package it.cavallium.dbengine;

import static it.cavallium.dbengine.DbTestUtils.destroyAllocator;
import static it.cavallium.dbengine.DbTestUtils.ensureNoLeaks;
import static it.cavallium.dbengine.DbTestUtils.newAllocator;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.fail;

import it.cavallium.dbengine.DbTestUtils.TempDb;
import it.cavallium.dbengine.DbTestUtils.TestAllocator;
import it.cavallium.dbengine.client.LuceneIndex;
import it.cavallium.dbengine.client.MultiSort;
import it.cavallium.dbengine.client.SearchResultKey;
import it.cavallium.dbengine.client.SearchResultKeys;
import it.cavallium.dbengine.client.query.ClientQueryParams;
import it.cavallium.dbengine.client.query.ClientQueryParamsBuilder;
import it.cavallium.dbengine.client.query.QueryParser;
import it.cavallium.dbengine.client.query.current.data.MatchAllDocsQuery;
import it.cavallium.dbengine.client.query.current.data.MatchNoDocsQuery;
import it.cavallium.dbengine.client.query.current.data.NoSort;
import it.cavallium.dbengine.client.query.current.data.TotalHitsCount;
import it.cavallium.dbengine.database.LLLuceneIndex;
import it.cavallium.dbengine.database.LLScoreMode;
import it.cavallium.dbengine.database.LLUtils;
import it.cavallium.dbengine.lucene.searcher.AdaptiveLuceneLocalSearcher;
import it.cavallium.dbengine.lucene.searcher.AdaptiveLuceneMultiSearcher;
import it.cavallium.dbengine.lucene.searcher.CountLuceneLocalSearcher;
import it.cavallium.dbengine.lucene.searcher.LuceneLocalSearcher;
import it.cavallium.dbengine.lucene.searcher.LuceneMultiSearcher;
import it.cavallium.dbengine.lucene.searcher.UnsortedScoredFullLuceneMultiSearcher;
import it.cavallium.dbengine.lucene.searcher.ScoredSimpleLuceneMultiSearcher;
import it.cavallium.dbengine.lucene.searcher.SimpleLuceneLocalSearcher;
import it.cavallium.dbengine.lucene.searcher.SimpleUnsortedUnscoredLuceneMultiSearcher;
import it.cavallium.dbengine.lucene.searcher.UnsortedUnscoredContinuousLuceneMultiSearcher;
import java.io.IOException;
import java.util.List;
import java.util.Objects;
import java.util.stream.Stream;
import org.jetbrains.annotations.Nullable;
import org.junit.jupiter.api.AfterEach;
import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.Arguments;
import org.junit.jupiter.params.provider.MethodSource;
import org.warp.commonutils.log.Logger;
import org.warp.commonutils.log.LoggerFactory;
import reactor.core.publisher.Flux;
import reactor.core.publisher.FluxSink.OverflowStrategy;
import reactor.core.publisher.Mono;
import reactor.core.scheduler.Schedulers;
import reactor.util.function.Tuples;

public class TestLuceneIndex {

	private final Logger log = LoggerFactory.getLogger(this.getClass());

	private TestAllocator allocator;
	private TempDb tempDb;
	private LLLuceneIndex luceneSingle;
	private LLLuceneIndex luceneMulti;

	protected TemporaryDbGenerator getTempDbGenerator() {
		return new MemoryTemporaryDbGenerator();
	}

	@BeforeEach
	public void beforeEach() {
		this.allocator = newAllocator();
		ensureNoLeaks(allocator.allocator(), false, false);
		tempDb = Objects.requireNonNull(getTempDbGenerator().openTempDb(allocator).block(), "TempDB");
		luceneSingle = tempDb.luceneSingle();
		luceneMulti = tempDb.luceneMulti();
	}

	public static Stream<Arguments> provideArguments() {
		return Stream.of(false, true).map(Arguments::of);
	}

	private static final Flux<Boolean> multi = Flux.just(false, true);
	private static final Flux<LLScoreMode> scoreModes = Flux.just(LLScoreMode.NO_SCORES,
			LLScoreMode.TOP_SCORES,
			LLScoreMode.COMPLETE_NO_SCORES,
			LLScoreMode.COMPLETE
	);
	private static final Flux<MultiSort<SearchResultKey<String>>> multiSort = Flux.just(MultiSort.topScore(),
			MultiSort.randomSortField(),
			MultiSort.noSort(),
			MultiSort.docSort(),
			MultiSort.numericSort("longsort", false),
			MultiSort.numericSort("longsort", true)
	);

