/*-
 * #%L
 * HAPI FHIR - Core Library
 * %%
 * Copyright (C) 2014 - 2023 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.context.FhirContext;
import ca.uhn.fhir.context.FhirVersionEnum;
import ca.uhn.fhir.context.RuntimeResourceDefinition;
import ca.uhn.fhir.model.primitive.IdDt;
import org.apache.commons.lang3.Validate;
import org.hl7.fhir.instance.model.api.IBase;
import org.hl7.fhir.instance.model.api.IBaseBackboneElement;
import org.hl7.fhir.instance.model.api.IBaseBundle;
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 javax.annotation.Nonnull;
import javax.annotation.Nullable;
import java.util.Date;
import java.util.Objects;

/**
 * This class can be used to build a Bundle resource to be used as a FHIR transaction. Convenience methods provide
 * support for setting various bundle fields and working with bundle parts such as metadata and entry
 * (method and search).
 *
 * <p>
 * <p>
 * This is not yet complete, and doesn't support all FHIR features. <b>USE WITH CAUTION</b> as the API
 * may change.
 *
 * @since 5.1.0
 */
public class BundleBuilder {

        private final FhirContext myContext;
        private final IBaseBundle myBundle;
        private final RuntimeResourceDefinition myBundleDef;
        private final BaseRuntimeChildDefinition myEntryChild;
        private final BaseRuntimeChildDefinition myMetaChild;
        private final BaseRuntimeChildDefinition mySearchChild;
        private final BaseRuntimeElementDefinition<?> myEntryDef;
        private final BaseRuntimeElementDefinition<?> myMetaDef;
        private final BaseRuntimeElementDefinition mySearchDef;
        private final BaseRuntimeChildDefinition myEntryResourceChild;
        private final BaseRuntimeChildDefinition myEntryFullUrlChild;
        private final BaseRuntimeChildDefinition myEntryRequestChild;
        private final BaseRuntimeElementDefinition<?> myEntryRequestDef;
        private final BaseRuntimeChildDefinition myEntryRequestUrlChild;
        private final BaseRuntimeChildDefinition myEntryRequestMethodChild;
        private final BaseRuntimeElementDefinition<?> myEntryRequestMethodDef;
        private final BaseRuntimeChildDefinition myEntryRequestIfNoneExistChild;

        /**
         * Constructor
         */
        public BundleBuilder(FhirContext theContext) {
                myContext = theContext;

                myBundleDef = myContext.getResourceDefinition("Bundle");
                myBundle = (IBaseBundle) myBundleDef.newInstance();

                myEntryChild = myBundleDef.getChildByName("entry");
                myEntryDef = myEntryChild.getChildByName("entry");

                mySearchChild = myEntryDef.getChildByName("search");
                mySearchDef = mySearchChild.getChildByName("search");

                if (myContext.getVersion().getVersion().isEqualOrNewerThan(FhirVersionEnum.DSTU3)) {
                        myMetaChild = myBundleDef.getChildByName("meta");
                        myMetaDef = myMetaChild.getChildByName("meta");
                } else {
                        myMetaChild = null;
                        myMetaDef = null;
                }

                myEntryResourceChild = myEntryDef.getChildByName("resource");
                myEntryFullUrlChild = myEntryDef.getChildByName("fullUrl");

                myEntryRequestChild = myEntryDef.getChildByName("request");
                myEntryRequestDef = myEntryRequestChild.getChildByName("request");

                myEntryRequestUrlChild = myEntryRequestDef.getChildByName("url");

                myEntryRequestMethodChild = myEntryRequestDef.getChildByName("method");
                myEntryRequestMethodDef = myEntryRequestMethodChild.getChildByName("method");

                myEntryRequestIfNoneExistChild = myEntryRequestDef.getChildByName("ifNoneExist");
        }

        /**
         * Sets the specified primitive field on the bundle with the value provided.
         *
         * @param theFieldName  Name of the primitive field.
         * @param theFieldValue Value of the field to be set.
         */
        public BundleBuilder setBundleField(String theFieldName, String theFieldValue) {
                BaseRuntimeChildDefinition typeChild = myBundleDef.getChildByName(theFieldName);
                Validate.notNull(typeChild, "Unable to find field %s", theFieldName);

                IPrimitiveType<?> type = (IPrimitiveType<?>) typeChild.getChildByName(theFieldName).newInstance(typeChild.getInstanceConstructorArguments());
                type.setValueAsString(theFieldValue);
                typeChild.getMutator().setValue(myBundle, type);
                return this;
        }

