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

import com.sun.xml.internal.ws.policy.sourcemodel.wspolicy.NamespaceVersion;

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

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

import java.util.Arrays;

import java.util.Collection;

import java.util.Collections;

import java.util.Iterator;

import java.util.LinkedList;

import java.util.List;

import java.util.Set;

import java.util.TreeSet;

import javax.xml.namespace.QName;

/**

 * A policy represents normalized policy as a wrapper of available policy alternatives represented by

 * child {@link AssertionSet AssertionSets}.

 *

 * @author Fabian Ritzmann, Marek Potociar

 */

public class Policy implements Iterable<AssertionSet> {

    /**

     * A string constant used in package private constructor to customize the object's toString() method output.

     */

    private static final String POLICY_TOSTRING_NAME = "policy";

    /**

     * Constant represents empty list of assertion sets. This represents the content of a 'NULL' policy - a policy with

     * no alternatives. The constant supports memory effective creation of 'NULL' policy objects.

     */

    private static final List<AssertionSet> NULL_POLICY_ASSERTION_SETS = Collections.unmodifiableList(new LinkedList<AssertionSet>());

    /**

     * Constant represents list of assertion sets with single empty assertion set. This represents the content of

     * an 'EMPTY' policy - a policy with a single empty alternative. The constant supports memory effective creation

     * of 'EMPTY' policy objects.

     */

    private static final List<AssertionSet> EMPTY_POLICY_ASSERTION_SETS = Collections.unmodifiableList(new LinkedList<AssertionSet>(Arrays.asList(new AssertionSet[] {AssertionSet.emptyAssertionSet()})));

    /**

     * Constant represents empty vocabulary of a 'NULL' or 'EMPTY' policies. The constant supports memory effective

     * creation of 'NULL' and 'EMPTY' policy objects.

     */

    private static final Set<QName> EMPTY_VOCABULARY = Collections.unmodifiableSet(new TreeSet<QName>(PolicyUtils.Comparison.QNAME_COMPARATOR));

    /**

     * Constant representation of all 'NULL' policies returned by createNullPolicy() factory method. This is to optimize

     * the memory footprint.

     */

    private static final Policy ANONYMOUS_NULL_POLICY = new Policy(null, null, NULL_POLICY_ASSERTION_SETS, EMPTY_VOCABULARY);

    /**

     * Constant representation of all 'EMPTY' policies returned by createEmptyPolicy() factory method. This constant is

     * to optimize the memory footprint.

     */

    private static final Policy ANONYMOUS_EMPTY_POLICY = new Policy(null, null, EMPTY_POLICY_ASSERTION_SETS, EMPTY_VOCABULARY);

    /**

     * Policy ID holder

     */

    private String policyId;

    /**

     * Policy name holder

     */

    private String name;

    /**

     * Namespace version holder

     */

    private NamespaceVersion nsVersion;

    /**

     * internal collection of policy alternatives

     */

    private final List<AssertionSet> assertionSets;

    /**

     * internal collection of policy vocabulary entries (qualified names of all assertion types present in the policy expression)

     */

    private final Set<QName> vocabulary;

    /**

     * immutable version of policy vocabulary that is made available to clients via getter method

     */

    private final Collection<QName> immutableVocabulary;

    /**

     * policy object name used in a toString() method. This ensures that Policy class children can customize

     * (via package private Policy constructors) the toString() method without having to override it.

     */

    private final String toStringName;

    /**

     * The factory method creates an <b>immutable</b> policy instance which represents a <emph>'nothing allowed'</emph>

     * policy expression. The policy is created using the latest namespace version supported.

     *

     * @return policy instance which represents a <emph>'nothing allowed'</emph> (no policy alternatives).

     */

    public static Policy createNullPolicy() {

        return ANONYMOUS_NULL_POLICY;

    }

    /**

     * The factory method creates an <b>immutable</b> policy instance which represents a <emph>'anything allowed'</emph>

     * policy expression. The policy is created using the latest namespace version supported.

     *

     * @return policy instance which represents a <emph>'anything allowed'</emph> (empty policy alternative with no plicy

     * assertions prescribed).

