtimedb/src/main/kotlin/de/sipgate/federmappe/realtimedb/DataSnapshotExt.kt
index 5306ecd..0061310 100644
--- a/realtimedb/src/main/kotlin/de/sipgate/federmappe/realtimedb/DataSnapshotExt.kt
+++ b/realtimedb/src/main/kotlin/de/sipgate/federmappe/realtimedb/DataSnapshotExt.kt
@@ -24,9 +24,27 @@ inline fun <reified T : Any> DataSnapshot.toObjectWithSerializer(
     customSerializers: SerializersModule = EmptySerializersModule()
 ): T = serializer.deserialize(StringMapToObjectDecoder(toObjectMap().unwrapRoot(), customSerializers))
 
-@Suppress("UNNECESSARY_NOT_NULL_ASSERTION")
-fun DataSnapshot.toObjectMap(): Pair<String, Any> =
-    (key ?: "root") to (if (hasChildren()) children.associate { it.toObjectMap() } else value)!!
+fun DataSnapshot.toObjectMap(): Pair<String, Any> {
+    val key = key ?: "root"
+    val value = when {
+        hasChildren() -> children
+            .map(DataSnapshot::toObjectMap)
+            .ensureTypeIsFirst()
+            .toMap()
+
+        else -> value
+    }
+    return key to value!!
+}
 
 @Suppress("UNCHECKED_CAST")
 fun Pair<String, Any>.unwrapRoot() = second as Map<String, Any>
+
+internal fun <A : Comparable<A>, B> Iterable<Pair<A, B>>.ensureTypeIsFirst(): Iterable<Pair<A, B>> =
+    sortedWith { a, b ->
+        when {
+            a.first == "type" -> -1
+            b.first == "type" -> 1
+            else -> a.first.compareTo(b.first)
+        }
+    }