/*
 * Copyright 2004-2022 the original author or authors.
 *
 * 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
 *
 *      https://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.
 */
package org.springframework.webflow.engine.builder.model;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import org.springframework.beans.factory.config.ConfigurableBeanFactory;
import org.springframework.beans.factory.support.BeanDefinitionBuilder;
import org.springframework.beans.factory.xml.XmlBeanDefinitionReader;
import org.springframework.binding.convert.ConversionExecutionException;
import org.springframework.binding.convert.ConversionExecutor;
import org.springframework.binding.convert.service.RuntimeBindingConversionExecutor;
import org.springframework.binding.expression.Expression;
import org.springframework.binding.expression.ExpressionParser;
import org.springframework.binding.expression.ParserContext;
import org.springframework.binding.expression.support.FluentParserContext;
import org.springframework.binding.mapping.Mapper;
import org.springframework.binding.mapping.impl.DefaultMapper;
import org.springframework.binding.mapping.impl.DefaultMapping;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigUtils;
import org.springframework.context.support.AbstractApplicationContext;
import org.springframework.context.support.GenericApplicationContext;
import org.springframework.context.support.ReloadableResourceBundleMessageSource;
import org.springframework.core.io.Resource;
import org.springframework.core.style.ToStringCreator;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
import org.springframework.util.StringUtils;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.context.request.RequestScope;
import org.springframework.web.context.support.GenericWebApplicationContext;
import org.springframework.webflow.action.EvaluateAction;
import org.springframework.webflow.action.ExternalRedirectAction;
import org.springframework.webflow.action.FlowDefinitionRedirectAction;
import org.springframework.webflow.action.RenderAction;
import org.springframework.webflow.action.SetAction;
import org.springframework.webflow.action.ViewFactoryActionAdapter;
import org.springframework.webflow.core.collection.AttributeMap;
import org.springframework.webflow.core.collection.LocalAttributeMap;
import org.springframework.webflow.core.collection.MutableAttributeMap;
import org.springframework.webflow.engine.Flow;
import org.springframework.webflow.engine.FlowExecutionExceptionHandler;
import org.springframework.webflow.engine.FlowVariable;
import org.springframework.webflow.engine.History;
import org.springframework.webflow.engine.SubflowAttributeMapper;
import org.springframework.webflow.engine.TargetStateResolver;
import org.springframework.webflow.engine.Transition;
import org.springframework.webflow.engine.TransitionCriteria;
import org.springframework.webflow.engine.VariableValueFactory;
import org.springframework.webflow.engine.ViewVariable;
import org.springframework.webflow.engine.builder.BinderConfiguration;
import org.springframework.webflow.engine.builder.BinderConfiguration.Binding;
import org.springframework.webflow.engine.builder.FlowBuilderContext;
import org.springframework.webflow.engine.builder.FlowBuilderException;
import org.springframework.webflow.engine.builder.support.AbstractFlowBuilder;
import org.springframework.webflow.engine.model.AbstractActionModel;
import org.springframework.webflow.engine.model.AbstractMappingModel;
import org.springframework.webflow.engine.model.AbstractStateModel;
import org.springframework.webflow.engine.model.ActionStateModel;
import org.springframework.webflow.engine.model.AttributeModel;
import org.springframework.webflow.engine.model.BeanImportModel;
import org.springframework.webflow.engine.model.BinderModel;
import org.springframework.webflow.engine.model.BindingModel;
import org.springframework.webflow.engine.model.DecisionStateModel;
import org.springframework.webflow.engine.model.EndStateModel;
import org.springframework.webflow.engine.model.EvaluateModel;
import org.springframework.webflow.engine.model.ExceptionHandlerModel;
import org.springframework.webflow.engine.model.FlowModel;
import org.springframework.webflow.engine.model.IfModel;
import org.springframework.webflow.engine.model.InputModel;
import org.springframework.webflow.engine.model.OutputModel;
import org.springframework.webflow.engine.model.PersistenceContextModel;
import org.springframework.webflow.engine.model.RenderModel;
import org.springframework.webflow.engine.model.SecuredModel;
import org.springframework.webflow.engine.model.SetModel;
import org.springframework.webflow.engine.model.SubflowStateModel;
import org.springframework.webflow.engine.model.TransitionModel;
import org.springframework.webflow.engine.model.VarModel;
import org.springframework.webflow.engine.model.ViewStateModel;
import org.springframework.webflow.engine.model.builder.FlowModelBuilderException;
import org.springframework.webflow.engine.model.registry.FlowModelHolder;
import org.springframework.webflow.engine.support.ActionExecutingViewFactory;
import org.springframework.webflow.engine.support.BeanFactoryVariableValueFactory;
import org.springframework.webflow.engine.support.DefaultTransitionCriteria;
import org.springframework.webflow.engine.support.GenericSubflowAttributeMapper;
import org.springframework.webflow.engine.support.TransitionCriteriaChain;
import org.springframework.webflow.engine.support.TransitionExecutingFlowExecutionExceptionHandler;
import org.springframework.webflow.execution.Action;
import org.springframework.webflow.execution.AnnotatedAction;
import org.springframework.webflow.execution.RequestContext;
import org.springframework.webflow.execution.ViewFactory;
import org.springframework.webflow.scope.ConversationScope;
import org.springframework.webflow.scope.FlashScope;
import org.springframework.webflow.scope.FlowScope;
import org.springframework.webflow.scope.ViewScope;
import org.springframework.webflow.security.SecurityRule;

