package ca.uhn.fhir.rest.server;

/*
 * #%L
 * HAPI FHIR - Server Framework
 * %%
 * Copyright (C) 2014 - 2022 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%
 */

import ca.uhn.fhir.i18n.Msg;
import ca.uhn.fhir.context.FhirContext;
import ca.uhn.fhir.context.RuntimeResourceDefinition;
import ca.uhn.fhir.context.RuntimeSearchParam;
import ca.uhn.fhir.rest.api.RestSearchParameterTypeEnum;
import ca.uhn.fhir.rest.server.method.BaseMethodBinding;
import ca.uhn.fhir.rest.server.method.OperationMethodBinding;
import ca.uhn.fhir.rest.server.method.SearchMethodBinding;
import ca.uhn.fhir.rest.server.method.SearchParameter;
import ca.uhn.fhir.rest.server.util.ISearchParamRegistry;
import ca.uhn.fhir.util.VersionUtil;
import com.google.common.collect.ArrayListMultimap;
import com.google.common.collect.ListMultimap;
import org.apache.commons.lang3.StringUtils;
import org.apache.commons.lang3.Validate;
import org.hl7.fhir.instance.model.api.IBaseResource;
import org.hl7.fhir.instance.model.api.IIdType;
import org.hl7.fhir.instance.model.api.IPrimitiveType;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.Date;
import java.util.HashMap;
import java.util.IdentityHashMap;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.TreeMap;
import java.util.TreeSet;
import java.util.stream.Collectors;

import static org.apache.commons.lang3.StringUtils.isBlank;

public class RestfulServerConfiguration implements ISearchParamRegistry {

        public static final String GLOBAL = "GLOBAL";
        private static final Logger ourLog = LoggerFactory.getLogger(RestfulServerConfiguration.class);
        private Collection<ResourceBinding> resourceBindings;
        private List<BaseMethodBinding<?>> serverBindings;
        private List<BaseMethodBinding<?>> myGlobalBindings;
        private Map<String, Class<? extends IBaseResource>> resourceNameToSharedSupertype;
        private String myImplementationDescription;
        private String myServerName = "HAPI FHIR";
        private String myServerVersion = VersionUtil.getVersion();
        private FhirContext myFhirContext;
        private IServerAddressStrategy myServerAddressStrategy;
        private IPrimitiveType<Date> myConformanceDate;

        /**
         * Constructor
         */
        public RestfulServerConfiguration() {
                super();
        }

        /**
         * Get the resourceBindings
         *
         * @return the resourceBindings
         */
        public Collection<ResourceBinding> getResourceBindings() {
                return resourceBindings;
        }

        /**
         * Set the resourceBindings
         *
         * @param resourceBindings the resourceBindings to set
         */
        public RestfulServerConfiguration setResourceBindings(Collection<ResourceBinding> resourceBindings) {
                this.resourceBindings = resourceBindings;
                return this;
        }

        /**
         * Get the serverBindings
         *
         * @return the serverBindings
         */
        public List<BaseMethodBinding<?>> getServerBindings() {
                return serverBindings;
        }

        /**
         * Set the theServerBindings
         */
        public RestfulServerConfiguration setServerBindings(List<BaseMethodBinding<?>> theServerBindings) {
                this.serverBindings = theServerBindings;
                return this;
        }

        public Map<String, Class<? extends IBaseResource>> getNameToSharedSupertype() {
                return resourceNameToSharedSupertype;
        }

        public RestfulServerConfiguration setNameToSharedSupertype(Map<String, Class<? extends IBaseResource>> resourceNameToSharedSupertype) {
                this.resourceNameToSharedSupertype = resourceNameToSharedSupertype;
                return this;
        }

        /**
         * Get the implementationDescription
         *
         * @return the implementationDescription
         */
        public String getImplementationDescription() {
                if (isBlank(myImplementationDescription)) {
                        return "HAPI FHIR";
                }
                return myImplementationDescription;
        }

        /**
         * Set the implementationDescription
         *
         * @param implementationDescription the implementationDescription to set
         */
        public RestfulServerConfiguration setImplementationDescription(String implementationDescription) {
                this.myImplementationDescription = implementationDescription;
                return this;
        }

        /**
         * Get the serverVersion
         *
         * @return the serverVersion
         */
        public String getServerVersion() {
                return myServerVersion;
        }

        /**
         * Set the serverVersion
         *
         * @param serverVersion the serverVersion to set
         */
        public RestfulServerConfiguration setServerVersion(String serverVersion) {
                this.myServerVersion = serverVersion;
                return this;
        }

        /**
         * Get the serverName
         *
         * @return the serverName
         */
        public String getServerName() {
                return myServerName;
        }

        /**
         * Set the serverName
         *
         * @param serverName the serverName to set
         */
        public RestfulServerConfiguration setServerName(String serverName) {
                this.myServerName = serverName;
                return this;
        }

