/**
 * 
 */
package org.apache.taverna.scufl2.validation.structural;
/*
 *
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.
 *
*/


import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.apache.taverna.scufl2.api.container.WorkflowBundle;
import org.apache.taverna.scufl2.api.core.DataLink;
import org.apache.taverna.scufl2.api.core.Processor;
import org.apache.taverna.scufl2.api.core.Workflow;
import org.apache.taverna.scufl2.api.iterationstrategy.CrossProduct;
import org.apache.taverna.scufl2.api.iterationstrategy.DotProduct;
import org.apache.taverna.scufl2.api.iterationstrategy.IterationStrategyNode;
import org.apache.taverna.scufl2.api.iterationstrategy.IterationStrategyStack;
import org.apache.taverna.scufl2.api.iterationstrategy.IterationStrategyTopNode;
import org.apache.taverna.scufl2.api.iterationstrategy.PortNode;
import org.apache.taverna.scufl2.api.port.InputProcessorPort;
import org.apache.taverna.scufl2.api.port.InputWorkflowPort;
import org.apache.taverna.scufl2.api.port.OutputProcessorPort;
import org.apache.taverna.scufl2.api.port.OutputWorkflowPort;
import org.apache.taverna.scufl2.validation.Validator;


/**
 * @author alanrw
 */
public final class StructuralValidator implements
		Validator<StructuralValidationListener> {
	private static enum ProcessorCheckStatus {
		COULD_NOT_CHECK, PASSED, FAILED
	};

	protected ThreadLocal<ValidatorState> validatorState = new ThreadLocal<ValidatorState>() {
		@Override
		protected ValidatorState initialValue() {
			return new ValidatorState();
		};
	};

	public void checkStructure(WorkflowBundle bundle,
			StructuralValidationListener eventListener) {
		validatorState.get().setEventListener(eventListener);
		validatorState.get().setWorkflowBundle(bundle);
		for (Workflow w : bundle.getWorkflows())
			checkStructure(w);
	}

	public ValidatorState getValidatorState() {
		return validatorState.get();
	}

	public void checkStructure(Workflow workflow,
			StructuralValidationListener eventListener) {
		validatorState.get().setEventListener(eventListener);
		checkStructure(workflow);
	}

	private void checkStructure(Workflow workflow) {
		validatorState.get().setWorkflow(workflow);
		validateWorkflow();
	}

	private void validateWorkflow() {
		clearWorkflowData();
		rememberDataLinkConnections();
		inheritDataLinkDepthsFromWorkflowInputPorts();
		checkProcessors();
		checkWorkflowOutputPorts();
		checkCompleteness();
	}

	private void clearWorkflowData() {
		validatorState.get().clearWorkflowData();
	}

	private void checkCompleteness() {
		Workflow w = validatorState.get().getWorkflow();
		if (w.getProcessors().isEmpty() && w.getOutputPorts().isEmpty()) {
			validatorState.get().getEventListener().incompleteWorkflow(w);
			// validatorState.get().addIncompleteWorkflow(w);
		}
	}

	private void checkProcessors() {
		Workflow workflow = validatorState.get().getWorkflow();
		List<Processor> failedProcessors = new ArrayList<>();
		List<Processor> unresolvedProcessors = new ArrayList<>();
		unresolvedProcessors.addAll(workflow.getProcessors());

		boolean finished = false;
		while (!finished) {
			// We're finished unless something happens later
			finished = true;
			/*
			 * Keep a list of processors to remove from the unresolved list
			 * because they've been resolved properly
			 */
			List<Processor> removeValidated = new ArrayList<>();
			// Keep another list of those that have failed
			List<Processor> removeFailed = new ArrayList<>();

			for (Processor p : unresolvedProcessors) {
				validatorState.get().setProcessor(p);
				ProcessorCheckStatus entityValid = checkProcessor();
				switch (entityValid) {
				case PASSED:
					validatorState.get().getEventListener().passedProcessor(p);
					// validatorState.get().addPassedProcessor(p);
					removeValidated.add(p);
					break;
				case FAILED:
					validatorState.get().getEventListener()
							.failedProcessorAdded(p);
					// validatorState.get().failCurrentProcessor();
					removeFailed.add(p);
					break;
				case COULD_NOT_CHECK:
					break;
				}
			}

