/*******************************************************************************
 * 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.processor.core.jpa.access.model;

import java.lang.reflect.Field;
import java.math.BigDecimal;
import java.util.Calendar;
import java.util.Date;
import java.util.UUID;

import javax.persistence.Temporal;
import javax.persistence.TemporalType;
import javax.persistence.metamodel.Attribute;

import com.sap.core.odata.api.edm.EdmSimpleTypeKind;
import com.sap.core.odata.processor.api.jpa.exception.ODataJPAModelException;
import com.sap.core.odata.processor.api.jpa.exception.ODataJPARuntimeException;

/**
 * This class holds utility methods for Type conversions between JPA and OData Types.
 * 
 * @author SAP AG
 *
 */
public class JPATypeConvertor {

  /**
   * This utility method converts a given jpa Type to equivalent
   * EdmSimpleTypeKind for maintaining compatibility between Java and OData
   * Types.
   *  @param jpaType
   *            The JPA Type input.
   * @return The corresponding EdmSimpleTypeKind.
   * @throws ODataJPAModelException
   * @throws ODataJPARuntimeException 
   * 
   * @see EdmSimpleTypeKind
   */
  public static EdmSimpleTypeKind convertToEdmSimpleType(final Class<?> jpaType, final Attribute<?, ?> currentAttribute) throws ODataJPAModelException {
    if (jpaType.equals(String.class)) {
      return EdmSimpleTypeKind.String;
    }
    else if (jpaType.equals(Long.class) || jpaType.equals(long.class)) {
      return EdmSimpleTypeKind.Int64;
    }
    else if (jpaType.equals(Short.class) || jpaType.equals(short.class)) {
      return EdmSimpleTypeKind.Int16;
    }
    else if (jpaType.equals(Integer.class) || jpaType.equals(int.class)) {
      return EdmSimpleTypeKind.Int32;
    }
    else if (jpaType.equals(Double.class) || jpaType.equals(double.class)) {
      return EdmSimpleTypeKind.Double;
    }
    else if (jpaType.equals(Float.class) || jpaType.equals(float.class)) {
      return EdmSimpleTypeKind.Single;
    }
    else if (jpaType.equals(BigDecimal.class)) {
      return EdmSimpleTypeKind.Decimal;
    }
    else if (jpaType.equals(byte[].class)) {
      return EdmSimpleTypeKind.Binary;
    }
    else if (jpaType.equals(Byte.class) || jpaType.equals(byte.class)) {
      return EdmSimpleTypeKind.SByte;
    }
    else if (jpaType.equals(Byte[].class)) {
      return EdmSimpleTypeKind.Binary;
    }
    else if (jpaType.equals(Boolean.class) || jpaType.equals(boolean.class)) {
      return EdmSimpleTypeKind.Boolean;
    }
    else if ((jpaType.equals(Date.class)) || (jpaType.equals(Calendar.class))) {
      return dateConversion(currentAttribute, false);
    }
    else if (jpaType.equals(UUID.class)) {
      return EdmSimpleTypeKind.Guid;
    }
    else if (jpaType.equals(java.sql.Date.class) ||
        jpaType.equals(java.sql.Time.class) ||
        jpaType.equals(java.sql.Timestamp.class)) {
      return dateConversion(currentAttribute, true);
    }
    throw ODataJPAModelException.throwException(ODataJPAModelException.TYPE_NOT_SUPPORTED.addContent(jpaType.toString()), null);
  }

  private static EdmSimpleTypeKind dateConversion(final Attribute<?, ?> currentAttribute, final boolean isInherited) throws ODataJPAModelException {
    try {
      Field jpaField = currentAttribute.getDeclaringType().getJavaType().getDeclaredField(currentAttribute.getName());
      if (isInherited) {
        Class<?> type = jpaField.getType();
        if (type.equals(Date.class) != true && type.equals(Calendar.class) != true) {
          throw ODataJPAModelException.throwException(ODataJPAModelException.TYPE_NOT_SUPPORTED.addContent(type.toString()), null);
        }
      }
      if ((currentAttribute != null) && (jpaField.getAnnotation(Temporal.class).value() == TemporalType.TIME)) {
        return EdmSimpleTypeKind.Time;
      } else {
        return EdmSimpleTypeKind.DateTime;
      }
    } catch (NoSuchFieldException e) {
      throw ODataJPAModelException
          .throwException(ODataJPAModelException.GENERAL.addContent(e.getMessage()), e);
    } catch (SecurityException e) {
      throw ODataJPAModelException
          .throwException(ODataJPAModelException.GENERAL.addContent(e.getMessage()), e);
    }

  }
}