/*-
 * #%L
 * HAPI FHIR - Server Framework
 * %%
 * Copyright (C) 2014 - 2024 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.api.server.storage;

import ca.uhn.fhir.context.FhirContext;
import ca.uhn.fhir.i18n.Msg;
import ca.uhn.fhir.interceptor.api.HookParams;
import ca.uhn.fhir.interceptor.api.Pointcut;
import ca.uhn.fhir.rest.api.InterceptorInvocationTimingEnum;
import ca.uhn.fhir.rest.server.exceptions.PreconditionFailedException;
import com.google.common.collect.ArrayListMultimap;
import com.google.common.collect.ListMultimap;
import jakarta.annotation.Nonnull;
import jakarta.annotation.Nullable;
import org.apache.commons.lang3.Validate;
import org.hl7.fhir.instance.model.api.IBaseResource;
import org.hl7.fhir.instance.model.api.IIdType;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Date;
import java.util.EnumSet;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.function.Supplier;

/**
 * This object contains runtime information that is gathered and relevant to a single <i>database transaction</i>.
 * This doesn't mean a FHIR transaction necessarily, but rather any operation that happens within a single DB transaction
 * (i.e. a FHIR create, read, transaction, etc.).
 * <p>
 * The intent with this class is to hold things we want to pass from operation to operation within a transaction in
 * order to avoid looking things up multiple times, etc.
 * </p>
 *
 * @since 5.0.0
 */
public class TransactionDetails {

        public static final IResourcePersistentId NOT_FOUND = IResourcePersistentId.NOT_FOUND;

        private final Date myTransactionDate;
        private List<Runnable> myRollbackUndoActions = Collections.emptyList();
        private Map<String, IResourcePersistentId> myResolvedResourceIds = Collections.emptyMap();
        private Map<String, IResourcePersistentId> myResolvedMatchUrls = Collections.emptyMap();
        private Map<String, Supplier<IBaseResource>> myResolvedResources = Collections.emptyMap();
        private Set<IResourcePersistentId> myDeletedResourceIds = Collections.emptySet();
        private Map<String, Object> myUserData;
        private ListMultimap<Pointcut, HookParams> myDeferredInterceptorBroadcasts;
        private EnumSet<Pointcut> myDeferredInterceptorBroadcastPointcuts;
        private boolean myFhirTransaction;

        /**
         * Constructor
         */
        public TransactionDetails() {
                this(new Date());
        }

        /**
         * Constructor
         */
        public TransactionDetails(Date theTransactionDate) {
                myTransactionDate = theTransactionDate;
        }

        /**
         * Get the actions that should be executed if the transaction is rolled back
         *
         * @since 5.5.0
         */
        public List<Runnable> getRollbackUndoActions() {
                return Collections.unmodifiableList(myRollbackUndoActions);
        }

        /**
         * Add an action that should be executed if the transaction is rolled back
         *
         * @since 5.5.0
         */
        public void addRollbackUndoAction(@Nonnull Runnable theRunnable) {
                assert theRunnable != null;
                if (myRollbackUndoActions.isEmpty()) {
                        myRollbackUndoActions = new ArrayList<>();
                }
                myRollbackUndoActions.add(theRunnable);
        }

        /**
         * Clears any previously added rollback actions
         *
         * @since 5.5.0
         */
        public void clearRollbackUndoActions() {
                if (!myRollbackUndoActions.isEmpty()) {
                        myRollbackUndoActions.clear();
                }
        }

        /**
         * @since 6.8.0
         */
        public void addDeletedResourceId(@Nonnull IResourcePersistentId theResourceId) {
                Validate.notNull(theResourceId, "theResourceId must not be null");
                if (myDeletedResourceIds.isEmpty()) {
                        myDeletedResourceIds = new HashSet<>();
                }
                myDeletedResourceIds.add(theResourceId);
        }

        /**
         * @since 6.8.0
         */
        public void addDeletedResourceIds(Collection<? extends IResourcePersistentId> theResourceIds) {
                for (IResourcePersistentId<?> next : theResourceIds) {
                        addDeletedResourceId(next);
                }
        }

        /**
         * @since 6.8.0
         */
        @Nonnull
        public Set<IResourcePersistentId> getDeletedResourceIds() {
                return Collections.unmodifiableSet(myDeletedResourceIds);
        }

        /**
         * A <b>Resolved Resource ID</b> is a mapping between a resource ID (e.g. "<code>Patient/ABC</code>" or
         * "<code>Observation/123</code>") and a storage ID for that resource. Resources should only be placed within
         * the TransactionDetails if they are known to exist and be valid targets for other resources to link to.
         */
        @Nullable
        public IResourcePersistentId getResolvedResourceId(IIdType theId) {
                String idValue = theId.toUnqualifiedVersionless().getValue();
                return myResolvedResourceIds.get(idValue);
        }

