/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.apache.asterix.om.typecomputer.impl;

import org.apache.asterix.om.exceptions.TypeMismatchException;
import org.apache.asterix.om.functions.BuiltinFunctions;
import org.apache.asterix.om.typecomputer.base.AbstractResultTypeComputer;
import org.apache.asterix.om.types.ATypeTag;
import org.apache.asterix.om.types.AUnionType;
import org.apache.asterix.om.types.AbstractCollectionType;
import org.apache.asterix.om.types.BuiltinType;
import org.apache.asterix.om.types.IAType;
import org.apache.asterix.om.types.hierachy.ATypeHierarchy;
import org.apache.hyracks.algebricks.common.exceptions.AlgebricksException;
import org.apache.hyracks.algebricks.core.algebra.base.ILogicalExpression;
import org.apache.hyracks.algebricks.core.algebra.functions.FunctionIdentifier;
import org.apache.hyracks.api.exceptions.SourceLocation;

public class NonTaggedGetItemResultType extends AbstractResultTypeComputer {

    public static final NonTaggedGetItemResultType INSTANCE = new NonTaggedGetItemResultType();

    private NonTaggedGetItemResultType() {
    }

    @Override
    protected void checkArgType(FunctionIdentifier funcId, int argIndex, IAType type, SourceLocation sourceLoc)
            throws AlgebricksException {
        ATypeTag actualTypeTag = type.getTypeTag();
        if (argIndex == 0) {
            if (type.getTypeTag() != ATypeTag.MULTISET && type.getTypeTag() != ATypeTag.ARRAY) {
                throw new TypeMismatchException(sourceLoc, funcId, argIndex, actualTypeTag, ATypeTag.MULTISET,
                        ATypeTag.ARRAY);
            }
        } else {
            if (!ATypeHierarchy.isCompatible(type.getTypeTag(), ATypeTag.INTEGER)) {
                throw new TypeMismatchException(sourceLoc, funcId, argIndex, actualTypeTag, ATypeTag.INTEGER);
            }
        }
    }

    @Override
    protected IAType getResultType(ILogicalExpression expr, IAType... strippedInputTypes) throws AlgebricksException {
        IAType type = strippedInputTypes[0];
        if (type.getTypeTag() == ATypeTag.ANY) {
            return BuiltinType.ANY;
        }
        if (!type.getTypeTag().isListType()) {
            throw new TypeMismatchException(expr.getSourceLocation(), BuiltinFunctions.GET_ITEM, 0, type.getTypeTag(),
                    ATypeTag.MULTISET, ATypeTag.ARRAY);
        }
        IAType itemType = ((AbstractCollectionType) type).getItemType();
        if (itemType.getTypeTag() == ATypeTag.ANY) {
            return itemType;
        }
        // Could have out-of-bound access or null elements.
        return AUnionType.createUnknownableType(itemType);
    }

}
