package org.springframework.roo.classpath.layers;

import java.util.ArrayList;
import java.util.List;

import org.apache.commons.lang3.Validate;
import org.springframework.roo.classpath.customdata.CustomDataKeys;
import org.springframework.roo.classpath.customdata.taggers.AnnotatedTypeMatcher;
import org.springframework.roo.classpath.customdata.taggers.Matcher;
import org.springframework.roo.classpath.details.MemberFindingUtils;
import org.springframework.roo.classpath.details.MemberHoldingTypeDetails;
import org.springframework.roo.classpath.details.annotations.AnnotationAttributeValue;
import org.springframework.roo.classpath.details.annotations.AnnotationMetadata;
import org.springframework.roo.classpath.details.annotations.ArrayAttributeValue;
import org.springframework.roo.classpath.details.annotations.ClassAttributeValue;
import org.springframework.roo.model.JavaSymbolName;
import org.springframework.roo.model.JavaType;

/**
 * A {@link Matcher} used for layering support; identifies layer components
 * (services, repositories, etc) by the presence of a given tag, and sets each
 * such component's {@link CustomDataKeys#LAYER_TYPE} tag to a list of the
 * domain types managed by that component (as a
 * <code>List&lt;{@link JavaType}&gt;</code>).
 * 
 * @author Stefan Schmidt
 * @since 1.2.0
 */
public class LayerTypeMatcher extends AnnotatedTypeMatcher {

  private final JavaSymbolName domainTypesAttribute;
  private final JavaType layerAnnotationType;

  /**
   * Constructor
   * 
   * @param layerAnnotation the annotation type to match on and read
   *            attributes of (required)
   * @param domainTypesAttribute the attribute of the above annotation that
   *            identifies the domain type(s) being managed (required)
   */
  public LayerTypeMatcher(final JavaType layerAnnotation, final JavaSymbolName domainTypesAttribute) {
    super(CustomDataKeys.LAYER_TYPE, layerAnnotation);
    Validate.notNull(layerAnnotation, "Layer annotation is required");
    Validate.notNull(domainTypesAttribute, "Domain types attribute is required");
    this.domainTypesAttribute = domainTypesAttribute;
    layerAnnotationType = layerAnnotation;
  }

  @Override
  public Object getTagValue(final MemberHoldingTypeDetails type) {
    final AnnotationMetadata layerAnnotation =
        MemberFindingUtils.getAnnotationOfType(type.getAnnotations(), layerAnnotationType);
    if (layerAnnotation == null || layerAnnotation.getAttribute(domainTypesAttribute) == null) {
      return null;
    }
    final AnnotationAttributeValue<?> value = layerAnnotation.getAttribute(domainTypesAttribute);
    final List<JavaType> domainTypes = new ArrayList<JavaType>();
    if (value instanceof ClassAttributeValue) {
      domainTypes.add(((ClassAttributeValue) value).getValue());
    } else if (value instanceof ArrayAttributeValue<?>) {
      final ArrayAttributeValue<?> castValue = (ArrayAttributeValue<?>) value;
      for (final AnnotationAttributeValue<?> val : castValue.getValue()) {
        if (val instanceof ClassAttributeValue) {
          domainTypes.add(((ClassAttributeValue) val).getValue());
        }
      }
    }
    return domainTypes;
  }
}