/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.ignite.internal.processors.cache.persistence.partstate;

import org.apache.ignite.internal.pagemem.FullPageId;
import org.apache.ignite.internal.pagemem.PageIdAllocator;
import org.apache.ignite.internal.pagemem.PageIdUtils;
import org.apache.ignite.internal.pagemem.PageMemory;
import org.apache.ignite.internal.util.typedef.internal.S;
import org.jetbrains.annotations.NotNull;

/**
 * Pair of cache group ID with partition ID. Immutable, comparable class, may be used as key in maps
 */
public class GroupPartitionId implements Comparable<GroupPartitionId> {
    /** Index for super(meta) page. There is always such page for iterated cache partition  */
    private static final int METAPAGE_IDX = 0;

    /** Cache group ID. */
    private final int grpId;

    /** Partition ID. */
    private final int partId;

    /**
     * Creates group-partition tuple.
     *
     * @param grpId Group ID.
     * @param partId Partition ID.
     */
    public GroupPartitionId(final int grpId, final int partId) {
        this.grpId = grpId;
        this.partId = partId;
    }

    /**
     * @param partId Partition ID.
     * @return flag to be used for partition
     */
    private static byte getFlagByPartId(final int partId) {
        return partId == PageIdAllocator.INDEX_PARTITION ? PageMemory.FLAG_IDX : PageMemory.FLAG_DATA;
    }

    /**
     * @return cache ID
     */
    public int getGroupId() {
        return grpId;
    }

    /**
     * @return Partition ID
     */
    public int getPartitionId() {
        return partId;
    }

    /** {@inheritDoc} */
    @Override public String toString() {
        return S.toString(GroupPartitionId.class, this);
    }

    /** {@inheritDoc} */
    @Override public boolean equals(Object o) {
        if (this == o)
            return true;

        if (o == null || getClass() != o.getClass())
            return false;

        GroupPartitionId key = (GroupPartitionId)o;

        if (grpId != key.grpId)
            return false;

        return partId == key.partId;
    }

    /** {@inheritDoc} */
    @Override public int hashCode() {
        int result = grpId;

        result = 31 * result + partId;

        return result;
    }

    /** {@inheritDoc} */
    @Override public int compareTo(@NotNull GroupPartitionId o) {
        if (getGroupId() < o.getGroupId())
            return -1;

        if (getGroupId() > o.getGroupId())
            return 1;

        if (getPartitionId() < o.getPartitionId())
            return -1;

        if (getPartitionId() > o.getPartitionId())
            return 1;
        return 0;
    }

    /**
     * @param pageIdx Page Index, monotonically growing number within each partition
     * @return page ID (64 bits) constructed from partition ID and given index
     */
    private long createPageId(final int pageIdx) {
        final int partId = getPartitionId();

        return PageIdUtils.pageId(partId, getFlagByPartId(partId), pageIdx);
    }

    /**
     * Returns Full page ID. For index 0 will return super-page of next partition
     *
     * @param pageIdx Page Index, monotonically growing number within each partition
     * @return FullPageId consists of cache ID (32 bits) and page ID (64 bits).
     */
    @NotNull private FullPageId createFullPageId(final int pageIdx) {
        return new FullPageId(createPageId(pageIdx), getGroupId());
    }

    /**
     * @return will return super-page (metapage) of this partition
     */
    @NotNull public FullPageId createFirstPageFullId() {
        return createFullPageId(METAPAGE_IDX);
    }
}