			/*
			 * Remove validated and failed items from the pending lists. If
			 * anything was removed because it validated okay then we're not
			 * finished yet and should reset the boolean finished flag
			 */
			if (!removeValidated.isEmpty()) {
				unresolvedProcessors.removeAll(removeValidated);
				finished = false;
			}
			unresolvedProcessors.removeAll(failedProcessors);
		}
		for (Processor p : unresolvedProcessors)
			validatorState.get().getEventListener().unresolvedProcessorAdded(p);
		// validatorState.get().addUnresolvedProcessors(unresolvedProcessors);
	}

	private void checkWorkflowOutputPorts() {
		for (OutputWorkflowPort owp : validatorState.get().getWorkflow()
				.getOutputPorts()) {
			DataLink mainIncomingLink = validatorState.get()
					.getMainIncomingDataLink(owp);
			if (mainIncomingLink == null) {
				validatorState.get().getEventListener()
						.missingMainIncomingLink(owp);
				// validatorState.get().addMissingMainIncomingDataLink(owp);
			}
			Integer dataLinkResolvedDepth = validatorState.get()
					.getDataLinkResolvedDepth(mainIncomingLink);
			if (dataLinkResolvedDepth == null) {
				validatorState.get().getEventListener().unresolvedOutput(owp);
				// validatorState.get().addUnresolvedOutput(owp);
				return;
			}

			// int granularDepth =
			// mainIncomingLink.getSource().getGranularDepth();
			Integer portResolvedDepth = dataLinkResolvedDepth
					+ (validatorState.get().isMergedPort(owp) ? 1 : 0);
			validatorState.get().getEventListener()
					.depthResolution(owp, portResolvedDepth);
			validatorState.get().setPortResolvedDepth(owp, portResolvedDepth);
			// dopi.setDepths(resolvedDepth, granularDepth);
		}
	}

	private ProcessorCheckStatus checkProcessor() {
		Processor p = validatorState.get().getProcessor();
		Map<InputProcessorPort, Integer> inputDepths = new HashMap<>();
		// Check whether all our input ports have inbound links
		for (InputProcessorPort input : p.getInputPorts()) {
			DataLink mainIncomingLink = validatorState.get()
					.getMainIncomingDataLink(input);
			if (mainIncomingLink == null) {
				validatorState.get().getEventListener()
						.missingMainIncomingLink(input);
				// validatorState.get().addMissingMainIncomingDataLink(input);
				return ProcessorCheckStatus.FAILED;
			}
			Integer dataLinkResolvedDepth = validatorState.get()
					.getDataLinkResolvedDepth(mainIncomingLink);
			if (dataLinkResolvedDepth == null)
				return ProcessorCheckStatus.COULD_NOT_CHECK;

			Integer resolvedDepth = dataLinkResolvedDepth
					+ (validatorState.get().isMergedPort(input) ? 1 : 0);
			validatorState.get().getEventListener()
					.depthResolution(input, resolvedDepth);
			validatorState.get().setPortResolvedDepth(input, resolvedDepth);
			inputDepths.put(input, resolvedDepth);
		}

