baku-toolkit/lib/src/main/java/io/v/rx/syncbase/SingleWatchEvent.java

// Copyright 2015 The Vanadium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package io.v.rx.syncbase;

import com.google.common.reflect.TypeToken;

import io.v.v23.services.watch.ResumeMarker;
import io.v.v23.syncbase.nosql.ChangeType;
import io.v.v23.syncbase.nosql.WatchChange;
import io.v.v23.verror.VException;
import io.v.v23.vom.VomUtil;
import java8.util.function.Function;
import lombok.Value;
import lombok.experimental.Accessors;

@Accessors(prefix = "m")
@Value
public class SingleWatchEvent<T> {
    T mValue;
    ResumeMarker mResumeMarker;
    boolean mFromSync;

    @SuppressWarnings("unchecked")
    private static <T> T getWatchValue(final WatchChange change, final TypeToken<T> tt,
                                       final T defaultValue) throws VException {
        if (change.getChangeType() == ChangeType.DELETE_CHANGE) {
            return defaultValue;
        } else {
            return (T) VomUtil.decode(change.getVomValue(),
                    tt == null? Object.class : tt.getType());
        }
    }

    public static <T> SingleWatchEvent<T> fromWatchChange(
            final WatchChange c, final TypeToken<T> tt, final T defaultValue) throws VException {
        return new SingleWatchEvent<>(getWatchValue(c, tt, defaultValue),
                c.getResumeMarker(), c.isFromSync());
    }

    public static <T> SingleWatchEvent<T> fromWatchChange(
            final WatchChange c, final Class<T> type, final T defaultValue) throws VException {
        return fromWatchChange(c, TypeToken.of(type), defaultValue);
    }

    public <U> SingleWatchEvent<U> map(final Function<T, U> fn) {
        return new SingleWatchEvent<>(fn.apply(mValue), mResumeMarker, mFromSync);
    }
}