Parse when condition in blueprint

lib/src/main/java/graphql/nadel/engine/blueprint/NadelExecutionBlueprintFactory.kt

@@ -8,7 +8,6 @@ import graphql.Scalars.GraphQLString
 import graphql.language.EnumTypeDefinition
 import graphql.language.FieldDefinition
 import graphql.language.ImplementingTypeDefinition
-import graphql.language.StringValue
 import graphql.nadel.Service
 import graphql.nadel.dsl.FieldMappingDefinition
 import graphql.nadel.dsl.RemoteArgumentSource.SourceType.FieldArgument
@@ -20,6 +19,7 @@ import graphql.nadel.engine.blueprint.hydration.NadelBatchHydrationMatchStrategy
 import graphql.nadel.engine.blueprint.hydration.NadelHydrationActorInputDef
 import graphql.nadel.engine.blueprint.hydration.NadelHydrationActorInputDef.ValueSource.FieldResultValue
 import graphql.nadel.engine.blueprint.hydration.NadelHydrationStrategy
+import graphql.nadel.engine.blueprint.hydration.NadelHydrationWhenCondition
 import graphql.nadel.engine.transform.query.NadelQueryPath
 import graphql.nadel.engine.util.AnyImplementingTypeDefinition
 import graphql.nadel.engine.util.AnyNamedNode
@@ -265,9 +265,35 @@ private class Factory(
                     is NadelHydrationActorInputDef.ValueSource.StaticValue -> null
                 }
             },
+            condition = getHydrationCondition(hydration),
         )
     }
 
+    private fun getHydrationCondition(hydration: UnderlyingServiceHydration): NadelHydrationWhenCondition? {
+        if (hydration.conditionalHydration == null) {
+            return null
+        }
+        if (hydration.conditionalHydration.predicate.equals != null) {
+            return NadelHydrationWhenCondition.ResultEquals(
+                fieldPath = NadelQueryPath(hydration.conditionalHydration.sourceField),
+                value = hydration.conditionalHydration.predicate.equals
+            )
+        }
+        if (hydration.conditionalHydration.predicate.startsWith != null) {
+            return NadelHydrationWhenCondition.StringResultStartsWith(
+                fieldPath = NadelQueryPath(hydration.conditionalHydration.sourceField),
+                prefix = hydration.conditionalHydration.predicate.startsWith
+            )
+        }
+        if (hydration.conditionalHydration.predicate.matches != null) {
+            return NadelHydrationWhenCondition.StringResultMatches(
+                fieldPath = NadelQueryPath(hydration.conditionalHydration.sourceField),
+                regex = hydration.conditionalHydration.predicate.matches
+            )
+        }
+        error("a conditional hydration is defined but doesnt have any predicate")
+    }
+
     private fun getHydrationStrategy(
         hydratedFieldParentType: GraphQLObjectType,
         hydratedFieldDef: GraphQLFieldDefinition,
@@ -352,6 +378,7 @@ private class Factory(
             batchHydrationMatchStrategy = matchStrategy,
             actorFieldDef = actorFieldDef,
             actorFieldContainer = actorFieldContainer,
+            condition = getHydrationCondition(hydration),
             sourceFields = Unit.let {
                 val paths = (when (matchStrategy) {
                     NadelBatchHydrationMatchStrategy.MatchIndex -> emptyList()
@@ -489,7 +516,7 @@ private class Factory(
                 }
                 StaticArgument -> {
                     NadelHydrationActorInputDef.ValueSource.StaticValue(
-                        value =  remoteArgDef.remoteArgumentSource.staticValue!!
+                        value = remoteArgDef.remoteArgumentSource.staticValue!!
                     )
                 }
             }

lib/src/main/java/graphql/nadel/engine/blueprint/NadelFieldInstruction.kt

@@ -4,6 +4,7 @@ import graphql.nadel.Service
 import graphql.nadel.engine.blueprint.hydration.NadelBatchHydrationMatchStrategy
 import graphql.nadel.engine.blueprint.hydration.NadelHydrationActorInputDef
 import graphql.nadel.engine.blueprint.hydration.NadelHydrationStrategy
+import graphql.nadel.engine.blueprint.hydration.NadelHydrationWhenCondition
 import graphql.nadel.engine.transform.query.NadelQueryPath
 import graphql.schema.FieldCoordinates
 import graphql.schema.GraphQLFieldDefinition
@@ -82,6 +83,11 @@ interface NadelGenericHydrationInstruction {
      * The container of the actor field in the overall schema referenced by [queryPathToActorField].
      */
     val actorFieldContainer: GraphQLFieldsContainer
+
+    /**
+     * The optional definition for conditional hydrations
+     */
+    val condition: NadelHydrationWhenCondition?
 }
 
 data class NadelHydrationFieldInstruction(
@@ -95,6 +101,7 @@ data class NadelHydrationFieldInstruction(
     override val sourceFields: List<NadelQueryPath>,
     override val actorFieldDef: GraphQLFieldDefinition,
     override val actorFieldContainer: GraphQLFieldsContainer,
+    override val condition: NadelHydrationWhenCondition?,
     val hydrationStrategy: NadelHydrationStrategy,
 ) : NadelFieldInstruction(), NadelGenericHydrationInstruction
 
@@ -109,6 +116,7 @@ data class NadelBatchHydrationFieldInstruction(
     override val sourceFields: List<NadelQueryPath>,
     override val actorFieldDef: GraphQLFieldDefinition,
     override val actorFieldContainer: GraphQLFieldsContainer,
+    override val condition: NadelHydrationWhenCondition?,
     val batchSize: Int,
     val batchHydrationMatchStrategy: NadelBatchHydrationMatchStrategy,
 ) : NadelFieldInstruction(), NadelGenericHydrationInstruction

lib/src/main/java/graphql/nadel/engine/blueprint/hydration/NadelHydrationWhenCondition.kt

@@ -0,0 +1,34 @@
+package graphql.nadel.engine.blueprint.hydration
+
+import graphql.nadel.engine.transform.query.NadelQueryPath
+
+sealed class NadelHydrationWhenCondition {
+    abstract fun evaluate(resultId: String): Boolean
+
+    data class ResultEquals(
+        val fieldPath: NadelQueryPath,
+        val value: Any,
+    ) : NadelHydrationWhenCondition() {
+        override fun evaluate(resultId: String): Boolean {
+            TODO("Not yet implemented")
+        }
+    }
+
+    data class StringResultMatches(
+        val fieldPath: NadelQueryPath,
+        val regex: Regex,
+    ) : NadelHydrationWhenCondition() {
+        override fun evaluate(resultId: String): Boolean {
+            TODO("Not yet implemented")
+        }
+    }
+
+    data class StringResultStartsWith(
+        val fieldPath: NadelQueryPath,
+        val prefix: String,
+    ) : NadelHydrationWhenCondition() {
+        override fun evaluate(resultId: String): Boolean {
+            TODO("Not yet implemented")
+        }
+    }
+}