		Integer resultWrappingDepth = calculateResultWrappingDepth(inputDepths);
		if (resultWrappingDepth == null)
			return ProcessorCheckStatus.FAILED;

		for (OutputProcessorPort output : p.getOutputPorts()) {
			Integer portDepth = output.getDepth();
			Integer resolvedDepth = portDepth + resultWrappingDepth;
			validatorState.get().getEventListener()
					.depthResolution(output, resolvedDepth);
			validatorState.get().setPortResolvedDepth(output, resolvedDepth);
			for (DataLink dl : validatorState.get()
					.getOutgoingDataLinks(output)) {
				validatorState.get().getEventListener()
						.depthResolution(dl, resolvedDepth);
				validatorState.get()
						.setDataLinkResolvedDepth(dl, resolvedDepth);
			}
		}

		return ProcessorCheckStatus.PASSED;
	}

	Integer calculateResultWrappingDepth(
			Map<InputProcessorPort, Integer> inputDepths) {
		Processor p = validatorState.get().getProcessor();
		IterationStrategyStack iss = p.getIterationStrategyStack();
		if (iss == null) {
			validatorState.get().getEventListener()
					.missingIterationStrategyStack(p);
			// validatorState.get().addMissingIterationStrategyStack(p);
			validatorState.get().getEventListener().failedProcessorAdded(p);
			// validatorState.get().failCurrentProcessor();
			return null;
		}

		if (iss.isEmpty())
			return 0;
		IterationStrategyTopNode iterationStrategyTopNode = iss.get(0);
		Integer depth = getIterationDepth(iterationStrategyTopNode, inputDepths);
		if (depth == null)
			return null;
		IterationStrategyTopNode previousNode = iterationStrategyTopNode;
		for (int index = 1; index < iss.size(); index++) {
			/*
			 * Construct the input depths for the staged iteration strategies
			 * after the first one by looking at the previous iteration
			 * strategy's desired cardinalities on its input ports.
			 */
			Map<InputProcessorPort, Integer> stagedInputDepths = getDesiredCardinalities(previousNode);
			iterationStrategyTopNode = iss.get(index);
			Integer nodeDepth = getIterationDepth(iterationStrategyTopNode,
					stagedInputDepths);
			if (nodeDepth == null)
				return null;
			depth += nodeDepth;
			previousNode = iterationStrategyTopNode;
		}
		return depth;
	}

	private Map<InputProcessorPort, Integer> getDesiredCardinalities(
			IterationStrategyTopNode iterationStrategyTopNode) {
		Map<InputProcessorPort, Integer> desiredCardinalities = new HashMap<>();
		fillInDesiredCardinalities(iterationStrategyTopNode,
				desiredCardinalities);
		return desiredCardinalities;
	}

	private void fillInDesiredCardinalities(
			IterationStrategyNode iterationStrategyNode,
			Map<InputProcessorPort, Integer> desiredCardinalities) {
		if (iterationStrategyNode instanceof IterationStrategyTopNode)
			for (IterationStrategyNode subNode : (IterationStrategyTopNode) iterationStrategyNode)
				fillInDesiredCardinalities(subNode, desiredCardinalities);
		else if (iterationStrategyNode instanceof PortNode) {
			PortNode portNode = (PortNode) iterationStrategyNode;
			desiredCardinalities.put(portNode.getInputProcessorPort(),
					portNode.getDesiredDepth());
		}
	}

	public Integer getIterationDepth(
			IterationStrategyNode iterationStrategyNode,
			Map<InputProcessorPort, Integer> inputDepths) {
		if (iterationStrategyNode instanceof CrossProduct)
			return getCrossProductIterationDepth(
					(CrossProduct) iterationStrategyNode, inputDepths);
		if (iterationStrategyNode instanceof DotProduct)
			return getDotProductIterationDepth(
					(DotProduct) iterationStrategyNode, inputDepths);
		if (iterationStrategyNode instanceof PortNode)
			return getPortNodeIterationDepth((PortNode) iterationStrategyNode,
					inputDepths);
		validatorState.get().getEventListener()
				.unrecognizedIterationStrategyNode(iterationStrategyNode);
		// validatorState.get().addUnrecognizedIterationStrategyNode(iterationStrategyNode);
		validatorState.get().getEventListener()
				.failedProcessorAdded(validatorState.get().getProcessor());
		// validatorState.get().failCurrentProcessor();
		return null;
	}