/**
 * Builds a runtime {@link Flow} definition object from a {@link FlowModel}.
 *
 * @author Keith Donald
 */
public class FlowModelFlowBuilder extends AbstractFlowBuilder {

	private static final boolean IS_SPRING_FACES_PRESENT = ClassUtils.isPresent(
			"org.springframework.faces.webflow.FlowActionListener", FlowModelFlowBuilder.class.getClassLoader());

	public static final String VALIDATOR_FLOW_ATTR = FlowModelFlowBuilder.class.getSimpleName() + ".validator";

	public static final String VALIDATION_HINT_RESOLVER_FLOW_ATTR = FlowModelFlowBuilder.class.getSimpleName() + ".validationHintResolver";

	private final FlowModelHolder flowModelHolder;

	private FlowModel flowModel;

	private LocalFlowBuilderContext localFlowBuilderContext;

	/**
	 * Creates a flow builder that can build a {@link Flow} from a {@link FlowModel}.
	 * @param flowModelHolder the flow model holder
	 */
	public FlowModelFlowBuilder(FlowModelHolder flowModelHolder) {
		Assert.notNull(flowModelHolder, "The FlowModelHolder is required");
		this.flowModelHolder = flowModelHolder;
	}

	/**
	 * Initialize this builder. This could cause the builder to open a stream to an externalized resource representing
	 * the flow definition, for example.
	 * @throws FlowBuilderException an exception occurred building the flow
	 */
	protected void doInit() throws FlowBuilderException {
		try {
			flowModel = flowModelHolder.getFlowModel();
			initLocalFlowContext();
		} catch (FlowModelBuilderException e) {
			throw new FlowBuilderException("Unable to get the model for this flow", e);
		}
		if ("true".equals(flowModel.getAbstract())) {
			throw new FlowBuilderException("Abstract flow models cannot be instantiated.");
		}
	}

	protected Flow createFlow() {
		String flowId = getContext().getFlowId();
		AttributeMap<Object> flowAttributes = parseFlowMetaAttributes(flowModel);
		flowAttributes = getContext().getFlowAttributes().union(flowAttributes);
		if (IS_SPRING_FACES_PRESENT) {
			flowAttributes.asMap().put(VALIDATOR_FLOW_ATTR, getLocalContext().getValidator());
			flowAttributes.asMap().put(VALIDATION_HINT_RESOLVER_FLOW_ATTR, getLocalContext().getValidationHintResolver());
		}
		Flow flow = getLocalContext().getFlowArtifactFactory().createFlow(flowId, flowAttributes);
		flow.setApplicationContext(getLocalContext().getApplicationContext());
		return flow;
	}

	/**
	 * Builds any variables initialized by the flow when it starts.
	 * @throws FlowBuilderException an exception occurred building the flow
	 */
	public void buildVariables() throws FlowBuilderException {
		if (flowModel.getVars() != null) {
			for (VarModel varModel : flowModel.getVars()) {
				getFlow().addVariable(parseFlowVariable(varModel));
			}
		}
	}

	/**
	 * Builds the input mapper responsible for mapping flow input on start.
	 * @throws FlowBuilderException an exception occurred building the flow
	 */
	public void buildInputMapper() throws FlowBuilderException {
		getFlow().setInputMapper(parseFlowInputMapper(flowModel.getInputs()));
	}

	/**
	 * Builds any start actions to execute when the flow starts.
	 * @throws FlowBuilderException an exception occurred building the flow
	 */
	public void buildStartActions() throws FlowBuilderException {
		getFlow().getStartActionList().addAll(parseActions(flowModel.getOnStartActions()));
	}

	/**
	 * Builds the states of the flow.
	 * @throws FlowBuilderException an exception occurred building the flow
	 */
	public void buildStates() throws FlowBuilderException {
		if (flowModel.getStates() == null) {
			throw new FlowBuilderException("At least one state is required to build a Flow");
		}
		for (AbstractStateModel state : flowModel.getStates()) {
			if (state instanceof ActionStateModel) {
				parseAndAddActionState((ActionStateModel) state, getFlow());
			} else if (state instanceof ViewStateModel) {
				parseAndAddViewState((ViewStateModel) state, getFlow());
			} else if (state instanceof DecisionStateModel) {
				parseAndAddDecisionState((DecisionStateModel) state, getFlow());
			} else if (state instanceof SubflowStateModel) {
				parseAndAddSubflowState((SubflowStateModel) state, getFlow());
			} else if (state instanceof EndStateModel) {
				parseAndAddEndState((EndStateModel) state, getFlow());
			}
		}
		if (flowModel.getStartStateId() != null) {
			getFlow().setStartState(flowModel.getStartStateId());
		}
	}

	/**
	 * Builds any transitions shared by all states of the flow.
	 * @throws FlowBuilderException an exception occurred building the flow
	 */
	public void buildGlobalTransitions() throws FlowBuilderException {
		getFlow().getGlobalTransitionSet().addAll(parseTransitions(flowModel.getGlobalTransitions()));
	}

	/**
	 * Builds any end actions to execute when the flow ends.
	 * @throws FlowBuilderException an exception occurred building the flow
	 */
	public void buildEndActions() throws FlowBuilderException {
		getFlow().getEndActionList().addAll(parseActions(flowModel.getOnEndActions()));
	}

	/**
	 * Builds the output mapper responsible for mapping flow output on end.
	 * @throws FlowBuilderException an exception occurred building the flow
	 */
	public void buildOutputMapper() throws FlowBuilderException {
		if (flowModel.getOutputs() != null) {
			getFlow().setOutputMapper(parseFlowOutputMapper(flowModel.getOutputs()));
		}
	}

