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package com.sun.xml.internal.ws.policy.sourcemodel;

import java.util.ArrayList;

import java.util.Collection;

import java.util.Collections;

import java.util.HashMap;

import java.util.LinkedList;

import java.util.List;

import java.util.Map;

import java.util.Queue;

import com.sun.xml.internal.ws.policy.AssertionSet;

import com.sun.xml.internal.ws.policy.Policy;

import com.sun.xml.internal.ws.policy.PolicyAssertion;

import com.sun.xml.internal.ws.policy.PolicyException;

import com.sun.xml.internal.ws.policy.privateutil.LocalizationMessages;

import com.sun.xml.internal.ws.policy.privateutil.PolicyLogger;

import com.sun.xml.internal.ws.policy.privateutil.PolicyUtils;

import com.sun.xml.internal.ws.policy.spi.AssertionCreationException;

import com.sun.xml.internal.ws.policy.spi.PolicyAssertionCreator;

/**

 * This class provides a method for translating a {@link PolicySourceModel} structure to a normalized {@link Policy} expression.

 * The resulting Policy is disconnected from its model, thus any additional changes in the model will have no effect on the Policy

 * expression.

 *

 * @author Marek Potociar

 * @author Fabian Ritzmann

 */

public class PolicyModelTranslator {

    private static final class ContentDecomposition {

        final List<Collection<ModelNode>> exactlyOneContents = new LinkedList<Collection<ModelNode>>();

        final List<ModelNode> assertions = new LinkedList<ModelNode>();

        void reset() {

            exactlyOneContents.clear();

            assertions.clear();

        }

    }

    private static final class RawAssertion {

        ModelNode originalNode; // used to initialize nestedPolicy and nestedAssertions in the constructor of RawAlternative

        Collection<RawAlternative> nestedAlternatives = null;

        final Collection<ModelNode> parameters;

        RawAssertion(ModelNode originalNode, Collection<ModelNode> parameters) {

            this.parameters = parameters;

            this.originalNode = originalNode;

        }

    }

    private static final class RawAlternative {

        private static final PolicyLogger LOGGER = PolicyLogger.getLogger(PolicyModelTranslator.RawAlternative.class);

        final List<RawPolicy> allNestedPolicies = new LinkedList<RawPolicy>(); // used to track the nested policies which need to be normalized

        final Collection<RawAssertion> nestedAssertions;

        RawAlternative(Collection<ModelNode> assertionNodes) throws PolicyException {

            this.nestedAssertions = new LinkedList<RawAssertion>();

            for (ModelNode node : assertionNodes) {

                RawAssertion assertion = new RawAssertion(node, new LinkedList<ModelNode>());

                nestedAssertions.add(assertion);

                for (ModelNode assertionNodeChild : assertion.originalNode.getChildren()) {

                    switch (assertionNodeChild.getType()) {

                        case ASSERTION_PARAMETER_NODE:

                            assertion.parameters.add(assertionNodeChild);

                            break;

                        case POLICY:

                        case POLICY_REFERENCE:

                            if (assertion.nestedAlternatives == null) {

                                assertion.nestedAlternatives = new LinkedList<RawAlternative>();

                                RawPolicy nestedPolicy;

                                if (assertionNodeChild.getType() == ModelNode.Type.POLICY) {

                                    nestedPolicy = new RawPolicy(assertionNodeChild, assertion.nestedAlternatives);

                                } else {

                                    nestedPolicy = new RawPolicy(getReferencedModelRootNode(assertionNodeChild), assertion.nestedAlternatives);

                                }

                                this.allNestedPolicies.add(nestedPolicy);

                            } else {

                                throw LOGGER.logSevereException(new PolicyException(LocalizationMessages.WSP_0006_UNEXPECTED_MULTIPLE_POLICY_NODES()));

                            }

                            break;

                        default:

                            throw LOGGER.logSevereException(new PolicyException(LocalizationMessages.WSP_0008_UNEXPECTED_CHILD_MODEL_TYPE(assertionNodeChild.getType())));

                    }

                }

            }

        }

    }

    private static final class RawPolicy {

        final Collection<ModelNode> originalContent;

        final Collection<RawAlternative> alternatives;

