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]+");
	}

}