/*
 * Licensed to Elasticsearch under one or more contributor
 * license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright
 * ownership. Elasticsearch 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.elasticsearch.index.shard;

import org.elasticsearch.cluster.metadata.IndexMetaData;
import org.elasticsearch.cluster.routing.AllocationId;
import org.elasticsearch.common.Nullable;
import org.elasticsearch.common.xcontent.XContentBuilder;
import org.elasticsearch.common.xcontent.XContentParser;
import org.elasticsearch.common.xcontent.XContentType;
import org.elasticsearch.gateway.CorruptStateException;
import org.elasticsearch.gateway.MetaDataStateFormat;

import java.io.IOException;
import java.io.OutputStream;

public final class ShardStateMetaData {

    private static final String SHARD_STATE_FILE_PREFIX = "state-";
    private static final String PRIMARY_KEY = "primary";
    private static final String VERSION_KEY = "version"; // for pre-5.0 shards that have not yet been active
    private static final String INDEX_UUID_KEY = "index_uuid";
    private static final String ALLOCATION_ID_KEY = "allocation_id";

    public final String indexUUID;
    public final boolean primary;
    @Nullable
    public final AllocationId allocationId; // can be null if we read from legacy format (see fromXContent and MultiDataPathUpgrader)

    public ShardStateMetaData(boolean primary, String indexUUID, AllocationId allocationId) {
        assert indexUUID != null;
        this.primary = primary;
        this.indexUUID = indexUUID;
        this.allocationId = allocationId;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) {
            return true;
        }
        if (o == null || getClass() != o.getClass()) {
            return false;
        }

        ShardStateMetaData that = (ShardStateMetaData) o;

        if (primary != that.primary) {
            return false;
        }
        if (indexUUID != null ? !indexUUID.equals(that.indexUUID) : that.indexUUID != null) {
          return false;
        }
        if (allocationId != null ? !allocationId.equals(that.allocationId) : that.allocationId != null) {
            return false;
        }

        return true;
    }

    @Override
    public int hashCode() {
        int result = (indexUUID != null ? indexUUID.hashCode() : 0);
        result = 31 * result + (allocationId != null ? allocationId.hashCode() : 0);
        result = 31 * result + (primary ? 1 : 0);
        return result;
    }

    @Override
    public String toString() {
        return "primary [" + primary + "], allocation [" + allocationId + "]";
    }

    public static final MetaDataStateFormat<ShardStateMetaData> FORMAT = new MetaDataStateFormat<ShardStateMetaData>(XContentType.SMILE, SHARD_STATE_FILE_PREFIX) {

        @Override
        protected XContentBuilder newXContentBuilder(XContentType type, OutputStream stream) throws IOException {
            XContentBuilder xContentBuilder = super.newXContentBuilder(type, stream);
            xContentBuilder.prettyPrint();
            return xContentBuilder;
        }

        @Override
        public void toXContent(XContentBuilder builder, ShardStateMetaData shardStateMetaData) throws IOException {
            builder.field(PRIMARY_KEY, shardStateMetaData.primary);
            builder.field(INDEX_UUID_KEY, shardStateMetaData.indexUUID);
            if (shardStateMetaData.allocationId != null) {
                builder.field(ALLOCATION_ID_KEY, shardStateMetaData.allocationId);
            }
        }

        @Override
        public ShardStateMetaData fromXContent(XContentParser parser) throws IOException {
            XContentParser.Token token = parser.nextToken();
            if (token == null) {
                return null;
            }
            Boolean primary = null;
            String currentFieldName = null;
            String indexUUID = IndexMetaData.INDEX_UUID_NA_VALUE;
            AllocationId allocationId = null;
            while ((token = parser.nextToken()) != XContentParser.Token.END_OBJECT) {
                if (token == XContentParser.Token.FIELD_NAME) {
                    currentFieldName = parser.currentName();
                } else if (token.isValue()) {
                    if (PRIMARY_KEY.equals(currentFieldName)) {
                        primary = parser.booleanValue();
                    } else if (INDEX_UUID_KEY.equals(currentFieldName)) {
                        indexUUID = parser.text();
                    } else if (VERSION_KEY.equals(currentFieldName)) {
                        // ES versions before 6.0 wrote this for legacy reasons, just ignore for now and remove in 7.0
                    } else {
                        throw new CorruptStateException("unexpected field in shard state [" + currentFieldName + "]");
                    }
                } else if (token == XContentParser.Token.START_OBJECT) {
                    if (ALLOCATION_ID_KEY.equals(currentFieldName)) {
                        allocationId = AllocationId.fromXContent(parser);
                    } else {
                        throw new CorruptStateException("unexpected object in shard state [" + currentFieldName + "]");
                    }
                } else {
                    throw new CorruptStateException("unexpected token in shard state [" + token.name() + "]");
                }
            }
            if (primary == null) {
                throw new CorruptStateException("missing value for [primary] in shard state");
            }
            return new ShardStateMetaData(primary, indexUUID, allocationId);
        }
    };
}