/*
    * SPDX-FileCopyrightText: none
    * SPDX-License-Identifier: CC0-1.0
    */
   
   package dev.metaschema.schemagen.xml.impl;
   
   import org.codehaus.stax2.XMLStreamWriter2;
   
  import java.io.IOException;
  import java.util.List;
  import java.util.Map;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.atomic.AtomicInteger;
  
  import javax.xml.namespace.QName;
  import javax.xml.stream.XMLStreamException;
  
  import dev.metaschema.core.configuration.IConfiguration;
  import dev.metaschema.core.datatype.IDataTypeAdapter;
  import dev.metaschema.core.model.IAssemblyDefinition;
  import dev.metaschema.core.model.IDefinition;
  import dev.metaschema.core.model.IFieldDefinition;
  import dev.metaschema.core.model.IFlagDefinition;
  import dev.metaschema.core.model.IModelElement;
  import dev.metaschema.core.model.IModule;
  import dev.metaschema.core.model.IValuedDefinition;
  import dev.metaschema.core.model.constraint.IAllowedValue;
  import dev.metaschema.core.util.AutoCloser;
  import dev.metaschema.core.util.ObjectUtils;
  import dev.metaschema.schemagen.AbstractGenerationState;
  import dev.metaschema.schemagen.SchemaGenerationException;
  import dev.metaschema.schemagen.SchemaGenerationFeature;
  import dev.metaschema.schemagen.xml.impl.schematype.IXmlComplexType;
  import dev.metaschema.schemagen.xml.impl.schematype.IXmlSimpleType;
  import dev.metaschema.schemagen.xml.impl.schematype.IXmlType;
  import dev.metaschema.schemagen.xml.impl.schematype.XmlComplexTypeAssemblyDefinition;
  import dev.metaschema.schemagen.xml.impl.schematype.XmlComplexTypeFieldDefinition;
  import dev.metaschema.schemagen.xml.impl.schematype.XmlSimpleTypeDataTypeReference;
  import dev.metaschema.schemagen.xml.impl.schematype.XmlSimpleTypeDataTypeRestriction;
  import dev.metaschema.schemagen.xml.impl.schematype.XmlSimpleTypeUnion;
  import edu.umd.cs.findbugs.annotations.NonNull;
  import edu.umd.cs.findbugs.annotations.Nullable;
  
  /**
   * Manages state and provides utility methods during XML Schema generation.
   * <p>
   * This class tracks types, namespaces, and provides methods for writing XML
   * Schema elements during the schema generation process.
   */
  public class XmlGenerationState
      extends AbstractGenerationState<AutoCloser<XMLStreamWriter2, SchemaGenerationException>, XmlDatatypeManager>
      implements IXmlGenerationState {
    @NonNull
    private final String defaultNS;
    @NonNull
    private final Map<String, String> namespaceToPrefixMap = new ConcurrentHashMap<>();
    @NonNull
    private final Map<IDataTypeAdapter<?>, IXmlSimpleType> dataTypeToSimpleTypeMap = new ConcurrentHashMap<>();
    @NonNull
    private final Map<IValuedDefinition, IXmlSimpleType> definitionToSimpleTypeMap = new ConcurrentHashMap<>();
    @NonNull
    private final Map<IDefinition, IXmlType> definitionToTypeMap = new ConcurrentHashMap<>();
  
    private final AtomicInteger prefixNum = new AtomicInteger(); // 0
  
    /**
     * Constructs a new XML generation state for the given module.
     *
     * @param module
     *          the Metaschema module being generated
     * @param writer
     *          the auto-closing XML stream writer wrapper
     * @param configuration
     *          the schema generation configuration options
     */
    public XmlGenerationState(
        @NonNull IModule module,
        @NonNull AutoCloser<XMLStreamWriter2, SchemaGenerationException> writer,
        @NonNull IConfiguration<SchemaGenerationFeature<?>> configuration) {
      super(module, writer, configuration, new XmlDatatypeManager());
      this.defaultNS = ObjectUtils.notNull(module.getXmlNamespace().toASCIIString());
    }
  
    /**
     * Retrieves the underlying XML stream writer.
     *
     * @return the XML stream writer
     */
    @Override
    @NonNull
    public XMLStreamWriter2 getXMLStreamWriter() {
      return getWriter().getResource();
    }
  
    /**
     * Retrieves the default XML namespace for this schema.
     *
     * @return the default namespace URI
    */
   @Override
   @NonNull
   public String getDefaultNS() {
     return defaultNS;
   }
 
   /**
    * Retrieves the namespace used for datatype definitions.
    *
    * @return the datatype namespace URI
    */
   @NonNull
   public String getDatatypeNS() {
     return getDefaultNS();
   }
 