	private static Flux<LuceneLocalSearcher> getSearchers(ExpectedQueryType info) {
		return Flux.push(sink -> {
			try {
				if (info.shard()) {
					sink.next(new AdaptiveLuceneMultiSearcher());
					if (info.onlyCount()) {
						sink.next(new SimpleUnsortedUnscoredLuceneMultiSearcher(new CountLuceneLocalSearcher()));
					} else {
						sink.next(new ScoredSimpleLuceneMultiSearcher());
						if (!info.sorted()) {
							sink.next(new UnsortedScoredFullLuceneMultiSearcher());
						}
						if (!info.scored() && !info.sorted()) {
							sink.next(new SimpleUnsortedUnscoredLuceneMultiSearcher(new SimpleLuceneLocalSearcher()));
							sink.next(new UnsortedUnscoredContinuousLuceneMultiSearcher());
						}
					}
				} else {
					sink.next(new AdaptiveLuceneLocalSearcher());
					if (info.onlyCount()) {
						sink.next(new CountLuceneLocalSearcher());
					} else {
						sink.next(new SimpleLuceneLocalSearcher());
					}
				}
				sink.complete();
			} catch (IOException e) {
				sink.error(e);
			}
		}, OverflowStrategy.BUFFER);
	}

	public static Stream<Arguments> provideQueryArgumentsScoreMode() {
		return multi
				.concatMap(shard -> scoreModes.map(scoreMode -> Tuples.of(shard, scoreMode)))
				.map(tuple -> Arguments.of(tuple.toArray()))
				.toStream();
	}

	public static Stream<Arguments> provideQueryArgumentsSort() {
		return multi
				.concatMap(shard -> multiSort.map(multiSort -> Tuples.of(shard, multiSort)))
				.map(tuple -> Arguments.of(tuple.toArray()))
				.toStream();
	}

	public static Stream<Arguments> provideQueryArgumentsScoreModeAndSort() {
		return multi
				.concatMap(shard -> scoreModes.map(scoreMode -> Tuples.of(shard, scoreMode)))
				.concatMap(tuple -> multiSort.map(multiSort -> Tuples.of(tuple.getT1(), tuple.getT2(), multiSort)))
				.map(tuple -> Arguments.of(tuple.toArray()))
				.toStream();
	}

	@AfterEach
	public void afterEach() {
		getTempDbGenerator().closeTempDb(tempDb).block();
		ensureNoLeaks(allocator.allocator(), true, false);
		destroyAllocator(allocator);
	}

	private LuceneIndex<String, String> getLuceneIndex(boolean shards, @Nullable LuceneLocalSearcher customSearcher) {
		LuceneIndex<String, String> index = run(DbTestUtils.tempLuceneIndex(shards ? luceneSingle : luceneMulti));
		index.updateDocument("test-key-1", "0123456789").block();
		index.updateDocument("test-key-2", "test 0123456789 test word").block();
		index.updateDocument("test-key-3", "0123456789 test example string").block();
		index.updateDocument("test-key-4", "hello world the quick brown fox jumps over the lazy dog").block();
		index.updateDocument("test-key-5", "hello the quick brown fox jumps over the lazy dog").block();
		index.updateDocument("test-key-6", "hello the quick brown fox jumps over the world dog").block();
		index.updateDocument("test-key-7", "the quick brown fox jumps over the world dog").block();
		index.updateDocument("test-key-8", "the quick brown fox jumps over the lazy dog").block();
		index.updateDocument("test-key-9", "Example1").block();
		index.updateDocument("test-key-10", "Example2").block();
		index.updateDocument("test-key-11", "Example3").block();
		index.updateDocument("test-key-12", "-234").block();
		index.updateDocument("test-key-13", "2111").block();
		index.updateDocument("test-key-14", "2999").block();
		index.updateDocument("test-key-15", "3902").block();
		Flux.range(1, 1000).concatMap(i -> index.updateDocument("test-key-" + (15 + i), "" + i)).blockLast();
		tempDb.swappableLuceneSearcher().setSingle(new CountLuceneLocalSearcher());
		tempDb.swappableLuceneSearcher().setMulti(new SimpleUnsortedUnscoredLuceneMultiSearcher(new CountLuceneLocalSearcher()));
		assertCount(index, 1000 + 15);
		try {
			if (customSearcher != null) {
				tempDb.swappableLuceneSearcher().setSingle(customSearcher);
				if (shards) {
					if (customSearcher instanceof LuceneMultiSearcher multiSearcher) {
						tempDb.swappableLuceneSearcher().setMulti(multiSearcher);
					} else {
						throw new IllegalArgumentException("Expected a LuceneMultiSearcher, got a LuceneLocalSearcher: " + customSearcher.getName());
					}
				}
			} else {
				tempDb.swappableLuceneSearcher().setSingle(new AdaptiveLuceneLocalSearcher());
				tempDb.swappableLuceneSearcher().setMulti(new AdaptiveLuceneMultiSearcher());
			}
		} catch (IOException e) {
			fail(e);
		}
		return index;
	}