     */

    public static Policy createEmptyPolicy() {

        return ANONYMOUS_EMPTY_POLICY;

    }

    /**

     * The factory method creates an <b>immutable</b> policy instance which represents a <emph>'nothing allowed'</emph>

     * policy expression. The policy is created using the latest namespace version supported.

     *

     * @param name global URI of the policy. May be {@code null}.

     * @param policyId local URI of the policy. May be {@code null}.

     * @return policy instance which represents a <emph>'nothing allowed'</emph> (no policy alternatives).

     */

    public static Policy createNullPolicy(final String name, final String policyId) {

        if (name == null && policyId == null) {

            return ANONYMOUS_NULL_POLICY;

        } else {

            return new Policy(name, policyId, NULL_POLICY_ASSERTION_SETS, EMPTY_VOCABULARY);

        }

    }

    /**

     * The factory method creates an <b>immutable</b> policy instance which represents a <emph>'nothing allowed'</emph>

     * policy expression. The policy is created using the latest namespace version supported.

     *

     * @param nsVersion Policy namespace version to be used when marshalling the policy expression

     * @param name global URI of the policy. May be {@code null}.

     * @param policyId local URI of the policy. May be {@code null}.

     * @return policy instance which represents a <emph>'nothing allowed'</emph> (no policy alternatives).

     */

    public static Policy createNullPolicy(final NamespaceVersion nsVersion, final String name, final String policyId) {

        if ((nsVersion == null || nsVersion == NamespaceVersion.getLatestVersion()) && name == null && policyId == null) {

            return ANONYMOUS_NULL_POLICY;

        } else {

            return new Policy(nsVersion, name, policyId, NULL_POLICY_ASSERTION_SETS, EMPTY_VOCABULARY);

        }

    }

    /**

     * The factory method creates an <b>immutable</b> policy instance which represents a <emph>'anything allowed'</emph>

     * policy expression. The policy is created using the latest namespace version supported.

     *

     * @param name global URI of the policy. May be {@code null}.

     * @param policyId local URI of the policy. May be {@code null}.

     *

     * @return policy instance which represents a <emph>'anything allowed'</emph> (empty policy alternative with no plicy

     * assertions prescribed).

     */

    public static Policy createEmptyPolicy(final String name, final String policyId) {

        if (name == null && policyId == null) {

            return ANONYMOUS_EMPTY_POLICY;

        } else {

            return new Policy(name, policyId, EMPTY_POLICY_ASSERTION_SETS, EMPTY_VOCABULARY);

        }

    }

    /**

     * The factory method creates an <b>immutable</b> policy instance which represents a <emph>'anything allowed'</emph>

     * policy expression. The policy is created using the latest namespace version supported.

     *

     * @param nsVersion Policy namespace version to be used when marshalling the policy expression

     * @param name global URI of the policy. May be {@code null}.

     * @param policyId local URI of the policy. May be {@code null}.

     *

     * @return policy instance which represents a <emph>'anything allowed'</emph> (empty policy alternative with no plicy

     * assertions prescribed).

     */

    public static Policy createEmptyPolicy(final NamespaceVersion nsVersion, final String name, final String policyId) {

        if ((nsVersion == null || nsVersion == NamespaceVersion.getLatestVersion()) && name == null && policyId == null) {

            return ANONYMOUS_EMPTY_POLICY;

        } else {

            return new Policy(nsVersion, name, policyId, EMPTY_POLICY_ASSERTION_SETS, EMPTY_VOCABULARY);

        }

    }

    /**

     * The factory method creates an <b>immutable</b> policy instance which represents a policy expression with

     * alternatives specified by {@code sets} input parameter. If the collection of policy alternatives is null or empty

     * an object representing a 'NULL' policy expression is returned. However, in such case it is better to use

     * {@link #createNullPolicy()} factory method directly. The policy is created using the latest namespace version supported.

     *

     * @param sets represents the collection of policy alternatives of the policy object created. During the creation of

     * the new policy object, the content of the alternatives collection is copied into an internal policy object structure,

     * thus any subsequent operations on the collection will have no impact on the newly constructed policy object.

     *

     * @return policy instance which represents the policy with given alternatives.

