org.jgrapes.util.events.KeyValueStoreUpdate Maven / Gradle / Ivy

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/*
 * JGrapes Event Driven Framework
 * Copyright (C) 2017-2018 Michael N. Lipp
 * 
 * This program is free software; you can redistribute it and/or modify it 
 * under the terms of the GNU Affero General Public License as published by 
 * the Free Software Foundation; either version 3 of the License, or 
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful, but 
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License 
 * for more details.
 * 
 * You should have received a copy of the GNU Affero General Public License along 
 * with this program; if not, see .
 */

package org.jgrapes.util.events;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import org.jgrapes.core.Event;

/**
 * An event that triggers updates or deletions in a key/value store.
 */
public class KeyValueStoreUpdate extends Event {

    private final List actions = new ArrayList<>();

    /**
     * Adds a new update action to the event.
     * 
     * @param key the key
     * @param value the value
     * @return the event for easy chaining
     */
    public KeyValueStoreUpdate update(String key, String value) {
        actions.add(new Update(key, value));
        return this;
    }

    /**
     * Adds a new update action to the event that stores the given value
     * on the path formed by the path segments.
     * 
     * @param value the value
     * @param segments the path segments
     * @return the event for easy chaining
     */
    public KeyValueStoreUpdate storeAs(String value, String... segments) {
        actions.add(new Update("/" + String.join("/", segments), value));
        return this;
    }

    /**
     * Adds a new deletion action to the event.
     * 
     * @param key the key
     * @return the event for easy chaining
     */
    public KeyValueStoreUpdate delete(String key) {
        actions.add(new Deletion(key));
        return this;
    }

    /**
     * Adds a new deletion action that clears all keys with the given
     * path prefix.
     * 
     * @param segments the path segments
     * @return the event for easy chaining
     */
    public KeyValueStoreUpdate clearAll(String... segments) {
        actions.add(new Deletion("/" + String.join("/", segments)));
        return this;
    }

    /**
     * Returns the actions.
     * 
     * @return the actions
     */
    public List actions() {
        return Collections.unmodifiableList(actions);
    }

    /**
     * The base class for all actions.
     */
    @SuppressWarnings("PMD.AbstractClassWithoutAbstractMethod")
    public abstract static class Action {

        private final String key;

        /**
         * Instantiates a new action.
         *
         * @param key the key
         */
        public Action(String key) {
            this.key = key;
        }

        /**
         * Key.
         *
         * @return the string
         */
        public String key() {
            return key;
        }
    }

    /**
     * A key (and value) deletion.
     */
    public static class Deletion extends Action {

        /**
         * Instantiates a new deletion.
         *
         * @param key the key
         */
        public Deletion(String key) {
            super(key);
        }
    }

    /**
     * A value update.
     */
    public static class Update extends Action {
        private final String value;

        /**
         * Instantiates a new update.
         *
         * @param key the key
         * @param value the value
         */
        public Update(String key, String value) {
            super(key);
            this.value = value;
        }

        /**
         * Value.
         *
         * @return the string
         */
        public String value() {
            return value;
        }
    }
}