/*
 * #%L
 * HAPI FHIR - Core Library
 * %%
 * 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
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 */
package ca.uhn.fhir.context.support;

import ca.uhn.fhir.context.FhirContext;
import ca.uhn.fhir.i18n.Msg;
import ca.uhn.fhir.rest.server.exceptions.ResourceNotFoundException;
import ca.uhn.fhir.util.ParametersUtil;
import ca.uhn.fhir.util.UrlUtil;
import jakarta.annotation.Nonnull;
import jakarta.annotation.Nullable;
import org.apache.commons.lang3.Validate;
import org.apache.commons.lang3.builder.EqualsBuilder;
import org.apache.commons.lang3.builder.HashCodeBuilder;
import org.apache.commons.lang3.builder.ToStringBuilder;
import org.hl7.fhir.instance.model.api.IBase;
import org.hl7.fhir.instance.model.api.IBaseCoding;
import org.hl7.fhir.instance.model.api.IBaseParameters;
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 java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.Set;
import java.util.function.Supplier;
import java.util.stream.Collectors;

import static org.apache.commons.lang3.StringUtils.defaultString;
import static org.apache.commons.lang3.StringUtils.isNotBlank;

/**
 * This interface is a version-independent representation of the
 * various functions that can be provided by validation and terminology
 * services.
 * <p>
 * This interface is invoked directly by internal parts of the HAPI FHIR API, including the
 * Validator and the FHIRPath evaluator. It is used to supply artifacts required for validation
 * (e.g. StructureDefinition resources, ValueSet resources, etc.) and also to provide
 * terminology functions such as code validation, ValueSet expansion, etc.
 * </p>
 * <p>
 * Implementations are not required to implement all of the functions
 * in this interface; in fact it is expected that most won't. Any
 * methods which are not implemented may simply return <code>null</code>
 * and calling code is expected to be able to handle this. Generally, a
 * series of implementations of this interface will be joined together using
 * the
 * <a href="https://hapifhir.io/hapi-fhir/apidocs/hapi-fhir-validation/org/hl7/fhir/common/hapi/validation/support/ValidationSupportChain.html">ValidationSupportChain</a>
 * class.
 * </p>
 * <p>
 * See <a href="https://hapifhir.io/hapi-fhir/docs/validation/validation_support_modules.html">Validation Support Modules</a>
 * for information on how to assemble and configure implementations of this interface. See also
 * the <code>org.hl7.fhir.common.hapi.validation.support</code>
 * <a href="./package-summary.html">package summary</a>
 * in the <code>hapi-fhir-validation</code> module for many implementations of this interface.
 * </p>
 *
 * @since 5.0.0
 */
public interface IValidationSupport {
        String URL_PREFIX_VALUE_SET = "http://hl7.org/fhir/ValueSet/";

        /**
         * Expands the given portion of a ValueSet
         *
         * @param theValidationSupportContext The validation support module will be passed in to this method. This is convenient in cases where the operation needs to make calls to
         *                                    other method in the support chain, so that they can be passed through the entire chain. Implementations of this interface may always safely ignore this parameter.
         * @param theExpansionOptions         If provided (can be <code>null</code>), contains options controlling the expansion
         * @param theValueSetToExpand         The valueset that should be expanded
         * @return The expansion, or null
         */
        @Nullable
        default ValueSetExpansionOutcome expandValueSet(
                        ValidationSupportContext theValidationSupportContext,
                        @Nullable ValueSetExpansionOptions theExpansionOptions,
                        @Nonnull IBaseResource theValueSetToExpand) {
                return null;
        }

        /**
         * Expands the given portion of a ValueSet by canonical URL.
         *
         * @param theValidationSupportContext The validation support module will be passed in to this method. This is convenient in cases where the operation needs to make calls to
         *                                    other method in the support chain, so that they can be passed through the entire chain. Implementations of this interface may always safely ignore this parameter.
         * @param theExpansionOptions         If provided (can be <code>null</code>), contains options controlling the expansion
         * @param theValueSetUrlToExpand      The valueset that should be expanded
         * @return The expansion, or null
         * @throws ResourceNotFoundException If no ValueSet can be found with the given URL
         * @since 6.0.0
         */
        @Nullable
        default ValueSetExpansionOutcome expandValueSet(
                        ValidationSupportContext theValidationSupportContext,
                        @Nullable ValueSetExpansionOptions theExpansionOptions,
                        @Nonnull String theValueSetUrlToExpand)
                        throws ResourceNotFoundException {
                Validate.notBlank(theValueSetUrlToExpand, "theValueSetUrlToExpand must not be null or blank");
                IBaseResource valueSet = fetchValueSet(theValueSetUrlToExpand);
                if (valueSet == null) {
                        throw new ResourceNotFoundException(
                                        Msg.code(2024) + "Unknown ValueSet: " + UrlUtil.escapeUrlParam(theValueSetUrlToExpand));
                }
                return expandValueSet(theValidationSupportContext, theExpansionOptions, valueSet);
        }