        /**
         * Gets the {@link FhirContext} associated with this server. For efficient processing, resource providers and plain providers should generally use this context if one is needed, as opposed to
         * creating their own.
         */
        public FhirContext getFhirContext() {
                return this.myFhirContext;
        }

        /**
         * Set the fhirContext
         *
         * @param fhirContext the fhirContext to set
         */
        public RestfulServerConfiguration setFhirContext(FhirContext fhirContext) {
                this.myFhirContext = fhirContext;
                return this;
        }

        /**
         * Get the serverAddressStrategy
         *
         * @return the serverAddressStrategy
         */
        public IServerAddressStrategy getServerAddressStrategy() {
                return myServerAddressStrategy;
        }

        /**
         * Set the serverAddressStrategy
         *
         * @param serverAddressStrategy the serverAddressStrategy to set
         */
        public void setServerAddressStrategy(IServerAddressStrategy serverAddressStrategy) {
                this.myServerAddressStrategy = serverAddressStrategy;
        }

        /**
         * Get the date that will be specified in the conformance profile
         * exported by this server. Typically this would be populated with
         * an InstanceType.
         */
        public IPrimitiveType<Date> getConformanceDate() {
                return myConformanceDate;
        }

        /**
         * Set the date that will be specified in the conformance profile
         * exported by this server. Typically this would be populated with
         * an InstanceType.
         */
        public void setConformanceDate(IPrimitiveType<Date> theConformanceDate) {
                myConformanceDate = theConformanceDate;
        }

        public Bindings provideBindings() {
                IdentityHashMap<SearchMethodBinding, String> namedSearchMethodBindingToName = new IdentityHashMap<>();
                HashMap<String, List<SearchMethodBinding>> searchNameToBindings = new HashMap<>();
                IdentityHashMap<OperationMethodBinding, String> operationBindingToId = new IdentityHashMap<>();
                HashMap<String, List<OperationMethodBinding>> operationIdToBindings = new HashMap<>();

                Map<String, List<BaseMethodBinding<?>>> resourceToMethods = collectMethodBindings();
                List<BaseMethodBinding<?>> methodBindings = resourceToMethods
                        .values()
                        .stream().flatMap(t -> t.stream())
                        .collect(Collectors.toList());
                if (myGlobalBindings != null) {
                        methodBindings.addAll(myGlobalBindings);
                }

                ListMultimap<String, OperationMethodBinding> nameToOperationMethodBindings = ArrayListMultimap.create();
                for (BaseMethodBinding<?> nextMethodBinding : methodBindings) {
                        if (nextMethodBinding instanceof OperationMethodBinding) {
                                OperationMethodBinding methodBinding = (OperationMethodBinding) nextMethodBinding;
                                nameToOperationMethodBindings.put(methodBinding.getName(), methodBinding);
                        } else if (nextMethodBinding instanceof SearchMethodBinding) {
                                SearchMethodBinding methodBinding = (SearchMethodBinding) nextMethodBinding;
                                if (namedSearchMethodBindingToName.containsKey(methodBinding)) {
                                        continue;
                                }

                                String name = createNamedQueryName(methodBinding);
                                ourLog.debug("Detected named query: {}", name);

                                namedSearchMethodBindingToName.put(methodBinding, name);
                                if (!searchNameToBindings.containsKey(name)) {
                                        searchNameToBindings.put(name, new ArrayList<>());
                                }
                                searchNameToBindings.get(name).add(methodBinding);
                        }
                }

                for (String nextName : nameToOperationMethodBindings.keySet()) {
                        List<OperationMethodBinding> nextMethodBindings = nameToOperationMethodBindings.get(nextName);

                        boolean global = false;
                        boolean system = false;
                        boolean instance = false;
                        boolean type = false;
                        Set<String> resourceTypes = null;

                        for (OperationMethodBinding nextMethodBinding : nextMethodBindings) {
                                global |= nextMethodBinding.isGlobalMethod();
                                system |= nextMethodBinding.isCanOperateAtServerLevel();
                                type |= nextMethodBinding.isCanOperateAtTypeLevel();
                                instance |= nextMethodBinding.isCanOperateAtInstanceLevel();
                                if (nextMethodBinding.getResourceName() != null) {
                                        resourceTypes = resourceTypes != null ? resourceTypes : new TreeSet<>();
                                        resourceTypes.add(nextMethodBinding.getResourceName());
                                }
                        }

                        StringBuilder operationIdBuilder = new StringBuilder();
                        if (global) {
                                operationIdBuilder.append("Global");
                        } else if (resourceTypes != null && resourceTypes.size() == 1) {
                                operationIdBuilder.append(resourceTypes.iterator().next());
                        } else if (resourceTypes != null && resourceTypes.size() == 2) {
                                Iterator<String> iterator = resourceTypes.iterator();
                                operationIdBuilder.append(iterator.next());
                                operationIdBuilder.append(iterator.next());
                        } else if (resourceTypes != null) {
                                operationIdBuilder.append("Multi");
                        }