	private void run(Flux<?> publisher) {
		publisher.subscribeOn(Schedulers.immediate()).blockLast();
	}

	private void runVoid(Mono<Void> publisher) {
		publisher.then().subscribeOn(Schedulers.immediate()).block();
	}

	private <T> T run(Mono<T> publisher) {
		return publisher.subscribeOn(Schedulers.immediate()).block();
	}

	private <T> T run(boolean shouldFail, Mono<T> publisher) {
		return publisher.subscribeOn(Schedulers.immediate()).transform(mono -> {
			if (shouldFail) {
				return mono.onErrorResume(ex -> Mono.empty());
			} else {
				return mono;
			}
		}).block();
	}

	private void runVoid(boolean shouldFail, Mono<Void> publisher) {
		publisher.then().subscribeOn(Schedulers.immediate()).transform(mono -> {
			if (shouldFail) {
				return mono.onErrorResume(ex -> Mono.empty());
			} else {
				return mono;
			}
		}).block();
	}

	private void assertCount(LuceneIndex<String, String> luceneIndex, long expected) {
		Assertions.assertEquals(expected, getCount(luceneIndex));
	}

	private long getCount(LuceneIndex<String, String> luceneIndex) {
		luceneIndex.refresh(true).block();
		var totalHitsCount = run(luceneIndex.count(null, new MatchAllDocsQuery()));
		Assertions.assertTrue(totalHitsCount.exact(), "Can't get count because the total hits count is not exact");
		return totalHitsCount.value();
	}

	@Test
	public void testNoOp() {
	}

	@Test
	public void testNoOpAllocation() {
		for (int i = 0; i < 10; i++) {
			var a = allocator.allocator().allocate(i * 512);
			a.send().receive().close();
		}
	}

	@ParameterizedTest
	@MethodSource("provideArguments")
	public void testGetLuceneIndex(boolean shards) {
		var luceneIndex = getLuceneIndex(shards, null);
		Assertions.assertNotNull(luceneIndex);
	}

	@ParameterizedTest
	@MethodSource("provideArguments")
	public void testDeleteAll(boolean shards) {
		var luceneIndex = getLuceneIndex(shards, null);
		runVoid(luceneIndex.deleteAll());
		assertCount(luceneIndex, 0);
	}

	@ParameterizedTest
	@MethodSource("provideArguments")
	public void testDelete(boolean shards) {
		var luceneIndex = getLuceneIndex(shards, null);
		var prevCount = getCount(luceneIndex);
		runVoid(luceneIndex.deleteDocument("test-key-1"));
		assertCount(luceneIndex, prevCount - 1);
	}

	@ParameterizedTest
	@MethodSource("provideArguments")
	public void testUpdateSameDoc(boolean shards) {
		var luceneIndex = getLuceneIndex(shards, null);
		var prevCount = getCount(luceneIndex);
		runVoid(luceneIndex.updateDocument("test-key-1", "new-value"));
		assertCount(luceneIndex, prevCount );
	}

