/*
 * 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.vxquery.runtime.functions.strings;

import java.io.DataOutput;
import java.io.IOException;

import org.apache.hyracks.algebricks.runtime.base.IScalarEvaluator;
import org.apache.hyracks.algebricks.runtime.base.IScalarEvaluatorFactory;
import org.apache.hyracks.api.context.IHyracksTaskContext;
import org.apache.hyracks.api.exceptions.HyracksDataException;
import org.apache.hyracks.data.std.api.IPointable;
import org.apache.hyracks.data.std.primitive.UTF8StringPointable;
import org.apache.hyracks.data.std.util.ArrayBackedValueStorage;
import org.apache.vxquery.datamodel.accessors.SequencePointable;
import org.apache.vxquery.datamodel.accessors.TaggedValuePointable;
import org.apache.vxquery.datamodel.builders.sequence.SequenceBuilder;
import org.apache.vxquery.datamodel.values.ValueTag;
import org.apache.vxquery.datamodel.values.XDMConstants;
import org.apache.vxquery.exceptions.ErrorCode;
import org.apache.vxquery.exceptions.SystemException;
import org.apache.vxquery.runtime.functions.base.AbstractTaggedValueArgumentScalarEvaluator;
import org.apache.vxquery.runtime.functions.base.AbstractTaggedValueArgumentScalarEvaluatorFactory;
import org.apache.vxquery.runtime.functions.util.FunctionHelper;

public class FnStringToCodepointsEvaluatorFactory extends AbstractTaggedValueArgumentScalarEvaluatorFactory {
    private static final long serialVersionUID = 1L;

    public FnStringToCodepointsEvaluatorFactory(IScalarEvaluatorFactory[] args) {
        super(args);
    }

    @Override
    protected IScalarEvaluator createEvaluator(IHyracksTaskContext ctx, IScalarEvaluator[] args)
            throws HyracksDataException {
        final UTF8StringPointable stringp = (UTF8StringPointable) UTF8StringPointable.FACTORY.createPointable();
        final UTF8StringCharacterIterator charIterator = new UTF8StringCharacterIterator(stringp);
        final SequencePointable seqp = (SequencePointable) SequencePointable.FACTORY.createPointable();
        final ArrayBackedValueStorage abvs = new ArrayBackedValueStorage();
        final SequenceBuilder sb = new SequenceBuilder();
        final ArrayBackedValueStorage abvsInner = new ArrayBackedValueStorage();
        final DataOutput dOutInner = abvsInner.getDataOutput();

        return new AbstractTaggedValueArgumentScalarEvaluator(args) {
            @Override
            protected void evaluate(TaggedValuePointable[] args, IPointable result) throws SystemException {
                TaggedValuePointable tvp1 = args[0];

                // Only accept strings as input.
                if (tvp1.getTag() == ValueTag.SEQUENCE_TAG) {
                    tvp1.getValue(seqp);
                    if (seqp.getEntryCount() == 0) {
                        XDMConstants.setEmptySequence(result);
                        return;
                    } else {
                        throw new SystemException(ErrorCode.FORG0006);
                    }
                } else {
                    if (!FunctionHelper.isDerivedFromString(tvp1.getTag())) {
                        throw new SystemException(ErrorCode.FORG0006);
                    }
                    tvp1.getValue(stringp);
                    if (stringp.getUTF8Length() == 0) {
                        XDMConstants.setEmptySequence(result);
                        return;
                    }
                }

                // Return sequence of character values.
                try {
                    charIterator.reset();
                    abvs.reset();
                    sb.reset(abvs);
                    int c;
                    while ((c = charIterator.next()) != ICharacterIterator.EOS_CHAR) {
                        abvsInner.reset();
                        dOutInner.write(ValueTag.XS_INTEGER_TAG);
                        dOutInner.writeLong(c);
                        sb.addItem(abvsInner);
                    }

                    sb.finish();
                    result.set(abvs);
                } catch (IOException e) {
                    throw new SystemException(ErrorCode.SYSE0001);
                }
            }
        };
    }
}