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Client library for working with the NATS messaging system.
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// Copyright 2021 The NATS Authors
// 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 io.nats.client.impl;

import io.nats.client.JetStreamApiException;
import io.nats.client.Message;
import io.nats.client.api.*;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

public class NatsKeyValueWatchSubscription extends NatsWatchSubscription {

    public NatsKeyValueWatchSubscription(NatsKeyValue kv, String keyPattern, KeyValueWatcher watcher, long fromRevision, KeyValueWatchOption... watchOptions) throws IOException, JetStreamApiException {
        this(kv, Collections.singletonList(keyPattern), watcher, fromRevision, watchOptions);
    }

    public NatsKeyValueWatchSubscription(NatsKeyValue kv, List keyPatterns, KeyValueWatcher watcher, long fromRevision, KeyValueWatchOption... watchOptions) throws IOException, JetStreamApiException {
        super(kv.js);
        kwWatchInit(kv, keyPatterns, watcher, fromRevision, watchOptions);
    }

    private void kwWatchInit(NatsKeyValue kv, List keyPatterns, KeyValueWatcher watcher, long fromRevision, KeyValueWatchOption[] watchOptions) throws IOException, JetStreamApiException {
        // figure out the result options
        boolean headersOnly = false;
        boolean ignoreDeletes = false;
        DeliverPolicy deliverPolicy = DeliverPolicy.LastPerSubject;
        for (KeyValueWatchOption wo : watchOptions) {
            if (wo != null) {
                switch (wo) {
                    case META_ONLY: headersOnly = true; break;
                    case IGNORE_DELETE: ignoreDeletes = true; break;
                    case UPDATES_ONLY: deliverPolicy = DeliverPolicy.New; break;
                    case INCLUDE_HISTORY: deliverPolicy = DeliverPolicy.All; break;
                }
            }
        }

        final boolean includeDeletes = !ignoreDeletes;
        WatchMessageHandler handler =
            new WatchMessageHandler(watcher) {
                @Override
                public void onMessage(Message m) throws InterruptedException {
                    KeyValueEntry kve = new KeyValueEntry(m);
                    if (includeDeletes || kve.getOperation() == KeyValueOperation.PUT) {
                        watcher.watch(kve);
                    }
                    if (!endOfDataSent && kve.getDelta() == 0) {
                        sendEndOfData();
                    }
                }
            };

        // convert each key to a read subject
        List readSubjects = new ArrayList<>();
        for (String keyPattern : keyPatterns) {
            readSubjects.add(kv.readSubject(keyPattern.trim()));
        }

        finishInit(kv, readSubjects, deliverPolicy, headersOnly, fromRevision, handler);
    }
}