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.
/**
 *  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.catalina.authenticator.jaspic;

import java.io.File;
import java.lang.reflect.Constructor;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.CopyOnWriteArrayList;

import javax.security.auth.message.config.AuthConfigFactory;
import javax.security.auth.message.config.AuthConfigProvider;
import javax.security.auth.message.config.RegistrationListener;

import org.apache.catalina.Globals;
import org.apache.catalina.authenticator.jaspic.PersistentProviderRegistrations.Provider;
import org.apache.catalina.authenticator.jaspic.PersistentProviderRegistrations.Providers;
import org.apache.juli.logging.Log;
import org.apache.juli.logging.LogFactory;
import org.apache.tomcat.util.res.StringManager;

public class AuthConfigFactoryImpl extends AuthConfigFactory {

    private final Log log = LogFactory.getLog(AuthConfigFactoryImpl.class); // must not be static
    private static final StringManager sm = StringManager.getManager(AuthConfigFactoryImpl.class);

    private static final String CONFIG_PATH = "conf/jaspic-providers.xml";
    private static final File CONFIG_FILE =
            new File(System.getProperty(Globals.CATALINA_BASE_PROP), CONFIG_PATH);
    private static final Object CONFIG_FILE_LOCK = new Object();

    private static final String[] EMPTY_STRING_ARRAY = new String[0];

    private static String DEFAULT_REGISTRATION_ID = getRegistrationID(null, null);

    private final Map<String,RegistrationContextImpl> layerAppContextRegistrations =
            new ConcurrentHashMap<>();
    private final Map<String,RegistrationContextImpl> appContextRegistrations =
            new ConcurrentHashMap<>();
    private final Map<String,RegistrationContextImpl> layerRegistrations =
            new ConcurrentHashMap<>();
    // Note: Although there will only ever be a maximum of one entry in this
    //       Map, use a ConcurrentHashMap for consistency
    private final Map<String,RegistrationContextImpl> defaultRegistration =
            new ConcurrentHashMap<>(1);


    public AuthConfigFactoryImpl() {
        loadPersistentRegistrations();
    }


    @Override
    public AuthConfigProvider getConfigProvider(String layer, String appContext,
            RegistrationListener listener) {
        RegistrationContextImpl registrationContext =
                findRegistrationContextImpl(layer, appContext);
        if (registrationContext != null) {
            if (listener != null) {
                RegistrationListenerWrapper wrapper = new RegistrationListenerWrapper(
                        layer, appContext, listener);
                registrationContext.addListener(wrapper);
            }
            return registrationContext.getProvider();
        }
        return null;
    }


    @Override
    public String registerConfigProvider(String className,
            @SuppressWarnings("rawtypes") Map properties, String layer, String appContext,
            String description) {
        String registrationID =
                doRegisterConfigProvider(className, properties, layer, appContext, description);
        savePersistentRegistrations();
        return registrationID;
    }


    @SuppressWarnings("unchecked")
    private String doRegisterConfigProvider(String className,
            @SuppressWarnings("rawtypes") Map properties, String layer, String appContext,
            String description) {
        if (log.isDebugEnabled()) {
            log.debug(sm.getString("authConfigFactoryImpl.registerClass",
                    className, layer, appContext));
        }

        AuthConfigProvider provider = null;
        if (className != null) {
            provider = createAuthConfigProvider(className, properties);
        }

        String registrationID = getRegistrationID(layer, appContext);
        RegistrationContextImpl registrationContextImpl = new RegistrationContextImpl(
                layer, appContext, description, true, provider, properties);
        addRegistrationContextImpl(layer, appContext, registrationID, registrationContextImpl);
        return registrationID;
    }


    private AuthConfigProvider createAuthConfigProvider(String className,
            @SuppressWarnings("rawtypes") Map properties) throws SecurityException {
        Class<?> clazz = null;
        AuthConfigProvider provider = null;
        try {
            clazz = Class.forName(className, true, Thread.currentThread().getContextClassLoader());
        } catch (ClassNotFoundException e) {
            // Ignore so the re-try below can proceed
        }
        try {
            if (clazz == null) {
                clazz = Class.forName(className);
            }
            Constructor<?> constructor = clazz.getConstructor(Map.class, AuthConfigFactory.class);
            provider = (AuthConfigProvider) constructor.newInstance(properties, null);
        } catch (ReflectiveOperationException | IllegalArgumentException e) {
            throw new SecurityException(e);
        }
        return provider;
    }