	private Integer getPortNodeIterationDepth(PortNode portNode,
			Map<InputProcessorPort, Integer> inputDepths) {
		int myInputDepth = inputDepths.get(portNode.getInputProcessorPort());
		int depthMismatch = myInputDepth - portNode.getDesiredDepth();
		return (depthMismatch > 0 ? depthMismatch : 0);
	}

	public Integer getDotProductIterationDepth(DotProduct dotProduct,
			Map<InputProcessorPort, Integer> inputDepths) {
		if (dotProduct.isEmpty()) {
			validatorState.get().getEventListener().emptyDotProduct(dotProduct);
			// validatorState.get().addEmptyDotProduct(dotProduct);
			validatorState.get().getEventListener()
					.failedProcessorAdded(validatorState.get().getProcessor());
			// validatorState.get().failCurrentProcessor();
			return null;
		}
		Integer depth = getIterationDepth(dotProduct.get(0), inputDepths);
		if (depth == null)
			return null;
		for (IterationStrategyNode childNode : dotProduct) {
			Integer childNodeDepth = getIterationDepth(childNode, inputDepths);
			if (childNodeDepth == null)
				return null;
			if (!childNodeDepth.equals(depth)) {
				validatorState.get().getEventListener()
						.dotProductIterationMismatch(dotProduct);
				// validatorState.get().addDotProductIterationMismatch(dotProduct);
				validatorState
						.get()
						.getEventListener()
						.failedProcessorAdded(
								validatorState.get().getProcessor());
				// validatorState.get().failCurrentProcessor();
				return null;
			}
		}
		return depth;
	}

	private Integer getCrossProductIterationDepth(CrossProduct crossProduct,
			Map<InputProcessorPort, Integer> inputDepths) {
		if (crossProduct.isEmpty()) {
			validatorState.get().getEventListener()
					.emptyCrossProduct(crossProduct);
			// validatorState.get().addEmptyCrossProduct(crossProduct);
			validatorState.get().getEventListener()
					.failedProcessorAdded(validatorState.get().getProcessor());
			// validatorState.get().failCurrentProcessor();
			return null;
		}
		int temp = 0;
		for (IterationStrategyNode child : crossProduct) {
			Integer childNodeDepth = getIterationDepth(child, inputDepths);
			if (childNodeDepth == null)
				return null;
			temp += childNodeDepth;
		}
		return temp;
	}

	private void rememberDataLinkConnections() {
		Workflow workflow = validatorState.get().getWorkflow();
		for (DataLink dl : workflow.getDataLinks()) {
			validatorState.get().getEventListener().dataLinkSender(dl);
			validatorState.get().rememberDataLinkSender(dl);
			validatorState.get().getEventListener().dataLinkReceiver(dl);
			validatorState.get().rememberDataLinkReceiver(dl);
		}
	}

	private void inheritDataLinkDepthsFromWorkflowInputPorts() {
		Workflow workflow = validatorState.get().getWorkflow();
		for (InputWorkflowPort iwp : workflow.getInputPorts()) {
			Integer iwpDepth = iwp.getDepth();
			validatorState.get().getEventListener()
					.depthResolution(iwp, iwpDepth);
			validatorState.get().setPortResolvedDepth(iwp, iwpDepth);
			for (DataLink dl : validatorState.get().getOutgoingDataLinks(iwp)) {
				validatorState.get().getEventListener()
						.depthResolution(dl, iwpDepth);
				validatorState.get().setDataLinkResolvedDepth(dl, iwpDepth);
			}
		}
	}

	@Override
	public StructuralValidationListener validate(WorkflowBundle workflowBundle) {
		StructuralValidationListener l = new ReportStructuralValidationListener();
		this.checkStructure(workflowBundle, l);
		return l;
	}
}