        /**
         * Load and return all conformance resources associated with this
         * validation support module. This method may return null if it doesn't
         * make sense for a given module.
         */
        @Nullable
        default List<IBaseResource> fetchAllConformanceResources() {
                return null;
        }

        /**
         * Load and return all possible search parameters
         *
         * @since 6.6.0
         */
        @Nullable
        default <T extends IBaseResource> List<T> fetchAllSearchParameters() {
                return null;
        }

        /**
         * Load and return all possible structure definitions
         */
        @Nullable
        default <T extends IBaseResource> List<T> fetchAllStructureDefinitions() {
                return null;
        }

        /**
         * Load and return all possible structure definitions aside from resource definitions themselves
         */
        @Nullable
        default <T extends IBaseResource> List<T> fetchAllNonBaseStructureDefinitions() {
                List<T> retVal = fetchAllStructureDefinitions();
                if (retVal != null) {
                        List<T> newList = new ArrayList<>(retVal.size());
                        for (T next : retVal) {
                                String url = defaultString(getFhirContext().newTerser().getSinglePrimitiveValueOrNull(next, "url"));
                                if (url.startsWith("http://hl7.org/fhir/StructureDefinition/")) {
                                        String lastPart = url.substring("http://hl7.org/fhir/StructureDefinition/".length());
                                        if (getFhirContext().getResourceTypes().contains(lastPart)) {
                                                continue;
                                        }
                                }

                                newList.add(next);
                        }

                        retVal = newList;
                }

                return retVal;
        }

        /**
         * Fetch a code system by ID
         *
         * @param theSystem The code system
         * @return The valueset (must not be null, but can be an empty ValueSet)
         */
        @Nullable
        default IBaseResource fetchCodeSystem(String theSystem) {
                return null;
        }

        /**
         * Loads a resource needed by the validation (a StructureDefinition, or a
         * ValueSet)
         *
         * <p>
         * Note: Since 5.3.0, {@literal theClass} can be {@literal null}
         * </p>
         *
         * @param theClass The type of the resource to load, or <code>null</code> to return any resource with the given canonical URI
         * @param theUri   The resource URI
         * @return Returns the resource, or <code>null</code> if no resource with the
         * given URI can be found
         */
        @SuppressWarnings("unchecked")
        @Nullable
        default <T extends IBaseResource> T fetchResource(@Nullable Class<T> theClass, String theUri) {
                Validate.notBlank(theUri, "theUri must not be null or blank");

                if (theClass == null) {
                        Supplier<IBaseResource>[] sources = new Supplier[] {
                                () -> fetchStructureDefinition(theUri), () -> fetchValueSet(theUri), () -> fetchCodeSystem(theUri)
                        };
                        return (T) Arrays.stream(sources)
                                        .map(t -> t.get())
                                        .filter(t -> t != null)
                                        .findFirst()
                                        .orElse(null);
                }

                switch (getFhirContext().getResourceType(theClass)) {
                        case "StructureDefinition":
                                return theClass.cast(fetchStructureDefinition(theUri));
                        case "ValueSet":
                                return theClass.cast(fetchValueSet(theUri));
                        case "CodeSystem":
                                return theClass.cast(fetchCodeSystem(theUri));
                }

                if (theUri.startsWith(URL_PREFIX_VALUE_SET)) {
                        return theClass.cast(fetchValueSet(theUri));
                }

                return null;
        }

        @Nullable
        default IBaseResource fetchStructureDefinition(String theUrl) {
                return null;
        }

        /**
         * Returns <code>true</code> if codes in the given code system can be expanded
         * or validated
         *
         * @param theValidationSupportContext The validation support module will be passed in to this method. This is convenient in cases where the operation needs to make calls to
         *                                    other method in the support chain, so that they can be passed through the entire chain. Implementations of this interface may always safely ignore this parameter.
         * @param theSystem                   The URI for the code system, e.g. <code>"http://loinc.org"</code>
         * @return Returns <code>true</code> if codes in the given code system can be
         * validated
         */
        default boolean isCodeSystemSupported(ValidationSupportContext theValidationSupportContext, String theSystem) {
                return false;
        }

        /**
         * Returns <code>true</code> if a Remote Terminology Service is currently configured
         *
         * @return Returns <code>true</code> if a Remote Terminology Service is currently configured
         */
        default boolean isRemoteTerminologyServiceConfigured() {
                return false;
        }

        /**
         * Fetch the given ValueSet by URL, or returns null if one can't be found for the given URL
         */
        @Nullable
        default IBaseResource fetchValueSet(String theValueSetUrl) {
                return null;
        }

        /**
         * Fetch the given binary data by key.
         *
         * @param binaryKey
         * @return
         */
        default byte[] fetchBinary(String binaryKey) {
                return null;
        }

