// Copyright (C) 2013 The Android Open Source Project
//
// Licensed 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 com.google.gerrit.server.index;

import static com.google.common.truth.Truth.assertThat;
import static com.google.gerrit.common.data.GlobalCapability.DEFAULT_MAX_QUERY_LIMIT;
import static com.google.gerrit.reviewdb.client.Change.Status.ABANDONED;
import static com.google.gerrit.reviewdb.client.Change.Status.DRAFT;
import static com.google.gerrit.reviewdb.client.Change.Status.MERGED;
import static com.google.gerrit.reviewdb.client.Change.Status.NEW;
import static com.google.gerrit.server.index.IndexedChangeQuery.convertOptions;
import static com.google.gerrit.server.query.Predicate.and;
import static com.google.gerrit.server.query.Predicate.or;
import static org.junit.Assert.assertEquals;

import com.google.gerrit.reviewdb.client.Change;
import com.google.gerrit.server.query.AndPredicate;
import com.google.gerrit.server.query.Predicate;
import com.google.gerrit.server.query.QueryParseException;
import com.google.gerrit.server.query.change.AndSource;
import com.google.gerrit.server.query.change.ChangeData;
import com.google.gerrit.server.query.change.ChangeQueryBuilder;
import com.google.gerrit.server.query.change.OrSource;
import com.google.gerrit.server.query.change.QueryOptions;

import org.junit.Before;
import org.junit.Rule;
import org.junit.Test;
import org.junit.rules.ExpectedException;

import java.util.Arrays;
import java.util.EnumSet;
import java.util.Set;

public class IndexRewriterTest {
  private static final IndexConfig CONFIG = IndexConfig.createDefault();

  @Rule
  public ExpectedException exception = ExpectedException.none();

  private FakeIndex index;
  private IndexCollection indexes;
  private ChangeQueryBuilder queryBuilder;
  private IndexRewriter rewrite;

  @Before
  public void setUp() throws Exception {
    index = new FakeIndex(FakeIndex.V2);
    indexes = new IndexCollection();
    indexes.setSearchIndex(index);
    queryBuilder = new FakeQueryBuilder(indexes);
    rewrite = new IndexRewriter(indexes,
        IndexConfig.create(0, 0, 3, 100));
  }

  @Test
  public void testIndexPredicate() throws Exception {
    Predicate<ChangeData> in = parse("file:a");
    assertThat(rewrite(in)).isEqualTo(query(in));
  }

  @Test
  public void testNonIndexPredicate() throws Exception {
    Predicate<ChangeData> in = parse("foo:a");
    assertThat(in).isSameAs(rewrite(in));
  }

  @Test
  public void testIndexPredicates() throws Exception {
    Predicate<ChangeData> in = parse("file:a file:b");
    assertThat(rewrite(in)).isEqualTo(query(in));
  }

  @Test
  public void testNonIndexPredicates() throws Exception {
    Predicate<ChangeData> in = parse("foo:a OR foo:b");
    assertThat(in).isEqualTo(rewrite(in));
  }

  @Test
  public void testOneIndexPredicate() throws Exception {
    Predicate<ChangeData> in = parse("foo:a file:b");
    Predicate<ChangeData> out = rewrite(in);
    assertThat(AndSource.class).isSameAs(out.getClass());
    assertThat(out.getChildren())
        .containsExactly(
            query(in.getChild(1)),
            in.getChild(0))
        .inOrder();
  }

  @Test
  public void testThreeLevelTreeWithAllIndexPredicates() throws Exception {
    Predicate<ChangeData> in =
        parse("-status:abandoned (file:a OR file:b)");
    assertThat(rewrite.rewrite(in, options(0, DEFAULT_MAX_QUERY_LIMIT)))
        .isEqualTo(query(in));
  }

  @Test
  public void testThreeLevelTreeWithSomeIndexPredicates() throws Exception {
    Predicate<ChangeData> in = parse("-foo:a (file:b OR file:c)");
    Predicate<ChangeData> out = rewrite(in);
    assertThat(out.getClass()).isSameAs(AndSource.class);
    assertThat(out.getChildren())
        .containsExactly(
          query(in.getChild(1)),
          in.getChild(0))
        .inOrder();
  }

  @Test
  public void testMultipleIndexPredicates() throws Exception {
    Predicate<ChangeData> in =
        parse("file:a OR foo:b OR file:c OR foo:d");
    Predicate<ChangeData> out = rewrite(in);
    assertThat(out.getClass()).isSameAs(OrSource.class);
    assertThat(out.getChildren())
        .containsExactly(
          query(or(in.getChild(0), in.getChild(2))),
          in.getChild(1),
          in.getChild(3))
        .inOrder();
  }

  @Test
  public void testIndexAndNonIndexPredicates() throws Exception {
    Predicate<ChangeData> in = parse("status:new bar:p file:a");
    Predicate<ChangeData> out = rewrite(in);
    assertThat(AndSource.class).isSameAs(out.getClass());
    assertThat(out.getChildren())
        .containsExactly(
          query(and(in.getChild(0), in.getChild(2))),
          in.getChild(1))
        .inOrder();
  }

  @Test
  public void testDuplicateCompoundNonIndexOnlyPredicates() throws Exception {
    Predicate<ChangeData> in =
        parse("(status:new OR status:draft) bar:p file:a");
    Predicate<ChangeData> out = rewrite(in);
    assertThat(out.getClass()).isEqualTo(AndSource.class);
    assertThat(out.getChildren())
        .containsExactly(
          query(and(in.getChild(0), in.getChild(2))),
          in.getChild(1))
        .inOrder();
  }