    @Override
    public String registerConfigProvider(AuthConfigProvider provider, String layer,
            String appContext, String description) {
        if (log.isDebugEnabled()) {
            log.debug(sm.getString("authConfigFactoryImpl.registerInstance",
                    provider.getClass().getName(), layer, appContext));
        }
        String registrationID = getRegistrationID(layer, appContext);
        RegistrationContextImpl registrationContextImpl = new RegistrationContextImpl(
                layer, appContext, description, false, provider, null);
        addRegistrationContextImpl(layer, appContext, registrationID, registrationContextImpl);
        return registrationID;
    }


    private void addRegistrationContextImpl(String layer, String appContext,
            String registrationID, RegistrationContextImpl registrationContextImpl) {
        RegistrationContextImpl previous = null;

        // Add the registration, noting any registration it replaces
        if (layer != null && appContext != null) {
            previous = layerAppContextRegistrations.put(registrationID, registrationContextImpl);
        } else if (layer == null && appContext != null) {
            previous = appContextRegistrations.put(registrationID, registrationContextImpl);
        } else if (layer != null && appContext == null) {
            previous = layerRegistrations.put(registrationID, registrationContextImpl);
        } else {
            previous = defaultRegistration.put(registrationID, registrationContextImpl);
        }

        if (previous == null) {
            // No match with previous registration so need to check listeners
            // for all less specific registrations to see if they need to be
            // notified of this new registration. That there is no exact match
            // with a previous registration allows a few short-cuts to be taken
            if (layer != null && appContext != null) {
                // Need to check existing appContext registrations
                // (and layer and default)
                // appContext must match
                RegistrationContextImpl registration =
                        appContextRegistrations.get(getRegistrationID(null, appContext));
                if (registration != null) {
                    for (RegistrationListenerWrapper wrapper : registration.listeners) {
                        if (layer.equals(wrapper.getMessageLayer()) &&
                                appContext.equals(wrapper.getAppContext())) {
                            registration.listeners.remove(wrapper);
                            wrapper.listener.notify(wrapper.messageLayer, wrapper.appContext);
                        }
                    }
                }
            }
            if (appContext != null) {
                // Need to check existing layer registrations
                // (and default)
                // Need to check registrations for all layers
                for (RegistrationContextImpl registration : layerRegistrations.values()) {
                    for (RegistrationListenerWrapper wrapper : registration.listeners) {
                        if (appContext.equals(wrapper.getAppContext())) {
                            registration.listeners.remove(wrapper);
                            wrapper.listener.notify(wrapper.messageLayer, wrapper.appContext);
                        }
                    }
                }
            }
            if (layer != null || appContext != null) {
                // Need to check default
                for (RegistrationContextImpl registration : defaultRegistration.values()) {
                    for (RegistrationListenerWrapper wrapper : registration.listeners) {
                        if (appContext != null && appContext.equals(wrapper.getAppContext()) ||
                                layer != null && layer.equals(wrapper.getMessageLayer())) {
                            registration.listeners.remove(wrapper);
                            wrapper.listener.notify(wrapper.messageLayer, wrapper.appContext);
                        }
                    }
                }
            }
        } else {
            // Replaced an existing registration so need to notify those listeners
            for (RegistrationListenerWrapper wrapper : previous.listeners) {
                previous.listeners.remove(wrapper);
                wrapper.listener.notify(wrapper.messageLayer, wrapper.appContext);
            }
        }
    }