        /**
         * Sets the specified primitive field on the search entry with the value provided.
         *
         * @param theSearch     Search part of the entry
         * @param theFieldName  Name of the primitive field.
         * @param theFieldValue Value of the field to be set.
         */
        public BundleBuilder setSearchField(IBase theSearch, String theFieldName, String theFieldValue) {
                BaseRuntimeChildDefinition typeChild = mySearchDef.getChildByName(theFieldName);
                Validate.notNull(typeChild, "Unable to find field %s", theFieldName);

                IPrimitiveType<?> type = (IPrimitiveType<?>) typeChild.getChildByName(theFieldName).newInstance(typeChild.getInstanceConstructorArguments());
                type.setValueAsString(theFieldValue);
                typeChild.getMutator().setValue(theSearch, type);
                return this;
        }

        public BundleBuilder setSearchField(IBase theSearch, String theFieldName, IPrimitiveType<?> theFieldValue) {
                BaseRuntimeChildDefinition typeChild = mySearchDef.getChildByName(theFieldName);
                Validate.notNull(typeChild, "Unable to find field %s", theFieldName);

                typeChild.getMutator().setValue(theSearch, theFieldValue);
                return this;
        }

        /**
         * Adds a FHIRPatch patch bundle to the transaction
         *
         * @param theTarget The target resource ID to patch
         * @param thePatch  The FHIRPath Parameters resource
         * @since 6.3.0
         */
        public PatchBuilder addTransactionFhirPatchEntry(IIdType theTarget, IBaseParameters thePatch) {
                Validate.notNull(theTarget, "theTarget must not be null");
                Validate.notBlank(theTarget.getResourceType(), "theTarget must contain a resource type");
                Validate.notBlank(theTarget.getIdPart(), "theTarget must contain an ID");

                IPrimitiveType<?> url = addAndPopulateTransactionBundleEntryRequest(thePatch, theTarget.getValue(), theTarget.toUnqualifiedVersionless().getValue(), "PATCH");

                return new PatchBuilder(url);
        }

        /**
         * Adds a FHIRPatch patch bundle to the transaction. This method is intended for conditional PATCH operations. If you
         * know the ID of the resource you wish to patch, use {@link #addTransactionFhirPatchEntry(IIdType, IBaseParameters)}
         * instead.
         *
         * @param thePatch The FHIRPath Parameters resource
         * @see #addTransactionFhirPatchEntry(IIdType, IBaseParameters)
         * @since 6.3.0
         */
        public PatchBuilder addTransactionFhirPatchEntry(IBaseParameters thePatch) {
                IPrimitiveType<?> url = addAndPopulateTransactionBundleEntryRequest(thePatch, null, null, "PATCH");

                return new PatchBuilder(url);
        }

        /**
         * Adds an entry containing an update (PUT) request.
         * Also sets the Bundle.type value to "transaction" if it is not already set.
         *
         * @param theResource The resource to update
         */
        public UpdateBuilder addTransactionUpdateEntry(IBaseResource theResource) {
                Validate.notNull(theResource, "theResource must not be null");

                IIdType id = theResource.getIdElement();
                if (id.hasIdPart() && !id.hasResourceType()) {
                        String resourceType = myContext.getResourceType(theResource);
                        id = id.withResourceType(resourceType);
                }

                String requestUrl = id.toUnqualifiedVersionless().getValue();
                String fullUrl = id.getValue();
                String verb = "PUT";

                IPrimitiveType<?> url = addAndPopulateTransactionBundleEntryRequest(theResource, fullUrl, requestUrl, verb);

                return new UpdateBuilder(url);
        }

        @Nonnull
        private IPrimitiveType<?> addAndPopulateTransactionBundleEntryRequest(IBaseResource theResource, String theFullUrl, String theRequestUrl, String theHttpVerb) {
                setBundleField("type", "transaction");

                IBase request = addEntryAndReturnRequest(theResource, theFullUrl);

                // Bundle.entry.request.url
                IPrimitiveType<?> url = (IPrimitiveType<?>) myContext.getElementDefinition("uri").newInstance();
                url.setValueAsString(theRequestUrl);
                myEntryRequestUrlChild.getMutator().setValue(request, url);

                // Bundle.entry.request.method
                IPrimitiveType<?> method = (IPrimitiveType<?>) myEntryRequestMethodDef.newInstance(myEntryRequestMethodChild.getInstanceConstructorArguments());
                method.setValueAsString(theHttpVerb);
                myEntryRequestMethodChild.getMutator().setValue(request, method);
                return url;
        }