	/**
	 * Creates and adds all exception handlers to the flow built by this builder.
	 * @throws FlowBuilderException an exception occurred building this flow
	 */
	public void buildExceptionHandlers() throws FlowBuilderException {
		getFlow().getExceptionHandlerSet().addAll(
				parseExceptionHandlers(flowModel.getExceptionHandlers(), flowModel.getGlobalTransitions()));
	}

	public boolean hasFlowChanged() {
		return flowModelHolder.hasFlowModelChanged();
	}
	
	public String getFlowResourceString() {
		return flowModelHolder.getFlowModelResource().getDescription();
	}

	/**
	 * Shutdown the builder, releasing any resources it holds. A new flow construction process should start with another
	 * call to the {@link #init(FlowBuilderContext)} method.
	 * @throws FlowBuilderException an exception occurred building this flow
	 */
	protected void doDispose() throws FlowBuilderException {
		flowModel = null;
		setLocalContext(null);
	}

	// subclassing hooks

	protected FlowModel getFlowModel() {
		return flowModel;
	}

	/**
	 * Return the {@link FlowModelHolder} that holds the Flow model.
	 * @since 3.0
	 */
	protected FlowModelHolder getFlowModelHolder() {
		return flowModelHolder;
	}

	protected LocalFlowBuilderContext getLocalContext() {
		return localFlowBuilderContext;
	}

	protected void setLocalContext(LocalFlowBuilderContext localFlowBuilderContext) {
		this.localFlowBuilderContext = localFlowBuilderContext;
	}

	/**
	 * Register beans in the bean factory local to the flow definition being built.
	 * <p>
	 * Subclasses may override this method to customize the population of the bean factory local to the flow definition
	 * being built; for example, to register mock implementations of services in a test environment.
	 * @param beanFactory the bean factory; register local beans with it using
	 * {@link ConfigurableBeanFactory#registerSingleton(String, Object)}
	 */
	protected void registerFlowBeans(ConfigurableBeanFactory beanFactory) {
	}

	/**
	 * Build a {@link GenericApplicationContext} for the flow definition being build.
	 * 
	 * <p>Subclasses may override this method to fully control the nature and behavior of the
	 * Spring context for the flow.</p>
	 * 
	 * @return the built and refreshed context
	 * @since 3.0
	 */
	protected GenericApplicationContext createFlowApplicationContext() {
		Resource[] contextResources = parseContextResources(getFlowModel().getBeanImports());
		return createFlowApplicationContext(contextResources);
	}
	
	// internal helpers

	private void initLocalFlowContext() {
		GenericApplicationContext flowContext = createFlowApplicationContext();
		setLocalContext(new LocalFlowBuilderContext(getContext(), flowContext));
	}

	private Resource[] parseContextResources(List<BeanImportModel> beanImports) {
		if (beanImports != null && !beanImports.isEmpty()) {
			Resource flowResource = flowModelHolder.getFlowModelResource();
			List<Resource> resources = new ArrayList<>(beanImports.size());
			for (BeanImportModel beanImport : getFlowModel().getBeanImports()) {
				try {
					resources.add(flowResource.createRelative(beanImport.getResource()));
				} catch (IOException e) {
					throw new FlowBuilderException("Could not access flow-relative artifact resource '"
							+ beanImport.getResource() + "'", e);
				}
			}
			return resources.toArray(new Resource[resources.size()]);
		} else {
			return new Resource[0];
		}
	}

	private GenericApplicationContext createFlowApplicationContext(Resource[] resources) {
		ApplicationContext parent = getContext().getApplicationContext();
		GenericApplicationContext flowContext;
		if (parent instanceof WebApplicationContext) {
			GenericWebApplicationContext webContext = new GenericWebApplicationContext();
			webContext.setServletContext(((WebApplicationContext) parent).getServletContext());
			flowContext = webContext;
		} else {
			flowContext = new GenericApplicationContext();
		}
		flowContext.setDisplayName("Flow ApplicationContext [" + getContext().getFlowId() + "]");
		flowContext.setParent(parent);
		flowContext.getBeanFactory().registerScope("request", new RequestScope());
		flowContext.getBeanFactory().registerScope("flash", new FlashScope());
		flowContext.getBeanFactory().registerScope("view", new ViewScope());
		flowContext.getBeanFactory().registerScope("flow", new FlowScope());
		flowContext.getBeanFactory().registerScope("conversation", new ConversationScope());

		// Ensure the current ClassLoader is used, or otherwise setting the ResourceLoader would suppress it
		ClassLoader classLoaderToUse = flowContext.getClassLoader();
		flowContext.setClassLoader(classLoaderToUse);

		Resource flowResource = flowModelHolder.getFlowModelResource();
		flowContext.setResourceLoader(new FlowRelativeResourceLoader(flowResource));

		AnnotationConfigUtils.registerAnnotationConfigProcessors(flowContext);
		new XmlBeanDefinitionReader(flowContext).loadBeanDefinitions(resources);
		registerFlowBeans(flowContext.getBeanFactory());
		registerMessageSource(flowContext, flowResource);

		flowContext.refresh();

		return flowContext;
	}

	private boolean isFlowInDevelopment() {
		return getContext().getFlowAttributes().getBoolean("development", false);
	}

	private void registerMessageSource(GenericApplicationContext flowContext, Resource flowResource) {
		boolean localMessageSourcePresent = flowContext
				.containsLocalBean(AbstractApplicationContext.MESSAGE_SOURCE_BEAN_NAME);
		if (!localMessageSourcePresent) {
			Resource messageBundle;
			try {
				messageBundle = flowResource.createRelative("messages.properties");
			} catch (IOException e) {
				messageBundle = null;
			}
			if (messageBundle != null && messageBundle.exists()) {
				BeanDefinitionBuilder builder = BeanDefinitionBuilder
						.rootBeanDefinition(ReloadableResourceBundleMessageSource.class);
				builder.addPropertyValue("basename", "messages");
				if (isFlowInDevelopment()) {
					builder.addPropertyValue("cacheSeconds", "0");
				}
				flowContext.registerBeanDefinition(AbstractApplicationContext.MESSAGE_SOURCE_BEAN_NAME,
						builder.getBeanDefinition());
			}
		}
	}

