/*
 * #%L
 * HAPI FHIR - Server Framework
 * %%
 * Copyright (C) 2014 - 2025 Smile CDR, Inc.
 * %%
 * 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.
 * #L%
 */
package ca.uhn.fhir.rest.server;

import ca.uhn.fhir.model.primitive.InstantDt;
import ca.uhn.fhir.rest.api.server.IBundleProvider;
import ca.uhn.fhir.rest.server.method.ResponsePage;
import ca.uhn.fhir.util.BundleUtil;
import jakarta.annotation.Nonnull;
import org.apache.commons.lang3.builder.ToStringBuilder;
import org.hl7.fhir.instance.model.api.IBaseResource;
import org.hl7.fhir.instance.model.api.IPrimitiveType;

import java.util.Arrays;
import java.util.Collections;
import java.util.Date;
import java.util.List;
import java.util.stream.Collectors;

public class SimpleBundleProvider implements IBundleProvider {

        private final List<? extends IBaseResource> myList;
        private final String myUuid;
        private Integer myPreferredPageSize;
        private Integer mySize;
        private IPrimitiveType<Date> myPublished = InstantDt.withCurrentTime();
        private Integer myCurrentPageOffset;
        private Integer myCurrentPageSize;
        private boolean myHasAllResources;
        private ResponsePage.ResponsePageBuilder myPageBuilder;

        /**
         * The actual number of resources we have tried to fetch.
         * This value will only be populated if there is a
         * _count query parameter provided.
         * In which case, it will be the total number of resources
         * we tried to fetch (should be _count + 1 for accurate paging)
         */
        private int myTotalResourcesRequestedReturned = -1;

        /**
         * Constructor
         */
        public SimpleBundleProvider(IBaseResource theResource) {
                this(Collections.singletonList(theResource));
        }

        /**
         * Create an empty bundle
         */
        public SimpleBundleProvider() {
                this(Collections.emptyList());
        }

        /**
         * Constructor
         */
        public SimpleBundleProvider(List<? extends IBaseResource> theList) {
                this(theList, null);
        }

        /**
         * Constructor
         *
         * @since 6.8.0
         */
        public SimpleBundleProvider(IBaseResource... theList) {
                this(Arrays.asList(theList), null);
        }

        public SimpleBundleProvider(List<? extends IBaseResource> theList, String theUuid) {
                myList = theList;
                myUuid = theUuid;
                int size = 0;
                for (IBaseResource r : theList) {
                        if (r != null && BundleUtil.isMatchResource(r)) {
                                size++;
                        }
                }
                myHasAllResources = true;
                setSize(size);
        }

        /**
         * Constructor that provides only a size but no actual data (useful for _count = 0)
         */
        public SimpleBundleProvider(int theSize) {
                myList = Collections.emptyList();
                myUuid = null;
                setSize(theSize);
        }

        /**
         * @since 5.5.0
         */
        @Override
        public Integer getCurrentPageOffset() {
                return myCurrentPageOffset;
        }

        /**
         * @since 5.5.0
         */
        public void setCurrentPageOffset(Integer theCurrentPageOffset) {
                myCurrentPageOffset = theCurrentPageOffset;
        }

        /**
         * @since 5.5.0
         */
        @Override
        public Integer getCurrentPageSize() {
                return myCurrentPageSize;
        }

        /**
         * @since 5.5.0
         */
        public void setCurrentPageSize(Integer theCurrentPageSize) {
                myCurrentPageSize = theCurrentPageSize;
        }

        /**
         * Returns the results stored in this provider
         */
        protected List<? extends IBaseResource> getList() {
                return myList;
        }

        @Override
        public IPrimitiveType<Date> getPublished() {
                return myPublished;
        }

        /**
         * By default this class uses the object creation date/time (for this object)
         * to determine {@link #getPublished() the published date} but this
         * method may be used to specify an alternate date/time
         */
        public void setPublished(IPrimitiveType<Date> thePublished) {
                myPublished = thePublished;
        }

        @SuppressWarnings("unchecked")
        @Nonnull
        @Override
        public List<IBaseResource> getResources(
                        int theFromIndex, int theToIndex, @Nonnull ResponsePage.ResponsePageBuilder theResponsePageBuilder) {
                theResponsePageBuilder.setTotalRequestedResourcesFetched(myTotalResourcesRequestedReturned);
                return (List<IBaseResource>)
                                myList.subList(Math.min(theFromIndex, myList.size()), Math.min(theToIndex, myList.size()));
        }

        @Override
        public String getUuid() {
                return myUuid;
        }

        public void setTotalResourcesRequestedReturned(int theAmount) {
                myTotalResourcesRequestedReturned = theAmount;
        }

        /**
         * Defaults to null
         */
        @Override
        public Integer preferredPageSize() {
                return myPreferredPageSize;
        }

        /**
         * Sets the preferred page size to be returned by {@link #preferredPageSize()}.
         * Default is <code>null</code>.
         */
        public void setPreferredPageSize(Integer thePreferredPageSize) {
                myPreferredPageSize = thePreferredPageSize;
        }

        /**
         * Sets the total number of results, if this provider
         * corresponds to a single page within a larger search result
         */
        public SimpleBundleProvider setSize(Integer theSize) {
                mySize = theSize;
                return this;
        }

        @Override
        public Integer size() {
                return mySize;
        }

        @Override
        public boolean containsAllResources() {
                return myHasAllResources;
        }

        @Override
        public List<IBaseResource> getResourceListComplete() {
                return myList.stream().map(r -> (IBaseResource) r).collect(Collectors.toList());
        }

        @Override
        public String toString() {
                return new ToStringBuilder(this).append("mySize", mySize).toString();
        }
}