/*
 * 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.lucene.queryparser.flexible.spans;

import org.apache.lucene.queries.spans.SpanOrQuery;
import org.apache.lucene.queries.spans.SpanQuery;
import org.apache.lucene.queries.spans.SpanTermQuery;
import org.apache.lucene.queryparser.flexible.core.QueryNodeException;
import org.apache.lucene.queryparser.flexible.core.nodes.OrQueryNode;
import org.apache.lucene.queryparser.flexible.core.nodes.QueryNode;
import org.apache.lucene.queryparser.flexible.core.parser.SyntaxParser;
import org.apache.lucene.queryparser.flexible.core.processors.QueryNodeProcessorPipeline;
import org.apache.lucene.queryparser.flexible.standard.parser.StandardSyntaxParser;
import org.apache.lucene.queryparser.flexible.standard.processors.WildcardQueryNodeProcessor;
import org.apache.lucene.search.Query;
import org.apache.lucene.tests.util.LuceneTestCase;

/**
 * This test case demonstrates how the new query parser can be used.<br>
 * <br>
 * It tests queries likes "term", "field:term" "term1 term2" "term1 OR term2", which are all already
 * supported by the current syntax parser ( {@link StandardSyntaxParser}).<br>
 * <br>
 * The goals is to create a new query parser that supports only the pair "field:term" or a list of
 * pairs separated or not by an OR operator, and from this query generate {@link SpanQuery} objects
 * instead of the regular {@link Query} objects. Basically, every pair will be converted to a {@link
 * SpanTermQuery} object and if there are more than one pair they will be grouped by an {@link
 * OrQueryNode}.<br>
 * <br>
 * Another functionality that will be added is the ability to convert every field defined in the
 * query to an unique specific field.<br>
 * <br>
 * The query generation is divided in three different steps: parsing (syntax), processing (semantic)
 * and building.<br>
 * <br>
 * The parsing phase, as already mentioned will be performed by the current query parser: {@link
 * StandardSyntaxParser}.<br>
 * <br>
 * The processing phase will be performed by a processor pipeline which is compound by 2 processors:
 * {@link SpansValidatorQueryNodeProcessor} and {@link UniqueFieldQueryNodeProcessor}.
 *
 * <pre>
 *
 *   {@link SpansValidatorQueryNodeProcessor}: as it's going to use the current
 *   query parser to parse the syntax, it will support more features than we want,
 *   this processor basically validates the query node tree generated by the parser
 *   and just let got through the elements we want, all the other elements as
 *   wildcards, range queries, etc...if found, an exception is thrown.
 *
 *   {@link UniqueFieldQueryNodeProcessor}: this processor will take care of reading
 *   what is the &quot;unique field&quot; from the configuration and convert every field defined
 *   in every pair to this &quot;unique field&quot;. For that, a {@link SpansQueryConfigHandler} is
 *   used, which has the {@link UniqueFieldAttribute} defined in it.
 * </pre>
 *
 * The building phase is performed by the {@link SpansQueryTreeBuilder}, which basically contains a
 * map that defines which builder will be used to generate {@link SpanQuery} objects from {@link
 * QueryNode} objects.<br>
 * <br>
 *
 * @see SpansQueryConfigHandler
 * @see SpansQueryTreeBuilder
 * @see SpansValidatorQueryNodeProcessor
 * @see SpanOrQueryNodeBuilder
 * @see SpanTermQueryNodeBuilder
 * @see StandardSyntaxParser
 * @see UniqueFieldQueryNodeProcessor
 * @see UniqueFieldAttribute
 */
public class TestSpanQueryParser extends LuceneTestCase {

  private QueryNodeProcessorPipeline spanProcessorPipeline;

  private SpansQueryConfigHandler spanQueryConfigHandler;

  private SpansQueryTreeBuilder spansQueryTreeBuilder;

  private SyntaxParser queryParser = new StandardSyntaxParser();

  public TestSpanQueryParser() {
    // empty constructor
  }

  @Override
  public void setUp() throws Exception {
    super.setUp();

    this.spanProcessorPipeline = new QueryNodeProcessorPipeline();
    this.spanQueryConfigHandler = new SpansQueryConfigHandler();
    this.spansQueryTreeBuilder = new SpansQueryTreeBuilder();

    // set up the processor pipeline
    this.spanProcessorPipeline.setQueryConfigHandler(this.spanQueryConfigHandler);

    this.spanProcessorPipeline.add(new WildcardQueryNodeProcessor());
    this.spanProcessorPipeline.add(new SpansValidatorQueryNodeProcessor());
    this.spanProcessorPipeline.add(new UniqueFieldQueryNodeProcessor());
  }

  public SpanQuery getSpanQuery(CharSequence query) throws QueryNodeException {
    return getSpanQuery("", query);
  }

  public SpanQuery getSpanQuery(String uniqueField, CharSequence query) throws QueryNodeException {

    this.spanQueryConfigHandler.set(SpansQueryConfigHandler.UNIQUE_FIELD, uniqueField);

    QueryNode queryTree = this.queryParser.parse(query, "defaultField");
    queryTree = this.spanProcessorPipeline.process(queryTree);

    return this.spansQueryTreeBuilder.build(queryTree);
  }

  public void testTermSpans() throws Exception {
    assertEquals(getSpanQuery("field:term").toString(), "term");
    assertEquals(getSpanQuery("term").toString(), "term");

    assertTrue(getSpanQuery("field:term") instanceof SpanTermQuery);
    assertTrue(getSpanQuery("term") instanceof SpanTermQuery);
  }

  public void testUniqueField() throws Exception {
    assertEquals(getSpanQuery("field", "term").toString(), "field:term");
    assertEquals(getSpanQuery("field", "field:term").toString(), "field:term");
    assertEquals(getSpanQuery("field", "anotherField:term").toString(), "field:term");
  }

  public void testOrSpans() throws Exception {
    assertEquals(getSpanQuery("term1 term2").toString(), "spanOr([term1, term2])");
    assertEquals(getSpanQuery("term1 OR term2").toString(), "spanOr([term1, term2])");

    assertTrue(getSpanQuery("term1 term2") instanceof SpanOrQuery);
    assertTrue(getSpanQuery("term1 term2") instanceof SpanOrQuery);
  }

  public void testQueryValidator() throws QueryNodeException {

    expectThrows(
        QueryNodeException.class,
        () -> {
          getSpanQuery("term*"); // wildcard queries should not be supported
        });

    expectThrows(
        QueryNodeException.class,
        () -> {
          getSpanQuery("[a TO z]"); // range queries should not be supported
        });

    expectThrows(
        QueryNodeException.class,
        () -> {
          getSpanQuery("a~0.5"); // boost queries should not be supported
        });

    expectThrows(
        QueryNodeException.class,
        () -> {
          getSpanQuery("a^0.5"); // fuzzy queries should not be supported
        });

    expectThrows(
        QueryNodeException.class,
        () -> {
          getSpanQuery("\"a b\""); // quoted queries should not be supported
        });

    expectThrows(
        QueryNodeException.class,
        () -> {
          getSpanQuery("(a b)"); // parenthesized queries should not be supported
        });

    expectThrows(
        QueryNodeException.class,
        () -> {
          getSpanQuery("a AND b"); // AND queries should not be supported
        });
  }
}