	private AttributeMap<Object> parseFlowMetaAttributes(FlowModel flow) {
		MutableAttributeMap<Object> flowAttributes = parseMetaAttributes(flow.getAttributes());
		parseAndPutPersistenceContext(flow.getPersistenceContext(), flowAttributes);
		parseAndPutSecured(flow.getSecured(), flowAttributes);
		return flowAttributes;
	}

	private FlowVariable parseFlowVariable(VarModel var) {
		Class<?> clazz = toClass(var.getClassName());
		VariableValueFactory valueFactory = new BeanFactoryVariableValueFactory(clazz, getFlow()
				.getApplicationContext().getAutowireCapableBeanFactory());
		return new FlowVariable(var.getName(), valueFactory);
	}

	private Mapper parseFlowInputMapper(List<InputModel> inputs) {
		if (inputs != null && !inputs.isEmpty()) {
			DefaultMapper inputMapper = new DefaultMapper();
			for (InputModel inputModel : inputs) {
				inputMapper.addMapping(parseFlowInputMapping(inputModel));
			}
			return inputMapper;
		} else {
			return null;
		}
	}

	private DefaultMapping parseFlowInputMapping(InputModel input) {
		ExpressionParser parser = getLocalContext().getExpressionParser();
		String name = input.getName();
		String value = null;
		if (StringUtils.hasText(input.getValue())) {
			value = input.getValue();
		} else {
			value = "flowScope." + name;
		}
		Expression source = parser.parseExpression(name, new FluentParserContext().evaluate(MutableAttributeMap.class));
		Expression target = parser.parseExpression(value, new FluentParserContext().evaluate(RequestContext.class));
		DefaultMapping mapping = new DefaultMapping(source, target);
		parseAndSetMappingConversionExecutor(input, mapping);
		parseAndSetMappingRequired(input, mapping);
		return mapping;
	}

	private Mapper parseSubflowInputMapper(List<InputModel> inputs) {
		if (inputs != null && !inputs.isEmpty()) {
			DefaultMapper inputMapper = new DefaultMapper();
			for (InputModel inputModel : inputs) {
				inputMapper.addMapping(parseSubflowInputMapping(inputModel));
			}
			return inputMapper;
		} else {
			return null;
		}
	}

	private DefaultMapping parseSubflowInputMapping(InputModel input) {
		ExpressionParser parser = getLocalContext().getExpressionParser();
		String name = input.getName();
		String value = null;
		if (StringUtils.hasText(input.getValue())) {
			value = input.getValue();
		} else {
			value = name;
		}
		Expression source = parser.parseExpression(value, new FluentParserContext().evaluate(RequestContext.class));
		Expression target = parser.parseExpression(name, new FluentParserContext().evaluate(MutableAttributeMap.class));
		DefaultMapping mapping = new DefaultMapping(source, target);
		parseAndSetMappingConversionExecutor(input, mapping);
		parseAndSetMappingRequired(input, mapping);
		return mapping;
	}

	private Mapper parseFlowOutputMapper(List<OutputModel> outputs) {
		if (outputs != null && !outputs.isEmpty()) {
			DefaultMapper outputMapper = new DefaultMapper();
			for (OutputModel outputModel : outputs) {
				outputMapper.addMapping(parseFlowOutputMapping(outputModel));
			}
			return outputMapper;
		} else {
			return null;
		}
	}

	private DefaultMapping parseFlowOutputMapping(OutputModel output) {
		ExpressionParser parser = getLocalContext().getExpressionParser();
		String name = output.getName();
		String value = null;
		if (StringUtils.hasText(output.getValue())) {
			value = output.getValue();
		} else {
			value = name;
		}
		Expression source = parser.parseExpression(value, new FluentParserContext().evaluate(RequestContext.class));
		Expression target = parser.parseExpression(name, new FluentParserContext().evaluate(MutableAttributeMap.class));
		DefaultMapping mapping = new DefaultMapping(source, target);
		parseAndSetMappingConversionExecutor(output, mapping);
		parseAndSetMappingRequired(output, mapping);
		return mapping;
	}

	private Mapper parseSubflowOutputMapper(List<OutputModel> outputs) {
		if (outputs != null && !outputs.isEmpty()) {
			DefaultMapper outputMapper = new DefaultMapper();
			for (OutputModel outputModel : outputs) {
				outputMapper.addMapping(parseSubflowOutputMapping(outputModel));
			}
			return outputMapper;
		} else {
			return null;
		}
	}

	private DefaultMapping parseSubflowOutputMapping(OutputModel output) {
		ExpressionParser parser = getLocalContext().getExpressionParser();
		String name = output.getName();
		String value = null;
		if (StringUtils.hasText(output.getValue())) {
			value = output.getValue();
		} else {
			value = "flowScope." + name;
		}
		Expression source = parser.parseExpression(name, new FluentParserContext().evaluate(MutableAttributeMap.class));
		Expression target = parser.parseExpression(value, new FluentParserContext().evaluate(RequestContext.class));
		DefaultMapping mapping = new DefaultMapping(source, target);
		parseAndSetMappingConversionExecutor(output, mapping);
		parseAndSetMappingRequired(output, mapping);
		return mapping;
	}

