/*
 * Copyright 2010-2023 the original author or authors.
 *
 * 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
 *
 *      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.
 */
package org.springframework.data.mongodb.repository.query;

import java.util.ArrayList;
import java.util.List;

import org.bson.Document;
import org.bson.codecs.configuration.CodecRegistry;
import org.springframework.data.mapping.model.SpELExpressionEvaluator;
import org.springframework.data.mongodb.core.ExecutableFindOperation.ExecutableFind;
import org.springframework.data.mongodb.core.ExecutableFindOperation.FindWithQuery;
import org.springframework.data.mongodb.core.ExecutableFindOperation.TerminatingFind;
import org.springframework.data.mongodb.core.ExecutableUpdateOperation.ExecutableUpdate;
import org.springframework.data.mongodb.core.MongoOperations;
import org.springframework.data.mongodb.core.aggregation.AggregationOperation;
import org.springframework.data.mongodb.core.aggregation.AggregationUpdate;
import org.springframework.data.mongodb.core.query.BasicUpdate;
import org.springframework.data.mongodb.core.query.Query;
import org.springframework.data.mongodb.core.query.UpdateDefinition;
import org.springframework.data.mongodb.repository.Update;
import org.springframework.data.mongodb.repository.query.MongoQueryExecution.DeleteExecution;
import org.springframework.data.mongodb.repository.query.MongoQueryExecution.GeoNearExecution;
import org.springframework.data.mongodb.repository.query.MongoQueryExecution.PagedExecution;
import org.springframework.data.mongodb.repository.query.MongoQueryExecution.PagingGeoNearExecution;
import org.springframework.data.mongodb.repository.query.MongoQueryExecution.SlicedExecution;
import org.springframework.data.mongodb.repository.query.MongoQueryExecution.UpdateExecution;
import org.springframework.data.mongodb.util.json.ParameterBindingContext;
import org.springframework.data.mongodb.util.json.ParameterBindingDocumentCodec;
import org.springframework.data.repository.query.ParameterAccessor;
import org.springframework.data.repository.query.QueryMethodEvaluationContextProvider;
import org.springframework.data.repository.query.RepositoryQuery;
import org.springframework.data.repository.query.ResultProcessor;
import org.springframework.data.spel.ExpressionDependencies;
import org.springframework.data.util.Lazy;
import org.springframework.expression.EvaluationContext;
import org.springframework.expression.ExpressionParser;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.ObjectUtils;
import org.springframework.util.StringUtils;

import com.mongodb.client.MongoDatabase;

/**
 * Base class for {@link RepositoryQuery} implementations for Mongo.
 *
 * @author Oliver Gierke
 * @author Thomas Darimont
 * @author Christoph Strobl
 * @author Mark Paluch
 */
public abstract class AbstractMongoQuery implements RepositoryQuery {

	private final MongoQueryMethod method;
	private final MongoOperations operations;
	private final ExecutableFind<?> executableFind;
	private final ExecutableUpdate<?> executableUpdate;
	private final ExpressionParser expressionParser;
	private final QueryMethodEvaluationContextProvider evaluationContextProvider;
	private final Lazy<ParameterBindingDocumentCodec> codec = Lazy
			.of(() -> new ParameterBindingDocumentCodec(getCodecRegistry()));

	/**
	 * Creates a new {@link AbstractMongoQuery} from the given {@link MongoQueryMethod} and {@link MongoOperations}.
	 *
	 * @param method must not be {@literal null}.
	 * @param operations must not be {@literal null}.
	 * @param expressionParser must not be {@literal null}.
	 * @param evaluationContextProvider must not be {@literal null}.
	 */
	public AbstractMongoQuery(MongoQueryMethod method, MongoOperations operations, ExpressionParser expressionParser,
			QueryMethodEvaluationContextProvider evaluationContextProvider) {

		Assert.notNull(operations, "MongoOperations must not be null");
		Assert.notNull(method, "MongoQueryMethod must not be null");
		Assert.notNull(expressionParser, "SpelExpressionParser must not be null");
		Assert.notNull(evaluationContextProvider, "QueryMethodEvaluationContextProvider must not be null");

		this.method = method;
		this.operations = operations;

		MongoEntityMetadata<?> metadata = method.getEntityInformation();
		Class<?> type = metadata.getCollectionEntity().getType();

		this.executableFind = operations.query(type);
		this.executableUpdate = operations.update(type);
		this.expressionParser = expressionParser;
		this.evaluationContextProvider = evaluationContextProvider;
	}

	public MongoQueryMethod getQueryMethod() {
		return method;
	}

	@Override
	public Object execute(Object[] parameters) {

		ConvertingParameterAccessor accessor = new ConvertingParameterAccessor(operations.getConverter(),
				new MongoParametersParameterAccessor(method, parameters));

		ResultProcessor processor = method.getResultProcessor().withDynamicProjection(accessor);
		Class<?> typeToRead = processor.getReturnedType().getTypeToRead();

		return processor.processResult(doExecute(method, processor, accessor, typeToRead));
	}

