/*
 * 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.cluster.routing.allocation.command;

import org.elasticsearch.ElasticsearchException;
import org.elasticsearch.ElasticsearchIllegalArgumentException;
import org.elasticsearch.ElasticsearchParseException;
import org.elasticsearch.cluster.node.DiscoveryNode;
import org.elasticsearch.cluster.routing.*;
import org.elasticsearch.cluster.routing.allocation.RerouteExplanation;
import org.elasticsearch.cluster.routing.allocation.RoutingAllocation;
import org.elasticsearch.cluster.routing.allocation.decider.Decision;
import org.elasticsearch.common.io.stream.StreamInput;
import org.elasticsearch.common.io.stream.StreamOutput;
import org.elasticsearch.common.xcontent.ToXContent;
import org.elasticsearch.common.xcontent.XContentBuilder;
import org.elasticsearch.common.xcontent.XContentParser;
import org.elasticsearch.index.shard.ShardId;

import java.io.IOException;

import static org.elasticsearch.cluster.routing.ShardRoutingState.INITIALIZING;
import static org.elasticsearch.cluster.routing.ShardRoutingState.RELOCATING;

/**
 * A command that cancels relocation, or recovery of a given shard on a node.
 */
public class CancelAllocationCommand implements AllocationCommand {

    public static final String NAME = "cancel";

    /**
     * Factory creating {@link CancelAllocationCommand}s
     */
    public static class Factory implements AllocationCommand.Factory<CancelAllocationCommand> {

        @Override
        public CancelAllocationCommand readFrom(StreamInput in) throws IOException {
            return new CancelAllocationCommand(ShardId.readShardId(in), in.readString(), in.readBoolean());
        }

        @Override
        public void writeTo(CancelAllocationCommand command, StreamOutput out) throws IOException {
            command.shardId().writeTo(out);
            out.writeString(command.node());
            out.writeBoolean(command.allowPrimary());
        }

        @Override
        public CancelAllocationCommand fromXContent(XContentParser parser) throws IOException {
            String index = null;
            int shardId = -1;
            String nodeId = null;
            boolean allowPrimary = false;

            String currentFieldName = null;
            XContentParser.Token token;
            while ((token = parser.nextToken()) != XContentParser.Token.END_OBJECT) {
                if (token == XContentParser.Token.FIELD_NAME) {
                    currentFieldName = parser.currentName();
                } else if (token.isValue()) {
                    if ("index".equals(currentFieldName)) {
                        index = parser.text();
                    } else if ("shard".equals(currentFieldName)) {
                        shardId = parser.intValue();
                    } else if ("node".equals(currentFieldName)) {
                        nodeId = parser.text();
                    } else if ("allow_primary".equals(currentFieldName) || "allowPrimary".equals(currentFieldName)) {
                        allowPrimary = parser.booleanValue();
                    } else {
                        throw new ElasticsearchParseException("[cancel] command does not support field [" + currentFieldName + "]");
                    }
                } else {
                    throw new ElasticsearchParseException("[cancel] command does not support complex json tokens [" + token + "]");
                }
            }
            if (index == null) {
                throw new ElasticsearchParseException("[cancel] command missing the index parameter");
            }
            if (shardId == -1) {
                throw new ElasticsearchParseException("[cancel] command missing the shard parameter");
            }
            if (nodeId == null) {
                throw new ElasticsearchParseException("[cancel] command missing the node parameter");
            }
            return new CancelAllocationCommand(new ShardId(index, shardId), nodeId, allowPrimary);
        }

        @Override
        public void toXContent(CancelAllocationCommand command, XContentBuilder builder, ToXContent.Params params, String objectName) throws IOException {
            if (objectName == null) {
                builder.startObject();
            } else {
                builder.startObject(objectName);
            }
            builder.field("index", command.shardId().index().name());
            builder.field("shard", command.shardId().id());
            builder.field("node", command.node());
            builder.field("allow_primary", command.allowPrimary());
            builder.endObject();
        }
    }


    private final ShardId shardId;
    private final String node;
    private final boolean allowPrimary;

    /**
     * Creates a new {@link CancelAllocationCommand}
     * 
     * @param shardId id of the shard which allocation should be canceled
     * @param node id of the node that manages the shard which allocation should be canceled
     * @param allowPrimary 
     */
    public CancelAllocationCommand(ShardId shardId, String node, boolean allowPrimary) {
        this.shardId = shardId;
        this.node = node;
        this.allowPrimary = allowPrimary;
    }

