🎨 Schema to Structure Definition conversion is diversified with respect to the existing flat schemas, other examples and onfhir validation rules.

Author: KeremHmd

tofhir-common/src/main/scala/io/tofhir/common/util/SchemaUtil.scala

@@ -16,6 +16,11 @@ object SchemaUtil {
    * @return
    */
   def convertToStructureDefinitionResource(schemaDefinition: SchemaDefinition, fhirVersion: String): Resource = {
+
+    val deepSchema = isDeepSchema(schemaDefinition)
+    val kindVal        = if (deepSchema) "resource"      else "logical"
+    val derivationVal  = if (deepSchema) "constraint"    else "specialization"
+
     var structureDefinitionResource: Resource =
       ("id" -> schemaDefinition.id) ~
         ("resourceType" -> "StructureDefinition") ~
@@ -28,11 +33,11 @@ object SchemaUtil {
     structureDefinitionResource ~
       ("status" -> "draft") ~
       ("fhirVersion" -> fhirVersion) ~
-      ("kind" -> "resource") ~
+      ("kind" -> kindVal) ~
       ("abstract" -> false) ~
       ("type" -> schemaDefinition.`type`) ~
       ("baseDefinition" -> "http://hl7.org/fhir/StructureDefinition/Element") ~
-      ("derivation" -> "constraint") ~
+      ("derivation"   -> derivationVal) ~
       ("differential" -> ("element" -> generateElementArray(schemaDefinition.id, schemaDefinition.`type`, schemaDefinition.fieldDefinitions.getOrElse(Seq.empty))))
   }
 
@@ -74,16 +79,18 @@ object SchemaUtil {
 
     val flatFds = flatten(fieldDefinitions)
 
-    // Validate types after flatten (defensive — we rely on types to build a correct SD)
+    // Validate types after flatten
     val integrityCheck = flatFds.forall(fd => fd.dataTypes.isDefined && fd.dataTypes.get.nonEmpty)
     if (!integrityCheck) {
       throw new IllegalArgumentException(s"Missing data type.A field definition must have at least one data type. Element rootPath: ${`type`}")
     }
 
     val rootElement =
       ("id" -> `type`) ~
-        ("path" -> `type`)
-
+          ("path" -> `type`) ~
+          ("min" -> 0) ~
+          ("max" -> "*") ~
+          ("type" -> JArray(List("code" -> "Element")))
     // Children (flat list)
     val elements = flatFds.map { fd =>
       val max: String = fd.maxCardinality match {