	/**
	 * Execute the {@link RepositoryQuery} of the given method with the parameters provided by the
	 * {@link ConvertingParameterAccessor accessor}
	 *
	 * @param method the {@link MongoQueryMethod} invoked. Never {@literal null}.
	 * @param processor {@link ResultProcessor} for post procession. Never {@literal null}.
	 * @param accessor for providing invocation arguments. Never {@literal null}.
	 * @param typeToRead the desired component target type. Can be {@literal null}.
	 */
	@Nullable
	protected Object doExecute(MongoQueryMethod method, ResultProcessor processor, ConvertingParameterAccessor accessor,
			@Nullable Class<?> typeToRead) {

		Query query = createQuery(accessor);

		applyQueryMetaAttributesWhenPresent(query);
		query = applyAnnotatedDefaultSortIfPresent(query);
		query = applyAnnotatedCollationIfPresent(query, accessor);
		query = applyHintIfPresent(query);

		FindWithQuery<?> find = typeToRead == null //
				? executableFind //
				: executableFind.as(typeToRead);

		return getExecution(accessor, find).execute(query);
	}

	private MongoQueryExecution getExecution(ConvertingParameterAccessor accessor, FindWithQuery<?> operation) {

		if (isDeleteQuery()) {
			return new DeleteExecution(operations, method);
		}

		if (method.isModifyingQuery()) {
			if (isLimiting()) {
				throw new IllegalStateException(
						String.format("Update method must not be limiting; Offending method: %s", method));
			}
			return new UpdateExecution(executableUpdate, method, () -> createUpdate(accessor), accessor);
		}

		if (method.isGeoNearQuery() && method.isPageQuery()) {
			return new PagingGeoNearExecution(operation, method, accessor, this);
		} else if (method.isGeoNearQuery()) {
			return new GeoNearExecution(operation, method, accessor);
		} else if (method.isSliceQuery()) {
			return new SlicedExecution(operation, accessor.getPageable());
		} else if (method.isStreamQuery()) {
			return q -> operation.matching(q).stream();
		} else if (method.isCollectionQuery()) {
			return q -> operation.matching(q.with(accessor.getPageable()).with(accessor.getSort())).all();
		} else if (method.isScrollQuery()) {
			return q -> operation.matching(q.with(accessor.getPageable()).with(accessor.getSort()))
					.scroll(accessor.getScrollPosition());
		} else if (method.isPageQuery()) {
			return new PagedExecution(operation, accessor.getPageable());
		} else if (isCountQuery()) {
			return q -> operation.matching(q).count();
		} else if (isExistsQuery()) {
			return q -> operation.matching(q).exists();
		} else {
			return q -> {
				TerminatingFind<?> find = operation.matching(q);
				return isLimiting() ? find.firstValue() : find.oneValue();
			};
		}
	}

	Query applyQueryMetaAttributesWhenPresent(Query query) {

		if (method.hasQueryMetaAttributes()) {
			query.setMeta(method.getQueryMetaAttributes());
		}

		return query;
	}

	/**
	 * Add a default sort derived from {@link org.springframework.data.mongodb.repository.Query#sort()} to the given
	 * {@link Query} if present.
	 *
	 * @param query the {@link Query} to potentially apply the sort to.
	 * @return the query with potential default sort applied.
	 * @since 2.1
	 */
	Query applyAnnotatedDefaultSortIfPresent(Query query) {

		if (!method.hasAnnotatedSort()) {
			return query;
		}

		return QueryUtils.decorateSort(query, Document.parse(method.getAnnotatedSort()));
	}

	/**
	 * If present apply a {@link org.springframework.data.mongodb.core.query.Collation} derived from the
	 * {@link org.springframework.data.repository.query.QueryMethod} the given {@link Query}.
	 *
	 * @param query must not be {@literal null}.
	 * @param accessor the {@link ParameterAccessor} used to obtain parameter placeholder replacement values.
	 * @return
	 * @since 2.2
	 */
	Query applyAnnotatedCollationIfPresent(Query query, ConvertingParameterAccessor accessor) {

		return QueryUtils.applyCollation(query, method.hasAnnotatedCollation() ? method.getAnnotatedCollation() : null,
				accessor, getQueryMethod().getParameters(), expressionParser, evaluationContextProvider);
	}

	/**
	 * If present apply the hint from the {@link org.springframework.data.mongodb.repository.Hint} annotation.
	 *
	 * @param query must not be {@literal null}.
	 * @return never {@literal null}.
	 * @since 4.1
	 */
	Query applyHintIfPresent(Query query) {

		if (!method.hasAnnotatedHint()) {
			return query;
		}

		return query.withHint(method.getAnnotatedHint());
	}

	/**
	 * Creates a {@link Query} instance using the given {@link ConvertingParameterAccessor}. Will delegate to
	 * {@link #createQuery(ConvertingParameterAccessor)} by default but allows customization of the count query to be
	 * triggered.
	 *
	 * @param accessor must not be {@literal null}.
	 * @return
	 */
	protected Query createCountQuery(ConvertingParameterAccessor accessor) {
		return applyQueryMetaAttributesWhenPresent(createQuery(accessor));
	}

