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/*
 * Copyright (c) 2010-2017, KolibriFX AS. Licensed under the Apache License, version 2.0.
 */

package com.kolibrifx.plovercrest.server.streams;

import com.kolibrifx.plovercrest.client.TableMetadata;

public interface Stream {
    PollableReader createReaderFromTimestamp(long timestamp, StreamObserver observer);

    PollableReader createReaderFromIndex(long index, StreamObserver observer);

    String getName();

    Class getElementClass();

    /**
     * Should return a valid writer, or throw a
     * {@link com.kolibrifx.plovercrest.client.PlovercrestException} if this stream does not
     * support writing.
     */
    StreamWriter getWriter();

    /**
     * Returns the first timestamp, or -1 if the stream is empty.
     * 
     * Non-materialized streams should return the earliest possible timestamp that can be generated,
     * typically zero, but not a negative value.
     */
    long getFirstTimestamp();

    /**
     * Returns the last timestamp, or -1 if the stream is empty.
     * 

     * Non-materialized streams should return the largest value that can be generated. (Maybe
     * {@link System#currentTimeMillis()}?)
     */
    long getLastTimestamp();

    /**
     * Returns the data size on disk, in bytes, not including metadata. Non-materialized streams
     * should return 0.
     */
    long getDataLengthInBytes();

    /**
     * Returns the number of entries in this stream.
     * 

     * Non-materialized streams should return the number of entries that can be generated if known,
     * or -1 if unknown.
     */
    long getEntryCount();

    /**
     * Get a key-value map of metadata.
     */
    TableMetadata getMetadata();

    /**
     * Returns the "last valid timestamp", which is usually the same as {@link #getLastTimestamp()},
     * but can also be larger.
     * 
     * The stream must guarantee that the next timestamp after {@link #getLastTimestamp()} will not
     * be smaller than {@link #getLastValidTimestamp()}.
     */
    long getLastValidTimestamp();

    /**
     * Is the stream frozen? (write-protected)
     */
    boolean isFrozen();

    /**
     * Delete the stream, if possible. Return true if successful, false if
     * deletion is not possible or supported.
     */
    boolean delete();

    /**
     * Rename the stream, if possible. Return true if successful, false if
     * renaming is not possible or supported.
     */
    boolean rename(String newName);

    /**
     * Returns the largest timestamp ≤ targetTimestamp, if such a timestamp exists. If the first
     * timestamp is larger than the target, the first timestamp should be returned. If the stream is
     * empty, -1 should be returned.
     */
    long seekPreviousTimestamp(long targetTimestamp);
}