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/*-
 * ============LICENSE_START=======================================================
 * policy-core
 * ================================================================================
 * Copyright (C) 2017-2019 AT&T Intellectual Property. All rights reserved.
 * ================================================================================
 * Licensed 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.
 * ============LICENSE_END=========================================================
 */

package org.onap.policy.drools.statemanagement;

import java.util.Observer;

import javax.validation.constraints.NotNull;

import org.onap.policy.common.capabilities.Lockable;
import org.onap.policy.common.im.AllSeemsWellException;
import org.onap.policy.common.im.StateManagement;
import org.onap.policy.common.utils.services.OrderedService;
import org.onap.policy.common.utils.services.OrderedServiceImpl;

/**
 * This interface provides a way to invoke optional features at various points in the code. At
 * appropriate points in the application, the code iterates through this list, invoking these
 * optional methods. Most of the methods here are notification only -- these tend to return a 'void'
 * value. In other cases, such as 'activatePolicySession', may
 */
public interface StateManagementFeatureAPI extends OrderedService, Lockable {

    public static final String LOCKED = StateManagement.LOCKED;
    public static final String UNLOCKED = StateManagement.UNLOCKED;
    public static final String ENABLED = StateManagement.ENABLED;
    public static final String DISABLED = StateManagement.DISABLED;
    public static final String ENABLE_NOT_FAILED = StateManagement.ENABLE_NOT_FAILED_ACTION;
    public static final String DISABLE_FAILED = StateManagement.DISABLE_FAILED_ACTION;
    public static final String FAILED = StateManagement.FAILED;
    public static final String DEPENDENCY = StateManagement.DEPENDENCY;
    public static final String DEPENDENCY_FAILED = StateManagement.DEPENDENCY_FAILED;
    public static final String DISABLE_DEPENDENCY = StateManagement.DISABLE_DEPENDENCY_ACTION;
    public static final String ENABLE_NO_DEPENDENCY = StateManagement.ENABLE_NO_DEPENDENCY_ACTION;
    public static final String NULL_VALUE = StateManagement.NULL_VALUE;
    public static final String DO_LOCK = StateManagement.LOCK_ACTION;
    public static final String DO_UNLOCK = StateManagement.UNLOCK_ACTION;
    public static final String DO_PROMOTE = StateManagement.PROMOTE_ACTION;
    public static final String DO_DEMOTE = StateManagement.DEMOTE_ACTION;
    public static final String HOT_STANDBY = StateManagement.HOT_STANDBY;
    public static final String COLD_STANDBY = StateManagement.COLD_STANDBY;
    public static final String PROVIDING_SERVICE = StateManagement.PROVIDING_SERVICE;

    public static final String ADMIN_STATE = StateManagement.ADMIN_STATE;
    public static final String OPERATION_STATE = StateManagement.OPERATION_STATE;
    public static final String AVAILABLE_STATUS = StateManagement.AVAILABLE_STATUS;
    public static final String STANDBY_STATUS = StateManagement.STANDBY_STATUS;

    public static final Boolean ALLSEEMSWELL_STATE = Boolean.TRUE;
    public static final Boolean ALLNOTWELL_STATE = Boolean.FALSE;

    public static final int SEQ_NUM = 0;
    /**
     * 'FeatureAPI.impl.getList()' returns an ordered list of objects implementing the 'FeatureAPI'
     * interface.
     */
    public static OrderedServiceImpl<StateManagementFeatureAPI> impl =
            new OrderedServiceImpl<>(StateManagementFeatureAPI.class);

    /**
     * ALL SEEMS/NOT WELL This interface is used to support the concept of All Seems/Not Well. It
     * provides a way for client code to indicate to the DroolsPDPIntegrityMonitor that an event has
     * occurred which is disabling (or enabling) for the Drools PDP. The call is actually
     * implemented in the common modules IntegrityMonitor where it will cause the testTransaction to
     * fail if any module has set the value ALLNOTWELL, stopping the forward progress counter and
     * eventually causing the operational state to become disabled.
     *
     * <p>ALLSEEMSWELL is passed to the method when the client is healthy ALLNOTWELL is passed to the
     * method when the client is disabled
     *
     * @param key - This should be a unique identifier for the entity making the call (e.g., class
     *        name)
     * @param asw - This is the indicator of health. See constants: ALLSEEMSWELL or ALLNOTWELL
     * @param msg - A message is required. It should indicate why all is not well or a message
     *        indicating that a component has been restored to health (perhaps indicating the
     *        problem that has resolved).
     * @throws AllSeemsWellException exception
     */
    public void allSeemsWell(@NotNull String key, @NotNull Boolean asw, @NotNull String msg)
            throws AllSeemsWellException;

    /**
     * This method is called to add an Observer to receive notifications of state changes.
     *
     * @param stateChangeObserver observer
     */
    public void addObserver(Observer stateChangeObserver);

    /**
     * Returns the X.731 Administrative State for this resource.
     *
     * @return String (locked, unlocked)
     */
    public String getAdminState();

    /**
     * Returns the X.731 Operational State for this resource.
     *
     * @return String (enabled, disabled)
     */
    public String getOpState();

    /**
     * Returns the X.731 Availability Status for this resource.
     *
     * @return String (failed; dependency; dependency,failed)
     */
    public String getAvailStatus();

    /**
     * Returns the X.731 Standby Status for this resource.
     *
     * @return String (providingservice, hotstandby or coldstandby)
     */
    public String getStandbyStatus();

    /**
     * Returns the X.731 Standby Status for the named resource
     *
     * @param String (resourceName)
     * @return String (providingservice, hotstandby or coldstandby)
     */
    public String getStandbyStatus(String resourceName);

    /**
     * This method moves the X.731 Operational State for the named resource into a value of disabled
     * and the Availability Status to a value of failed. As a consequence the Standby Status value
     * will take a value of coldstandby.
     *
     * @param resourceName resource name
     * @throws Exception exception
     */
    public void disableFailed(String resourceName) throws Exception;

    /**
     * This method moves the X.731 Operational State for this resource into a value of disabled and
     * the Availability Status to a value of failed. As a consequence the Standby Status value will
     * take a value of coldstandby.
     *
     * @throws Exception exception
     */
    public void disableFailed() throws Exception;

    /**
     * This method moves the X.731 Standby Status for this resource from hotstandby to
     * providingservice. If the current value is coldstandby, no change is made. If the current
     * value is null, it will move to providingservice assuming the Operational State is enabled and
     * Administrative State is unlocked.
     *
     * @throws Exception exception
     */
    public void promote() throws Exception;

    /**
     * This method moves the X.731 Standby Status for this resource from providingservice to
     * hotstandby. If the current value is null, it will move to hotstandby assuming the Operational
     * State is enabled and Administrative State is unlocked. Else, it will move to coldstandby
     *
     * @throws Exception exception
     */
    public void demote() throws Exception;

    /**
     * Returns the resourceName associated with this instance of the
     * StateManagementFeature.
     *
     * @return String (resourceName)
     */
    public String getResourceName();

    /**
     * This Lockable method will lock the StateManagement object Admin state.
     *
     * @return true if successful, false otherwise
     */
    @Override
    public boolean lock();

    /**
     * This Lockable method will unlock the StateManagement object Admin state.
     *
     * @return true if successfull, false otherwise
     */
    @Override
    public boolean unlock();

    /**
     * This Lockable method indicates the Admin state StateManagement object.
     *
     * @return true if locked, false otherwise
     */
    @Override
    public boolean isLocked();
}