/*
 * #%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.context;

import ca.uhn.fhir.i18n.Msg;
import ca.uhn.fhir.util.UrlUtil;
import jakarta.annotation.Nonnull;
import jakarta.annotation.Nullable;
import org.apache.commons.lang3.StringUtils;
import org.apache.commons.lang3.Validate;
import org.hl7.fhir.instance.model.api.IBase;

import java.lang.reflect.Constructor;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

public abstract class BaseRuntimeElementDefinition<T extends IBase> {

        private static final Class<Void> VOID_CLASS = Void.class;
        private final Class<? extends T> myImplementingClass;
        private final String myName;
        private final boolean myStandardType;
        private final Map<Class<?>, Constructor<T>> myConstructors = new ConcurrentHashMap<>();
        private List<RuntimeChildDeclaredExtensionDefinition> myExtensions = new ArrayList<>();
        private List<RuntimeChildDeclaredExtensionDefinition> myExtensionsModifier = new ArrayList<>();
        private List<RuntimeChildDeclaredExtensionDefinition> myExtensionsNonModifier = new ArrayList<>();
        private Map<String, RuntimeChildDeclaredExtensionDefinition> myUrlToExtension = new HashMap<>();
        private BaseRuntimeElementDefinition<?> myRootParentDefinition;

        public BaseRuntimeElementDefinition(
                        String theName, Class<? extends T> theImplementingClass, boolean theStandardType) {
                assert StringUtils.isNotBlank(theName);
                assert theImplementingClass != null;

                String name = theName;
                // TODO: remove this and fix for the model
                if (name.endsWith("Dt")) {
                        name = name.substring(0, name.length() - 2);
                }

                myName = name;
                myStandardType = theStandardType;
                myImplementingClass = theImplementingClass;
        }

        public void addExtension(@Nonnull RuntimeChildDeclaredExtensionDefinition theExtension) {
                Validate.notNull(theExtension, "theExtension must not be null");
                myExtensions.add(theExtension);
        }

        public abstract ChildTypeEnum getChildType();

        public List<BaseRuntimeChildDefinition> getChildren() {
                return Collections.emptyList();
        }

        @SuppressWarnings("unchecked")
        private Constructor<T> getConstructor(@Nullable Object theArgument) {

                Class<?> argumentType;
                if (theArgument == null) {
                        argumentType = VOID_CLASS;
                } else {
                        argumentType = theArgument.getClass();
                }

                Constructor<T> retVal = myConstructors.computeIfAbsent(argumentType, type -> {
                        for (Constructor<?> next : getImplementingClass().getConstructors()) {
                                if (type == VOID_CLASS) {
                                        if (next.getParameterTypes().length == 0) {
                                                return (Constructor<T>) next;
                                        }
                                } else if (next.getParameterTypes().length == 1 && next.getParameterTypes()[0].isAssignableFrom(type)) {
                                        return (Constructor<T>) next;
                                }
                        }
                        return null;
                });

                if (retVal == null) {
                        throw new ConfigurationException(Msg.code(1695) + "Class " + getImplementingClass()
                                        + " has no constructor with a single argument of type " + argumentType);
                }

                return retVal;
        }

        /**
         * @return Returns null if none
         */
        public RuntimeChildDeclaredExtensionDefinition getDeclaredExtension(
                        String theExtensionUrl, final String serverBaseUrl) {
                validateSealed();
                RuntimeChildDeclaredExtensionDefinition definition = myUrlToExtension.get(theExtensionUrl);
                if (definition == null && StringUtils.isNotBlank(serverBaseUrl)) {
                        for (final Map.Entry<String, RuntimeChildDeclaredExtensionDefinition> entry : myUrlToExtension.entrySet()) {
                                final String key = (!UrlUtil.isValid(entry.getKey()) && StringUtils.isNotBlank(serverBaseUrl))
                                                ? serverBaseUrl + entry.getKey()
                                                : entry.getKey();
                                if (key.equals(theExtensionUrl)) {
                                        definition = entry.getValue();
                                        break;
                                }
                        }
                }
                return definition;
        }

        public List<RuntimeChildDeclaredExtensionDefinition> getExtensions() {
                validateSealed();
                return myExtensions;
        }

        public List<RuntimeChildDeclaredExtensionDefinition> getExtensionsModifier() {
                validateSealed();
                return myExtensionsModifier;
        }

        public List<RuntimeChildDeclaredExtensionDefinition> getExtensionsNonModifier() {
                validateSealed();
                return myExtensionsNonModifier;
        }

        public Class<? extends T> getImplementingClass() {
                return myImplementingClass;
        }