        /**
         * Adds an entry containing an create (POST) request.
         * Also sets the Bundle.type value to "transaction" if it is not already set.
         *
         * @param theResource The resource to create
         */
        public CreateBuilder addTransactionCreateEntry(IBaseResource theResource) {
                setBundleField("type", "transaction");

                IBase request = addEntryAndReturnRequest(theResource, theResource.getIdElement().getValue());

                String resourceType = myContext.getResourceType(theResource);

                // Bundle.entry.request.url
                IPrimitiveType<?> url = (IPrimitiveType<?>) myContext.getElementDefinition("uri").newInstance();
                url.setValueAsString(resourceType);
                myEntryRequestUrlChild.getMutator().setValue(request, url);

                // Bundle.entry.request.url
                IPrimitiveType<?> method = (IPrimitiveType<?>) myEntryRequestMethodDef.newInstance(myEntryRequestMethodChild.getInstanceConstructorArguments());
                method.setValueAsString("POST");
                myEntryRequestMethodChild.getMutator().setValue(request, method);

                return new CreateBuilder(request);
        }

        /**
         * Adds an entry containing a delete (DELETE) request.
         * Also sets the Bundle.type value to "transaction" if it is not already set.
         * <p>
         * Note that the resource is only used to extract its ID and type, and the body of the resource is not included in the entry,
         *
         * @param theResource The resource to delete.
         */
        public DeleteBuilder addTransactionDeleteEntry(IBaseResource theResource) {
                String resourceType = myContext.getResourceType(theResource);
                String idPart = theResource.getIdElement().toUnqualifiedVersionless().getIdPart();
                return addTransactionDeleteEntry(resourceType, idPart);
        }

        /**
         * Adds an entry containing a delete (DELETE) request.
         * Also sets the Bundle.type value to "transaction" if it is not already set.
         * <p>
         * Note that the resource is only used to extract its ID and type, and the body of the resource is not included in the entry,
         *
         * @param theResourceId The resource ID to delete.
         * @return
         */
        public DeleteBuilder addTransactionDeleteEntry(IIdType theResourceId) {
                String resourceType = theResourceId.getResourceType();
                String idPart = theResourceId.getIdPart();
                return addTransactionDeleteEntry(resourceType, idPart);
        }

        /**
         * Adds an entry containing a delete (DELETE) request.
         * Also sets the Bundle.type value to "transaction" if it is not already set.
         *
         * @param theResourceType The type resource to delete.
         * @param theIdPart       the ID of the resource to delete.
         */
        public DeleteBuilder addTransactionDeleteEntry(String theResourceType, String theIdPart) {
                setBundleField("type", "transaction");
                IdDt idDt = new IdDt(theIdPart);

                String deleteUrl = idDt.toUnqualifiedVersionless().withResourceType(theResourceType).getValue();

                return addDeleteEntry(deleteUrl);
        }

        /**
         * Adds an entry containing a delete (DELETE) request.
         * Also sets the Bundle.type value to "transaction" if it is not already set.
         *
         * @param theMatchUrl The match URL, e.g. <code>Patient?identifier=http://foo|123</code>
         * @since 6.3.0
         */
        public BaseOperationBuilder addTransactionDeleteEntryConditional(String theMatchUrl) {
                Validate.notBlank(theMatchUrl, "theMatchUrl must not be null or blank");
                return addDeleteEntry(theMatchUrl);
        }

        @Nonnull
        private DeleteBuilder addDeleteEntry(String theDeleteUrl) {
                IBase request = addEntryAndReturnRequest();

                // Bundle.entry.request.url
                IPrimitiveType<?> url = (IPrimitiveType<?>) myContext.getElementDefinition("uri").newInstance();
                url.setValueAsString(theDeleteUrl);
                myEntryRequestUrlChild.getMutator().setValue(request, url);

                // Bundle.entry.request.method
                IPrimitiveType<?> method = (IPrimitiveType<?>) myEntryRequestMethodDef.newInstance(myEntryRequestMethodChild.getInstanceConstructorArguments());
                method.setValueAsString("DELETE");
                myEntryRequestMethodChild.getMutator().setValue(request, method);

                return new DeleteBuilder();
        }


        /**
         * Adds an entry for a Collection bundle type
         */
        public void addCollectionEntry(IBaseResource theResource) {
                setType("collection");
                addEntryAndReturnRequest(theResource, theResource.getIdElement().getValue());
        }