	private void parseAndSetMappingConversionExecutor(AbstractMappingModel mappingModel, DefaultMapping mapping) {
		if (StringUtils.hasText(mappingModel.getType())) {
			Class<?> type = toClass(mappingModel.getType());
			ConversionExecutor typeConverter = new RuntimeBindingConversionExecutor(type, getLocalContext()
					.getConversionService());
			mapping.setTypeConverter(typeConverter);
		}
	}

	private void parseAndSetMappingRequired(AbstractMappingModel mappingModel, DefaultMapping mapping) {
		if (StringUtils.hasText(mappingModel.getRequired())) {
			boolean required = ((Boolean) fromStringTo(Boolean.class).execute(mappingModel.getRequired()));
			mapping.setRequired(required);
		}
	}

	private void parseAndAddViewState(ViewStateModel state, Flow flow) {
		ViewFactory viewFactory = parseViewFactory(state.getView(), state.getId(), false, state.getBinder());
		Boolean redirect = null;
		if (StringUtils.hasText(state.getRedirect())) {
			redirect = (Boolean) fromStringTo(Boolean.class).execute(state.getRedirect());
		}
		boolean popup = false;
		if (StringUtils.hasText(state.getPopup())) {
			popup = ((Boolean) fromStringTo(Boolean.class).execute(state.getPopup()));
		}
		MutableAttributeMap<Object> attributes = parseMetaAttributes(state.getAttributes());
		if (state.getModel() != null) {
			attributes.put(
					"model",
					getLocalContext().getExpressionParser().parseExpression(state.getModel(),
							new FluentParserContext().evaluate(RequestContext.class)));
		}
		if (state.getValidationHints() != null) {
			attributes.put("validationHints",
					getLocalContext().getExpressionParser().parseExpression(state.getValidationHints(),
							new FluentParserContext().evaluate(RequestContext.class)));
		}
		parseAndPutSecured(state.getSecured(), attributes);
		getLocalContext().getFlowArtifactFactory().createViewState(state.getId(), flow,
				parseViewVariables(state.getVars()), parseActions(state.getOnEntryActions()), viewFactory, redirect,
				popup, parseActions(state.getOnRenderActions()), parseTransitions(state.getTransitions()),
				parseExceptionHandlers(state.getExceptionHandlers(), state.getTransitions()),
				parseActions(state.getOnExitActions()), attributes);
	}

	private void parseAndAddActionState(ActionStateModel state, Flow flow) {
		MutableAttributeMap<Object> attributes = parseMetaAttributes(state.getAttributes());
		parseAndPutSecured(state.getSecured(), attributes);
		getLocalContext().getFlowArtifactFactory().createActionState(state.getId(), flow,
				parseActions(state.getOnEntryActions()), parseActions(state.getActions()),
				parseTransitions(state.getTransitions()),
				parseExceptionHandlers(state.getExceptionHandlers(), state.getTransitions()),
				parseActions(state.getOnExitActions()), attributes);
	}

	private void parseAndAddDecisionState(DecisionStateModel state, Flow flow) {
		MutableAttributeMap<Object> attributes = parseMetaAttributes(state.getAttributes());
		parseAndPutSecured(state.getSecured(), attributes);
		getLocalContext().getFlowArtifactFactory().createDecisionState(state.getId(), flow,
				parseActions(state.getOnEntryActions()), parseIfs(state.getIfs()),
				parseExceptionHandlers(state.getExceptionHandlers(), null), parseActions(state.getOnExitActions()),
				attributes);
	}

	private void parseAndAddSubflowState(SubflowStateModel state, Flow flow) {
		MutableAttributeMap<Object> attributes = parseMetaAttributes(state.getAttributes());
		parseAndPutSecured(state.getSecured(), attributes);
		getLocalContext().getFlowArtifactFactory().createSubflowState(state.getId(), flow,
				parseActions(state.getOnEntryActions()), parseSubflowExpression(state.getSubflow()),
				parseSubflowAttributeMapper(state), parseTransitions(state.getTransitions()),
				parseExceptionHandlers(state.getExceptionHandlers(), state.getTransitions()),
				parseActions(state.getOnExitActions()), attributes);
	}

	private void parseAndAddEndState(EndStateModel state, Flow flow) {
		MutableAttributeMap<Object> attributes = parseMetaAttributes(state.getAttributes());
		if (StringUtils.hasText(state.getCommit())) {
			attributes.put("commit", fromStringTo(Boolean.class).execute(state.getCommit()));
		}
		parseAndPutSecured(state.getSecured(), attributes);
		Action finalResponseAction;
		ViewFactory viewFactory = parseViewFactory(state.getView(), state.getId(), true, null);
		if (viewFactory != null) {
			finalResponseAction = new ViewFactoryActionAdapter(viewFactory);
		} else {
			finalResponseAction = null;
		}
		getLocalContext().getFlowArtifactFactory().createEndState(state.getId(), flow,
				parseActions(state.getOnEntryActions()), finalResponseAction,
				parseFlowOutputMapper(state.getOutputs()), parseExceptionHandlers(state.getExceptionHandlers(), null),
				attributes);
	}