   /**
    * Retrieves the XML namespace for the given model element.
    *
    * @param modelElement
    *          the model element to get the namespace for
    * @return the XML namespace URI
    */
   @SuppressWarnings("null")
   @Override
   @NonNull
   public String getNS(@NonNull IModelElement modelElement) {
     return modelElement.getContainingModule().getXmlNamespace().toASCIIString();
   }
 
   /**
    * Retrieves or generates a namespace prefix for the given namespace.
    * <p>
    * Returns {@code null} for the default namespace. For other namespaces,
    * generates a unique prefix if one does not already exist.
    *
    * @param namespace
    *          the namespace URI to get a prefix for
    * @return the namespace prefix, or {@code null} if it is the default namespace
    */
   public String getNSPrefix(String namespace) {
     String retval = null;
     if (!getDefaultNS().equals(namespace)) {
       retval = namespaceToPrefixMap.computeIfAbsent(
           namespace,
           key -> String.format("ns%d", prefixNum.incrementAndGet()));
     }
     return retval;
   }
 
   /**
    * Creates a new qualified name with the given local name and namespace.
    *
    * @param localName
    *          the local name for the QName
    * @param namespace
    *          the namespace URI for the QName
    * @return a new QName with an appropriate prefix
    */
   @NonNull
   protected QName newQName(
       @NonNull String localName,
       @NonNull String namespace) {
     String prefix = null;
     if (!getDefaultNS().equals(namespace)) {
       prefix = getNSPrefix(namespace);
     }
 
     return ObjectUtils.notNull(
         prefix == null ? new QName(namespace, localName) : new QName(namespace, localName, prefix));
   }
 
   /**
    * Creates a new qualified name for a definition type.
    *
    * @param definition
    *          the definition to create a type name for
    * @param suffix
    *          an optional suffix to append to the type name, or {@code null}
    * @return a new QName for the definition type
    */
   @NonNull
   protected QName newQName(
       @NonNull IDefinition definition,
       @Nullable String suffix) {
     return newQName(
         getTypeNameForDefinition(definition, suffix),
         getNS(definition));
   }
 
   /**
    * Retrieves or creates the XML type representation for a definition.
    * <p>
    * Creates and caches the appropriate XML type based on the definition's model
    * type (flag, field, or assembly).
    *
    * @param definition
    *          the definition to get the XML type for
    * @return the XML type representing the definition
    * @throws UnsupportedOperationException
    *           if the definition is a choice or choice group
    */
   @Override
   public IXmlType getXmlForDefinition(@NonNull IDefinition definition) {
     IXmlType retval = definitionToTypeMap.get(definition);
     if (retval == null) {
       switch (definition.getModelType()) {
       case FIELD: {
         IFieldDefinition field = (IFieldDefinition) definition;
         if (field.getFlagInstances().isEmpty()) {
           retval = getSimpleType(field);
         } else {
           retval = newComplexType(field);
         }
         break;
       }
       case ASSEMBLY: {
         retval = newComplexType((IAssemblyDefinition) definition);
         break;
       }
       case FLAG:
         retval = getSimpleType((IFlagDefinition) definition);
         break;
       case CHOICE_GROUP:
       case CHOICE:
         throw new UnsupportedOperationException(definition.getModelType().toString());
       }
       assert retval != null : definition.getModelType();
       definitionToTypeMap.put(definition, retval);
     }
     return retval;
   }
 
   /**
    * Retrieves or creates a simple type for a data type adapter.
    *
    * @param dataType
    *          the data type adapter
    * @return the XML simple type representation
    */
   @Override
   @NonNull
   public IXmlSimpleType getSimpleType(@NonNull IDataTypeAdapter<?> dataType) {
     IXmlSimpleType type = dataTypeToSimpleTypeMap.get(dataType);
     if (type == null) {
       // lazy initialize and cache the type
       QName qname = newQName(
           getDatatypeManager().getTypeNameForDatatype(dataType),
           getDatatypeNS());
       type = new XmlSimpleTypeDataTypeReference(qname, dataType);
       dataTypeToSimpleTypeMap.put(dataType, type);
     }
     return type;
   }
 
   /**
    * Retrieves or creates a simple type for a valued definition.
    * <p>
    * If the definition has allowed value constraints, creates an appropriate
    * restriction or union type. Otherwise, returns the simple type for the
    * underlying data type.
    *
    * @param definition
    *          the valued definition
    * @return the XML simple type representation
    */
   @Override
   @NonNull
   public IXmlSimpleType getSimpleType(@NonNull IValuedDefinition definition) {
     IXmlSimpleType simpleType = definitionToSimpleTypeMap.get(definition);
     if (simpleType == null) {
       AllowedValueCollection allowedValuesCollection = getContextIndependentEnumeratedValues(definition);
       List<IAllowedValue> allowedValues = allowedValuesCollection.getValues();
 