     */

    public static Policy createPolicy(final Collection<AssertionSet> sets) {

        if (sets == null || sets.isEmpty()) {

            return createNullPolicy();

        } else {

            return new Policy(POLICY_TOSTRING_NAME, sets);

        }

    }

    /**

     * The factory method creates an <b>immutable</b> policy instance which represents a policy expression with

     * alternatives specified by {@code sets} input parameter. If the collection of policy alternatives is null or empty

     * an object representing a 'NULL' policy expression is returned. However, in such case it is better to use

     * {@link #createNullPolicy(String, String)} factory method directly. The policy is created using the latest namespace version supported.

     *

     * @param name global URI of the policy. May be {@code null}.

     * @param policyId local URI of the policy. May be {@code null}.

     * @param sets represents the collection of policy alternatives of the policy object created. During the creation of

     * the new policy object, the content of the alternatives collection is copied into an internal policy object structure,

     * thus any subsequent operations on the collection will have no impact on the newly constructed policy object.

     *

     * @return policy instance which represents the policy with given alternatives.

     */

    public static Policy createPolicy(final String name, final String policyId, final Collection<AssertionSet> sets) {

        if (sets == null || sets.isEmpty()) {

            return createNullPolicy(name, policyId);

        } else {

            return new Policy(POLICY_TOSTRING_NAME, name, policyId, sets);

        }

    }

    /**

     * The factory method creates an <b>immutable</b> policy instance which represents a policy expression with

     * alternatives specified by {@code sets} input parameter. If the collection of policy alternatives is null or empty

     * an object representing a 'NULL' policy expression is returned. However, in such case it is better to use

     * {@link #createNullPolicy(String, String)} factory method directly. The policy is created using the latest namespace version supported.

     *

     * @param nsVersion Policy namespace version to be used when marshalling the policy expression

     * @param name global URI of the policy. May be {@code null}.

     * @param policyId local URI of the policy. May be {@code null}.

     * @param sets represents the collection of policy alternatives of the policy object created. During the creation of

     * the new policy object, the content of the alternatives collection is copied into an internal policy object structure,

     * thus any subsequent operations on the collection will have no impact on the newly constructed policy object.

     *

     * @return policy instance which represents the policy with given alternatives.

     */

    public static Policy createPolicy(NamespaceVersion nsVersion, final String name, final String policyId, final Collection<AssertionSet> sets) {

        if (sets == null || sets.isEmpty()) {

            return createNullPolicy(nsVersion, name, policyId);

        } else {

            return new Policy(nsVersion, POLICY_TOSTRING_NAME, name, policyId, sets);

        }

    }

    /**

     * A most flexible policy object constructor that allows private creation of policy objects and direct setting

     * of all its attributes.

     *

     * @param name global URI of the policy. May be {@code null}.

     * @param policyId local URI of the policy. May be {@code null}.

     * @param assertionSets represents the collection of policy alternatives of the policy object created. The list is directly

     * assigned to the policy object internal attribute. Subsequent manipulations on the collection must be handled with

     * care.

     * @param vocabulary represents the vocabulary of the policy object. Subsequent manipulations on the collection

     * must be handled with care.

     */

    private Policy(final String name, final String policyId, final List<AssertionSet> assertionSets, final Set<QName> vocabulary) {

        this.nsVersion = NamespaceVersion.getLatestVersion();

        this.toStringName = POLICY_TOSTRING_NAME;

        this.name = name;

        this.policyId = policyId;

        this.assertionSets = assertionSets;

        this.vocabulary = vocabulary;

        this.immutableVocabulary = Collections.unmodifiableCollection(this.vocabulary);

    }

    /**

     * Constructor that should be overridden by child implementation. The constructor allows for easy toString() output

     * customization.

     *

     * @param toStringName a general name of the object (such as 'policy' or 'nested policy') that will be used in the

     * toString() method to identify the object.

     * @param sets represents the collection of policy alternatives of the policy object created. During the creation of

     * the new policy object, the content of the alternatives collection is copied into an internal policy object structure,

     * thus any subsequent operations on the collection will have no impact on the newly constructed policy object. The

     * collection may be {@code null} or empty. In such case a 'NULL' policy object is constructed.