        /**
         * @return Returns the runtime name for this resource (i.e. the name that
         * will be used in encoded messages)
         */
        public String getName() {
                return myName;
        }

        public boolean hasExtensions() {
                validateSealed();
                return myExtensions.size() > 0;
        }

        public boolean isStandardType() {
                return myStandardType;
        }

        @Nonnull
        public T newInstance() {
                return newInstance(null);
        }

        @Nonnull
        public T newInstance(Object theArgument) {
                try {
                        if (theArgument == null) {
                                return getConstructor(null).newInstance();
                        }
                        return getConstructor(theArgument).newInstance(theArgument);

                } catch (Exception e) {
                        throw new ConfigurationException(
                                        Msg.code(1696) + "Failed to instantiate type:"
                                                        + getImplementingClass().getName(),
                                        e);
                }
        }

        public BaseRuntimeElementDefinition<?> getRootParentDefinition() {
                return myRootParentDefinition;
        }

        /**
         * Invoked prior to use to perform any initialization and make object
         * mutable.
         *
         * @param theContext TODO
         */
        void sealAndInitialize(
                        FhirContext theContext,
                        Map<Class<? extends IBase>, BaseRuntimeElementDefinition<?>> theClassToElementDefinitions) {
                for (BaseRuntimeChildDefinition next : myExtensions) {
                        next.sealAndInitialize(theContext, theClassToElementDefinitions);
                }

                for (RuntimeChildDeclaredExtensionDefinition next : myExtensions) {
                        String extUrl = next.getExtensionUrl();
                        if (myUrlToExtension.containsKey(extUrl)) {
                                throw new ConfigurationException(
                                                Msg.code(1697) + "Duplicate extension URL[" + extUrl + "] in Element[" + getName() + "]");
                        }
                        myUrlToExtension.put(extUrl, next);
                        if (next.isModifier()) {
                                myExtensionsModifier.add(next);
                        } else {
                                myExtensionsNonModifier.add(next);
                        }
                }

                myExtensions = Collections.unmodifiableList(myExtensions);

                Class parent = myImplementingClass;
                do {
                        BaseRuntimeElementDefinition<?> parentDefinition = theClassToElementDefinitions.get(parent);
                        if (parentDefinition != null) {
                                myRootParentDefinition = parentDefinition;
                        }
                        parent = parent.getSuperclass();
                } while (!parent.equals(Object.class));
        }

        @Override
        public String toString() {
                return getClass().getSimpleName() + "[" + getName() + ", "
                                + getImplementingClass().getSimpleName() + "]";
        }

        protected void validateSealed() {
                /*
                 * this does nothing, but BaseRuntimeElementCompositeDefinition
                 * overrides this method to provide functionality because that class
                 * defers the sealing process
                 */
        }

        public BaseRuntimeChildDefinition getChildByName(String theChildName) {
                return null;
        }

        public enum ChildTypeEnum {
                COMPOSITE_DATATYPE,
                /**
                 * HL7.org structure style.
                 */
                CONTAINED_RESOURCE_LIST,
                /**
                 * HAPI structure style.
                 */
                CONTAINED_RESOURCES,
                EXTENSION_DECLARED,
                ID_DATATYPE,
                PRIMITIVE_DATATYPE,
                /**
                 * HAPI style.
                 */
                PRIMITIVE_XHTML,
                /**
                 * HL7.org style.
                 */
                PRIMITIVE_XHTML_HL7ORG,
                RESOURCE,
                RESOURCE_BLOCK,

                UNDECL_EXT,
        }
}