	private ViewFactory parseViewFactory(String view, String stateId, boolean endState, BinderModel binderModel) {
		if (!StringUtils.hasText(view)) {
			if (endState) {
				return null;
			} else {
				view = getLocalContext().getViewFactoryCreator().getViewIdByConvention(stateId);
				Expression viewId = getLocalContext().getExpressionParser().parseExpression(view,
						new FluentParserContext().template().evaluate(RequestContext.class).expectResult(String.class));
				return createViewFactory(viewId, binderModel);
			}
		} else if (view.startsWith("externalRedirect:")) {
			String encodedUrl = view.substring("externalRedirect:".length());
			Expression externalUrl = getLocalContext().getExpressionParser().parseExpression(encodedUrl,
					new FluentParserContext().template().evaluate(RequestContext.class).expectResult(String.class));
			return new ActionExecutingViewFactory(new ExternalRedirectAction(externalUrl));
		} else if (view.startsWith("flowRedirect:")) {
			String flowRedirect = view.substring("flowRedirect:".length());
			Expression expression = getLocalContext().getExpressionParser().parseExpression(flowRedirect,
					new FluentParserContext().template().evaluate(RequestContext.class).expectResult(String.class));
			return new ActionExecutingViewFactory(new FlowDefinitionRedirectAction(expression));
		} else {
			Expression viewId = getLocalContext().getExpressionParser().parseExpression(view,
					new FluentParserContext().template().evaluate(RequestContext.class).expectResult(String.class));
			return createViewFactory(viewId, binderModel);
		}
	}

	private ViewFactory createViewFactory(Expression viewId, BinderModel binderModel) {
		BinderConfiguration binderConfiguration = createBinderConfiguration(binderModel);
		return getLocalContext().getViewFactoryCreator().createViewFactory(viewId,
				getLocalContext().getExpressionParser(), getLocalContext().getConversionService(), binderConfiguration,
				getLocalContext().getValidator(), getLocalContext().getValidationHintResolver());
	}

	private BinderConfiguration createBinderConfiguration(BinderModel binderModel) {
		if (binderModel != null && binderModel.getBindings() != null) {
			BinderConfiguration binderConfiguration = new BinderConfiguration();
			List<BindingModel> bindings = binderModel.getBindings();
			for (BindingModel bindingModel : bindings) {
				boolean required = false;
				if (StringUtils.hasText(bindingModel.getRequired())) {
					required = ((Boolean) fromStringTo(Boolean.class).execute(bindingModel.getRequired()));
				}
				Binding binding = new Binding(bindingModel.getProperty(), bindingModel.getConverter(), required);
				binderConfiguration.addBinding(binding);
			}
			return binderConfiguration;
		} else {
			return null;
		}
	}

	private ViewVariable[] parseViewVariables(List<VarModel> vars) {
		if (vars != null && !vars.isEmpty()) {
			List<ViewVariable> variables = new ArrayList<>(vars.size());
			for (VarModel varModel : vars) {
				variables.add(parseViewVariable(varModel));
			}
			return variables.toArray(new ViewVariable[variables.size()]);
		} else {
			return new ViewVariable[0];
		}
	}

	private ViewVariable parseViewVariable(VarModel var) {
		Class<?> clazz = toClass(var.getClassName());
		VariableValueFactory valueFactory = new BeanFactoryVariableValueFactory(clazz, getFlow()
				.getApplicationContext().getAutowireCapableBeanFactory());
		return new ViewVariable(var.getName(), valueFactory);
	}

	private Transition[] parseIfs(List<IfModel> ifModels) {
		if (ifModels != null && !ifModels.isEmpty()) {
			List<Transition> transitions = new ArrayList<>(ifModels.size());
			for (IfModel ifModel : ifModels) {
				transitions.addAll(Arrays.asList(parseIf(ifModel)));
			}
			return transitions.toArray(new Transition[transitions.size()]);
		} else {
			return new Transition[0];
		}
	}

	private Transition[] parseIf(IfModel ifModel) {
		Transition thenTransition = parseThen(ifModel);
		if (StringUtils.hasText(ifModel.getElse())) {
			Transition elseTransition = parseElse(ifModel);
			return new Transition[] { thenTransition, elseTransition };
		} else {
			return new Transition[] { thenTransition };
		}
	}

	private Transition parseThen(IfModel ifModel) {
		Expression test = getLocalContext().getExpressionParser().parseExpression(ifModel.getTest(),
				new FluentParserContext().evaluate(RequestContext.class).expectResult(Boolean.class));
		TransitionCriteria matchingCriteria = new DefaultTransitionCriteria(test);
		TargetStateResolver targetStateResolver = (TargetStateResolver) fromStringTo(TargetStateResolver.class)
				.execute(ifModel.getThen());
		return getLocalContext().getFlowArtifactFactory().createTransition(targetStateResolver, matchingCriteria, null,
				null);
	}

	private Transition parseElse(IfModel ifModel) {
		TargetStateResolver stateResolver = (TargetStateResolver) fromStringTo(TargetStateResolver.class).execute(
				ifModel.getElse());
		return getLocalContext().getFlowArtifactFactory().createTransition(stateResolver, null, null, null);
	}

	private Expression parseSubflowExpression(String subflow) {
		Expression subflowId = getLocalContext().getExpressionParser().parseExpression(subflow,
				new FluentParserContext().template().evaluate(RequestContext.class).expectResult(String.class));
		return new SubflowExpression(subflowId, getLocalContext().getFlowDefinitionLocator());
	}

	private SubflowAttributeMapper parseSubflowAttributeMapper(SubflowStateModel state) {
		if (StringUtils.hasText(state.getSubflowAttributeMapper())) {
			String beanId = state.getSubflowAttributeMapper();
			return getLocalContext().getApplicationContext().getBean(beanId, SubflowAttributeMapper.class);
		} else {
			Mapper inputMapper = parseSubflowInputMapper(state.getInputs());
			Mapper outputMapper = parseSubflowOutputMapper(state.getOutputs());
			return new GenericSubflowAttributeMapper(inputMapper, outputMapper);
		}
	}