        RawPolicy(ModelNode policyNode, Collection<RawAlternative> alternatives) {

            originalContent = policyNode.getChildren();

            this.alternatives = alternatives;

        }

    }

    private static final PolicyLogger LOGGER = PolicyLogger.getLogger(PolicyModelTranslator.class);

    private static final PolicyAssertionCreator defaultCreator = new DefaultPolicyAssertionCreator();

    private final Map<String, PolicyAssertionCreator> assertionCreators;

    private PolicyModelTranslator() throws PolicyException {

        this(null);

    }

    protected PolicyModelTranslator(final Collection<PolicyAssertionCreator> creators) throws PolicyException {

        LOGGER.entering(creators);

        final Collection<PolicyAssertionCreator> allCreators = new LinkedList<PolicyAssertionCreator>();

        final PolicyAssertionCreator[] discoveredCreators = PolicyUtils.ServiceProvider.load(PolicyAssertionCreator.class);

        for (PolicyAssertionCreator creator : discoveredCreators) {

            allCreators.add(creator);

        }

        if (creators != null) {

            for (PolicyAssertionCreator creator : creators) {

                allCreators.add(creator);

            }

        }

        final Map<String, PolicyAssertionCreator> pacMap = new HashMap<String, PolicyAssertionCreator>();

        for (PolicyAssertionCreator creator : allCreators) {

            final String[] supportedURIs = creator.getSupportedDomainNamespaceURIs();

            final String creatorClassName = creator.getClass().getName();

            if (supportedURIs == null || supportedURIs.length == 0) {

                LOGGER.warning(LocalizationMessages.WSP_0077_ASSERTION_CREATOR_DOES_NOT_SUPPORT_ANY_URI(creatorClassName));

                continue;

            }

            for (String supportedURI : supportedURIs) {

                LOGGER.config(LocalizationMessages.WSP_0078_ASSERTION_CREATOR_DISCOVERED(creatorClassName, supportedURI));

                if (supportedURI == null || supportedURI.length() == 0) {

                    throw LOGGER.logSevereException(new PolicyException(

                            LocalizationMessages.WSP_0070_ERROR_REGISTERING_ASSERTION_CREATOR(creatorClassName)));

                }

                final PolicyAssertionCreator oldCreator = pacMap.put(supportedURI, creator);

                if (oldCreator != null) {

                    throw LOGGER.logSevereException(new PolicyException(

                            LocalizationMessages.WSP_0071_ERROR_MULTIPLE_ASSERTION_CREATORS_FOR_NAMESPACE(

                            supportedURI, oldCreator.getClass().getName(), creator.getClass().getName())));

                }

            }

        }

        this.assertionCreators = Collections.unmodifiableMap(pacMap);

        LOGGER.exiting();

    }

    /**

     * Method returns thread-safe policy model translator instance.

     *

     * This method is only intended to be used by code that has no dependencies on

     * JAX-WS. Otherwise use com.sun.xml.internal.ws.policy.api.ModelTranslator.

     *

     * @return A policy model translator instance.

     * @throws PolicyException If instantiating a PolicyAssertionCreator failed.

     */

    public static PolicyModelTranslator getTranslator() throws PolicyException {

        return new PolicyModelTranslator();

    }

    /**

     * The method translates {@link PolicySourceModel} structure into normalized {@link Policy} expression. The resulting Policy

     * is disconnected from its model, thus any additional changes in model will have no effect on the Policy expression.

     *

     * @param model the model to be translated into normalized policy expression. Must not be {@code null}.

     * @return translated policy expression in it's normalized form.