        /**
         * Adds an entry for a Document bundle type
         */
        public void addDocumentEntry(IBaseResource theResource) {
                setType("document");
                addEntryAndReturnRequest(theResource, theResource.getIdElement().getValue());
        }

        /**
         * Creates new entry and adds it to the bundle
         *
         * @return Returns the new entry.
         */
        public IBase addEntry() {
                IBase entry = myEntryDef.newInstance();
                myEntryChild.getMutator().addValue(myBundle, entry);
                return entry;
        }

        /**
         * Creates new search instance for the specified entry.
         * Note that this method does not work for DSTU2 model classes, it will only work
         * on DSTU3+.
         *
         * @param entry Entry to create search instance for
         * @return Returns the search instance
         */
        public IBaseBackboneElement addSearch(IBase entry) {
                Validate.isTrue(myContext.getVersion().getVersion().isEqualOrNewerThan(FhirVersionEnum.DSTU3), "This method may only be called for FHIR version DSTU3 and above");

                IBase searchInstance = mySearchDef.newInstance();
                mySearchChild.getMutator().setValue(entry, searchInstance);
                return (IBaseBackboneElement) searchInstance;
        }

        private IBase addEntryAndReturnRequest(IBaseResource theResource, String theFullUrl) {
                Validate.notNull(theResource, "theResource must not be null");

                IBase entry = addEntry();

                // Bundle.entry.fullUrl
                IPrimitiveType<?> fullUrl = (IPrimitiveType<?>) myContext.getElementDefinition("uri").newInstance();
                fullUrl.setValueAsString(theFullUrl);
                myEntryFullUrlChild.getMutator().setValue(entry, fullUrl);

                // Bundle.entry.resource
                myEntryResourceChild.getMutator().setValue(entry, theResource);

                // Bundle.entry.request
                IBase request = myEntryRequestDef.newInstance();
                myEntryRequestChild.getMutator().setValue(entry, request);
                return request;
        }

        public IBase addEntryAndReturnRequest() {
                IBase entry = addEntry();

                // Bundle.entry.request
                IBase request = myEntryRequestDef.newInstance();
                myEntryRequestChild.getMutator().setValue(entry, request);
                return request;

        }


        public IBaseBundle getBundle() {
                return myBundle;
        }

        /**
         * Convenience method which auto-casts the results of {@link #getBundle()}
         *
         * @since 6.3.0
         */
        public <T extends IBaseBundle> T getBundleTyped() {
                return (T) myBundle;
        }

        /**
         * Note that this method does not work for DSTU2 model classes, it will only work
         * on DSTU3+.
         */
        public BundleBuilder setMetaField(String theFieldName, IBase theFieldValue) {
                Validate.isTrue(myContext.getVersion().getVersion().isEqualOrNewerThan(FhirVersionEnum.DSTU3), "This method may only be called for FHIR version DSTU3 and above");

                BaseRuntimeChildDefinition.IMutator mutator = myMetaDef.getChildByName(theFieldName).getMutator();
                mutator.setValue(myBundle.getMeta(), theFieldValue);
                return this;
        }

        /**
         * Sets the specified entry field.
         *
         * @param theEntry          The entry instance to set values on
         * @param theEntryChildName The child field name of the entry instance to be set
         * @param theValue          The field value to set
         */
        public void addToEntry(IBase theEntry, String theEntryChildName, IBase theValue) {
                addToBase(theEntry, theEntryChildName, theValue, myEntryDef);
        }

        /**
         * Sets the specified search field.
         *
         * @param theSearch           The search instance to set values on
         * @param theSearchFieldName  The child field name of the search instance to be set
         * @param theSearchFieldValue The field value to set
         */
        public void addToSearch(IBase theSearch, String theSearchFieldName, IBase theSearchFieldValue) {
                addToBase(theSearch, theSearchFieldName, theSearchFieldValue, mySearchDef);
        }

        private void addToBase(IBase theBase, String theSearchChildName, IBase theValue, BaseRuntimeElementDefinition mySearchDef) {
                BaseRuntimeChildDefinition defn = mySearchDef.getChildByName(theSearchChildName);
                Validate.notNull(defn, "Unable to get child definition %s from %s", theSearchChildName, theBase);
                defn.getMutator().addValue(theBase, theValue);
        }

