import xxx.EnumAlternativeName;
import com.google.common.base.Preconditions;
import com.google.common.collect.Lists;
import com.google.common.collect.Maps;
import org.apache.ibatis.type.BaseTypeHandler;
import org.apache.ibatis.type.JdbcType;

import java.sql.CallableStatement;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;
import java.util.Map;

/**
 * <result column="location" property="location" jdbcType="VARCHAR" typeHandler="xxx.noscan.EnumAlternativeNameTypeHandler"/>
 *
 * @author Sebastien Lorber <i>(lorber.sebastien@gmail.com)</i>
 * @param <E>
 */
public class EnumAlternativeNameTypeHandler<E extends Enum<E> & EnumAlternativeName> extends BaseTypeHandler<E> {

  private Class<E> type;
  private Map<String,E> mappedByAlternativeName;


  public EnumAlternativeNameTypeHandler() {
    throw new IllegalStateException("" +
            "You are trying to use a EnumAlternativeNameTypeHandler without declaring the javaType." +
            "Read the EnumAlternativeNameTypeHandler javadoc for details! " +
            "If this happens, it may be because  ");
  }

  public EnumAlternativeNameTypeHandler(Class<E> type) {
    Preconditions.checkNotNull(type);
    Preconditions.checkNotNull(type.getEnumConstants(),type.getSimpleName() + " does not represent an enum type.");
    List<E> enums = Lists.newArrayList(type.getEnumConstants());
    this.type = type;
    this.mappedByAlternativeName = Maps.uniqueIndex(enums,EnumAlternativeName.GET_ALTERNATIVE_NAME);
  }

  private E getEnumConstFromAlternativeName(String alternativeName) {
    if ( alternativeName == null ) {
      return null;
    } else {
      E enumConst = mappedByAlternativeName.get(alternativeName);
      Preconditions.checkNotNull(enumConst,"No enum could be found for "+type+" with alternative name " + alternativeName);
      return enumConst;
    }
  }

  @Override
  public void setNonNullParameter(PreparedStatement ps, int i, E parameter, JdbcType jdbcType) throws SQLException {
    if (jdbcType == null) {
      ps.setString(i, parameter.getAlternativeName() );
    } else {
      ps.setObject(i, parameter.getAlternativeName() , jdbcType.TYPE_CODE);
    }
  }

  @Override
  public E getNullableResult(ResultSet rs, String columnName) throws SQLException {
    String s = rs.getString(columnName);
    return getEnumConstFromAlternativeName(s);
  }

  @Override
  public E getNullableResult(ResultSet rs, int columnIndex) throws SQLException {
    String s = rs.getString(columnIndex);
    return getEnumConstFromAlternativeName(s);
  }

  @Override
  public E getNullableResult(CallableStatement cs, int columnIndex) throws SQLException {
    String s = cs.getString(columnIndex);
    return getEnumConstFromAlternativeName(s);
  }

}