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

import com.sun.xml.internal.ws.policy.privateutil.PolicyUtils;
import com.sun.xml.internal.ws.policy.sourcemodel.wspolicy.NamespaceVersion;
import java.util.ArrayList;
import java.util.Collection;
import java.util.LinkedList;

Merge policies and return the effective policy.
WS-PolicyAttachment defines a merge algorithm for WSDL 1.1 policy attachments.
/**
 * Merge policies and return the effective policy.
 *
 * WS-PolicyAttachment defines a merge algorithm for WSDL 1.1 policy attachments.
 */
public final class PolicyMerger {
    private static final PolicyMerger merger = new PolicyMerger();

    
This private constructor is to avoid direct class instantiation from outsied of the package
/**
     * This private constructor is to avoid direct class instantiation from outsied of the package
     */
    private PolicyMerger() {
        // nothing to instantiate
    }

    
Factory method for obtaining thread-safe policy merger instance.
Returns:
policy merger instance./**
     * Factory method for obtaining thread-safe policy merger instance.
     *
     * @return policy merger instance.
     */
    public static PolicyMerger getMerger() {
        return merger;
    }

    
Takes collection of policies and merges them into a single policy using algorithm described in
WS-PolicyAttachment specification. None of the original policies in the collection are modified in
any way.
The newly created policy has an ID that is a concatentation of all merged policy IDs.
Params:
policies – collection of policies to be merged. The collection must not contain 'null' elements!
Returns:
merged policy containing combination of policy alternatives stored in all input policies. If provided collection of policies is null or empty, returns null. If provided collection of policies contains only single policy, the policy is returned./**
     * Takes collection of policies and merges them into a single policy using algorithm described in
     * WS-PolicyAttachment specification. None of the original policies in the collection are modified in
     * any way.
     *
     * The newly created policy has an ID that is a concatentation of all merged policy IDs.
     *
     * @param policies collection of policies to be merged. The collection must not contain '{@code null}' elements!
     * @return merged policy containing combination of policy alternatives stored in all input policies.
     *         If provided collection of policies is {@code null} or empty, returns {@code null}. If provided
     *         collection of policies contains only single policy, the policy is returned.
     */
    public Policy merge(final Collection<Policy> policies) {
        if (policies == null || policies.isEmpty()) {
            return null;
        } else if (policies.size() == 1) {
            return policies.iterator().next();
        }

        final Collection<Collection<AssertionSet>> alternativeSets = new LinkedList<Collection<AssertionSet>>();
        final StringBuilder id = new StringBuilder();
        NamespaceVersion mergedVersion = policies.iterator().next().getNamespaceVersion();
        for (Policy policy : policies) {
            alternativeSets.add(policy.getContent());
            if (mergedVersion.compareTo(policy.getNamespaceVersion()) < 0) {
                mergedVersion = policy.getNamespaceVersion();
            }
            final String policyId = policy.getId();
            if (policyId != null) {
                if (id.length() > 0) {
                    id.append('-');
                }
                id.append(policyId);
            }
        }

        final Collection<Collection<AssertionSet>> combinedAlternatives = PolicyUtils.Collections.combine(null, alternativeSets, false);

        if (combinedAlternatives == null || combinedAlternatives.isEmpty()) {
            return Policy.createNullPolicy(mergedVersion, null, id.length() == 0 ? null : id.toString());
        } else {
            final Collection<AssertionSet> mergedSetList = new ArrayList<AssertionSet>(combinedAlternatives.size());
            for (Collection<AssertionSet> toBeMerged : combinedAlternatives) {
                mergedSetList.add(AssertionSet.createMergedAssertionSet(toBeMerged));
            }
            return Policy.createPolicy(mergedVersion, null, id.length() == 0 ? null : id.toString(), mergedSetList);
        }
    }
}