/*
 * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
 * or more contributor license agreements. Licensed under the Elastic License
 * 2.0 and the Server Side Public License, v 1; you may not use this file except
 * in compliance with, at your election, the Elastic License 2.0 or the Server
 * Side Public License, v 1.
 */

package org.elasticsearch.index.reindex;

import org.elasticsearch.ElasticsearchException;
import org.elasticsearch.ElasticsearchParseException;
import org.elasticsearch.action.ActionResponse;
import org.elasticsearch.action.bulk.BulkItemResponse.Failure;
import org.elasticsearch.common.io.stream.StreamInput;
import org.elasticsearch.common.io.stream.StreamOutput;
import org.elasticsearch.core.Nullable;
import org.elasticsearch.core.TimeValue;
import org.elasticsearch.index.reindex.BulkByScrollTask.Status;
import org.elasticsearch.index.reindex.ScrollableHitSource.SearchFailure;
import org.elasticsearch.rest.RestStatus;
import org.elasticsearch.xcontent.ObjectParser;
import org.elasticsearch.xcontent.ParseField;
import org.elasticsearch.xcontent.ToXContentFragment;
import org.elasticsearch.xcontent.XContentBuilder;
import org.elasticsearch.xcontent.XContentParser;
import org.elasticsearch.xcontent.XContentParser.Token;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import static java.lang.Math.max;
import static java.lang.Math.min;
import static java.util.Objects.requireNonNull;
import static org.elasticsearch.common.xcontent.XContentParserUtils.ensureExpectedToken;
import static org.elasticsearch.core.TimeValue.timeValueNanos;

/**
 * Response used for actions that index many documents using a scroll request.
 */
public class BulkByScrollResponse extends ActionResponse implements ToXContentFragment {
    private TimeValue took;
    private BulkByScrollTask.Status status;
    private List<Failure> bulkFailures;
    private List<ScrollableHitSource.SearchFailure> searchFailures;
    private boolean timedOut;

    private static final String TOOK_FIELD = "took";
    private static final String TIMED_OUT_FIELD = "timed_out";
    private static final String FAILURES_FIELD = "failures";

    @SuppressWarnings("unchecked")
    private static final ObjectParser<BulkByScrollResponseBuilder, Void> PARSER = new ObjectParser<>(
        "bulk_by_scroll_response",
        true,
        BulkByScrollResponseBuilder::new
    );
    static {
        PARSER.declareLong(BulkByScrollResponseBuilder::setTook, new ParseField(TOOK_FIELD));
        PARSER.declareBoolean(BulkByScrollResponseBuilder::setTimedOut, new ParseField(TIMED_OUT_FIELD));
        PARSER.declareObjectArray(BulkByScrollResponseBuilder::setFailures, (p, c) -> parseFailure(p), new ParseField(FAILURES_FIELD));
        // since the result of BulkByScrollResponse.Status are mixed we also parse that in this
        Status.declareFields(PARSER);
    }

    public BulkByScrollResponse(StreamInput in) throws IOException {
        super(in);
        took = in.readTimeValue();
        status = new BulkByScrollTask.Status(in);
        bulkFailures = in.readList(Failure::new);
        searchFailures = in.readList(ScrollableHitSource.SearchFailure::new);
        timedOut = in.readBoolean();
    }

    public BulkByScrollResponse(
        TimeValue took,
        BulkByScrollTask.Status status,
        List<Failure> bulkFailures,
        List<ScrollableHitSource.SearchFailure> searchFailures,
        boolean timedOut
    ) {
        this.took = took;
        this.status = requireNonNull(status, "Null status not supported");
        this.bulkFailures = bulkFailures;
        this.searchFailures = searchFailures;
        this.timedOut = timedOut;
    }

    public BulkByScrollResponse(Iterable<BulkByScrollResponse> toMerge, @Nullable String reasonCancelled) {
        long mergedTook = 0;
        List<BulkByScrollTask.StatusOrException> statuses = new ArrayList<>();
        bulkFailures = new ArrayList<>();
        searchFailures = new ArrayList<>();
        for (BulkByScrollResponse response : toMerge) {
            mergedTook = max(mergedTook, response.getTook().nanos());
            statuses.add(new BulkByScrollTask.StatusOrException(response.status));
            bulkFailures.addAll(response.getBulkFailures());
            searchFailures.addAll(response.getSearchFailures());
            timedOut |= response.isTimedOut();
        }
        took = timeValueNanos(mergedTook);
        status = new BulkByScrollTask.Status(statuses, reasonCancelled);
    }

    public TimeValue getTook() {
        return took;
    }

    public BulkByScrollTask.Status getStatus() {
        return status;
    }

    public long getCreated() {
        return status.getCreated();
    }

    public long getTotal() {
        return status.getTotal();
    }

    public long getDeleted() {
        return status.getDeleted();
    }

    public long getUpdated() {
        return status.getUpdated();
    }

    public int getBatches() {
        return status.getBatches();
    }

    public long getVersionConflicts() {
        return status.getVersionConflicts();
    }

    public long getNoops() {
        return status.getNoops();
    }

    /**
     * The reason that the request was canceled or null if it hasn't been.
     */
    public String getReasonCancelled() {
        return status.getReasonCancelled();
    }