    @Override
    public boolean removeRegistration(String registrationID) {
        RegistrationContextImpl registration = null;
        if (DEFAULT_REGISTRATION_ID.equals(registrationID)) {
            registration = defaultRegistration.remove(registrationID);
        }
        if (registration == null) {
            registration = layerAppContextRegistrations.remove(registrationID);
        }
        if (registration == null) {
            registration =  appContextRegistrations.remove(registrationID);
        }
        if (registration == null) {
            registration = layerRegistrations.remove(registrationID);
        }

        if (registration == null) {
            return false;
        } else {
            for (RegistrationListenerWrapper wrapper : registration.listeners) {
                wrapper.getListener().notify(wrapper.getMessageLayer(), wrapper.getAppContext());
            }
            if (registration.isPersistent()) {
                savePersistentRegistrations();
            }
            return true;
        }
    }


    @Override
    public String[] detachListener(RegistrationListener listener, String layer, String appContext) {
        String registrationID = getRegistrationID(layer, appContext);
        RegistrationContextImpl registrationContext = findRegistrationContextImpl(layer, appContext);
        if (registrationContext != null && registrationContext.removeListener(listener)) {
            return new String[] { registrationID };
        }
        return EMPTY_STRING_ARRAY;
    }


    @Override
    public String[] getRegistrationIDs(AuthConfigProvider provider) {
        List<String> result = new ArrayList<>();
        if (provider == null) {
            result.addAll(layerAppContextRegistrations.keySet());
            result.addAll(appContextRegistrations.keySet());
            result.addAll(layerRegistrations.keySet());
            if (!defaultRegistration.isEmpty()) {
                result.add(DEFAULT_REGISTRATION_ID);
            }
        } else {
            findProvider(provider, layerAppContextRegistrations, result);
            findProvider(provider, appContextRegistrations, result);
            findProvider(provider, layerRegistrations, result);
            findProvider(provider, defaultRegistration, result);
        }
        return result.toArray(EMPTY_STRING_ARRAY);
    }


    private void findProvider(AuthConfigProvider provider,
            Map<String,RegistrationContextImpl> registrations, List<String> result) {
        for (Entry<String,RegistrationContextImpl> entry : registrations.entrySet()) {
            if (provider.equals(entry.getValue().getProvider())) {
                result.add(entry.getKey());
            }
        }
    }


    @Override
    public RegistrationContext getRegistrationContext(String registrationID) {
        RegistrationContext result = defaultRegistration.get(registrationID);
        if (result == null) {
            result = layerAppContextRegistrations.get(registrationID);
        }
        if (result == null) {
            result = appContextRegistrations.get(registrationID);
        }
        if (result == null) {
            result = layerRegistrations.get(registrationID);
        }
        return result;
    }


    @Override
    public void refresh() {
        loadPersistentRegistrations();
    }


    private static String getRegistrationID(String layer, String appContext) {
        if (layer != null && layer.length() == 0) {
            throw new IllegalArgumentException(
                    sm.getString("authConfigFactoryImpl.zeroLengthMessageLayer"));
        }
        if (appContext != null && appContext.length() == 0) {
            throw new IllegalArgumentException(
                    sm.getString("authConfigFactoryImpl.zeroLengthAppContext"));
        }
        return (layer == null ? "" : layer) + ":" + (appContext == null ? "" : appContext);
    }


    private void loadPersistentRegistrations() {
        synchronized (CONFIG_FILE_LOCK) {
            if (log.isDebugEnabled()) {
                log.debug(sm.getString("authConfigFactoryImpl.load",
                        CONFIG_FILE.getAbsolutePath()));
            }
            if (!CONFIG_FILE.isFile()) {
                return;
            }
            Providers providers = PersistentProviderRegistrations.loadProviders(CONFIG_FILE);
            for (Provider provider : providers.getProviders()) {
                doRegisterConfigProvider(provider.getClassName(), provider.getProperties(),
                        provider.getLayer(), provider.getAppContext(), provider.getDescription());
            }
        }
    }


