/*
 * 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 org.jdbi.v3.core.mapper;

import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;

import org.jdbi.v3.core.statement.StatementContext;

Column mapper for Java enum types. 
Type parameters:
<E> – the enum type mapped/**
 * Column mapper for Java {@code enum} types.
 * @param <E> the enum type mapped
 */
public abstract class EnumMapper<E extends Enum<E>> implements ColumnMapper<E> {
    EnumMapper() {}

    
Params:
type – the enum type to map
Type parameters:
<E> – the enum type to map
Returns:
an enum mapper that matches on Enum.name()/**
     * @param <E> the enum type to map
     * @param type the enum type to map
     * @return an enum mapper that matches on {@link Enum#name()}
     */
    public static <E extends Enum<E>> ColumnMapper<E> byName(Class<E> type) {
        return new ByName<>(type);
    }

    
Params:
type – the enum type to map
Type parameters:
<E> – the enum type to map
Returns:
an enum mapper that matches on Enum.ordinal()/**
     * @param <E> the enum type to map
     * @param type the enum type to map
     * @return an enum mapper that matches on {@link Enum#ordinal()}
     */
    public static <E extends Enum<E>> ColumnMapper<E> byOrdinal(Class<E> type) {
        return new ByOrdinal<>(type);
    }

    private static class ByName<E extends Enum<E>> extends EnumMapper<E> {
        private final Class<E> type;
        private final ConcurrentMap<String, E> insensitiveLookup = new ConcurrentHashMap<>();

        private ByName(Class<E> type) {
            this.type = type;
        }

        @Override
        public E map(ResultSet r, int columnNumber, StatementContext ctx) throws SQLException {
            String name = r.getString(columnNumber);
            return name == null ? null : insensitiveLookup.computeIfAbsent(name, this::resolve);
        }

        private E resolve(String name) {
            final IllegalArgumentException failure;
            try {
                return Enum.valueOf(type, name);
            } catch (IllegalArgumentException e) {
                failure = e;
            }
            for (E e : type.getEnumConstants()) {
                if (e.name().equalsIgnoreCase(name)) {
                    return e;
                }
            }
            throw failure;
        }
    }

    private static class ByOrdinal<E extends Enum<E>> extends EnumMapper<E> {
        private final E[] constants;

        private ByOrdinal(Class<E> type) {
            this.constants = type.getEnumConstants();
        }

        @Override
        public E map(ResultSet r, int columnNumber, StatementContext ctx) throws SQLException {
            int ordinal = r.getInt(columnNumber);
            return r.wasNull() ? null : constants[ordinal];
        }
    }
}