                        operationIdBuilder.append('-');
                        if (instance) {
                                operationIdBuilder.append('i');
                        }
                        if (type) {
                                operationIdBuilder.append('t');
                        }
                        if (system) {
                                operationIdBuilder.append('s');
                        }
                        operationIdBuilder.append('-');

                        // Exclude the leading $
                        operationIdBuilder.append(nextName, 1, nextName.length());

                        String operationId = operationIdBuilder.toString();
                        operationIdToBindings.put(operationId, nextMethodBindings);
                        nextMethodBindings.forEach(t->operationBindingToId.put(t, operationId));
                }

                for (BaseMethodBinding<?> nextMethodBinding : methodBindings) {
                        if (nextMethodBinding instanceof OperationMethodBinding) {
                                OperationMethodBinding methodBinding = (OperationMethodBinding) nextMethodBinding;
                                if (operationBindingToId.containsKey(methodBinding)) {
                                        continue;
                                }

                                String name = createOperationName(methodBinding);
                                ourLog.debug("Detected operation: {}", name);

                                operationBindingToId.put(methodBinding, name);
                                if (operationIdToBindings.containsKey(name) == false) {
                                        operationIdToBindings.put(name, new ArrayList<>());
                                }
                                operationIdToBindings.get(name).add(methodBinding);
                        }
                }

                return new Bindings(namedSearchMethodBindingToName, searchNameToBindings, operationIdToBindings, operationBindingToId);
        }

        public Map<String, List<BaseMethodBinding<?>>> collectMethodBindings() {
                Map<String, List<BaseMethodBinding<?>>> resourceToMethods = new TreeMap<>();
                for (ResourceBinding next : getResourceBindings()) {
                        String resourceName = next.getResourceName();
                        for (BaseMethodBinding<?> nextMethodBinding : next.getMethodBindings()) {
                                if (resourceToMethods.containsKey(resourceName) == false) {
                                        resourceToMethods.put(resourceName, new ArrayList<>());
                                }
                                resourceToMethods.get(resourceName).add(nextMethodBinding);
                        }
                }
                for (BaseMethodBinding<?> nextMethodBinding : getServerBindings()) {
                        String resourceName = "";
                        if (resourceToMethods.containsKey(resourceName) == false) {
                                resourceToMethods.put(resourceName, new ArrayList<>());
                        }
                        resourceToMethods.get(resourceName).add(nextMethodBinding);
                }
                return resourceToMethods;
        }

        public List<BaseMethodBinding<?>> getGlobalBindings() {
                return myGlobalBindings;
        }

        public void setGlobalBindings(List<BaseMethodBinding<?>> theGlobalBindings) {
                myGlobalBindings = theGlobalBindings;
        }

        /*
         * Populates {@link #resourceNameToSharedSupertype} by scanning the given resource providers. Only resource provider getResourceType values
         * are taken into account. {@link ProvidesResources} and method return types are deliberately ignored.
         *
         * Given a resource name, the common superclass for all getResourceType return values for that name's providers is the common superclass
         * for all returned/received resources with that name. Since {@link ProvidesResources} resources and method return types must also be
         * subclasses of this common supertype, they can't affect the result of this method.
         */
        public void computeSharedSupertypeForResourcePerName(Collection<IResourceProvider> providers) {
                Map<String, CommonResourceSupertypeScanner> resourceNameToScanner = new HashMap<>();

                List<Class<? extends IBaseResource>> providedResourceClasses = providers.stream()
                        .map(provider -> provider.getResourceType())
                        .collect(Collectors.toList());
                providedResourceClasses.stream()
                        .forEach(resourceClass -> {
                                RuntimeResourceDefinition baseDefinition = getFhirContext().getResourceDefinition(resourceClass).getBaseDefinition();
                                CommonResourceSupertypeScanner scanner = resourceNameToScanner.computeIfAbsent(baseDefinition.getName(), key -> new CommonResourceSupertypeScanner());
                                scanner.register(resourceClass);
                        });

                resourceNameToSharedSupertype = resourceNameToScanner.entrySet().stream()
                        .filter(entry -> entry.getValue().getLowestCommonSuperclass().isPresent())
                        .collect(Collectors.toMap(
                                entry -> entry.getKey(),
                                entry -> entry.getValue().getLowestCommonSuperclass().get()));
        }

        private String createNamedQueryName(SearchMethodBinding searchMethodBinding) {
                StringBuilder retVal = new StringBuilder();
                if (searchMethodBinding.getResourceName() != null) {
                        retVal.append(searchMethodBinding.getResourceName());
                }
                retVal.append("-query-");
                retVal.append(searchMethodBinding.getQueryName());

                return retVal.toString();
        }

        @Override
        public RuntimeSearchParam getActiveSearchParam(String theResourceName, String theParamName) {
                return getActiveSearchParams(theResourceName).get(theParamName);
        }

