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/**
 * JBoss, Home of Professional Open Source
 * Copyright Red Hat, Inc., and individual contributors.
 *
 * 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.
 */
package org.jboss.aerogear.sync.server;

import com.fasterxml.jackson.databind.JsonNode;
import org.jboss.aerogear.sync.Diff;
import org.jboss.aerogear.sync.Document;
import org.jboss.aerogear.sync.Edit;
import org.jboss.aerogear.sync.PatchMessage;
import org.jboss.aerogear.sync.ShadowDocument;

import java.util.Queue;

/**
 * A instance of this class will be able to handle tasks needed to implement
 * Differential Synchronization for a specific type of documents.
 *
 * @param  The type of documents that this engine can handle.
 * @param  The type of {@link Edit}s that this synchronizer can handle
 */
public interface ServerSynchronizer> {

    /**
     * Called when the shadow should be patched. Is called when an update is recieved.
     *
     * @param edit The edits.
     * @param shadowDocument the {@link ShadowDocument} to patch
     * @return {@link ShadowDocument} a new patched shadow document.
     */
    ShadowDocument patchShadow(S edit, ShadowDocument shadowDocument);

    /**
     * Called when the document should be patched.
     *
     * @param edit the edit to use to path the document
     * @param document the document to be patched.
     * @return {@link Document} a new patched document.
     */
    Document patchDocument(S edit, Document document);

    /**
     * The first step in a sync is to produce a an edit for the changes.
     * The produced edit can then be sent to the opposing side perform an update/sync.
     *
     * @param document the document containing
     * @param shadowDocument the document shadow.
     * @return {@link Edit} the edit representing the diff between the document and it's shadow document.
     */
    S serverDiff(Document document, ShadowDocument shadowDocument);

    /**
     * Is called to produce an {@link Edit} of changes coming from a client.
     *
     * @param document the server side document .
     * @param shadowDocument the document shadow containing the client changes.
     * @return {@link Edit} the edit representing the diff between the document and it's shadow document.
     */
    S clientDiff(Document document, ShadowDocument shadowDocument);

    /**
     * Creates a new {@link PatchMessage} with the with the type of {@link Edit} that this
     * synchronizer can handle.
     *
     * @param documentId the document identifier for the {@code PatchMessage}
     * @param clientId the client identifier for the {@code PatchMessage}
     * @param edits the {@link Edit}s for the {@code PatchMessage}
     * @return {@link PatchMessage} the created {code PatchMessage}
     */
    PatchMessage createPatchMessage(String documentId, String clientId, Queue edits);

    /**
     * Creates a {link PatchMessage} by parsing the passed-in json.
     *
     * @param json the json representation of a {@code PatchMessage}
     * @return {@link PatchMessage} the created {code PatchMessage}
     */
    PatchMessage patchMessageFromJson(String json);

    /**
     * Converts the {@link JsonNode} into a {@link Document} instance.
     *
     * @param json the {@link JsonNode} to convert
     * @return {@link Document} the document representing the contents of the {@link JsonNode} instance.
     */
    Document documentFromJson(JsonNode json);

}