     */

    Policy(final String toStringName, final Collection<AssertionSet> sets) {

        this.nsVersion = NamespaceVersion.getLatestVersion();

        this.toStringName = toStringName;

        if (sets == null || sets.isEmpty()) {

            this.assertionSets = NULL_POLICY_ASSERTION_SETS;

            this.vocabulary = EMPTY_VOCABULARY;

            this.immutableVocabulary = EMPTY_VOCABULARY;

        } else {

            this.assertionSets = new LinkedList<AssertionSet>();

            this.vocabulary = new TreeSet<QName>(PolicyUtils.Comparison.QNAME_COMPARATOR);

            this.immutableVocabulary = Collections.unmodifiableCollection(this.vocabulary);

            addAll(sets);

        }

    }

    /**

     * Constructor that should be overridden by child implementation. The constructor allows for easy toString() output

     * customization.

     *

     * @param toStringName a general name of the object (such as 'policy' or 'nested policy') that will be used in the

     * toString() method to identify the object.

     * @param name global URI of the policy. May be {@code null}.

     * @param policyId local URI of the policy. May be {@code null}.

     * @param sets represents the collection of policy alternatives of the policy object created. During the creation of

     * the new policy object, the content of the alternatives collection is copied into an internal policy object structure,

     * thus any subsequent operations on the collection will have no impact on the newly constructed policy object. The

     * collection may be {@code null} or empty. In such case a 'NULL' policy object is constructed.

     */

    Policy(final String toStringName, final String name, final String policyId, final Collection<AssertionSet> sets) {

        this(toStringName, sets);

        this.name = name;

        this.policyId = policyId;

    }

    /**

     * A most flexible policy object constructor that allows private creation of policy objects and direct setting

     * of all its attributes.

     *

     * @param nsVersion Policy namespace version to be used when marshalling the policy expression

     * @param name global URI of the policy. May be {@code null}.

     * @param policyId local URI of the policy. May be {@code null}.

     * @param assertionSets represents the collection of policy alternatives of the policy object created. The list is directly

     * assigned to the policy object internal attribute. Subsequent manipulations on the collection must be handled with

     * care.

     * @param vocabulary represents the vocabulary of the policy object. Subsequent manipulations on the collection

     * must be handled with care.

     */

    private Policy(final NamespaceVersion nsVersion, final String name, final String policyId, final List<AssertionSet> assertionSets, final Set<QName> vocabulary) {

        this.nsVersion = nsVersion;

        this.toStringName = POLICY_TOSTRING_NAME;

        this.name = name;

        this.policyId = policyId;

        this.assertionSets = assertionSets;

        this.vocabulary = vocabulary;

        this.immutableVocabulary = Collections.unmodifiableCollection(this.vocabulary);

    }

    /**

     * Constructor that should be overridden by child implementation. The constructor allows for easy toString() output

     * customization.

     *

     * @param nsVersion Policy namespace version to be used when marshalling the policy expression

     * @param toStringName a general name of the object (such as 'policy' or 'nested policy') that will be used in the

     * toString() method to identify the object.

     * @param sets represents the collection of policy alternatives of the policy object created. During the creation of

     * the new policy object, the content of the alternatives collection is copied into an internal policy object structure,

     * thus any subsequent operations on the collection will have no impact on the newly constructed policy object. The

     * collection may be {@code null} or empty. In such case a 'NULL' policy object is constructed.

     */

    Policy(final NamespaceVersion nsVersion, final String toStringName, final Collection<AssertionSet> sets) {

        this.nsVersion = nsVersion;

        this.toStringName = toStringName;

        if (sets == null || sets.isEmpty()) {

            this.assertionSets = NULL_POLICY_ASSERTION_SETS;

            this.vocabulary = EMPTY_VOCABULARY;

            this.immutableVocabulary = EMPTY_VOCABULARY;

        } else {

            this.assertionSets = new LinkedList<AssertionSet>();

            this.vocabulary = new TreeSet<QName>(PolicyUtils.Comparison.QNAME_COMPARATOR);

            this.immutableVocabulary = Collections.unmodifiableCollection(this.vocabulary);

            addAll(sets);

        }

    }

    /**

     * Constructor that should be overridden by child implementation. The constructor allows for easy toString() output

     * customization.

