Fix: Config reset on unknown enum values (#1990)

3 files changed, 62 insertions, 1 deletions

diff --git a/src/main/java/at/hannibal2/skyhanni/utils/json/BaseGsonBuilder.kt b/src/main/java/at/hannibal2/skyhanni/utils/json/BaseGsonBuilder.kt
index d73edc0b0..bc9f706f8 100644
--- a/src/main/java/at/hannibal2/skyhanni/utils/json/BaseGsonBuilder.kt
+++ b/src/main/java/at/hannibal2/skyhanni/utils/json/BaseGsonBuilder.kt
@@ -33,5 +33,7 @@ object BaseGsonBuilder {
         .registerTypeAdapter(SimpleTimeMark::class.java, SkyHanniTypeAdapters.TIME_MARK.nullSafe())
         .enableComplexMapKeySerialization()
 
-    fun lenientGson(): GsonBuilder = gson().registerTypeAdapterFactory(SkippingTypeAdapterFactory)
+    fun lenientGson(): GsonBuilder = gson()
+        .registerTypeAdapterFactory(SkippingTypeAdapterFactory)
+        .registerTypeAdapterFactory(ListEnumSkippingTypeAdapterFactory)
 }
diff --git a/src/main/java/at/hannibal2/skyhanni/utils/json/EnumSkippingTypeAdapterFactory.kt b/src/main/java/at/hannibal2/skyhanni/utils/json/EnumSkippingTypeAdapterFactory.kt
new file mode 100644
index 000000000..c17462472
--- /dev/null
+++ b/src/main/java/at/hannibal2/skyhanni/utils/json/EnumSkippingTypeAdapterFactory.kt
@@ -0,0 +1,53 @@
+package at.hannibal2.skyhanni.utils.json
+
+import com.google.gson.Gson
+import com.google.gson.TypeAdapter
+import com.google.gson.TypeAdapterFactory
+import com.google.gson.reflect.TypeToken
+import com.google.gson.stream.JsonReader
+import com.google.gson.stream.JsonToken
+import com.google.gson.stream.JsonWriter
+import java.lang.reflect.ParameterizedType
+
+object ListEnumSkippingTypeAdapterFactory : TypeAdapterFactory {
+    override fun <T> create(gson: Gson, type: TypeToken<T>): TypeAdapter<T>? {
+        val rawType = type.rawType
+        if (rawType == List::class.java) {
+            val actualType = (type.type as ParameterizedType).actualTypeArguments[0]
+            if (actualType is Class<*> && actualType.isEnum) {
+                @Suppress("UNCHECKED_CAST")
+                return ListEnumSkippingTypeAdapter(actualType as Class<out Enum<*>>) as TypeAdapter<T>
+            }
+        }
+        return null
+    }
+}
+
+/*
+    Instead of saving null to the config when the enum value is unknown we instead skip the value.
+    We also skip the value if it is null inside a list of enums. This ensures we don't crash later,
+    either in moulconfig or outside of it, as we assume lists of enums don't contain null values.
+ */
+class ListEnumSkippingTypeAdapter<T : Enum<T>>(private val enumClass: Class<T>) : TypeAdapter<List<T>>() {
+    override fun write(out: JsonWriter, value: List<T>?) {
+        value ?: return
+        out.beginArray()
+        value.forEach { out.value(it.name) }
+        out.endArray()
+    }
+
+    override fun read(reader: JsonReader): List<T> {
+        val list = mutableListOf<T>()
+        reader.beginArray()
+        while (reader.hasNext()) {
+            if (reader.peek() == JsonToken.NULL) {
+                reader.skipValue()
+                continue
+            }
+            val name = reader.nextString()
+            enumClass.enumConstants.firstOrNull { it.name == name }?.let { list.add(it) }
+        }
+        reader.endArray()
+        return list
+    }
+}
diff --git a/src/main/java/at/hannibal2/skyhanni/utils/json/SkippingTypeAdapterFactory.kt b/src/main/java/at/hannibal2/skyhanni/utils/json/SkippingTypeAdapterFactory.kt
index 3a2505495..d99650f0c 100644
--- a/src/main/java/at/hannibal2/skyhanni/utils/json/SkippingTypeAdapterFactory.kt
+++ b/src/main/java/at/hannibal2/skyhanni/utils/json/SkippingTypeAdapterFactory.kt
@@ -8,6 +8,12 @@ import com.google.gson.reflect.TypeToken
 import com.google.gson.stream.JsonReader
 import com.google.gson.stream.JsonWriter
 
+/*
+    Instead of crashing on a wrong value in the config we set the value to null and log a warning.
+    This prevents user's config from resetting to default values.
+    Which is especially important for when people downgrade their mod version, either on purpose or by accident.
+    This does not always work, and can cause a crash later on, but the full config reset is avoided.
+ */
 object SkippingTypeAdapterFactory : TypeAdapterFactory {
 
     override fun <T : Any?> create(gson: Gson, type: TypeToken<T>): TypeAdapter<T> {