        /**
         * Validates that the given code exists and if possible returns a display
         * name. This method is called to check codes which are found in "example"
         * binding fields (e.g. <code>Observation.code</code>) in the default profile.
         *
         * @param theValidationSupportContext The validation support module will be passed in to this method. This is convenient in cases where the operation needs to make calls to
         *                                    other method in the support chain, so that they can be passed through the entire chain. Implementations of this interface may always safely ignore this parameter.
         * @param theOptions                  Provides options controlling the validation
         * @param theCodeSystem               The code system, e.g. "<code>http://loinc.org</code>"
         * @param theCode                     The code, e.g. "<code>1234-5</code>"
         * @param theDisplay                  The display name, if it should also be validated
         * @return Returns a validation result object
         */
        @Nullable
        default CodeValidationResult validateCode(
                        ValidationSupportContext theValidationSupportContext,
                        ConceptValidationOptions theOptions,
                        String theCodeSystem,
                        String theCode,
                        String theDisplay,
                        String theValueSetUrl) {
                return null;
        }

        /**
         * Validates that the given code exists and if possible returns a display
         * name. This method is called to check codes which are found in "example"
         * binding fields (e.g. <code>Observation.code</code>) in the default profile.
         *
         * @param theValidationSupportContext The validation support module will be passed in to this method. This is convenient in cases where the operation needs to make calls to
         *                                    other method in the support chain, so that they can be passed through the entire chain. Implementations of this interface may always safely ignore this parameter.
         * @param theCodeSystem               The code system, e.g. "<code>http://loinc.org</code>"
         * @param theCode                     The code, e.g. "<code>1234-5</code>"
         * @param theDisplay                  The display name, if it should also be validated
         * @param theValueSet                 The ValueSet to validate against. Must not be null, and must be a ValueSet resource.
         * @return Returns a validation result object, or <code>null</code> if this validation support module can not handle this kind of request
         */
        @Nullable
        default CodeValidationResult validateCodeInValueSet(
                        ValidationSupportContext theValidationSupportContext,
                        ConceptValidationOptions theOptions,
                        String theCodeSystem,
                        String theCode,
                        String theDisplay,
                        @Nonnull IBaseResource theValueSet) {
                return null;
        }

        /**
         * Look up a code using the system and code value.
         * @deprecated This method has been deprecated in HAPI FHIR 7.0.0. Use {@link IValidationSupport#lookupCode(ValidationSupportContext, LookupCodeRequest)} instead.
         *
         * @param theValidationSupportContext The validation support module will be passed in to this method. This is convenient in cases where the operation needs to make calls to
         *                                    other method in the support chain, so that they can be passed through the entire chain. Implementations of this interface may always safely ignore this parameter.
         * @param theSystem                   The CodeSystem URL
         * @param theCode                     The code
         * @param theDisplayLanguage          Used to filter out the designation by the display language. To return all designation, set this value to <code>null</code>.
         */
        @Deprecated
        @Nullable
        default LookupCodeResult lookupCode(
                        ValidationSupportContext theValidationSupportContext,
                        String theSystem,
                        String theCode,
                        String theDisplayLanguage) {
                return null;
        }

        /**
         * Look up a code using the system and code value
         * @deprecated This method has been deprecated in HAPI FHIR 7.0.0. Use {@link IValidationSupport#lookupCode(ValidationSupportContext, LookupCodeRequest)} instead.
         *
         * @param theValidationSupportContext The validation support module will be passed in to this method. This is convenient in cases where the operation needs to make calls to
         *                                    other method in the support chain, so that they can be passed through the entire chain. Implementations of this interface may always safely ignore this parameter.
         * @param theSystem                   The CodeSystem URL
         * @param theCode                     The code
         */
        @Deprecated
        @Nullable
        default LookupCodeResult lookupCode(
                        ValidationSupportContext theValidationSupportContext, String theSystem, String theCode) {
                return lookupCode(theValidationSupportContext, theSystem, theCode, null);
        }

        /**
         * Look up a code using the system, code and other parameters captured in {@link LookupCodeRequest}.
         * @since 7.0.0
         *
         * @param theValidationSupportContext      The validation support module will be passed in to this method. This is convenient in cases where the operation needs to make calls to
         *                                         other method in the support chain, so that they can be passed through the entire chain. Implementations of this interface may always safely ignore this parameter.
         * @param theLookupCodeRequest             The parameters used to perform the lookup, including system and code.
         */
        @Nullable
        default LookupCodeResult lookupCode(
                        ValidationSupportContext theValidationSupportContext, @Nonnull LookupCodeRequest theLookupCodeRequest) {
                // TODO: can change to return null once the deprecated methods are removed
                return lookupCode(
                                theValidationSupportContext,
                                theLookupCodeRequest.getSystem(),
                                theLookupCodeRequest.getCode(),
                                theLookupCodeRequest.getDisplayLanguage());
        }

        /**
         * Returns <code>true</code> if the given ValueSet can be validated by the given
         * validation support module
         *
         * @param theValidationSupportContext The validation support module will be passed in to this method. This is convenient in cases where the operation needs to make calls to
         *                                    other method in the support chain, so that they can be passed through the entire chain. Implementations of this interface may always safely ignore this parameter.
         * @param theValueSetUrl              The ValueSet canonical URL
         */
        default boolean isValueSetSupported(ValidationSupportContext theValidationSupportContext, String theValueSetUrl) {
                return false;
        }