     *

     * @param nsVersion Policy namespace version to be used when marshalling the policy expression

     * @param toStringName a general name of the object (such as 'policy' or 'nested policy') that will be used in the

     * toString() method to identify the object.

     * @param name global URI of the policy. May be {@code null}.

     * @param policyId local URI of the policy. May be {@code null}.

     * @param sets represents the collection of policy alternatives of the policy object created. During the creation of

     * the new policy object, the content of the alternatives collection is copied into an internal policy object structure,

     * thus any subsequent operations on the collection will have no impact on the newly constructed policy object. The

     * collection may be {@code null} or empty. In such case a 'NULL' policy object is constructed.

     */

    Policy(final NamespaceVersion nsVersion, final String toStringName, final String name, final String policyId, final Collection<AssertionSet> sets) {

        this(nsVersion, toStringName, sets);

        this.name = name;

        this.policyId = policyId;

    }

    /**

     * Adds single alternative to the internal alternatives set of the policy object.

     *

     * @param set assertion set (policy alternative) object to be added. May be {@code null}; in such case the method

     * returns false.

     *

     * @return {@code true} or {@code false} depending on whether the new alternative was added to the policy object or not.

     */

    private boolean add(final AssertionSet set) {

        if (set == null) {

            return false;

        }

        if (this.assertionSets.contains(set)) {

            return false;

        } else {

            this.assertionSets.add(set);

            this.vocabulary.addAll(set.getVocabulary());

            return true;

        }

    }

    /**

     * Adds all alternatives from the input collection of assertion sets to the policy object's internal set of alternatives.

     * The policy object's vocabulary structure is updated as well.

     *

     * @param sets collection of new alternatives. Must NOT be {@code null} or empty. The check for null or empty input

     * parameter is performed with help of {@code assert} keyword, thus during the testing and development of this class

     * {@code -ea} switch should be turned on for this class.

     *

     * @return {@code true} if all elements in the input collection were added to internal structure, {@code false} otherwise.

     */

    private boolean addAll(final Collection<AssertionSet> sets) {

        assert (sets != null && !sets.isEmpty()) : LocalizationMessages.WSP_0036_PRIVATE_METHOD_DOES_NOT_ACCEPT_NULL_OR_EMPTY_COLLECTION();

        boolean result = true;

        for (AssertionSet set : sets) {

            result &= add(set); // this is here to ensure that vocabulary is built correctly as well

        }

        Collections.sort(this.assertionSets);

        return result;

    }

    Collection<AssertionSet> getContent() {

        return assertionSets;

    }

    /**

     * Returns the policy identifier that serves as a local relative policy URI.

     *

     * @return policy identifier - a local relative policy URI. If no policy identifier is set, returns {@code null}.

     */

    public String getId() {

        return policyId;

    }

    /**

     * Returns the policy name that serves as a global policy URI.

     *

     * @return policy name - a global policy URI. If no policy name is set, returns {@code null}.

     */

    public String getName() {

        return name;

    }

    public NamespaceVersion getNamespaceVersion() {

        return nsVersion;

    }

    /**

     * Returns the policy ID or if that is null the policy name. May return null

     * if both attributes are null.

     *

     * @see #getId()

     * @see #getName()

     * @return The policy ID if it was set, or the name or null if no attribute was set.

     */

    public String getIdOrName() {

        if (policyId != null) {

            return policyId;

        }

        return name;

    }

    /**

     * Method returns how many policy alternatives this policy instance contains.

     *

     * @return number of policy alternatives contained in this policy instance

     */

    public int getNumberOfAssertionSets() {

        return assertionSets.size();

    }

    /**

     * A policy usually contains one or more assertion sets. Each assertion set

     * corresponds to a policy alternative as defined by WS-Policy.

     *

     * @return An iterator to iterate through all contained assertion sets

     */

    public Iterator<AssertionSet> iterator() {

        return assertionSets.iterator();

    }

    /**

     * Returns {@code true} if the policy instance represents "nothing allowed" policy expression

     *

     * @return {@code true} if the policy instance represents "nothing allowed" policy expression, {@code false} otherwise.

     */

    public boolean isNull() {

        return assertionSets.size() == 0;

    }