	@ParameterizedTest
	@MethodSource("provideArguments")
	public void testUpdateNewDoc(boolean shards) {
		var luceneIndex = getLuceneIndex(shards, null);
		var prevCount = getCount(luceneIndex);
		runVoid(luceneIndex.updateDocument("test-key-new", "new-value"));
		assertCount(luceneIndex, prevCount + 1);
	}

	@ParameterizedTest
	@MethodSource("provideQueryArgumentsScoreModeAndSort")
	public void testSearchNoDocs(boolean shards, LLScoreMode scoreMode, MultiSort<SearchResultKey<String>> multiSort) {
		var searchers = run(getSearchers(new ExpectedQueryType(shards, isSorted(multiSort), isScored(scoreMode, multiSort), true, false)).collectList());
		for (LuceneLocalSearcher searcher : searchers) {
			log.info("Using searcher \"{}\"", searcher.getName());

			var luceneIndex = getLuceneIndex(shards, searcher);
			ClientQueryParamsBuilder<SearchResultKey<String>> queryBuilder = ClientQueryParams.builder();
			queryBuilder.query(new MatchNoDocsQuery());
			queryBuilder.snapshot(null);
			queryBuilder.scoreMode(scoreMode);
			queryBuilder.sort(multiSort);
			var query = queryBuilder.build();
			try (var results = run(luceneIndex.search(query)).receive()) {
				var hits = results.totalHitsCount();
				if (supportsPreciseHitsCount(searcher, query)) {
					assertEquals(new TotalHitsCount(0, true), hits);
				}

				var keys = getResults(results);
				assertEquals(List.of(), keys);
			}
		}
	}

	private boolean supportsPreciseHitsCount(LuceneLocalSearcher searcher,
			ClientQueryParams<SearchResultKey<String>> query) {
		if (searcher instanceof UnsortedUnscoredContinuousLuceneMultiSearcher) {
			return false;
		}
		var scored = isScored(query.scoreMode(), Objects.requireNonNullElse(query.sort(), MultiSort.noSort()));
		var sorted = isSorted(Objects.requireNonNullElse(query.sort(), MultiSort.noSort()));
		if (!sorted && !scored) {
			if (searcher instanceof AdaptiveLuceneMultiSearcher || searcher instanceof AdaptiveLuceneLocalSearcher) {
				return false;
			}
		}
		return true;
	}

	@ParameterizedTest
	@MethodSource("provideQueryArgumentsScoreModeAndSort")
	public void testSearchAllDocs(boolean shards, LLScoreMode scoreMode, MultiSort<SearchResultKey<String>> multiSort) {
		var searchers = run(getSearchers(new ExpectedQueryType(shards, isSorted(multiSort), isScored(scoreMode, multiSort), true, false)).collectList());
		for (LuceneLocalSearcher searcher : searchers) {
			log.info("Using searcher \"{}\"", searcher.getName());

			var luceneIndex = getLuceneIndex(shards, searcher);
			ClientQueryParamsBuilder<SearchResultKey<String>> queryBuilder = ClientQueryParams.builder();
			queryBuilder.query(new MatchNoDocsQuery());
			queryBuilder.snapshot(null);
			queryBuilder.scoreMode(scoreMode);
			queryBuilder.sort(multiSort);
			var query = queryBuilder.build();
			try (var results = run(luceneIndex.search(query)).receive()) {
				var hits = results.totalHitsCount();
				if (supportsPreciseHitsCount(searcher, query)) {
					assertEquals(new TotalHitsCount(0, true), hits);
				}

				var keys = getResults(results);
				assertEquals(List.of(), keys);
			}
		}
	}

	private boolean isSorted(MultiSort<SearchResultKey<String>> multiSort) {
		return !(multiSort.getQuerySort() instanceof NoSort);
	}

	private boolean isScored(LLScoreMode scoreMode, MultiSort<SearchResultKey<String>> multiSort) {
		var needsScores = LLUtils.toScoreMode(scoreMode).needsScores();
		var sort =QueryParser.toSort(multiSort.getQuerySort());
		if (sort != null) {
			needsScores |= sort.needsScores();
		}
		return needsScores;
	}

	private List<Scored> getResults(SearchResultKeys<String> results) {
		return run(results
				.results()
				.flatMapSequential(searchResultKey -> searchResultKey
						.key()
						.single()
						.map(key -> new Scored(key, searchResultKey.score()))
				)
				.collectList());
	}

}