	private FlowExecutionExceptionHandler[] parseExceptionHandlers(List<ExceptionHandlerModel> modelExceptionHandlers,
			List<TransitionModel> modelTransitions) {
		FlowExecutionExceptionHandler[] transitionExecutingHandlers = parseTransitionExecutingExceptionHandlers(modelTransitions);
		FlowExecutionExceptionHandler[] customHandlers = parseCustomExceptionHandlers(modelExceptionHandlers);
		FlowExecutionExceptionHandler[] exceptionHandlers = new FlowExecutionExceptionHandler[transitionExecutingHandlers.length
				+ customHandlers.length];
		System.arraycopy(transitionExecutingHandlers, 0, exceptionHandlers, 0, transitionExecutingHandlers.length);
		System.arraycopy(customHandlers, 0, exceptionHandlers, transitionExecutingHandlers.length,
				customHandlers.length);
		return exceptionHandlers;
	}

	private FlowExecutionExceptionHandler[] parseTransitionExecutingExceptionHandlers(
			List<TransitionModel> transitionModels) {
		if (transitionModels != null && !transitionModels.isEmpty()) {
			List<FlowExecutionExceptionHandler> exceptionHandlers = new ArrayList<>(
					transitionModels.size());
			for (TransitionModel model : transitionModels) {
				if (StringUtils.hasText(model.getOnException())) {
					if (model.getSecured() != null) {
						throw new FlowBuilderException("Exception based transitions cannot be secured");
					}
					exceptionHandlers.add(parseTransitionExecutingExceptionHandler(model));
				}
			}
			return exceptionHandlers.toArray(new FlowExecutionExceptionHandler[exceptionHandlers.size()]);
		} else {
			return new FlowExecutionExceptionHandler[0];
		}
	}

	private FlowExecutionExceptionHandler parseTransitionExecutingExceptionHandler(TransitionModel transition) {
		TransitionExecutingFlowExecutionExceptionHandler handler = new TransitionExecutingFlowExecutionExceptionHandler();
		Class<Throwable> exceptionClass = toClass(transition.getOnException(), Throwable.class);
		TargetStateResolver targetStateResolver = (TargetStateResolver) fromStringTo(TargetStateResolver.class)
				.execute(transition.getTo());
		handler.add(exceptionClass, targetStateResolver);
		handler.getActionList().addAll(parseActions(transition.getActions()));
		return handler;
	}

	private FlowExecutionExceptionHandler[] parseCustomExceptionHandlers(
			List<ExceptionHandlerModel> exceptionHandlerModels) {
		if (exceptionHandlerModels != null && !exceptionHandlerModels.isEmpty()) {
			List<FlowExecutionExceptionHandler> exceptionHandlers = new ArrayList<>(
					exceptionHandlerModels.size());
			for (ExceptionHandlerModel exceptionHandlerModel : exceptionHandlerModels) {
				exceptionHandlers.add(parseCustomExceptionHandler(exceptionHandlerModel));
			}
			return exceptionHandlers.toArray(new FlowExecutionExceptionHandler[exceptionHandlers.size()]);
		} else {
			return new FlowExecutionExceptionHandler[0];
		}
	}

	private FlowExecutionExceptionHandler parseCustomExceptionHandler(ExceptionHandlerModel exceptionHandler) {
		return getLocalContext().getApplicationContext().getBean(exceptionHandler.getBean(),
				FlowExecutionExceptionHandler.class);
	}

	private Transition[] parseTransitions(List<TransitionModel> transitionModels) {
		if (transitionModels != null && !transitionModels.isEmpty()) {
			List<Transition> transitions = new ArrayList<>(transitionModels.size());
			if (transitionModels != null) {
				for (TransitionModel transition : transitionModels) {
					if (!StringUtils.hasText(transition.getOnException())) {
						transitions.add(parseTransition(transition));
					}
				}
			}
			return transitions.toArray(new Transition[transitions.size()]);
		} else {
			return new Transition[0];
		}
	}

	private Transition parseTransition(TransitionModel transition) {
		TransitionCriteria matchingCriteria = (TransitionCriteria) fromStringTo(TransitionCriteria.class).execute(
				transition.getOn());
		TargetStateResolver stateResolver = (TargetStateResolver) fromStringTo(TargetStateResolver.class).execute(
				transition.getTo());
		TransitionCriteria executionCriteria = TransitionCriteriaChain.criteriaChainFor(parseActions(transition
				.getActions()));
		MutableAttributeMap<Object> attributes = parseMetaAttributes(transition.getAttributes());
		if (StringUtils.hasText(transition.getBind())) {
			attributes.put("bind", fromStringTo(Boolean.class).execute(transition.getBind()));
		}
		if (StringUtils.hasText(transition.getValidate())) {
			attributes.put("validate", fromStringTo(Boolean.class).execute(transition.getValidate()));
		}
		if (StringUtils.hasText(transition.getValidationHints())) {
			attributes.put("validationHints",
					getLocalContext().getExpressionParser().parseExpression(transition.getValidationHints(),
							new FluentParserContext().evaluate(RequestContext.class)));
		}
		if (StringUtils.hasText(transition.getHistory())) {
			attributes.put("history", fromStringTo(History.class).execute(transition.getHistory().toUpperCase()));
		}
		parseAndPutSecured(transition.getSecured(), attributes);
		return getLocalContext().getFlowArtifactFactory().createTransition(stateResolver, matchingCriteria,
				executionCriteria, attributes);
	}

	private Action[] parseActions(List<AbstractActionModel> actionModels) {
		if (actionModels != null && !actionModels.isEmpty()) {
			List<AnnotatedAction> actions = new ArrayList<>(actionModels.size());
			for (AbstractActionModel actionModel : actionModels) {
				Action action;
				if (actionModel instanceof EvaluateModel) {
					action = parseEvaluateAction((EvaluateModel) actionModel);
				} else if (actionModel instanceof RenderModel) {
					action = parseRenderAction((RenderModel) actionModel);
				} else if (actionModel instanceof SetModel) {
					action = parseSetAction((SetModel) actionModel);
				} else {
					action = null;
				}
				if (action != null) {
					AnnotatedAction annotatedAction = new AnnotatedAction(action);
					annotatedAction.getAttributes().putAll(parseMetaAttributes(actionModel.getAttributes()));
					actions.add(annotatedAction);
				}
			}
			return actions.toArray(new Action[actions.size()]);
		} else {
			return new Action[0];
		}
	}

