/*
 * #%L
 * HAPI FHIR - Core Library
 * %%
 * Copyright (C) 2014 - 2025 Smile CDR, Inc.
 * %%
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * #L%
 */
package ca.uhn.fhir.util;

import ca.uhn.fhir.context.BaseRuntimeChildDefinition;
import ca.uhn.fhir.context.BaseRuntimeElementDefinition;
import ca.uhn.fhir.i18n.Msg;
import ca.uhn.fhir.model.api.ICompositeElement;
import ca.uhn.fhir.model.api.IElement;
import jakarta.annotation.Nullable;
import org.hl7.fhir.instance.model.api.IBase;
import org.hl7.fhir.instance.model.api.IBaseResource;
import org.hl7.fhir.instance.model.api.IPrimitiveType;

import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import java.util.function.Function;

public class ElementUtil {

        public static final Function<IBase, String> CONVERT_PRIMITIVE_TO_STRING =
                        e -> ((IPrimitiveType<?>) e).getValueAsString();
        public static final Function<IBase, IBaseResource> CAST_BASE_TO_RESOURCE = e -> (IBaseResource) e;

        @SuppressWarnings("unchecked")
        public static final Function<IBase, IPrimitiveType<Date>> CAST_TO_PRIMITIVE_DATE = e -> ((IPrimitiveType<Date>) e);

        @SuppressWarnings("unchecked")
        public static boolean isEmpty(Object... theElements) {
                if (theElements == null) {
                        return true;
                }
                for (int i = 0; i < theElements.length; i++) {
                        Object next = theElements[i];
                        if (next instanceof List) {
                                if (!isEmpty((List<? extends IBase>) next)) {
                                        return false;
                                }
                        } else if (next instanceof String && (!((String) next).isEmpty())) {
                                return false;
                        } else if (next != null && !((IBase) next).isEmpty()) {
                                return false;
                        }
                }
                return true;
        }

        public static boolean isEmpty(IBase... theElements) {
                if (theElements == null) {
                        return true;
                }
                for (int i = 0; i < theElements.length; i++) {
                        IBase next = theElements[i];
                        if (next != null && !next.isEmpty()) {
                                return false;
                        }
                }
                return true;
        }

        public static boolean isEmpty(IElement... theElements) {
                if (theElements == null) {
                        return true;
                }
                for (int i = 0; i < theElements.length; i++) {
                        IBase next = theElements[i];
                        if (next != null && !next.isEmpty()) {
                                return false;
                        }
                }
                return true;
        }

        public static boolean isEmpty(List<? extends IBase> theElements) {
                if (theElements == null) {
                        return true;
                }
                for (int i = 0; i < theElements.size(); i++) {
                        IBase next;
                        try {
                                next = theElements.get(i);
                        } catch (ClassCastException e) {
                                List<?> elements = theElements;
                                String s = "Found instance of " + elements.get(i).getClass()
                                                + " - Did you set a field value to the incorrect type? Expected " + IBase.class.getName();
                                throw new ClassCastException(Msg.code(1748) + s);
                        }
                        if (next != null && !next.isEmpty()) {
                                return false;
                        }
                }
                return true;
        }

        /**
         * Note that this method does not work on HL7.org structures
         */
        public static <T extends IElement> List<T> allPopulatedChildElements(Class<T> theType, Object... theElements) {
                ArrayList<T> retVal = new ArrayList<>();
                for (Object next : theElements) {
                        if (next == null) {
                                continue;
                        } else if (next instanceof IElement) {
                                addElement(retVal, (IElement) next, theType);
                        } else if (next instanceof List) {
                                for (Object nextElement : ((List<?>) next)) {
                                        if (!(nextElement instanceof IBase)) {
                                                throw new IllegalArgumentException(
                                                                Msg.code(1749) + "Found element of " + nextElement.getClass());
                                        }
                                        addElement(retVal, (IElement) nextElement, theType);
                                }
                        } else {
                                throw new IllegalArgumentException(Msg.code(1750) + "Found element of " + next.getClass());
                        }
                }
                return retVal;
        }

        // @SuppressWarnings("unchecked")
        private static <T extends IElement> void addElement(ArrayList<T> retVal, IElement next, Class<T> theType) {
                if (theType != null && theType.isAssignableFrom(next.getClass())) {
                        retVal.add(theType.cast(next));
                }
                if (next instanceof ICompositeElement) {
                        ICompositeElement iCompositeElement = (ICompositeElement) next;
                        // TODO: Use of a deprecated method should be resolved.
                        retVal.addAll(iCompositeElement.getAllPopulatedChildElementsOfType(theType));
                }
        }

        public static IBase setValue(IBase theTarget, BaseRuntimeChildDefinition theChildDef, Object theValue) {
                BaseRuntimeElementDefinition<?> elementDefinition = theChildDef.getChildByName(theChildDef.getElementName());
                IBase value;
                if (theValue == null || elementDefinition.getImplementingClass().isInstance(theValue)) {
                        value = (IBase) theValue;
                } else {
                        value = elementDefinition.newInstance(theValue);
                }
                theChildDef.getMutator().setValue(theTarget, value);
                return value;
        }

        @Nullable
        public static <T> T getSingleValueOrNull(
                        IBase theParentElement, BaseRuntimeChildDefinition theChildDefinition, Function<IBase, T> theConverter) {
                if (theParentElement == null) {
                        return null;
                }
                return theChildDefinition
                                .getAccessor()
                                .getFirstValueOrNull(theParentElement)
                                .map(theConverter)
                                .orElse(null);
        }
}