        /**
         * A <b>Resolved Resource ID</b> is a mapping between a resource ID (e.g. "<code>Patient/ABC</code>" or
         * "<code>Observation/123</code>") and the actual persisted/resolved resource with this ID.
         */
        @Nullable
        public IBaseResource getResolvedResource(IIdType theId) {
                String idValue = theId.toUnqualifiedVersionless().getValue();
                IBaseResource retVal = null;
                Supplier<IBaseResource> supplier = myResolvedResources.get(idValue);
                if (supplier != null) {
                        retVal = supplier.get();
                }
                return retVal;
        }

        /**
         * Was the given resource ID resolved previously in this transaction as not existing
         */
        public boolean isResolvedResourceIdEmpty(IIdType theId) {
                if (myResolvedResourceIds != null) {
                        if (myResolvedResourceIds.containsKey(theId.toVersionless().getValue())) {
                                return myResolvedResourceIds.get(theId.toVersionless().getValue()) == null;
                        }
                }
                return false;
        }

        /**
         * Was the given resource ID resolved previously in this transaction
         */
        public boolean hasResolvedResourceId(IIdType theId) {
                if (myResolvedResourceIds != null) {
                        return myResolvedResourceIds.containsKey(theId.toVersionless().getValue());
                }
                return false;
        }

        /**
         * A <b>Resolved Resource ID</b> is a mapping between a resource ID (e.g. "<code>Patient/ABC</code>" or
         * "<code>Observation/123</code>") and a storage ID for that resource. Resources should only be placed within
         * the TransactionDetails if they are known to exist and be valid targets for other resources to link to.
         */
        public void addResolvedResourceId(IIdType theResourceId, @Nullable IResourcePersistentId thePersistentId) {
                assert theResourceId != null;

                if (myResolvedResourceIds.isEmpty()) {
                        myResolvedResourceIds = new HashMap<>();
                }
                myResolvedResourceIds.put(theResourceId.toVersionless().getValue(), thePersistentId);
        }

        /**
         * A <b>Resolved Resource ID</b> is a mapping between a resource ID (e.g. "<code>Patient/ABC</code>" or
         * "<code>Observation/123</code>") and the actual persisted/resolved resource.
         * This version takes a {@link Supplier} which will only be fetched if the
         * resource is actually needed. This is good in cases where the resource is
         * lazy loaded.
         */
        public void addResolvedResource(IIdType theResourceId, @Nonnull Supplier<IBaseResource> theResource) {
                assert theResourceId != null;

                if (myResolvedResources.isEmpty()) {
                        myResolvedResources = new HashMap<>();
                }
                myResolvedResources.put(theResourceId.toVersionless().getValue(), theResource);
        }

        /**
         * A <b>Resolved Resource ID</b> is a mapping between a resource ID (e.g. "<code>Patient/ABC</code>" or
         * "<code>Observation/123</code>") and the actual persisted/resolved resource.
         */
        public void addResolvedResource(IIdType theResourceId, @Nonnull IBaseResource theResource) {
                addResolvedResource(theResourceId, () -> theResource);
        }

        public Map<String, IResourcePersistentId> getResolvedMatchUrls() {
                return myResolvedMatchUrls;
        }

        /**
         * A <b>Resolved Conditional URL</b> is a mapping between a conditional URL (e.g. "<code>Patient?identifier=foo|bar</code>" or
         * "<code>Observation/123</code>") and a storage ID for that resource. Resources should only be placed within
         * the TransactionDetails if they are known to exist and be valid targets for other resources to link to.
         */
        public void addResolvedMatchUrl(
                        FhirContext theFhirContext, String theConditionalUrl, @Nonnull IResourcePersistentId thePersistentId) {
                Validate.notBlank(theConditionalUrl);
                Validate.notNull(thePersistentId);

                if (myResolvedMatchUrls.isEmpty()) {
                        myResolvedMatchUrls = new HashMap<>();
                } else if (matchUrlWithDiffIdExists(theConditionalUrl, thePersistentId)) {
                        String msg = theFhirContext
                                        .getLocalizer()
                                        .getMessage(TransactionDetails.class, "invalidMatchUrlMultipleMatches", theConditionalUrl);
                        throw new PreconditionFailedException(Msg.code(2207) + msg);
                }
                myResolvedMatchUrls.put(theConditionalUrl, thePersistentId);
        }

        /**
         * @since 6.8.0
         * @see #addResolvedMatchUrl(FhirContext, String, IResourcePersistentId)
         */
        public void removeResolvedMatchUrl(String theMatchUrl) {
                myResolvedMatchUrls.remove(theMatchUrl);
        }

        private boolean matchUrlWithDiffIdExists(String theConditionalUrl, @Nonnull IResourcePersistentId thePersistentId) {
                if (myResolvedMatchUrls.containsKey(theConditionalUrl)
                                && myResolvedMatchUrls.get(theConditionalUrl) != NOT_FOUND) {
                        return !myResolvedMatchUrls.get(theConditionalUrl).getId().equals(thePersistentId.getId());
                }
                return false;
        }