	private Action parseEvaluateAction(EvaluateModel evaluate) {
		FluentParserContext evaluateExpressionParserContext = new FluentParserContext().evaluate(RequestContext.class);
		if (StringUtils.hasText(evaluate.getResultType())) {
			evaluateExpressionParserContext.expectResult(toClass(evaluate.getResultType()));
		}
		Expression evaluateExpression = getLocalContext().getExpressionParser().parseExpression(
				evaluate.getExpression(), evaluateExpressionParserContext);
		Expression resultExpression = null;
		if (StringUtils.hasText(evaluate.getResult())) {
			resultExpression = getLocalContext().getExpressionParser().parseExpression(evaluate.getResult(),
					new FluentParserContext().evaluate(RequestContext.class));
		}
		return new EvaluateAction(evaluateExpression, resultExpression);
	}

	private Action parseRenderAction(RenderModel render) {
		String[] fragmentExpressionStrings = StringUtils.commaDelimitedListToStringArray(render.getFragments());
		fragmentExpressionStrings = StringUtils.trimArrayElements(fragmentExpressionStrings);
		ParserContext context = new FluentParserContext().template().evaluate(RequestContext.class)
				.expectResult(String.class);
		Expression[] fragments = new Expression[fragmentExpressionStrings.length];
		for (int i = 0; i < fragmentExpressionStrings.length; i++) {
			String fragment = fragmentExpressionStrings[i];
			fragments[i] = getLocalContext().getExpressionParser().parseExpression(fragment, context);
		}
		return new RenderAction(fragments);
	}

	private Action parseSetAction(SetModel set) {
		Expression nameExpression = getLocalContext().getExpressionParser().parseExpression(set.getName(),
				new FluentParserContext().evaluate(RequestContext.class));
		FluentParserContext valueParserContext = new FluentParserContext().evaluate(RequestContext.class);
		if (StringUtils.hasText(set.getType())) {
			valueParserContext.expectResult(toClass(set.getType()));
		}
		Expression valueExpression = getLocalContext().getExpressionParser().parseExpression(set.getValue(),
				valueParserContext);
		return new SetAction(nameExpression, valueExpression);
	}

	private MutableAttributeMap<Object> parseMetaAttributes(List<AttributeModel> attributeModels) {
		if (attributeModels != null && !attributeModels.isEmpty()) {
			LocalAttributeMap<Object> attributes = new LocalAttributeMap<>();
			for (AttributeModel attributeModel : attributeModels) {
				parseAndPutMetaAttribute(attributeModel, attributes);
			}
			return attributes;
		} else {
			return new LocalAttributeMap<>();
		}
	}

	private void parseAndPutMetaAttribute(AttributeModel attribute, MutableAttributeMap<Object> attributes) {
		String name = attribute.getName();
		String value = attribute.getValue();
		attributes.put(name, parseAttributeValueIfNecessary(attribute, value));
	}

	private Object parseAttributeValueIfNecessary(AttributeModel attribute, String stringValue) {
		if (StringUtils.hasText(attribute.getType())) {
			Class<?> targetClass = toClass(attribute.getType());
			return fromStringTo(targetClass).execute(stringValue);
		} else {
			return stringValue;
		}
	}

	private void parseAndPutPersistenceContext(PersistenceContextModel persistenceContext,
			MutableAttributeMap<Object> attributes) {
		if (persistenceContext != null) {
			attributes.put("persistenceContext", true);
		}
	}

	private void parseAndPutSecured(SecuredModel secured, MutableAttributeMap<Object> attributes) {
		if (secured != null) {
			SecurityRule rule = new SecurityRule();
			rule.setAttributes(SecurityRule.commaDelimitedListToSecurityAttributes(secured.getAttributes()));
			String comparisonType = secured.getMatch();
			if ("any".equals(comparisonType)) {
				rule.setComparisonType(SecurityRule.COMPARISON_ANY);
			} else if ("all".equals(comparisonType)) {
				rule.setComparisonType(SecurityRule.COMPARISON_ALL);
			} else {
				// default to any
				rule.setComparisonType(SecurityRule.COMPARISON_ANY);
			}
			attributes.put(SecurityRule.SECURITY_ATTRIBUTE_NAME, rule);
		}
	}

	private ConversionExecutor fromStringTo(Class<?> targetType) throws ConversionExecutionException {
		return getLocalContext().getConversionService().getConversionExecutor(String.class, targetType);
	}

	private Class<?> toClass(String name) {
		Class<?> clazz = getLocalContext().getConversionService().getClassForAlias(name);
		if (clazz != null) {
			return clazz;
		} else {
			try {
				ClassLoader classLoader = getLocalContext().getApplicationContext().getClassLoader();
				return ClassUtils.forName(name, classLoader);
			} catch (ClassNotFoundException e) {
				throw new IllegalArgumentException("Unable to load class '" + name + "'");
			}
		}
	}

	@SuppressWarnings("unchecked")
	private <T> Class<T> toClass(String name, Class<T> superType) {
		Class<?> clazz = toClass(name);
		Assert.isAssignable(superType, clazz);
		return (Class<T>) clazz;
	}

	public String toString() {
		return new ToStringCreator(this).append("flowModelResource", flowModelHolder.getFlowModelResource()).toString();
	}

}
