/*
 * 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
 *
 *   https://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.
 *
 *   SPDX-License-Identifier: Apache-2.0
 */

package org.apache.jena.atlas.data;

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.fail;

import java.io.File ;
import java.util.*;

import org.junit.jupiter.api.Test;

import org.apache.jena.atlas.iterator.Iter ;
import org.apache.jena.datatypes.xsd.XSDDatatype ;
import org.apache.jena.graph.NodeFactory ;
import org.apache.jena.query.Query ;
import org.apache.jena.query.QueryCancelledException ;
import org.apache.jena.query.SortCondition ;
import org.apache.jena.sparql.core.Var ;
import org.apache.jena.sparql.engine.QueryIterator ;
import org.apache.jena.sparql.engine.binding.Binding;
import org.apache.jena.sparql.engine.binding.BindingBuilder;
import org.apache.jena.sparql.engine.binding.BindingComparator;
import org.apache.jena.sparql.expr.ExprVar ;
import org.apache.jena.sparql.system.SerializationFactoryFinder;

public class TestSortedDataBag
{
    private static final String LETTERS = "qwertyuiopasdfghjklzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNM";
    private Random random;

    @Test
    public void testSorting() {
        testSorting(500, 10);
    }

    private void testSorting(int numBindings, int threshold) {
        List<Binding> unsorted = randomBindings(numBindings);

        List<SortCondition> conditions = new ArrayList<>();
        conditions.add(new SortCondition(new ExprVar("8"), Query.ORDER_ASCENDING));
        conditions.add(new SortCondition(new ExprVar("1"), Query.ORDER_ASCENDING));
        conditions.add(new SortCondition(new ExprVar("0"), Query.ORDER_DESCENDING));
        BindingComparator comparator = new BindingComparator(conditions);

        List<Binding> sorted = new ArrayList<>();

        SortedDataBag<Binding> db = new SortedDataBag<>(new ThresholdPolicyCount<Binding>(threshold),
                                                        SerializationFactoryFinder.bindingSerializationFactory(), comparator);
        try {
            db.addAll(unsorted);
            Iterator<Binding> iter = db.iterator();
            while (iter.hasNext()) {
                sorted.add(iter.next());
            }
            Iter.close(iter);
        } finally {
            db.close();
        }

        Collections.sort(unsorted, comparator);
        assertEquals(unsorted, sorted);
    }

    @Test
    public void testSortingWithPreMerge() {
        // Save the original value...
        int origMaxSpillFiles = SortedDataBag.MAX_SPILL_FILES;
        try {
            // Vary the number of spill files and bindings so we get a variable number of premerge rounds
            // @formatter:off
            SortedDataBag.MAX_SPILL_FILES = 2;    testSorting(1, 1);
            SortedDataBag.MAX_SPILL_FILES = 2;    testSorting(2, 1);
            SortedDataBag.MAX_SPILL_FILES = 2;    testSorting(3, 1);
            SortedDataBag.MAX_SPILL_FILES = 2;    testSorting(4, 1);
            SortedDataBag.MAX_SPILL_FILES = 2;    testSorting(5, 1);
            SortedDataBag.MAX_SPILL_FILES = 2;    testSorting(1, 10);
            SortedDataBag.MAX_SPILL_FILES = 2;    testSorting(1000, 10);
            SortedDataBag.MAX_SPILL_FILES = 100;  testSorting(1000, 10);
            SortedDataBag.MAX_SPILL_FILES = 2;    testSorting(10, 10);
            SortedDataBag.MAX_SPILL_FILES = 5;    testSorting(10, 10);
            // @formatter:on
        } finally {
            SortedDataBag.MAX_SPILL_FILES = origMaxSpillFiles;
        }
    }

    @Test
    public void testTemporaryFilesAreCleanedUpAfterCompletion() {
        List<Binding> unsorted = randomBindings(500);

        List<SortCondition> conditions = new ArrayList<>();
        conditions.add(new SortCondition(new ExprVar("8"), Query.ORDER_ASCENDING));
        BindingComparator comparator = new BindingComparator(conditions);

        SortedDataBag<Binding> db = new SortedDataBag<>(new ThresholdPolicyCount<Binding>(10),
                                                        SerializationFactoryFinder.bindingSerializationFactory(), comparator);

        List<File> spillFiles = new ArrayList<>();
        try {
            db.addAll(unsorted);
            spillFiles.addAll(db.getSpillFiles());

            int count = 0;
            for ( File file : spillFiles ) {
                if ( file.exists() ) {
                    count++;
                }
            }
            // 500 bindings divided into 50 chunks (49 in files, and 1 in memory)
            assertEquals(49, count);

            Iterator<Binding> iter = db.iterator();
            while (iter.hasNext()) {
                iter.next();
            }
            Iter.close(iter);
        } finally {
            db.close();
        }

        int count = 0;
        for ( File file : spillFiles ) {
            if ( file.exists() ) {
                count++;
            }
        }
        assertEquals(0, count);
    }

    private List<Binding> randomBindings(int numBindings) {
        random = new Random();
        Var[] vars = new Var[]{Var.alloc("1"), Var.alloc("2"), Var.alloc("3"), Var.alloc("4"), Var.alloc("5"), Var.alloc("6"),
            Var.alloc("7"), Var.alloc("8"), Var.alloc("9"), Var.alloc("0")};
        List<Binding> toReturn = new ArrayList<>();
        for ( int i = 0 ; i < numBindings ; i++ ) {
            toReturn.add(randomBinding(vars));
        }

        return toReturn;
    }

    private Binding randomBinding(Var[] vars) {
        BindingBuilder builder = Binding.builder();
        builder.add(vars[0], NodeFactory.createBlankNode());
        builder.add(vars[1], NodeFactory.createURI(randomURI()));
        builder.add(vars[2], NodeFactory.createURI(randomURI()));
        builder.add(vars[3], NodeFactory.createLiteralString(randomString(20)));
        builder.add(vars[4], NodeFactory.createBlankNode());
        builder.add(vars[5], NodeFactory.createURI(randomURI()));
        builder.add(vars[6], NodeFactory.createURI(randomURI()));
        builder.add(vars[7], NodeFactory.createLiteralString(randomString(5)));
        builder.add(vars[8], NodeFactory.createLiteralDT("" + random.nextInt(), XSDDatatype.XSDinteger));
        builder.add(vars[9], NodeFactory.createBlankNode());
        return builder.build();
    }

    private String randomURI() {
        return String.format("http://%s.example.com/%s", randomString(10), randomString(10));
    }

    private String randomString(int length) {
        StringBuilder builder = new StringBuilder();
        for ( int i = 0 ; i < length ; i++ ) {
            builder.append(LETTERS.charAt(random.nextInt(LETTERS.length())));
        }
        return builder.toString();
    }

    private void getNextAndExpectException(QueryIterator iter) {
        try {
            iter.hasNext();
            fail("Expected an exception here");
        } catch (QueryCancelledException e) {
            // expected
        } catch (Exception e) {
            fail("Unexpected exception");
        }
    }
}