  @Test
  public void testDuplicateCompoundIndexOnlyPredicates() throws Exception {
    Predicate<ChangeData> in =
        parse("(status:new OR file:a) bar:p file:b");
    Predicate<ChangeData> out = rewrite(in);
    assertThat(out.getClass()).isEqualTo(AndSource.class);
    assertThat(out.getChildren())
        .containsExactly(
          query(and(in.getChild(0), in.getChild(2))),
          in.getChild(1))
        .inOrder();
  }

  @Test
  public void testOptionsArgumentOverridesAllLimitPredicates()
      throws Exception {
    Predicate<ChangeData> in = parse("limit:1 file:a limit:3");
    Predicate<ChangeData> out = rewrite(in, options(0, 5));
    assertThat(out.getClass()).isEqualTo(AndSource.class);
    assertThat(out.getChildren())
        .containsExactly(
          query(in.getChild(1), 5),
          parse("limit:5"),
          parse("limit:5"))
        .inOrder();
  }

  @Test
  public void testStartIncreasesLimitInQueryButNotPredicate() throws Exception {
    int n = 3;
    Predicate<ChangeData> f = parse("file:a");
    Predicate<ChangeData> l = parse("limit:" + n);
    Predicate<ChangeData> in = andSource(f, l);
    assertThat(rewrite.rewrite(in, options(0, n)))
        .isEqualTo(andSource(query(f, 3), l));
    assertThat(rewrite.rewrite(in, options(1, n)))
        .isEqualTo(andSource(query(f, 4), l));
    assertThat(rewrite.rewrite(in, options(2, n)))
        .isEqualTo(andSource(query(f, 5), l));
  }

  @Test
  public void testGetPossibleStatus() throws Exception {
    assertThat(status("file:a")).isEqualTo(EnumSet.allOf(Change.Status.class));
    assertThat(status("is:new")).containsExactly(NEW);
    assertThat(status("-is:new"))
        .containsExactly(DRAFT, MERGED, ABANDONED);
    assertThat(status("is:new OR is:merged")).containsExactly(NEW, MERGED);

    assertThat(status("is:new is:merged")).isEmpty();
    assertThat(status("(is:new is:draft) (is:merged)")).isEmpty();
    assertThat(status("(is:new is:draft) (is:merged)")).isEmpty();

    assertThat(status("(is:new is:draft) OR (is:merged)"))
        .containsExactly(MERGED);
  }

  @Test
  public void testUnsupportedIndexOperator() throws Exception {
    Predicate<ChangeData> in = parse("status:merged file:a");
    assertThat(rewrite(in)).isEqualTo(query(in));

    indexes.setSearchIndex(new FakeIndex(FakeIndex.V1));
    Predicate<ChangeData> out = rewrite(in);
    assertThat(out).isInstanceOf(AndPredicate.class);
    assertThat(out.getChildren())
        .containsExactly(
          query(in.getChild(0)),
          in.getChild(1))
        .inOrder();
  }

  @Test
  public void testTooManyTerms() throws Exception {
    String q = "file:a OR file:b OR file:c";
    Predicate<ChangeData> in = parse(q);
    assertEquals(query(in), rewrite(in));

    exception.expect(QueryParseException.class);
    exception.expectMessage("too many terms in query");
    rewrite(parse(q + " OR file:d"));
  }

  @Test
  public void testConvertOptions() throws Exception {
    assertEquals(options(0, 3), convertOptions(options(0, 3)));
    assertEquals(options(0, 4), convertOptions(options(1, 3)));
    assertEquals(options(0, 5), convertOptions(options(2, 3)));
  }

  @Test
  public void testAddingStartToLimitDoesNotExceedBackendLimit() throws Exception {
    int max = CONFIG.maxLimit();
    assertEquals(options(0, max), convertOptions(options(0, max)));
    assertEquals(options(0, max), convertOptions(options(1, max)));
    assertEquals(options(0, max), convertOptions(options(1, max - 1)));
    assertEquals(options(0, max), convertOptions(options(2, max - 1)));
  }

  private Predicate<ChangeData> parse(String query) throws QueryParseException {
    return queryBuilder.parse(query);
  }

  @SafeVarargs
  private static AndSource andSource(Predicate<ChangeData>... preds) {
    return new AndSource(Arrays.asList(preds));
  }

  private Predicate<ChangeData> rewrite(Predicate<ChangeData> in)
      throws QueryParseException {
    return rewrite.rewrite(in, options(0, DEFAULT_MAX_QUERY_LIMIT));
  }

  private Predicate<ChangeData> rewrite(Predicate<ChangeData> in,
      QueryOptions opts) throws QueryParseException {
    return rewrite.rewrite(in, opts);
  }

  private IndexedChangeQuery query(Predicate<ChangeData> p)
      throws QueryParseException {
    return query(p, DEFAULT_MAX_QUERY_LIMIT);
  }

  private IndexedChangeQuery query(Predicate<ChangeData> p, int limit)
      throws QueryParseException {
    return new IndexedChangeQuery(index, p, options(0, limit));
  }

  private static QueryOptions options(int start, int limit) {
    return QueryOptions.create(CONFIG, start, limit);
  }

  private Set<Change.Status> status(String query) throws QueryParseException {
    return IndexRewriter.getPossibleStatus(parse(query));
  }
}