     * @throws PolicyException in case of translation failure

     */

    public Policy translate(final PolicySourceModel model) throws PolicyException {

        LOGGER.entering(model);

        if (model == null) {

            throw LOGGER.logSevereException(new PolicyException(LocalizationMessages.WSP_0043_POLICY_MODEL_TRANSLATION_ERROR_INPUT_PARAM_NULL()));

        }

        PolicySourceModel localPolicyModelCopy;

        try {

            localPolicyModelCopy = model.clone();

        } catch (CloneNotSupportedException e) {

            throw LOGGER.logSevereException(new PolicyException(LocalizationMessages.WSP_0016_UNABLE_TO_CLONE_POLICY_SOURCE_MODEL(), e));

        }

        final String policyId = localPolicyModelCopy.getPolicyId();

        final String policyName = localPolicyModelCopy.getPolicyName();

        final Collection<AssertionSet> alternatives = createPolicyAlternatives(localPolicyModelCopy);

        LOGGER.finest(LocalizationMessages.WSP_0052_NUMBER_OF_ALTERNATIVE_COMBINATIONS_CREATED(alternatives.size()));

        Policy policy = null;

        if (alternatives.size() == 0) {

            policy = Policy.createNullPolicy(model.getNamespaceVersion(), policyName, policyId);

            LOGGER.finest(LocalizationMessages.WSP_0055_NO_ALTERNATIVE_COMBINATIONS_CREATED());

        } else if (alternatives.size() == 1 && alternatives.iterator().next().isEmpty()) {

            policy = Policy.createEmptyPolicy(model.getNamespaceVersion(), policyName, policyId);

            LOGGER.finest(LocalizationMessages.WSP_0026_SINGLE_EMPTY_ALTERNATIVE_COMBINATION_CREATED());

        } else {

            policy = Policy.createPolicy(model.getNamespaceVersion(), policyName, policyId, alternatives);

            LOGGER.finest(LocalizationMessages.WSP_0057_N_ALTERNATIVE_COMBINATIONS_M_POLICY_ALTERNATIVES_CREATED(alternatives.size(), policy.getNumberOfAssertionSets()));

        }

        LOGGER.exiting(policy);

        return policy;

    }

    /**

     * Method creates policy alternatives according to provided model. The model structure is modified in the process.

     *

     * @return created policy alternatives resulting from policy source model.

     */

    private Collection<AssertionSet> createPolicyAlternatives(final PolicySourceModel model) throws PolicyException {

        // creating global method variables

        final ContentDecomposition decomposition = new ContentDecomposition();

        // creating processing queue and starting the processing iterations

        final Queue<RawPolicy> policyQueue = new LinkedList<RawPolicy>();

        final Queue<Collection<ModelNode>> contentQueue = new LinkedList<Collection<ModelNode>>();

        final RawPolicy rootPolicy = new RawPolicy(model.getRootNode(), new LinkedList<RawAlternative>());

        RawPolicy processedPolicy = rootPolicy;

        do {

            Collection<ModelNode> processedContent = processedPolicy.originalContent;

            do {

                decompose(processedContent, decomposition);

                if (decomposition.exactlyOneContents.isEmpty()) {

                    final RawAlternative alternative = new RawAlternative(decomposition.assertions);

                    processedPolicy.alternatives.add(alternative);

                    if (!alternative.allNestedPolicies.isEmpty()) {

                        policyQueue.addAll(alternative.allNestedPolicies);

                    }

                } else { // we have a non-empty collection of exactly ones

                    final Collection<Collection<ModelNode>> combinations = PolicyUtils.Collections.combine(decomposition.assertions, decomposition.exactlyOneContents, false);

                    if (combinations != null && !combinations.isEmpty()) {

                        // processed alternative was split into some new alternatives, which we need to process

                        contentQueue.addAll(combinations);

                    }

                }

            } while ((processedContent = contentQueue.poll()) != null);

        } while ((processedPolicy = policyQueue.poll()) != null);

        // normalize nested policies to contain single alternative only

        final Collection<AssertionSet> assertionSets = new LinkedList<AssertionSet>();

        for (RawAlternative rootAlternative : rootPolicy.alternatives) {

            final Collection<AssertionSet> normalizedAlternatives = normalizeRawAlternative(rootAlternative);

            assertionSets.addAll(normalizedAlternatives);

        }

        return assertionSets;

    }

    /**

     * Decomposes the unprocessed alternative content into two different collections:

     * <p/>

     * Content of 'EXACTLY_ONE' child nodes is expanded and placed in one list and

     * 'ASSERTION' nodes are placed into other list. Direct 'ALL' and 'POLICY' child nodes are 'dissolved' in the process.

