source: src/main/java/geniusweb/profilesserver/DefaultProfilesRepository.java@ 30

package geniusweb.profilesserver;

import java.io.IOException;
import java.util.Collections;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Optional;
import java.util.concurrent.ConcurrentHashMap;
import java.util.stream.Collectors;

import geniusweb.issuevalue.Domain;
import geniusweb.profile.Profile;
import geniusweb.profilesserver.events.ChangeEvent;
import geniusweb.profilesserver.events.DomainChangeEvent;
import geniusweb.profilesserver.events.ProfileChangeEvent;
import tudelft.utilities.listener.DefaultListenable;

/**
 * Listeners will get a notification call with a {@link ChangeEvent} when a
 * {@link Domain} or {@link Profile} is changed/removed.
 * <p>
 * Warning: If possible create only 1 instance of this to avoid expensive
 * duplicate bookkeeping. This class could , but is not made a singleton to
 * facilitate testing.
 * <p>
 * This object is mutable: the {@link #available} map is updated with the
 * current state of available domains and profiles.
 */
public class DefaultProfilesRepository extends DefaultListenable<ChangeEvent>
                implements ProfilesRepository {
        /**
         * all currently available profiles and domains. Invariant for this class:
         * All {@link Domain}s in this map have a unique name that matches the
         * directory name and file name on the file system below the given
         * directory. All profile values in the map their
         * {@link Profile#getDomain()} match with the domain key in the map.
         */
        protected final Map<Domain, List<Profile>> available = new ConcurrentHashMap<>();

        @Override
        public synchronized Domain getDomain(String name) {
                if (name == null) {
                        throw new IllegalArgumentException("domain = null");
                }
                Optional<Domain> optional = available.keySet().stream()
                                .filter(domain -> name.equals(domain.getName())).findFirst();
                return optional.isPresent() ? optional.get() : null;
        }

        @Override
        public synchronized Profile getProfile(String domainprofilename) {
                if (domainprofilename == null) {
                        throw new IllegalArgumentException("profilename=null");
                }
                String[] values = domainprofilename.split("/", 2);
                if (values.length != 2) {
                        throw new IllegalArgumentException(
                                        "profile name must be <domainname>/<profilename> but got "
                                                        + domainprofilename);
                }
                // check if domain exists.
                Domain domain = getDomain(values[0]);
                if (domain == null) {
                        return null;
                }
                String profilename = values[1];
                Optional<Profile> profile = available.get(domain).stream()
                                .filter(prof -> profilename.equals(prof.getName())).findFirst();
                return profile.isPresent() ? profile.get() : null;
        }

        @Override
        public synchronized List<Profile> getProfiles(String domainname) {
                Domain domain = getDomain(domainname);
                return domain == null ? Collections.EMPTY_LIST
                                : Collections.unmodifiableList(available.get(domain));

        }

        @Override
        public synchronized List<String> getDomains() {
                return available.keySet().stream().map(domain -> domain.getName())
                                .collect(Collectors.toList());
        }

        @Override
        public synchronized void putProfile(Profile profile) throws IOException {
                if (!available.containsKey(profile.getDomain())) {
                        throw new IOException("profile's domain does not exist");
                }
                add(profile);
        }

        /**************** support for updating ***************/
        /**
         * Add or replace domain. For internal use so little checking of arguments.
         * If the domain already exists and is the same, we exit immediately. If
         * such a domain does not yet exist, or a domain with the same name already
         * exists but that domain is different, the old domain is removed (and all
         * associated profiles). The new domain is inserted without any known
         * profiles.
         * 
         * @param domain the new domain.
         */
        protected void add(Domain domain) {
                synchronized (this) {
                        if (domain == null) {
                                throw new IllegalArgumentException("domain=null");
                        }
                        if (available.containsKey(domain))
                                return;
                        Optional<Domain> existingdom = available.keySet().stream()
                                        .filter(dom -> dom.getName().equals(domain.getName()))
                                        .findFirst();
                        if (existingdom.isPresent()) {
                                remove(existingdom.get());
                        }
                        available.put(domain, new LinkedList<>());
                }
                notifyListeners(new DomainChangeEvent(null, domain));
        }

        /**
         * Removes domain from the known domains list, plus all profiles associated
         * with the domain. For internal use so little checking of arguments.
         * 
         * @param domain the domain to remove. If null, nothing happens.
         */
        protected void remove(Domain domain) {
                if (domain == null)
                        return;

                List<Profile> removedprofiles;
                synchronized (this) {
                        removedprofiles = available.get(domain);
                        available.remove(domain);
                }

                for (Profile prof : removedprofiles) {
                        notifyListeners(new ProfileChangeEvent(prof, null));
                }
                notifyListeners(new DomainChangeEvent(domain, null));
        }

        /**
         * Adds profile. Internal use only. Domain must exist already. If a profile
         * with same name already exists, that one is replaced with the given
         * profile.
         * 
         * @param profile the profile to add. Ignored if profile=null or if profile
         *                already known. Profile MUST contain a registered domain.
         */
        protected void add(Profile profile) {
                Profile oldprofile = null;
                synchronized (this) {
                        if (profile == null)
                                return;
                        List<Profile> profiles = available.get(profile.getDomain());
                        if (profiles == null) {
                                throw new IllegalArgumentException("Profile "
                                                + profile.getName() + "  uses unknown domain "
                                                + profile.getDomain());
                        }
                        Optional<Profile> knownprofile = profiles.stream()
                                        .filter(prof -> profile.getName().equals(prof.getName()))
                                        .findFirst();
                        if (knownprofile.isPresent()) {
                                oldprofile = knownprofile.get();
                                if (profile.equals(oldprofile))
                                        return;

                                profiles.remove(oldprofile);
                        }
                        profiles.add(profile);
                }
                notifyListeners(new ProfileChangeEvent(oldprofile, profile));

        }

        /**
         * Removes profile. Internal use only.
         * 
         * @param profile to be removed {@link Profile}
         */
        protected void remove(Profile profile) {
                synchronized (this) {
                        if (profile == null) {
                                throw new IllegalArgumentException("profile=null");
                        }
                        List<Profile> profilelist = available.get(profile.getDomain());
                        if (profilelist == null) {
                                throw new IllegalArgumentException("Profile "
                                                + profile.getName() + "  uses unknown domain "
                                                + profile.getDomain());
                        }
                        profilelist.remove(profile);
                }
                notifyListeners(new ProfileChangeEvent(profile, null));

        }

        /**
         * 
         * @param name the name to check
         * @return true iff name is simple name. False if not (also if name=null)
         */
        protected boolean isSimpleName(String name) {
                if (name == null)
                        return false;
                return name.matches("[a-zA-Z0-9]+");
        }

}