        /**
         * This is the wall-clock time that a given transaction started.
         */
        public Date getTransactionDate() {
                return myTransactionDate;
        }

        /**
         * Remove an item previously stored in user data
         *
         * @see #getUserData(String)
         */
        public void clearUserData(String theKey) {
                if (myUserData != null) {
                        myUserData.remove(theKey);
                }
        }

        /**
         * Sets an arbitrary object that will last the lifetime of the current transaction
         *
         * @see #getUserData(String)
         */
        public void putUserData(String theKey, Object theValue) {
                if (myUserData == null) {
                        myUserData = new HashMap<>();
                }
                myUserData.put(theKey, theValue);
        }

        /**
         * Gets an arbitrary object that will last the lifetime of the current transaction
         *
         * @see #putUserData(String, Object)
         */
        @SuppressWarnings("unchecked")
        public <T> T getUserData(String theKey) {
                if (myUserData != null) {
                        return (T) myUserData.get(theKey);
                }
                return null;
        }

        /**
         * Fetches the existing value in the user data map, or uses {@literal theSupplier} to create a new object and
         * puts that in the map, and returns it
         */
        @SuppressWarnings("unchecked")
        public <T> T getOrCreateUserData(String theKey, Supplier<T> theSupplier) {
                T retVal = getUserData(theKey);
                if (retVal == null) {
                        retVal = theSupplier.get();
                        putUserData(theKey, retVal);
                }
                return retVal;
        }

        /**
         * This can be used by processors for FHIR transactions to defer interceptor broadcasts on sub-requests if needed
         *
         * @since 5.2.0
         */
        public void beginAcceptingDeferredInterceptorBroadcasts(Pointcut... thePointcuts) {
                Validate.isTrue(!isAcceptingDeferredInterceptorBroadcasts());
                myDeferredInterceptorBroadcasts = ArrayListMultimap.create();
                myDeferredInterceptorBroadcastPointcuts = EnumSet.of(thePointcuts[0], thePointcuts);
        }

        /**
         * This can be used by processors for FHIR transactions to defer interceptor broadcasts on sub-requests if needed
         *
         * @since 5.2.0
         */
        public boolean isAcceptingDeferredInterceptorBroadcasts() {
                return myDeferredInterceptorBroadcasts != null;
        }

        /**
         * This can be used by processors for FHIR transactions to defer interceptor broadcasts on sub-requests if needed
         *
         * @since 5.2.0
         */
        public boolean isAcceptingDeferredInterceptorBroadcasts(Pointcut thePointcut) {
                return myDeferredInterceptorBroadcasts != null && myDeferredInterceptorBroadcastPointcuts.contains(thePointcut);
        }

        /**
         * This can be used by processors for FHIR transactions to defer interceptor broadcasts on sub-requests if needed
         *
         * @since 5.2.0
         */
        public ListMultimap<Pointcut, HookParams> endAcceptingDeferredInterceptorBroadcasts() {
                Validate.isTrue(isAcceptingDeferredInterceptorBroadcasts());
                ListMultimap<Pointcut, HookParams> retVal = myDeferredInterceptorBroadcasts;
                myDeferredInterceptorBroadcasts = null;
                myDeferredInterceptorBroadcastPointcuts = null;
                return retVal;
        }

        /**
         * This can be used by processors for FHIR transactions to defer interceptor broadcasts on sub-requests if needed
         *
         * @since 5.2.0
         */
        public void addDeferredInterceptorBroadcast(Pointcut thePointcut, HookParams theHookParams) {
                Validate.isTrue(isAcceptingDeferredInterceptorBroadcasts(thePointcut));
                myDeferredInterceptorBroadcasts.put(thePointcut, theHookParams);
        }

        public InterceptorInvocationTimingEnum getInvocationTiming(Pointcut thePointcut) {
                if (myDeferredInterceptorBroadcasts == null) {
                        return InterceptorInvocationTimingEnum.ACTIVE;
                }
                List<HookParams> hookParams = myDeferredInterceptorBroadcasts.get(thePointcut);
                return hookParams == null ? InterceptorInvocationTimingEnum.ACTIVE : InterceptorInvocationTimingEnum.DEFERRED;
        }

        public void deferredBroadcastProcessingFinished() {}

        public void clearResolvedItems() {
                myResolvedResourceIds.clear();
                myResolvedMatchUrls.clear();
        }

        public boolean hasResolvedResourceIds() {
                return !myResolvedResourceIds.isEmpty();
        }

        public boolean isFhirTransaction() {
                return myFhirTransaction;
        }

        public void setFhirTransaction(boolean theFhirTransaction) {
                myFhirTransaction = theFhirTransaction;
        }
}