    private void savePersistentRegistrations() {
        synchronized (CONFIG_FILE_LOCK) {
            Providers providers = new Providers();
            savePersistentProviders(providers, layerAppContextRegistrations);
            savePersistentProviders(providers, appContextRegistrations);
            savePersistentProviders(providers, layerRegistrations);
            savePersistentProviders(providers, defaultRegistration);
            PersistentProviderRegistrations.writeProviders(providers, CONFIG_FILE);
        }
    }


    private void savePersistentProviders(Providers providers,
            Map<String,RegistrationContextImpl> registrations) {
        for (Entry<String,RegistrationContextImpl> entry : registrations.entrySet()) {
            savePersistentProvider(providers, entry.getValue());
        }
    }


    private void savePersistentProvider(Providers providers,
            RegistrationContextImpl registrationContextImpl) {
        if (registrationContextImpl != null && registrationContextImpl.isPersistent()) {
            Provider provider = new Provider();
            provider.setAppContext(registrationContextImpl.getAppContext());
            if (registrationContextImpl.getProvider() != null) {
                provider.setClassName(registrationContextImpl.getProvider().getClass().getName());
            }
            provider.setDescription(registrationContextImpl.getDescription());
            provider.setLayer(registrationContextImpl.getMessageLayer());
            for (Entry<String,String> property : registrationContextImpl.getProperties().entrySet()) {
                provider.addProperty(property.getKey(), property.getValue());
            }
            providers.addProvider(provider);
        }
    }


    private RegistrationContextImpl findRegistrationContextImpl(String layer, String appContext) {
        RegistrationContextImpl result;
        result = layerAppContextRegistrations.get(getRegistrationID(layer, appContext));
        if (result == null) {
            result = appContextRegistrations.get(getRegistrationID(null, appContext));
        }
        if (result == null) {
            result = layerRegistrations.get(getRegistrationID(layer, null));
        }
        if (result == null) {
            result = defaultRegistration.get(DEFAULT_REGISTRATION_ID);
        }
        return result;
    }


    private static class RegistrationContextImpl implements RegistrationContext {

        private RegistrationContextImpl(String messageLayer, String appContext, String description,
                boolean persistent, AuthConfigProvider provider, Map<String,String> properties) {
            this.messageLayer = messageLayer;
            this.appContext = appContext;
            this.description = description;
            this.persistent = persistent;
            this.provider = provider;
            Map<String,String> propertiesCopy = new HashMap<>();
            if (properties != null) {
                propertiesCopy.putAll(properties);
            }
            this.properties = Collections.unmodifiableMap(propertiesCopy);
        }

        private final String messageLayer;
        private final String appContext;
        private final String description;
        private final boolean persistent;
        private final AuthConfigProvider provider;
        private final Map<String,String> properties;
        private final List<RegistrationListenerWrapper> listeners = new CopyOnWriteArrayList<>();

        @Override
        public String getMessageLayer() {
            return messageLayer;
        }


        @Override
        public String getAppContext() {
            return appContext;
        }

        @Override
        public String getDescription() {
            return description;
        }


        @Override
        public boolean isPersistent() {
            return persistent;
        }


        private AuthConfigProvider getProvider() {
            return provider;
        }


        private void addListener(RegistrationListenerWrapper listener) {
            if (listener != null) {
                listeners.add(listener);
            }
        }


        private Map<String,String> getProperties() {
            return properties;
        }


        private boolean removeListener(RegistrationListener listener) {
            boolean result = false;
            for (RegistrationListenerWrapper wrapper : listeners) {
                if (wrapper.getListener().equals(listener)) {
                    listeners.remove(wrapper);
                    result = true;
                }
            }
            return result;
        }
    }


    private static class RegistrationListenerWrapper {

        private final String messageLayer;
        private final String appContext;
        private final RegistrationListener listener;


        public RegistrationListenerWrapper(String messageLayer, String appContext,
                RegistrationListener listener) {
            this.messageLayer = messageLayer;
            this.appContext = appContext;
            this.listener = listener;
        }


        public String getMessageLayer() {
            return messageLayer;
        }


        public String getAppContext() {
            return appContext;
        }


        public RegistrationListener getListener() {
            return listener;
        }
    }
}