	/**
	 * Retrieves the {@link UpdateDefinition update} from the given
	 * {@link org.springframework.data.mongodb.repository.query.MongoParameterAccessor#getUpdate() accessor} or creates
	 * one via by parsing the annotated statement extracted from {@link Update}.
	 *
	 * @param accessor never {@literal null}.
	 * @return the computed {@link UpdateDefinition}.
	 * @throws IllegalStateException if no update could be found.
	 * @since 3.4
	 */
	protected UpdateDefinition createUpdate(ConvertingParameterAccessor accessor) {

		if (accessor.getUpdate() != null) {
			return accessor.getUpdate();
		}

		if (method.hasAnnotatedUpdate()) {

			Update updateSource = method.getUpdateSource();
			if (StringUtils.hasText(updateSource.update())) {
				return new BasicUpdate(bindParameters(updateSource.update(), accessor));
			}
			if (!ObjectUtils.isEmpty(updateSource.pipeline())) {
				return AggregationUpdate.from(parseAggregationPipeline(updateSource.pipeline(), accessor));
			}
		}

		throw new IllegalStateException(String.format("No Update provided for method %s.", method));
	}

	/**
	 * Parse the given aggregation pipeline stages applying values to placeholders to compute the actual list of
	 * {@link AggregationOperation operations}.
	 *
	 * @param sourcePipeline must not be {@literal null}.
	 * @param accessor must not be {@literal null}.
	 * @return the parsed aggregation pipeline.
	 * @since 3.4
	 */
	protected List<AggregationOperation> parseAggregationPipeline(String[] sourcePipeline,
			ConvertingParameterAccessor accessor) {

		List<AggregationOperation> stages = new ArrayList<>(sourcePipeline.length);
		for (String source : sourcePipeline) {
			stages.add(computePipelineStage(source, accessor));
		}
		return stages;
	}

	private AggregationOperation computePipelineStage(String source, ConvertingParameterAccessor accessor) {
		return ctx -> ctx.getMappedObject(bindParameters(source, accessor), getQueryMethod().getDomainClass());
	}

	protected Document decode(String source, ParameterBindingContext bindingContext) {
		return getParameterBindingCodec().decode(source, bindingContext);
	}

	private Document bindParameters(String source, ConvertingParameterAccessor accessor) {
		return decode(source, prepareBindingContext(source, accessor));
	}

	/**
	 * Create the {@link ParameterBindingContext binding context} used for SpEL evaluation.
	 *
	 * @param source the JSON source.
	 * @param accessor value provider for parameter binding.
	 * @return never {@literal null}.
	 * @since 3.4
	 */
	protected ParameterBindingContext prepareBindingContext(String source, ConvertingParameterAccessor accessor) {

		ExpressionDependencies dependencies = getParameterBindingCodec().captureExpressionDependencies(source,
				accessor::getBindableValue, expressionParser);

		SpELExpressionEvaluator evaluator = getSpELExpressionEvaluatorFor(dependencies, accessor);
		return new ParameterBindingContext(accessor::getBindableValue, evaluator);
	}

	/**
	 * Obtain the {@link ParameterBindingDocumentCodec} used for parsing JSON expressions.
	 *
	 * @return never {@literal null}.
	 * @since 3.4
	 */
	protected ParameterBindingDocumentCodec getParameterBindingCodec() {
		return codec.get();
	}

	/**
	 * Obtain a the {@link EvaluationContext} suitable to evaluate expressions backed by the given dependencies.
	 *
	 * @param dependencies must not be {@literal null}.
	 * @param accessor must not be {@literal null}.
	 * @return the {@link SpELExpressionEvaluator}.
	 * @since 2.4
	 */
	protected SpELExpressionEvaluator getSpELExpressionEvaluatorFor(ExpressionDependencies dependencies,
			ConvertingParameterAccessor accessor) {

		return new DefaultSpELExpressionEvaluator(expressionParser, evaluationContextProvider
				.getEvaluationContext(getQueryMethod().getParameters(), accessor.getValues(), dependencies));
	}

	/**
	 * @return the {@link CodecRegistry} used.
	 * @since 2.4
	 */
	protected CodecRegistry getCodecRegistry() {
		return operations.execute(MongoDatabase::getCodecRegistry);
	}

	/**
	 * Creates a {@link Query} instance using the given {@link ParameterAccessor}
	 *
	 * @param accessor must not be {@literal null}.
	 * @return
	 */
	protected abstract Query createQuery(ConvertingParameterAccessor accessor);

	/**
	 * Returns whether the query should get a count projection applied.
	 *
	 * @return
	 */
	protected abstract boolean isCountQuery();

	/**
	 * Returns whether the query should get an exists projection applied.
	 *
	 * @return
	 * @since 1.10
	 */
	protected abstract boolean isExistsQuery();

	/**
	 * Return weather the query should delete matching documents.
	 *
	 * @return
	 * @since 1.5
	 */
	protected abstract boolean isDeleteQuery();

	/**
	 * Return whether the query has an explicit limit set.
	 *
	 * @return
	 * @since 2.0.4
	 */
	protected abstract boolean isLimiting();
}
