/*
 * Copyright © 2014, 2017 EBay Software Foundation and others. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 which accompanies this distribution,
 * and is available at http://www.eclipse.org/legal/epl-v10.html
 */

package org.opendaylight.ovsdb.lib.impl;

import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.google.common.util.concurrent.Futures;
import com.google.common.util.concurrent.ListenableFuture;
import com.google.common.util.concurrent.MoreExecutors;
import java.util.ArrayList;
import java.util.List;
import org.opendaylight.ovsdb.lib.operations.Operation;
import org.opendaylight.ovsdb.lib.operations.OperationResult;

public final class FutureTransformUtils {
    private static final ObjectMapper OBJECT_MAPPER = new ObjectMapper()
            .configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);

    private FutureTransformUtils() {
    }

    public static ListenableFuture<List<OperationResult>> transformTransactResponse(
            final ListenableFuture<List<JsonNode>> transactResponseFuture, final List<Operation> operations) {
        return Futures.transform(transactResponseFuture, jsonNodes -> {
            final List<OperationResult> operationResults = new ArrayList<>();
            for (int index = 0; index < jsonNodes.size(); index++) {
                JsonNode jsonNode = jsonNodes.get(index);
                OperationResult or;
                if (jsonNode != null && jsonNode.size() > 0) {
                    /*
                     * As per RFC 7047, section 4.1.3 :
                     * "In general, "result" contains some number of successful results,
                     * possibly followed by an error, in turn followed by enough JSON null
                     * values to match the number of elements in "params".  There is one
                     * exception: if all of the operations succeed, but the results cannot
                     * be committed, then "result" will have one more element than "params",
                     * with the additional element being an <error>."
                     *
                     * Hence, it is possible for a transaction response to contain more
                     * json elements than the transaction operation request.
                     * Also handle that case by checking for i < operations.size().
                     */
                    if (index < operations.size()) {
                        Operation op = operations.get(index);
                        switch (op.getOp()) {
                            case "select":
                                or = new OperationResult();
                                or.setRows(op.getTableSchema().createRows(jsonNode));
                                break;

                            default:
                                or = OBJECT_MAPPER.convertValue(jsonNode, OperationResult.class);

                                break;
                        }
                    } else {
                        or = OBJECT_MAPPER.convertValue(jsonNode, OperationResult.class);
                    }
                } else {
                    or = new OperationResult();
                }
                operationResults.add(or);
            }

            return operationResults;
        }, MoreExecutors.directExecutor());
    }
}