        /**
         * Generate a snapshot from the given differential profile.
         *
         * @param theValidationSupportContext The validation support module will be passed in to this method. This is convenient in cases where the operation needs to make calls to
         *                                    other method in the support chain, so that they can be passed through the entire chain. Implementations of this interface may always safely ignore this parameter.
         * @return Returns null if this module does not know how to handle this request
         */
        @Nullable
        default IBaseResource generateSnapshot(
                        ValidationSupportContext theValidationSupportContext,
                        IBaseResource theInput,
                        String theUrl,
                        String theWebUrl,
                        String theProfileName) {
                return null;
        }

        /**
         * Returns the FHIR Context associated with this module
         */
        FhirContext getFhirContext();

        /**
         * This method clears any temporary caches within the validation support. It is mainly intended for unit tests,
         * but could be used in non-test scenarios as well.
         */
        default void invalidateCaches() {
                // nothing
        }

        /**
         * Attempt to translate the given concept from one code system to another
         */
        @Nullable
        default TranslateConceptResults translateConcept(TranslateCodeRequest theRequest) {
                return null;
        }

        /**
         * This field is used by the Terminology Troubleshooting Log to log which validation support module was used for the operation being logged.
         */
        default String getName() {
                return "Unknown " + getFhirContext().getVersion().getVersion() + " Validation Support";
        }

        enum IssueSeverity {
                /**
                 * The issue caused the action to fail, and no further checking could be performed.
                 */
                FATAL,
                /**
                 * The issue is sufficiently important to cause the action to fail.
                 */
                ERROR,
                /**
                 * The issue is not important enough to cause the action to fail, but may cause it to be performed suboptimally or in a way that is not as desired.
                 */
                WARNING,
                /**
                 * The issue has no relation to the degree of success of the action.
                 */
                INFORMATION
        }

        enum CodeValidationIssueCode {
                NOT_FOUND,
                CODE_INVALID,
                INVALID,
                OTHER
        }

        enum CodeValidationIssueCoding {
                VS_INVALID,
                NOT_FOUND,
                NOT_IN_VS,

                INVALID_CODE,
                INVALID_DISPLAY,
                OTHER
        }

        class CodeValidationIssue {

                private final String myMessage;
                private final IssueSeverity mySeverity;
                private final CodeValidationIssueCode myCode;
                private final CodeValidationIssueCoding myCoding;

                public CodeValidationIssue(
                                String theMessage,
                                IssueSeverity mySeverity,
                                CodeValidationIssueCode theCode,
                                CodeValidationIssueCoding theCoding) {
                        this.myMessage = theMessage;
                        this.mySeverity = mySeverity;
                        this.myCode = theCode;
                        this.myCoding = theCoding;
                }

                public String getMessage() {
                        return myMessage;
                }

                public IssueSeverity getSeverity() {
                        return mySeverity;
                }

                public CodeValidationIssueCode getCode() {
                        return myCode;
                }

                public CodeValidationIssueCoding getCoding() {
                        return myCoding;
                }
        }

        class ConceptDesignation {

                private String myLanguage;
                private String myUseSystem;
                private String myUseCode;
                private String myUseDisplay;
                private String myValue;

                public String getLanguage() {
                        return myLanguage;
                }

                public ConceptDesignation setLanguage(String theLanguage) {
                        myLanguage = theLanguage;
                        return this;
                }

                public String getUseSystem() {
                        return myUseSystem;
                }

                public ConceptDesignation setUseSystem(String theUseSystem) {
                        myUseSystem = theUseSystem;
                        return this;
                }

                public String getUseCode() {
                        return myUseCode;
                }

                public ConceptDesignation setUseCode(String theUseCode) {
                        myUseCode = theUseCode;
                        return this;
                }

                public String getUseDisplay() {
                        return myUseDisplay;
                }

                public ConceptDesignation setUseDisplay(String theUseDisplay) {
                        myUseDisplay = theUseDisplay;
                        return this;
                }

                public String getValue() {
                        return myValue;
                }

                public ConceptDesignation setValue(String theValue) {
                        myValue = theValue;
                        return this;
                }
        }

        abstract class BaseConceptProperty {
                private final String myPropertyName;

                /**
                 * Constructor
                 */
                protected BaseConceptProperty(String thePropertyName) {
                        myPropertyName = thePropertyName;
                }

                public String getPropertyName() {
                        return myPropertyName;
                }

                public abstract String getType();
        }

        // The reason these cannot be declared within an enum is because a Remote Terminology Service
        // can support arbitrary types. We do not restrict against the types in the spec.
        // Some of the types in the spec are not yet implemented as well.
        // @see https://github.com/hapifhir/hapi-fhir/issues/5700
        String TYPE_STRING = "string";
        String TYPE_CODING = "Coding";
        String TYPE_GROUP = "group";

        class StringConceptProperty extends BaseConceptProperty {
                private final String myValue;

