/*
 * 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.facebook.presto.hive;

import com.facebook.presto.spi.type.Type;
import com.facebook.presto.spi.type.TypeManager;
import com.facebook.presto.spi.type.VarcharType;

import javax.inject.Inject;

import static com.facebook.presto.hive.HiveType.HIVE_BYTE;
import static com.facebook.presto.hive.HiveType.HIVE_DOUBLE;
import static com.facebook.presto.hive.HiveType.HIVE_FLOAT;
import static com.facebook.presto.hive.HiveType.HIVE_INT;
import static com.facebook.presto.hive.HiveType.HIVE_LONG;
import static com.facebook.presto.hive.HiveType.HIVE_SHORT;
import static java.util.Objects.requireNonNull;

public class HiveCoercionPolicy
        implements CoercionPolicy
{
    private final TypeManager typeManager;

    @Inject
    public HiveCoercionPolicy(TypeManager typeManager)
    {
        this.typeManager = requireNonNull(typeManager, "typeManager is null");
    }

    @Override
    public boolean canCoerce(HiveType fromHiveType, HiveType toHiveType)
    {
        Type fromType = typeManager.getType(fromHiveType.getTypeSignature());
        Type toType = typeManager.getType(toHiveType.getTypeSignature());
        if (fromType instanceof VarcharType) {
            return toHiveType.equals(HIVE_BYTE) || toHiveType.equals(HIVE_SHORT) || toHiveType.equals(HIVE_INT) || toHiveType.equals(HIVE_LONG);
        }
        if (toType instanceof VarcharType) {
            return fromHiveType.equals(HIVE_BYTE) || fromHiveType.equals(HIVE_SHORT) || fromHiveType.equals(HIVE_INT) || fromHiveType.equals(HIVE_LONG);
        }
        if (fromHiveType.equals(HIVE_BYTE)) {
            return toHiveType.equals(HIVE_SHORT) || toHiveType.equals(HIVE_INT) || toHiveType.equals(HIVE_LONG);
        }
        if (fromHiveType.equals(HIVE_SHORT)) {
            return toHiveType.equals(HIVE_INT) || toHiveType.equals(HIVE_LONG);
        }
        if (fromHiveType.equals(HIVE_INT)) {
            return toHiveType.equals(HIVE_LONG);
        }
        if (fromHiveType.equals(HIVE_FLOAT)) {
            return toHiveType.equals(HIVE_DOUBLE);
        }

        return false;
    }
}