     *

     * Method reuses precreated ContentDecomposition object, which is reset before reuse.

     */

    private void decompose(final Collection<ModelNode> content, final ContentDecomposition decomposition) throws PolicyException {

        decomposition.reset();

        final Queue<ModelNode> allContentQueue = new LinkedList<ModelNode>(content);

        ModelNode node;

        while ((node = allContentQueue.poll()) != null) {

            // dissolving direct 'POLICY', 'POLICY_REFERENCE' and 'ALL' child nodes

            switch (node.getType()) {

                case POLICY :

                case ALL :

                    allContentQueue.addAll(node.getChildren());

                    break;

                case POLICY_REFERENCE :

                    allContentQueue.addAll(getReferencedModelRootNode(node).getChildren());

                    break;

                case EXACTLY_ONE :

                    decomposition.exactlyOneContents.add(expandsExactlyOneContent(node.getChildren()));

                    break;

                case ASSERTION :

                    decomposition.assertions.add(node);

                    break;

                default :

                    throw LOGGER.logSevereException(new PolicyException(LocalizationMessages.WSP_0007_UNEXPECTED_MODEL_NODE_TYPE_FOUND(node.getType())));

            }

        }

    }

    private static ModelNode getReferencedModelRootNode(final ModelNode policyReferenceNode) throws PolicyException {

        final PolicySourceModel referencedModel = policyReferenceNode.getReferencedModel();

        if (referencedModel == null) {

            final PolicyReferenceData refData = policyReferenceNode.getPolicyReferenceData();

            if (refData == null) {

                throw LOGGER.logSevereException(new PolicyException(LocalizationMessages.WSP_0041_POLICY_REFERENCE_NODE_FOUND_WITH_NO_POLICY_REFERENCE_IN_IT()));

            } else {

                throw LOGGER.logSevereException(new PolicyException(LocalizationMessages.WSP_0010_UNEXPANDED_POLICY_REFERENCE_NODE_FOUND_REFERENCING(refData.getReferencedModelUri())));

            }

        } else {

            return referencedModel.getRootNode();

        }

    }

    /**

     * Expands content of 'EXACTLY_ONE' node. Direct 'EXACTLY_ONE' child nodes are dissolved in the process.

     */

    private Collection<ModelNode> expandsExactlyOneContent(final Collection<ModelNode> content) throws PolicyException {

        final Collection<ModelNode> result = new LinkedList<ModelNode>();

        final Queue<ModelNode> eoContentQueue = new LinkedList<ModelNode>(content);

        ModelNode node;

        while ((node = eoContentQueue.poll()) != null) {

            // dissolving direct 'EXACTLY_ONE' child nodes

            switch (node.getType()) {

                case POLICY :

                case ALL :

                case ASSERTION :

                    result.add(node);

                    break;

                case POLICY_REFERENCE :

                    result.add(getReferencedModelRootNode(node));

                    break;

                case EXACTLY_ONE :

                    eoContentQueue.addAll(node.getChildren());

                    break;

                default :

                    throw LOGGER.logSevereException(new PolicyException(LocalizationMessages.WSP_0001_UNSUPPORTED_MODEL_NODE_TYPE(node.getType())));

            }

        }

        return result;

    }

    private List<AssertionSet> normalizeRawAlternative(final RawAlternative alternative) throws AssertionCreationException, PolicyException {

        final List<PolicyAssertion> normalizedContentBase = new LinkedList<PolicyAssertion>();

        final Collection<List<PolicyAssertion>> normalizedContentOptions = new LinkedList<List<PolicyAssertion>>();

        if (!alternative.nestedAssertions.isEmpty()) {

            final Queue<RawAssertion> nestedAssertionsQueue = new LinkedList<RawAssertion>(alternative.nestedAssertions);

            RawAssertion rawAssertion;

            while((rawAssertion = nestedAssertionsQueue.poll()) != null) {

                final List<PolicyAssertion> normalized = normalizeRawAssertion(rawAssertion);

                // if there is only a single result, we can add it direclty to the content base collection