                /**
                 * Constructor
                 *
                 * @param theName The name
                 */
                public StringConceptProperty(String theName, String theValue) {
                        super(theName);
                        myValue = theValue;
                }

                public String getValue() {
                        return myValue;
                }

                public String getType() {
                        return TYPE_STRING;
                }
        }

        class CodingConceptProperty extends BaseConceptProperty {
                private final String myCode;
                private final String myCodeSystem;
                private final String myDisplay;

                /**
                 * Constructor
                 *
                 * @param theName The name
                 */
                public CodingConceptProperty(String theName, String theCodeSystem, String theCode, String theDisplay) {
                        super(theName);
                        myCodeSystem = theCodeSystem;
                        myCode = theCode;
                        myDisplay = theDisplay;
                }

                public String getCode() {
                        return myCode;
                }

                public String getCodeSystem() {
                        return myCodeSystem;
                }

                public String getDisplay() {
                        return myDisplay;
                }

                public String getType() {
                        return TYPE_CODING;
                }
        }

        class GroupConceptProperty extends BaseConceptProperty {
                public GroupConceptProperty(String thePropertyName) {
                        super(thePropertyName);
                }

                private List<BaseConceptProperty> subProperties;

                public BaseConceptProperty addSubProperty(BaseConceptProperty theProperty) {
                        if (subProperties == null) {
                                subProperties = new ArrayList<>();
                        }
                        subProperties.add(theProperty);
                        return this;
                }

                public List<BaseConceptProperty> getSubProperties() {
                        return subProperties != null ? subProperties : Collections.emptyList();
                }

                @Override
                public String getType() {
                        return TYPE_GROUP;
                }
        }

        class CodeValidationResult {
                public static final String SOURCE_DETAILS = "sourceDetails";
                public static final String RESULT = "result";
                public static final String MESSAGE = "message";
                public static final String DISPLAY = "display";

                private String myCode;
                private String myMessage;
                private IssueSeverity mySeverity;
                private String myCodeSystemName;
                private String myCodeSystemVersion;
                private List<BaseConceptProperty> myProperties;
                private String myDisplay;
                private String mySourceDetails;

                private List<CodeValidationIssue> myCodeValidationIssues;

                public CodeValidationResult() {
                        super();
                }

                /**
                 * This field may contain information about what the source of the
                 * validation information was.
                 */
                public String getSourceDetails() {
                        return mySourceDetails;
                }

                /**
                 * This field may contain information about what the source of the
                 * validation information was.
                 */
                public CodeValidationResult setSourceDetails(String theSourceDetails) {
                        mySourceDetails = theSourceDetails;
                        return this;
                }

                public String getDisplay() {
                        return myDisplay;
                }

                public CodeValidationResult setDisplay(String theDisplay) {
                        myDisplay = theDisplay;
                        return this;
                }

                public String getCode() {
                        return myCode;
                }

                public CodeValidationResult setCode(String theCode) {
                        myCode = theCode;
                        return this;
                }

                public String getCodeSystemName() {
                        return myCodeSystemName;
                }

                public CodeValidationResult setCodeSystemName(String theCodeSystemName) {
                        myCodeSystemName = theCodeSystemName;
                        return this;
                }

                public String getCodeSystemVersion() {
                        return myCodeSystemVersion;
                }

                public CodeValidationResult setCodeSystemVersion(String theCodeSystemVersion) {
                        myCodeSystemVersion = theCodeSystemVersion;
                        return this;
                }

                public String getMessage() {
                        return myMessage;
                }

                public CodeValidationResult setMessage(String theMessage) {
                        myMessage = theMessage;
                        return this;
                }

                public List<BaseConceptProperty> getProperties() {
                        return myProperties;
                }

                public void setProperties(List<BaseConceptProperty> theProperties) {
                        myProperties = theProperties;
                }

                public IssueSeverity getSeverity() {
                        return mySeverity;
                }

                public CodeValidationResult setSeverity(IssueSeverity theSeverity) {
                        mySeverity = theSeverity;
                        return this;
                }

                public List<CodeValidationIssue> getCodeValidationIssues() {
                        if (myCodeValidationIssues == null) {
                                myCodeValidationIssues = new ArrayList<>();
                        }
                        return myCodeValidationIssues;
                }

                public CodeValidationResult setCodeValidationIssues(List<CodeValidationIssue> theCodeValidationIssues) {
                        myCodeValidationIssues = new ArrayList<>(theCodeValidationIssues);
                        return this;
                }

                public CodeValidationResult addCodeValidationIssue(CodeValidationIssue theCodeValidationIssue) {
                        getCodeValidationIssues().add(theCodeValidationIssue);
                        return this;
                }

                public boolean isOk() {
                        return isNotBlank(myCode);
                }

                public LookupCodeResult asLookupCodeResult(String theSearchedForSystem, String theSearchedForCode) {
                        LookupCodeResult retVal = new LookupCodeResult();
                        retVal.setSearchedForSystem(theSearchedForSystem);
                        retVal.setSearchedForCode(theSearchedForCode);
                        if (isOk()) {
                                retVal.setFound(true);
                                retVal.setCodeDisplay(myDisplay);
                                retVal.setCodeSystemDisplayName(getCodeSystemName());
                                retVal.setCodeSystemVersion(getCodeSystemVersion());
                        }
                        return retVal;
                }