        @Override
        public Map<String, RuntimeSearchParam> getActiveSearchParams(@Nonnull String theResourceName) {
                Validate.notBlank(theResourceName, "theResourceName must not be null or blank");

                Map<String, RuntimeSearchParam> retVal = new LinkedHashMap<>();

                collectMethodBindings()
                        .getOrDefault(theResourceName, Collections.emptyList())
                        .stream()
                        .filter(t -> theResourceName.equals(t.getResourceName()))
                        .filter(t -> t instanceof SearchMethodBinding)
                        .map(t -> (SearchMethodBinding) t)
                        .filter(t -> t.getQueryName() == null)
                        .forEach(t -> createRuntimeBinding(retVal, t));

                return retVal;
        }

        @Nullable
        @Override
        public RuntimeSearchParam getActiveSearchParamByUrl(String theUrl) {
                throw new UnsupportedOperationException(Msg.code(286));
        }

        private void createRuntimeBinding(Map<String, RuntimeSearchParam> theMapToPopulate, SearchMethodBinding theSearchMethodBinding) {

                List<SearchParameter> parameters = theSearchMethodBinding
                        .getParameters()
                        .stream()
                        .filter(t -> t instanceof SearchParameter)
                        .map(t -> (SearchParameter) t)
                        .sorted(SearchParameterComparator.INSTANCE)
                        .collect(Collectors.toList());

                for (SearchParameter nextParameter : parameters) {

                        String nextParamName = nextParameter.getName();

                        String nextParamUnchainedName = nextParamName;
                        if (nextParamName.contains(".")) {
                                nextParamUnchainedName = nextParamName.substring(0, nextParamName.indexOf('.'));
                        }

                        String nextParamDescription = nextParameter.getDescription();

                        /*
                         * If the parameter has no description, default to the one from the resource
                         */
                        if (StringUtils.isBlank(nextParamDescription)) {
                                RuntimeResourceDefinition def = getFhirContext().getResourceDefinition(theSearchMethodBinding.getResourceName());
                                RuntimeSearchParam paramDef = def.getSearchParam(nextParamUnchainedName);
                                if (paramDef != null) {
                                        nextParamDescription = paramDef.getDescription();
                                }
                        }

                        if (theMapToPopulate.containsKey(nextParamUnchainedName)) {
                                continue;
                        }

                        IIdType id = getFhirContext().getVersion().newIdType().setValue("SearchParameter/" + theSearchMethodBinding.getResourceName() + "-" + nextParamName);
                        String uri = null;
                        String description = nextParamDescription;
                        String path = null;
                        RestSearchParameterTypeEnum type = nextParameter.getParamType();
                        Set<String> providesMembershipInCompartments = Collections.emptySet();
                        Set<String> targets = Collections.emptySet();
                        RuntimeSearchParam.RuntimeSearchParamStatusEnum status = RuntimeSearchParam.RuntimeSearchParamStatusEnum.ACTIVE;
                        Collection<String> base = Collections.singletonList(theSearchMethodBinding.getResourceName());
                        RuntimeSearchParam param = new RuntimeSearchParam(id, uri, nextParamName, description, path, type, providesMembershipInCompartments, targets, status, null, null, base);
                        theMapToPopulate.put(nextParamName, param);

                }

        }

        private static class SearchParameterComparator implements Comparator<SearchParameter> {
                private static final SearchParameterComparator INSTANCE = new SearchParameterComparator();

                @Override
                public int compare(SearchParameter theO1, SearchParameter theO2) {
                        if (theO1.isRequired() == theO2.isRequired()) {
                                return theO1.getName().compareTo(theO2.getName());
                        }
                        if (theO1.isRequired()) {
                                return -1;
                        }
                        return 1;
                }
        }

        private static String createOperationName(OperationMethodBinding theMethodBinding) {
                StringBuilder retVal = new StringBuilder();
                if (theMethodBinding.getResourceName() != null) {
                        retVal.append(theMethodBinding.getResourceName());
                } else if (theMethodBinding.isGlobalMethod()) {
                        retVal.append("Global");
                }

                retVal.append('-');
                if (theMethodBinding.isCanOperateAtInstanceLevel()) {
                        retVal.append('i');
                }
                if (theMethodBinding.isCanOperateAtServerLevel()) {
                        retVal.append('s');
                }
                retVal.append('-');

                // Exclude the leading $
                retVal.append(theMethodBinding.getName(), 1, theMethodBinding.getName().length());

                return retVal.toString();
        }
}