       IDataTypeAdapter<?> dataType = definition.getJavaTypeAdapter();
       if (allowedValues.isEmpty()) {
         // just use the built-in type
         simpleType = getSimpleType(dataType);
       } else {
 
         // generate a restriction on the built-in type for the enumerated values
         simpleType = new XmlSimpleTypeDataTypeRestriction(
             newQName(definition, null),
             definition,
             allowedValuesCollection);
 
         if (!allowedValuesCollection.isClosed()) {
           // if other values are allowed, we need to make a union of the restriction type
           // and the base
           // built-in type
           simpleType = new XmlSimpleTypeUnion(
               newQName(definition, "Union"),
               definition,
               getSimpleType(dataType),
               simpleType);
         }
       }
 
       definitionToSimpleTypeMap.put(definition, simpleType);
     }
     return simpleType;
   }
 
   /**
    * Creates a new complex type for a field definition.
    *
    * @param definition
    *          the field definition
    * @return a new complex type representation
    */
   @NonNull
   protected IXmlComplexType newComplexType(@NonNull IFieldDefinition definition) {
     QName qname = newQName(definition, null);
     return new XmlComplexTypeFieldDefinition(qname, definition);
   }
 
   /**
    * Creates a new complex type for an assembly definition.
    *
    * @param definition
    *          the assembly definition
    * @return a new complex type representation
    */
   @NonNull
   protected IXmlComplexType newComplexType(@NonNull IAssemblyDefinition definition) {
     QName qname = newQName(definition, null);
     return new XmlComplexTypeAssemblyDefinition(qname, definition);
   }
 
   /**
    * Generates all XML types that are not inline and are referenced.
    * <p>
    * Iterates through all definitions and generates types that need to be written
    * as separate type definitions in the schema.
    *
    * @throws XMLStreamException
    *           if an error occurs while writing XML content
    */
   public void generateXmlTypes() throws XMLStreamException {
 
     for (IXmlType type : definitionToTypeMap.values()) {
       if (!type.isInline(this) && type.isGeneratedType(this) && type.isReferenced(this)) {
         type.generate(this);
       } else {
         assert !type.isGeneratedType(this) || type.isInline(this) || !type.isReferenced(this);
       }
     }
     getDatatypeManager().generateDatatypes(getXMLStreamWriter());
   }
 
   /**
    * Writes an attribute to the current element.
    *
    * @param localName
    *          the local name of the attribute
    * @param value
    *          the value of the attribute
    * @throws XMLStreamException
    *           if an error occurs while writing
    */
   @Override
   public void writeAttribute(@NonNull String localName, @NonNull String value) throws XMLStreamException {
     getXMLStreamWriter().writeAttribute(localName, value);
   }
 
   /**
    * Writes a start element with the given namespace and local name.
    *
    * @param namespaceUri
    *          the namespace URI for the element
    * @param localName
    *          the local name of the element
    * @throws XMLStreamException
    *           if an error occurs while writing
    */
   @Override
   public void writeStartElement(@NonNull String namespaceUri, @NonNull String localName) throws XMLStreamException {
     getXMLStreamWriter().writeStartElement(namespaceUri, localName);
   }
 
   /**
    * Writes a start element with the given prefix, local name, and namespace.
    *
    * @param prefix
    *          the namespace prefix for the element
    * @param localName
    *          the local name of the element
    * @param namespaceUri
    *          the namespace URI for the element
    * @throws XMLStreamException
    *           if an error occurs while writing
    */
   @Override
   public void writeStartElement(
       @NonNull String prefix,
       @NonNull String localName,
       @NonNull String namespaceUri) throws XMLStreamException {
     getXMLStreamWriter().writeStartElement(prefix, localName, namespaceUri);
   }
 
   /**
    * Writes an end element for the current element.
    *
    * @throws XMLStreamException
    *           if an error occurs while writing
    */
   @Override
   public void writeEndElement() throws XMLStreamException {
     getXMLStreamWriter().writeEndElement();
   }
 
   /**
    * Writes character content to the current element.
    *
    * @param text
    *          the text content to write
    * @throws XMLStreamException
    *           if an error occurs while writing
    */
   @Override
   public void writeCharacters(@NonNull String text) throws XMLStreamException {
     getXMLStreamWriter().writeCharacters(text);
   }
 
   /**
    * Writes a namespace declaration.
    *
    * @param prefix
    *          the namespace prefix
    * @param namespaceUri
    *          the namespace URI
    * @throws XMLStreamException
    *           if an error occurs while writing
    */
   @Override
   public void writeNamespace(String prefix, String namespaceUri) throws XMLStreamException {
     getXMLStreamWriter().writeNamespace(prefix, namespaceUri);
   }
 
   @Override
   public void flushWriter() throws IOException {
     try {
       getWriter().getResource().flush();
     } catch (XMLStreamException ex) {
       throw new IOException(ex);
     }
   }
 }