/*******************************************************************************
 * Copyright 2013 SAP AG
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 ******************************************************************************/
package com.sap.core.odata.core.edm;

import java.util.UUID;

import com.sap.core.odata.api.edm.EdmFacets;
import com.sap.core.odata.api.edm.EdmLiteralKind;
import com.sap.core.odata.api.edm.EdmSimpleTypeException;

/**
 * Implementation of the EDM simple type Guid.
 * @author SAP AG
 */
public class EdmGuid extends AbstractSimpleType {

  private static final String PATTERN = "\\p{XDigit}{8}-\\p{XDigit}{4}-\\p{XDigit}{4}-\\p{XDigit}{4}-\\p{XDigit}{12}";
  private static final EdmGuid instance = new EdmGuid();

  public static EdmGuid getInstance() {
    return instance;
  }

  @Override
  public Class<?> getDefaultType() {
    return UUID.class;
  }

  @Override
  public boolean validate(final String value, final EdmLiteralKind literalKind, final EdmFacets facets) {
    return value == null ?
        facets == null || facets.isNullable() == null || facets.isNullable() :
        validateLiteral(value, literalKind);
  }

  private boolean validateLiteral(final String value, final EdmLiteralKind literalKind) {
    return value.matches(literalKind == EdmLiteralKind.URI ? toUriLiteral(PATTERN) : PATTERN);
  }

  @Override
  protected <T> T internalValueOfString(final String value, final EdmLiteralKind literalKind, final EdmFacets facets, final Class<T> returnType) throws EdmSimpleTypeException {
    UUID result;
    if (validateLiteral(value, literalKind)) {
      result = UUID.fromString(
          literalKind == EdmLiteralKind.URI ? value.substring(5, value.length() - 1) : value);
    } else {
      throw new EdmSimpleTypeException(EdmSimpleTypeException.LITERAL_ILLEGAL_CONTENT.addContent(value));
    }

    if (returnType.isAssignableFrom(UUID.class)) {
      return returnType.cast(result);
    } else {
      throw new EdmSimpleTypeException(EdmSimpleTypeException.VALUE_TYPE_NOT_SUPPORTED.addContent(returnType));
    }
  }

  @Override
  protected <T> String internalValueToString(final T value, final EdmLiteralKind literalKind, final EdmFacets facets) throws EdmSimpleTypeException {
    if (value instanceof UUID) {
      return ((UUID) value).toString();
    } else {
      throw new EdmSimpleTypeException(EdmSimpleTypeException.VALUE_TYPE_NOT_SUPPORTED.addContent(value.getClass()));
    }
  }

  @Override
  public String toUriLiteral(final String literal) {
    return "guid'" + literal + "'";
  }
}