                /**
                 * Convenience method that returns {@link #getSeverity()} as an IssueSeverity code string
                 */
                public String getSeverityCode() {
                        String retVal = null;
                        if (getSeverity() != null) {
                                retVal = getSeverity().name().toLowerCase();
                        }
                        return retVal;
                }

                /**
                 * Sets an issue severity as a string code. Value must be the name of
                 * one of the enum values in {@link IssueSeverity}. Value is case-insensitive.
                 */
                public CodeValidationResult setSeverityCode(@Nonnull String theIssueSeverity) {
                        setSeverity(IssueSeverity.valueOf(theIssueSeverity.toUpperCase()));
                        return this;
                }

                public IBaseParameters toParameters(FhirContext theContext) {
                        IBaseParameters retVal = ParametersUtil.newInstance(theContext);

                        ParametersUtil.addParameterToParametersBoolean(theContext, retVal, RESULT, isOk());
                        if (isNotBlank(getMessage())) {
                                ParametersUtil.addParameterToParametersString(theContext, retVal, MESSAGE, getMessage());
                        }
                        if (isNotBlank(getDisplay())) {
                                ParametersUtil.addParameterToParametersString(theContext, retVal, DISPLAY, getDisplay());
                        }
                        if (isNotBlank(getSourceDetails())) {
                                ParametersUtil.addParameterToParametersString(theContext, retVal, SOURCE_DETAILS, getSourceDetails());
                        }

                        return retVal;
                }
        }

        class ValueSetExpansionOutcome {

                private final IBaseResource myValueSet;
                private final String myError;

                private boolean myErrorIsFromServer;

                public ValueSetExpansionOutcome(String theError, boolean theErrorIsFromServer) {
                        myValueSet = null;
                        myError = theError;
                        myErrorIsFromServer = theErrorIsFromServer;
                }

                public ValueSetExpansionOutcome(IBaseResource theValueSet) {
                        myValueSet = theValueSet;
                        myError = null;
                        myErrorIsFromServer = false;
                }

                public String getError() {
                        return myError;
                }

                public IBaseResource getValueSet() {
                        return myValueSet;
                }

                public boolean getErrorIsFromServer() {
                        return myErrorIsFromServer;
                }
        }

        class LookupCodeResult {

                private String myCodeDisplay;
                private boolean myCodeIsAbstract;
                private String myCodeSystemDisplayName;
                private String myCodeSystemVersion;
                private boolean myFound;
                private String mySearchedForCode;
                private String mySearchedForSystem;
                private List<BaseConceptProperty> myProperties;
                private List<ConceptDesignation> myDesignations;
                private String myErrorMessage;

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

                public List<BaseConceptProperty> getProperties() {
                        if (myProperties == null) {
                                myProperties = new ArrayList<>();
                        }
                        return myProperties;
                }

                public void setProperties(List<BaseConceptProperty> theProperties) {
                        myProperties = theProperties;
                }

                @Nonnull
                public List<ConceptDesignation> getDesignations() {
                        if (myDesignations == null) {
                                myDesignations = new ArrayList<>();
                        }
                        return myDesignations;
                }

                public String getCodeDisplay() {
                        return myCodeDisplay;
                }

                public void setCodeDisplay(String theCodeDisplay) {
                        myCodeDisplay = theCodeDisplay;
                }

                public String getCodeSystemDisplayName() {
                        return myCodeSystemDisplayName;
                }

                public void setCodeSystemDisplayName(String theCodeSystemDisplayName) {
                        myCodeSystemDisplayName = theCodeSystemDisplayName;
                }

                public String getCodeSystemVersion() {
                        return myCodeSystemVersion;
                }

                public void setCodeSystemVersion(String theCodeSystemVersion) {
                        myCodeSystemVersion = theCodeSystemVersion;
                }

                public String getSearchedForCode() {
                        return mySearchedForCode;
                }

                public LookupCodeResult setSearchedForCode(String theSearchedForCode) {
                        mySearchedForCode = theSearchedForCode;
                        return this;
                }

                public String getSearchedForSystem() {
                        return mySearchedForSystem;
                }

                public LookupCodeResult setSearchedForSystem(String theSearchedForSystem) {
                        mySearchedForSystem = theSearchedForSystem;
                        return this;
                }

                public boolean isCodeIsAbstract() {
                        return myCodeIsAbstract;
                }

                public void setCodeIsAbstract(boolean theCodeIsAbstract) {
                        myCodeIsAbstract = theCodeIsAbstract;
                }

                public boolean isFound() {
                        return myFound;
                }

                public LookupCodeResult setFound(boolean theFound) {
                        myFound = theFound;
                        return this;
                }

                public void throwNotFoundIfAppropriate() {
                        if (isFound() == false) {
                                throw new ResourceNotFoundException(Msg.code(1738) + "Unable to find code[" + getSearchedForCode()
                                                + "] in system[" + getSearchedForSystem() + "]");
                        }
                }

