/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.ki.subject;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;


/**
 * A simple implementation of the {@link MutablePrincipalCollection} interface that tracks principals internally
 * by storing them in a {@link LinkedHashMap}.
 *
 * @author Les Hazlewood
 * @since 0.9
 */
@SuppressWarnings({"unchecked"})
public class SimplePrincipalCollection implements MutablePrincipalCollection {

    //TODO - complete JavaDoc

    private Map<String, Set> realmPrincipals;

    public SimplePrincipalCollection() {
    }

    public SimplePrincipalCollection(Object principal, String realmName) {
        if (principal instanceof Collection) {
            addAll((Collection) principal, realmName);
        } else {
            add(principal, realmName);
        }
    }

    public SimplePrincipalCollection(Collection principals, String realmName) {
        addAll(principals, realmName);
    }

    public SimplePrincipalCollection(PrincipalCollection principals) {
        addAll(principals);
    }

    protected Collection getPrincipalsLazy(String realmName) {
        if (realmPrincipals == null) {
            realmPrincipals = new LinkedHashMap<String, Set>();
        }
        Set principals = realmPrincipals.get(realmName);
        if (principals == null) {
            principals = new LinkedHashSet();
            realmPrincipals.put(realmName, principals);
        }
        return principals;
    }

    public void add(Object principal, String realmName) {
        if (realmName == null) {
            throw new IllegalArgumentException("realmName argument cannot be null.");
        }
        if (principal == null) {
            throw new IllegalArgumentException("principal argument cannot be null.");
        }
        getPrincipalsLazy(realmName).add(principal);
    }

    public void addAll(Collection principals, String realmName) {
        if (realmName == null) {
            throw new IllegalArgumentException("realmName argument cannot be null.");
        }
        if (principals == null) {
            throw new IllegalArgumentException("principals argument cannot be null.");
        }
        if (principals.isEmpty()) {
            throw new IllegalArgumentException("principals argument cannot be an empty collection.");
        }
        getPrincipalsLazy(realmName).addAll(principals);
    }

    public void addAll(PrincipalCollection principals) {
        if (principals.getRealmNames() != null) {
            for (String realmName : principals.getRealmNames()) {
                for (Object principal : principals.fromRealm(realmName)) {
                    add(principal, realmName);
                }
            }
        }
    }

    public <T> T oneByType(Class<T> type) {
        if (realmPrincipals == null || realmPrincipals.isEmpty()) {
            return null;
        }
        Collection<Set> values = realmPrincipals.values();
        for (Set set : values) {
            for (Object o : set) {
                if (type.isAssignableFrom(o.getClass())) {
                    return (T) o;
                }
            }
        }
        return null;
    }

    public <T> Collection<T> byType(Class<T> type) {
        if (realmPrincipals == null || realmPrincipals.isEmpty()) {
            return Collections.EMPTY_SET;
        }
        Set<T> typed = new LinkedHashSet<T>();
        Collection<Set> values = realmPrincipals.values();
        for (Set set : values) {
            for (Object o : set) {
                if (type.isAssignableFrom(o.getClass())) {
                    typed.add((T) o);
                }
            }
        }
        if (typed.isEmpty()) {
            return Collections.EMPTY_SET;
        }
        return Collections.unmodifiableSet(typed);
    }

    public List asList() {
        Set all = asSet();
        if (all.isEmpty()) {
            return Collections.EMPTY_LIST;
        }
        return Collections.unmodifiableList(new ArrayList(all));
    }

    public Set asSet() {
        if (realmPrincipals == null || realmPrincipals.isEmpty()) {
            return Collections.EMPTY_SET;
        }
        Set aggregated = new LinkedHashSet();
        Collection<Set> values = realmPrincipals.values();
        for (Set set : values) {
            aggregated.addAll(set);
        }
        if (aggregated.isEmpty()) {
            return Collections.EMPTY_SET;
        }
        return Collections.unmodifiableSet(aggregated);
    }

    public Collection fromRealm(String realmName) {
        if (realmPrincipals == null || realmPrincipals.isEmpty()) {
            return Collections.EMPTY_SET;
        }
        Set principals = realmPrincipals.get(realmName);
        if (principals == null || principals.isEmpty()) {
            principals = Collections.EMPTY_SET;
        }
        return Collections.unmodifiableSet(principals);
    }

    public Set<String> getRealmNames() {
        if (realmPrincipals == null) {
            return null;
        } else {
            return realmPrincipals.keySet();
        }
    }

    public boolean isEmpty() {
        return realmPrincipals == null || realmPrincipals.isEmpty();
    }

    public void clear() {
        if (realmPrincipals != null) {
            realmPrincipals.clear();
            realmPrincipals = null;
        }
    }

    public Iterator iterator() {
        return asSet().iterator();
    }

    public boolean equals(Object o) {
        if (o == this) {
            return true;
        }
        if (o instanceof SimplePrincipalCollection) {
            SimplePrincipalCollection other = (SimplePrincipalCollection) o;
            return this.realmPrincipals != null ? this.realmPrincipals.equals(other.realmPrincipals) : other.realmPrincipals == null;
        }
        return false;
    }

    public int hashCode() {
        if (this.realmPrincipals != null && !realmPrincipals.isEmpty()) {
            return realmPrincipals.hashCode();
        }
        return super.hashCode();
    }
}