    @Override
    public String name() {
        return NAME;
    }

    /**
     * Get the id of the shard which allocation should be canceled
     * @return id of the shard which allocation should be canceled
     */
    public ShardId shardId() {
        return this.shardId;
    }

    /**
     * Get the id of the node that manages the shard which allocation should be canceled
     * @return id of the node that manages the shard which allocation should be canceled
     */
    public String node() {
        return this.node;
    }

    public boolean allowPrimary() {
        return this.allowPrimary;
    }

    @Override
    public RerouteExplanation execute(RoutingAllocation allocation, boolean explain) throws ElasticsearchException {
        DiscoveryNode discoNode = allocation.nodes().resolveNode(node);
        boolean found = false;
        for (RoutingNodes.RoutingNodeIterator it = allocation.routingNodes().routingNodeIter(discoNode.id()); it.hasNext(); ) {
            MutableShardRouting shardRouting = it.next();
            if (!shardRouting.shardId().equals(shardId)) {
                continue;
            }
            found = true;
            if (shardRouting.relocatingNodeId() != null) {
                if (shardRouting.initializing()) {
                    // the shard is initializing and recovering from another node, simply cancel the recovery
                    it.remove();
                    // and cancel the relocating state from the shard its being relocated from
                    RoutingNode relocatingFromNode = allocation.routingNodes().node(shardRouting.relocatingNodeId());
                    if (relocatingFromNode != null) {
                        for (MutableShardRouting fromShardRouting : relocatingFromNode) {
                            if (fromShardRouting.shardId().equals(shardRouting.shardId()) && fromShardRouting.state() == RELOCATING) {
                                allocation.routingNodes().cancelRelocation(fromShardRouting);
                                break;
                            }
                        }
                    }
                } else if (shardRouting.relocating()) {

                    // the shard is relocating to another node, cancel the recovery on the other node, and deallocate this one
                    if (!allowPrimary && shardRouting.primary()) {
                        // can't cancel a primary shard being initialized
                        if (explain) {
                            return new RerouteExplanation(this, allocation.decision(Decision.NO, "cancel_allocation_command",
                                    "can't cancel " + shardId + " on node " + discoNode + ", shard is primary and initializing its state"));
                        }
                        throw new ElasticsearchIllegalArgumentException("[cancel_allocation] can't cancel " + shardId + " on node " +
                                discoNode + ", shard is primary and initializing its state");
                    }
                    it.moveToUnassigned(new UnassignedInfo(UnassignedInfo.Reason.REROUTE_CANCELLED, null));
                    // now, go and find the shard that is initializing on the target node, and cancel it as well...
                    RoutingNodes.RoutingNodeIterator initializingNode = allocation.routingNodes().routingNodeIter(shardRouting.relocatingNodeId());
                    if (initializingNode != null) {
                        while (initializingNode.hasNext()) {
                            MutableShardRouting initializingShardRouting = initializingNode.next();
                            if (initializingShardRouting.shardId().equals(shardRouting.shardId()) && initializingShardRouting.state() == INITIALIZING) {
                                initializingNode.remove();
                            }
                        }
                    }
                }
            } else {
                // the shard is not relocating, its either started, or initializing, just cancel it and move on...
                if (!allowPrimary && shardRouting.primary()) {
                    // can't cancel a primary shard being initialized
                    if (explain) {
                        return new RerouteExplanation(this, allocation.decision(Decision.NO, "cancel_allocation_command",
                                "can't cancel " + shardId + " on node " + discoNode + ", shard is primary and started"));
                    }
                    throw new ElasticsearchIllegalArgumentException("[cancel_allocation] can't cancel " + shardId + " on node " +
                            discoNode + ", shard is primary and started");
                }
                it.moveToUnassigned(new UnassignedInfo(UnassignedInfo.Reason.REROUTE_CANCELLED, null));
            }
        }
        if (!found) {
            if (explain) {
                return new RerouteExplanation(this, allocation.decision(Decision.NO, "cancel_allocation_command",
                        "can't cancel " + shardId + ", failed to find it on node " + discoNode));
            }
            throw new ElasticsearchIllegalArgumentException("[cancel_allocation] can't cancel " + shardId + ", failed to find it on node " + discoNode);
        }
        return new RerouteExplanation(this, allocation.decision(Decision.YES, "cancel_allocation_command",
                "shard " + shardId + " on node " + discoNode + " can be cancelled"));
    }
}