                /**
                 * Converts the current LookupCodeResult instance into a IBaseParameters instance which is returned
                 * to the client of the $lookup operation.
                 * @param theContext the FHIR context used for running the operation
                 * @param thePropertyNamesToFilter the properties which are passed as parameter to filter the result.
                 * @return the output for the lookup operation.
                 */
                public IBaseParameters toParameters(
                                FhirContext theContext, List<? extends IPrimitiveType<String>> thePropertyNamesToFilter) {

                        IBaseParameters retVal = ParametersUtil.newInstance(theContext);
                        if (isNotBlank(getCodeSystemDisplayName())) {
                                ParametersUtil.addParameterToParametersString(theContext, retVal, "name", getCodeSystemDisplayName());
                        }
                        if (isNotBlank(getCodeSystemVersion())) {
                                ParametersUtil.addParameterToParametersString(theContext, retVal, "version", getCodeSystemVersion());
                        }
                        ParametersUtil.addParameterToParametersString(theContext, retVal, "display", getCodeDisplay());
                        ParametersUtil.addParameterToParametersBoolean(theContext, retVal, "abstract", isCodeIsAbstract());

                        if (myProperties != null) {

                                final List<BaseConceptProperty> propertiesToReturn;
                                if (thePropertyNamesToFilter != null && !thePropertyNamesToFilter.isEmpty()) {
                                        // TODO MM: The logic to filter of properties could actually be moved to the lookupCode provider.
                                        // That is where the rest of the lookupCode input parameter handling is done.
                                        // This was left as is for now but can be done with next opportunity.
                                        Set<String> propertyNameList = thePropertyNamesToFilter.stream()
                                                        .map(IPrimitiveType::getValueAsString)
                                                        .collect(Collectors.toSet());
                                        propertiesToReturn = myProperties.stream()
                                                        .filter(p -> propertyNameList.contains(p.getPropertyName()))
                                                        .collect(Collectors.toList());
                                } else {
                                        propertiesToReturn = myProperties;
                                }

                                for (BaseConceptProperty next : propertiesToReturn) {
                                        IBase property = ParametersUtil.addParameterToParameters(theContext, retVal, "property");
                                        populateProperty(theContext, property, next);
                                }
                        }

                        if (myDesignations != null) {
                                for (ConceptDesignation next : myDesignations) {
                                        IBase property = ParametersUtil.addParameterToParameters(theContext, retVal, "designation");
                                        ParametersUtil.addPartCode(theContext, property, "language", next.getLanguage());
                                        ParametersUtil.addPartCoding(
                                                        theContext, property, "use", next.getUseSystem(), next.getUseCode(), next.getUseDisplay());
                                        ParametersUtil.addPartString(theContext, property, "value", next.getValue());
                                }
                        }

                        return retVal;
                }

                private void populateProperty(
                                FhirContext theContext, IBase theProperty, BaseConceptProperty theConceptProperty) {
                        ParametersUtil.addPartCode(theContext, theProperty, "code", theConceptProperty.getPropertyName());
                        String propertyType = theConceptProperty.getType();
                        switch (propertyType) {
                                case TYPE_STRING:
                                        StringConceptProperty stringConceptProperty = (StringConceptProperty) theConceptProperty;
                                        ParametersUtil.addPartString(theContext, theProperty, "value", stringConceptProperty.getValue());
                                        break;
                                case TYPE_CODING:
                                        CodingConceptProperty codingConceptProperty = (CodingConceptProperty) theConceptProperty;
                                        ParametersUtil.addPartCoding(
                                                        theContext,
                                                        theProperty,
                                                        "value",
                                                        codingConceptProperty.getCodeSystem(),
                                                        codingConceptProperty.getCode(),
                                                        codingConceptProperty.getDisplay());
                                        break;
                                case TYPE_GROUP:
                                        GroupConceptProperty groupConceptProperty = (GroupConceptProperty) theConceptProperty;
                                        if (groupConceptProperty.getSubProperties().isEmpty()) {
                                                break;
                                        }
                                        groupConceptProperty.getSubProperties().forEach(p -> {
                                                IBase subProperty = ParametersUtil.addPart(theContext, theProperty, "subproperty", null);
                                                populateProperty(theContext, subProperty, p);
                                        });
                                        break;
                                default:
                                        throw new IllegalStateException(
                                                        Msg.code(1739) + "Don't know how to handle " + theConceptProperty.getClass());
                        }
                }

                public LookupCodeResult setErrorMessage(String theErrorMessage) {
                        myErrorMessage = theErrorMessage;
                        return this;
                }