        /**
         * Creates a new primitive.
         *
         * @param theTypeName The element type for the primitive
         * @param <T>         Actual type of the parameterized primitive type interface
         * @return Returns the new empty instance of the element definition.
         */
        public <T> IPrimitiveType<T> newPrimitive(String theTypeName) {
                BaseRuntimeElementDefinition primitiveDefinition = myContext.getElementDefinition(theTypeName);
                Validate.notNull(primitiveDefinition, "Unable to find definition for %s", theTypeName);
                return (IPrimitiveType<T>) primitiveDefinition.newInstance();
        }

        /**
         * Creates a new primitive instance of the specified element type.
         *
         * @param theTypeName     Element type to create
         * @param theInitialValue Initial value to be set on the new instance
         * @param <T>             Actual type of the parameterized primitive type interface
         * @return Returns the newly created instance
         */
        public <T> IPrimitiveType<T> newPrimitive(String theTypeName, T theInitialValue) {
                IPrimitiveType<T> retVal = newPrimitive(theTypeName);
                retVal.setValue(theInitialValue);
                return retVal;
        }

        /**
         * Sets a value for <code>Bundle.type</code>. That this is a coded field so {@literal theType}
         * must be an actual valid value for this field or a {@link ca.uhn.fhir.parser.DataFormatException}
         * will be thrown.
         */
        public void setType(String theType) {
                setBundleField("type", theType);
        }

        /**
         * Adds an identifier to <code>Bundle.identifier</code>
         *
         * @param theSystem The system
         * @param theValue  The value
         * @since 6.4.0
         */
        public void setIdentifier(@Nullable String theSystem, @Nullable String theValue) {
                FhirTerser terser = myContext.newTerser();
                IBase identifier = terser.addElement(myBundle, "identifier");
                terser.setElement(identifier, "system", theSystem);
                terser.setElement(identifier, "value", theValue);
        }

        /**
         * Sets the timestamp in <code>Bundle.timestamp</code>
         *
         * @since 6.4.0
         */
        public void setTimestamp(@Nonnull IPrimitiveType<Date> theTimestamp) {
                FhirTerser terser = myContext.newTerser();
                terser.setElement(myBundle, "Bundle.timestamp", theTimestamp.getValueAsString());
        }


        public class DeleteBuilder extends BaseOperationBuilder {

                // nothing yet

        }


        public class PatchBuilder extends BaseOperationBuilderWithConditionalUrl<PatchBuilder> {

                PatchBuilder(IPrimitiveType<?> theUrl) {
                        super(theUrl);
                }

        }

        public class UpdateBuilder extends BaseOperationBuilderWithConditionalUrl<UpdateBuilder> {
                UpdateBuilder(IPrimitiveType<?> theUrl) {
                        super(theUrl);
                }

        }

        public class CreateBuilder extends BaseOperationBuilder {
                private final IBase myRequest;

                CreateBuilder(IBase theRequest) {
                        myRequest = theRequest;
                }

                /**
                 * Make this create a Conditional Create
                 */
                public CreateBuilder conditional(String theConditionalUrl) {
                        BaseRuntimeElementDefinition<?> stringDefinition = Objects.requireNonNull(myContext.getElementDefinition("string"));
                        IPrimitiveType<?> ifNoneExist = (IPrimitiveType<?>) stringDefinition.newInstance();
                        ifNoneExist.setValueAsString(theConditionalUrl);

                        myEntryRequestIfNoneExistChild.getMutator().setValue(myRequest, ifNoneExist);

                        return this;
                }

        }

        public abstract class BaseOperationBuilder {

                /**
                 * Returns a reference to the BundleBuilder instance.
                 * <p>
                 * Calling this method has no effect at all, it is only
                 * provided for easy method chaning if you want to build
                 * your bundle as a single fluent call.
                 *
                 * @since 6.3.0
                 */
                public BundleBuilder andThen() {
                        return BundleBuilder.this;
                }


        }

        public abstract class BaseOperationBuilderWithConditionalUrl<T extends BaseOperationBuilder> extends BaseOperationBuilder {

                private final IPrimitiveType<?> myUrl;

                BaseOperationBuilderWithConditionalUrl(IPrimitiveType<?> theUrl) {
                        myUrl = theUrl;
                }

                /**
                 * Make this update a Conditional Update
                 */
                @SuppressWarnings("unchecked")
                public T conditional(String theConditionalUrl) {
                        myUrl.setValueAsString(theConditionalUrl);
                        return (T) this;
                }

        }
}