    /**
     * The number of times that the request had retry bulk actions.
     */
    public long getBulkRetries() {
        return status.getBulkRetries();
    }

    /**
     * The number of times that the request had retry search actions.
     */
    public long getSearchRetries() {
        return status.getSearchRetries();
    }

    /**
     * All of the bulk failures. Version conflicts are only included if the request sets abortOnVersionConflict to true (the default).
     */
    public List<Failure> getBulkFailures() {
        return bulkFailures;
    }

    /**
     * All search failures.
     */
    public List<ScrollableHitSource.SearchFailure> getSearchFailures() {
        return searchFailures;
    }

    /**
     * Did any of the sub-requests that were part of this request timeout?
     */
    public boolean isTimedOut() {
        return timedOut;
    }

    @Override
    public void writeTo(StreamOutput out) throws IOException {
        out.writeTimeValue(took);
        status.writeTo(out);
        out.writeList(bulkFailures);
        out.writeList(searchFailures);
        out.writeBoolean(timedOut);
    }

    @Override
    public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
        builder.field(TOOK_FIELD, took.millis());
        builder.field(TIMED_OUT_FIELD, timedOut);
        status.innerXContent(builder, params);
        builder.startArray("failures");
        for (Failure failure : bulkFailures) {
            builder.startObject();
            failure.toXContent(builder, params);
            builder.endObject();
        }
        for (ScrollableHitSource.SearchFailure failure : searchFailures) {
            failure.toXContent(builder, params);
        }
        builder.endArray();
        return builder;
    }

    public static BulkByScrollResponse fromXContent(XContentParser parser) {
        return PARSER.apply(parser, null).buildResponse();
    }

    private static Object parseFailure(XContentParser parser) throws IOException {
        ensureExpectedToken(Token.START_OBJECT, parser.currentToken(), parser);
        Token token;
        String index = null;
        String id = null;
        Integer status = null;
        Integer shardId = null;
        String nodeId = null;
        ElasticsearchException bulkExc = null;
        ElasticsearchException searchExc = null;
        while ((token = parser.nextToken()) != Token.END_OBJECT) {
            ensureExpectedToken(Token.FIELD_NAME, token, parser);
            String name = parser.currentName();
            token = parser.nextToken();
            if (token == Token.START_ARRAY) {
                parser.skipChildren();
            } else if (token == Token.START_OBJECT) {
                switch (name) {
                    case SearchFailure.REASON_FIELD -> searchExc = ElasticsearchException.fromXContent(parser);
                    case Failure.CAUSE_FIELD -> bulkExc = ElasticsearchException.fromXContent(parser);
                    default -> parser.skipChildren();
                }
            } else if (token == Token.VALUE_STRING) {
                switch (name) {
                    // This field is the same as SearchFailure.index
                    case Failure.INDEX_FIELD -> index = parser.text();
                    case Failure.ID_FIELD -> id = parser.text();
                    case SearchFailure.NODE_FIELD -> nodeId = parser.text();
                }
            } else if (token == Token.VALUE_NUMBER) {
                switch (name) {
                    case Failure.STATUS_FIELD -> status = parser.intValue();
                    case SearchFailure.SHARD_FIELD -> shardId = parser.intValue();
                }
            }
        }
        if (bulkExc != null) {
            return new Failure(index, id, bulkExc, RestStatus.fromCode(status));
        } else if (searchExc != null) {
            if (status == null) {
                return new SearchFailure(searchExc, index, shardId, nodeId);
            } else {
                return new SearchFailure(searchExc, index, shardId, nodeId, RestStatus.fromCode(status));
            }
        } else {
            throw new ElasticsearchParseException("failed to parse failures array. At least one of {reason,cause} must be present");
        }
    }

    @Override
    public String toString() {
        StringBuilder builder = new StringBuilder();
        builder.append(getClass().getSimpleName()).append("[");
        builder.append("took=").append(took).append(',');
        builder.append("timed_out=").append(timedOut).append(',');
        status.innerToString(builder);
        builder.append(",bulk_failures=").append(getBulkFailures().subList(0, min(3, getBulkFailures().size())));
        builder.append(",search_failures=").append(getSearchFailures().subList(0, min(3, getSearchFailures().size())));
        return builder.append(']').toString();
    }
}