                // more elements in the result indicate that we will have to create combinations

                if (normalized.size() == 1) {

                    normalizedContentBase.addAll(normalized);

                } else {

                    normalizedContentOptions.add(normalized);

                }

            }

        }

        final List<AssertionSet> options = new LinkedList<AssertionSet>();

        if (normalizedContentOptions.isEmpty()) {

            // we do not have any options to combine => returning this assertion

            options.add(AssertionSet.createAssertionSet(normalizedContentBase));

        } else {

            // we have some options to combine => creating assertion options based on content combinations

            final Collection<Collection<PolicyAssertion>> contentCombinations = PolicyUtils.Collections.combine(normalizedContentBase, normalizedContentOptions, true);

            for (Collection<PolicyAssertion> contentOption : contentCombinations) {

                options.add(AssertionSet.createAssertionSet(contentOption));

            }

        }

        return options;

    }

    private List<PolicyAssertion> normalizeRawAssertion(final RawAssertion assertion) throws AssertionCreationException, PolicyException {

        List<PolicyAssertion> parameters;

        if (assertion.parameters.isEmpty()) {

            parameters = null;

        } else {

            parameters = new ArrayList<PolicyAssertion>(assertion.parameters.size());

            for (ModelNode parameterNode : assertion.parameters) {

                parameters.add(createPolicyAssertionParameter(parameterNode));

            }

        }

        final List<AssertionSet> nestedAlternatives = new LinkedList<AssertionSet>();

        if (assertion.nestedAlternatives != null && !assertion.nestedAlternatives.isEmpty()) {

            final Queue<RawAlternative> nestedAlternativeQueue = new LinkedList<RawAlternative>(assertion.nestedAlternatives);

            RawAlternative rawAlternative;

            while((rawAlternative = nestedAlternativeQueue.poll()) != null) {

                nestedAlternatives.addAll(normalizeRawAlternative(rawAlternative));

            }

            // if there is only a single result, we can add it direclty to the content base collection

            // more elements in the result indicate that we will have to create combinations

        }

        final List<PolicyAssertion> assertionOptions = new LinkedList<PolicyAssertion>();

        final boolean nestedAlternativesAvailable = !nestedAlternatives.isEmpty();

        if (nestedAlternativesAvailable) {

            for (AssertionSet nestedAlternative : nestedAlternatives) {

                assertionOptions.add(createPolicyAssertion(assertion.originalNode.getNodeData(), parameters, nestedAlternative));

            }

        } else {

            assertionOptions.add(createPolicyAssertion(assertion.originalNode.getNodeData(), parameters, null));

        }

        return assertionOptions;

    }

    private PolicyAssertion createPolicyAssertionParameter(final ModelNode parameterNode) throws AssertionCreationException, PolicyException {

        if (parameterNode.getType() != ModelNode.Type.ASSERTION_PARAMETER_NODE) {

            throw LOGGER.logSevereException(new PolicyException(LocalizationMessages.WSP_0065_INCONSISTENCY_IN_POLICY_SOURCE_MODEL(parameterNode.getType())));

        }

        List<PolicyAssertion> childParameters = null;

        if (parameterNode.hasChildren()) {

            childParameters = new ArrayList<PolicyAssertion>(parameterNode.childrenSize());

            for (ModelNode childParameterNode : parameterNode) {

                childParameters.add(createPolicyAssertionParameter(childParameterNode));

            }

        }

        return createPolicyAssertion(parameterNode.getNodeData(), childParameters, null /* parameters do not have any nested alternatives */);

    }

    private PolicyAssertion createPolicyAssertion(final AssertionData data, final Collection<PolicyAssertion> assertionParameters, final AssertionSet nestedAlternative) throws AssertionCreationException {

        final String assertionNamespace = data.getName().getNamespaceURI();

        final PolicyAssertionCreator domainSpecificPAC = assertionCreators.get(assertionNamespace);

        if (domainSpecificPAC == null) {

            return defaultCreator.createAssertion(data, assertionParameters, nestedAlternative, null);

        } else {

            return domainSpecificPAC.createAssertion(data, assertionParameters, nestedAlternative, defaultCreator);

        }

    }

}