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

package org.apache.jena.sparql.engine.join;

import static org.junit.jupiter.api.Assertions.assertTrue;

import java.util.HashSet;
import java.util.Set;

import org.junit.jupiter.api.Test;

import org.apache.jena.query.ResultSet;
import org.apache.jena.query.ResultSetFactory;
import org.apache.jena.sparql.algebra.Table;
import org.apache.jena.sparql.algebra.table.TableEmpty;
import org.apache.jena.sparql.algebra.table.TableN;
import org.apache.jena.sparql.algebra.table.TableUnit;
import org.apache.jena.sparql.engine.ExecutionContext;
import org.apache.jena.sparql.engine.QueryIterator;
import org.apache.jena.sparql.engine.ref.TableJoin;
import org.apache.jena.sparql.expr.ExprList;
import org.apache.jena.sparql.resultset.ResultsCompare;
import org.apache.jena.sparql.sse.SSE;

/** Tests on tables and the simple nest loop join (TableJoin) used by the reference query engine */
public class TestTableJoin
{
    Table unit = new TableUnit();
    Table zero = new TableEmpty();
    Table zeroData = SSE.parseTable("(table)");
    Table unitData = SSE.parseTable("(table (row))");

    Table data1 = SSE.parseTable("(table (row (?a 1) (?b 2)))");
    Table data2 = SSE.parseTable("(table (row (?a 1) (?c 3)) (row (?a 9) (?c 5))  )");
    Table data3 = SSE.parseTable("(table (row (?a 1) (?c 3)) (row (?a 1) (?c 4)) (row (?a 9) (?c 5))  )");

    Table data1J2 = SSE.parseTable("(table (row (?a 1) (?b 2) (?c 3)) )");
    Table data1LJ2 = SSE.parseTable("(table (row (?a 1) (?b 2) (?c 3)) )");
    Table data2LJ1 = SSE.parseTable("(table (row (?a 1) (?b 2) (?c 3)) (row (?a 9) (?c 5)) )");

    Table data1J3 = SSE.parseTable("(table (row (?a 1) (?b 2) (?c 3)) (row (?a 1) (?b 2) (?c 4)) )");

    @Test public void table_01() { test(unit, zero, true, null, zero); }
    @Test public void table_02() { test(zero, unit, true, null, zero); }
    @Test public void table_03() { test(unit, zero, false, null, unit); }
    @Test public void table_04() { test(zero, unit, false, null, zero); }
    // Same again but with non-special tables.
    @Test public void table_05() { test(unitData, zeroData, true, null, zeroData); }
    @Test public void table_06() { test(zeroData, unitData, true, null, zeroData); }
    @Test public void table_07() { test(unitData, zeroData, false, null, unitData); }
    @Test public void table_08() { test(zeroData, unitData, false, null, zeroData); }

    @Test public void table_10() { test(data1, zero, true, null, zero); }
    @Test public void table_11() { test(zero, data1, true, null, zero); }
    @Test public void table_12() { test(data1, zero, false, null, data1); }
    @Test public void table_13() { test(zero, data1, false, null, zero); }

    @Test public void table_14() { test(data1, zeroData, true, null, zeroData); }
    @Test public void table_15() { test(zeroData, data1, true, null, zeroData); }
    @Test public void table_16() { test(data1, zeroData, false, null, data1); }
    @Test public void table_17() { test(zeroData, data1, false, null, zeroData); }

    @Test public void table_18() { test(data2, unitData, true, null, data2); }
    @Test public void table_19() { test(unitData, data2, true, null, data2); }

    @Test public void table_20() { test(data1, data2, true, null, data1J2); }
    @Test public void table_21() { test(data2, data1, true, null, data1J2); }
    @Test public void table_22() { test(data1, data2, false, null, data1LJ2); }
    @Test public void table_23() { test(data2, data1, false, null, data2LJ1); }

    @Test public void table_24() { test(data1, data3, true, null, data1J3); }
    @Test public void table_25() { test(data3, data1, true, null, data1J3); }

    private void test(Table left, Table right, boolean normalJoin, ExprList exprs, Table expected) {
        ExecutionContext execCxt = ExecutionContext.createForGraph(null);
        QueryIterator leftIter = left.iterator(execCxt);
        QueryIterator qIter = normalJoin
            ? TableJoin.join(leftIter, right, exprs, execCxt)
            : TableJoin.leftJoin(leftIter, right, exprs, execCxt);

            // Order issues

        Set<String> vars1 = new HashSet<>();
        vars1.addAll(left.getVarNames());
        vars1.addAll(right.getVarNames());

        TableN results = new TableN(qIter);
        boolean b = TableCompare.equalsByTerm(expected, results);
        if ( !b ) {
            System.out.println("** Expected");
            System.out.println(expected);
            System.out.println("** Actual");
            System.out.println(results);
        }
        assertTrue(b);
    }

    static class TableCompare {
        public static boolean equalsByTerm(Table table1, Table table2) {
            ResultSet rs1 = ResultSetFactory.create(table1.iterator(null), table1.getVarNames());
            ResultSet rs2 = ResultSetFactory.create(table2.iterator(null), table2.getVarNames());
            return ResultsCompare.equalsByTerm(rs1, rs2);
        }
    }

}
