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Fun I/O Delta

There is a newer version: 2.4.1

package global.namespace.fun.io.delta;

import global.namespace.fun.io.api.ArchiveSink;
import global.namespace.fun.io.api.ArchiveSource;

import java.util.Optional;

import static java.util.Optional.empty;

/**
 * A builder for an archive file patch.
 *
 * @author Christian Schlichtherle
 */
@SuppressWarnings({"OptionalUsedAsFieldOrParameterType", "ConstantConditions"})
public final class ArchivePatchBuilder {

    private Optional base = empty(), delta = empty();

    ArchivePatchBuilder() {
    }

    /**
     * Returns this archive patch builder with the given source for reading the base archive file.
     * This is an alias for {@link #base(ArchiveSource)}.
     */
    public ArchivePatchBuilder first(ArchiveSource base) {
        return base(base);
    }

    /**
     * Returns this archive patch builder with the given source for reading the base archive file.
     */
    public ArchivePatchBuilder base(final ArchiveSource base) {
        this.base = Optional.of(base);
        return this;
    }

    /**
     * Returns this archive patch builder with the given source for reading the delta archive file.
     */
    public ArchivePatchBuilder delta(final ArchiveSource delta) {
        this.delta = Optional.of(delta);
        return this;
    }

    /**
     * Writes the update archive file computed from the base and delta archive files to the given sink.
     */
    @SuppressWarnings("unchecked")
    public void to(ArchiveSink update) throws Exception {
        build().to(update);
    }

    private ArchivePatch build() {
        return create(base.get(), delta.get());
    }

    private static ArchivePatch create(ArchiveSource baseSource, ArchiveSource deltaSource) {
        return new ArchivePatch() {

            ArchiveSource baseSource() {
                return baseSource;
            }

            ArchiveSource deltaSource() {
                return deltaSource;
            }
        };
    }
}