Backend: Add feature toggle adapter to automatically turn on features (#581)

Co-authored-by: hannibal2 <24389977+hannibal00212@users.noreply.github.com>

1 files changed, 79 insertions, 0 deletions

diff --git a/src/main/java/at/hannibal2/skyhanni/utils/FeatureTogglesByDefaultAdapter.kt b/src/main/java/at/hannibal2/skyhanni/utils/FeatureTogglesByDefaultAdapter.kt
new file mode 100644
index 000000000..011dcc10c
--- /dev/null
+++ b/src/main/java/at/hannibal2/skyhanni/utils/FeatureTogglesByDefaultAdapter.kt
@@ -0,0 +1,79 @@
+package at.hannibal2.skyhanni.utils
+
+import at.hannibal2.skyhanni.config.FeatureToggle
+import com.google.gson.Gson
+import com.google.gson.JsonObject
+import com.google.gson.JsonPrimitive
+import com.google.gson.TypeAdapter
+import com.google.gson.TypeAdapterFactory
+import com.google.gson.internal.bind.JsonTreeReader
+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.Field
+import java.lang.reflect.Type
+import com.google.gson.internal.`$Gson$Types` as InternalGsonTypes
+
+object FeatureTogglesByDefaultAdapter : TypeAdapterFactory {
+    fun <T> getType(typeToken: TypeToken<T>, field: Field): Type {
+        return InternalGsonTypes.resolve(typeToken.type, typeToken.rawType, field.genericType)
+    }
+
+    class Adapter<T>(
+        val originalWrite: TypeAdapter<T>,
+        val clazz: Class<T>,
+        val gson: Gson,
+        val type: TypeToken<T>,
+    ) : TypeAdapter<T>() {
+        override fun write(out: JsonWriter, value: T) {
+            // Delegate the original config write, since that one is unchanged
+            originalWrite.write(out, value)
+        }
+
+        override fun read(reader: JsonReader): T {
+            reader.beginObject()
+            // Create a default initialized instance
+            val obj = clazz.newInstance()
+
+            // Overwrite the default with true (or false) for feature toggles
+            clazz.fields.forEach {
+                val featureToggle = it.getAnnotation(FeatureToggle::class.java)
+                val adapt = gson.getAdapter(TypeToken.get(getType(type, it)))
+                if (featureToggle != null)
+                    it.set(obj, adapt.read(JsonTreeReader(JsonPrimitive(featureToggle.trueIsEnabled))))
+                if (adapt is Adapter) {
+                    it.set(obj, adapt.read(JsonTreeReader(JsonObject())))
+                }
+            }
+
+            // Read the actual JSON Object
+            while (reader.peek() != JsonToken.END_OBJECT) {
+                val name = reader.nextName()
+                val field = clazz.getDeclaredField(name)
+                val fieldType = gson.getAdapter(TypeToken.get(getType(type, field)))
+                // Read the field data
+                val data = fieldType.read(reader)
+                // Set the field or override the feature toggle with the saved data, leaving only the unset feature toggles to deviate from their defaults
+                field.set(obj, data)
+            }
+
+            reader.endObject()
+            return obj
+        }
+    }
+
+    override fun <T : Any?> create(gson: Gson?, type: TypeToken<T>): TypeAdapter<T>? {
+        gson!!
+        val t = type.rawType
+
+        // Check if this object has any feature toggles present
+        if (t.fields.none {
+                it.isAnnotationPresent(FeatureToggle::class.java) ||
+                        gson.getAdapter(TypeToken.get(getType(type, it))) is Adapter
+            }) return null
+
+        val originalWrite = gson.getDelegateAdapter(this, type)
+        return Adapter(originalWrite, t as Class<T>, gson, type)
+    }
+}
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