                public String getErrorMessage() {
                        return myErrorMessage;
                }

                public static LookupCodeResult notFound(String theSearchedForSystem, String theSearchedForCode) {
                        return new LookupCodeResult()
                                        .setFound(false)
                                        .setSearchedForSystem(theSearchedForSystem)
                                        .setSearchedForCode(theSearchedForCode);
                }
        }

        class TranslateCodeRequest {
                private final String myTargetSystemUrl;
                private final String myConceptMapUrl;
                private final String myConceptMapVersion;
                private final String mySourceValueSetUrl;
                private final String myTargetValueSetUrl;
                private final IIdType myResourceId;
                private final boolean myReverse;
                private List<IBaseCoding> myCodings;

                public TranslateCodeRequest(List<IBaseCoding> theCodings, String theTargetSystemUrl) {
                        myCodings = theCodings;
                        myTargetSystemUrl = theTargetSystemUrl;
                        myConceptMapUrl = null;
                        myConceptMapVersion = null;
                        mySourceValueSetUrl = null;
                        myTargetValueSetUrl = null;
                        myResourceId = null;
                        myReverse = false;
                }

                public TranslateCodeRequest(
                                List<IBaseCoding> theCodings,
                                String theTargetSystemUrl,
                                String theConceptMapUrl,
                                String theConceptMapVersion,
                                String theSourceValueSetUrl,
                                String theTargetValueSetUrl,
                                IIdType theResourceId,
                                boolean theReverse) {
                        myCodings = theCodings;
                        myTargetSystemUrl = theTargetSystemUrl;
                        myConceptMapUrl = theConceptMapUrl;
                        myConceptMapVersion = theConceptMapVersion;
                        mySourceValueSetUrl = theSourceValueSetUrl;
                        myTargetValueSetUrl = theTargetValueSetUrl;
                        myResourceId = theResourceId;
                        myReverse = theReverse;
                }

                @Override
                public boolean equals(Object theO) {
                        if (this == theO) {
                                return true;
                        }

                        if (theO == null || getClass() != theO.getClass()) {
                                return false;
                        }

                        TranslateCodeRequest that = (TranslateCodeRequest) theO;

                        return new EqualsBuilder()
                                        .append(myCodings, that.myCodings)
                                        .append(myTargetSystemUrl, that.myTargetSystemUrl)
                                        .append(myConceptMapUrl, that.myConceptMapUrl)
                                        .append(myConceptMapVersion, that.myConceptMapVersion)
                                        .append(mySourceValueSetUrl, that.mySourceValueSetUrl)
                                        .append(myTargetValueSetUrl, that.myTargetValueSetUrl)
                                        .append(myResourceId, that.myResourceId)
                                        .append(myReverse, that.myReverse)
                                        .isEquals();
                }

                @Override
                public int hashCode() {
                        return new HashCodeBuilder(17, 37)
                                        .append(myCodings)
                                        .append(myTargetSystemUrl)
                                        .append(myConceptMapUrl)
                                        .append(myConceptMapVersion)
                                        .append(mySourceValueSetUrl)
                                        .append(myTargetValueSetUrl)
                                        .append(myResourceId)
                                        .append(myReverse)
                                        .toHashCode();
                }

                public List<IBaseCoding> getCodings() {
                        return myCodings;
                }

                public String getTargetSystemUrl() {
                        return myTargetSystemUrl;
                }

                public String getConceptMapUrl() {
                        return myConceptMapUrl;
                }

                public String getConceptMapVersion() {
                        return myConceptMapVersion;
                }

                public String getSourceValueSetUrl() {
                        return mySourceValueSetUrl;
                }

                public String getTargetValueSetUrl() {
                        return myTargetValueSetUrl;
                }

                public IIdType getResourceId() {
                        return myResourceId;
                }

                public boolean isReverse() {
                        return myReverse;
                }

                @Override
                public String toString() {
                        return new ToStringBuilder(this)
                                        .append("sourceValueSetUrl", mySourceValueSetUrl)
                                        .append("targetSystemUrl", myTargetSystemUrl)
                                        .append("targetValueSetUrl", myTargetValueSetUrl)
                                        .append("reverse", myReverse)
                                        .toString();
                }
        }

        /**
         * <p
         * Warning: This method's behaviour and naming is preserved for backwards compatibility, BUT the actual naming and
         * function are not aligned.
         * </p
         * <p>
         * See VersionSpecificWorkerContextWrapper#validateCode in hapi-fhir-validation, and the refer to the values below
         * for the behaviour associated with each value.
         * </p>
         * <p>
         *   <ul>
         *     <li>If <code>false</code> (default setting) the validation for codings will return a positive result only if
         *     ALL codings are valid.</li>
         *         <li>If <code>true</code> the validation for codings will return a positive result if ANY codings are valid.
         *         </li>
         *        </ul>
         * </p>
         * @return true or false depending on the desired coding validation behaviour.
         */
        default boolean isEnabledValidationForCodingsLogicalAnd() {
                return false;
        }
}