/*
 * 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", the "GNU Affero General Public License v3.0 only", 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", the "GNU Affero General Public
 * License v3.0 only", or the "Server Side Public License, v 1".
 */

package org.elasticsearch.rest.action;

import org.elasticsearch.action.fieldcaps.FieldCapabilitiesRequest;
import org.elasticsearch.action.support.IndicesOptions;
import org.elasticsearch.client.internal.node.NodeClient;
import org.elasticsearch.common.Strings;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.rest.BaseRestHandler;
import org.elasticsearch.rest.RestRequest;
import org.elasticsearch.rest.Scope;
import org.elasticsearch.rest.ServerlessScope;
import org.elasticsearch.search.crossproject.CrossProjectModeDecider;
import org.elasticsearch.xcontent.ObjectParser;
import org.elasticsearch.xcontent.ParseField;

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

import static org.elasticsearch.index.query.AbstractQueryBuilder.parseTopLevelQuery;
import static org.elasticsearch.rest.RestRequest.Method.GET;
import static org.elasticsearch.rest.RestRequest.Method.POST;
import static org.elasticsearch.xcontent.ObjectParser.fromList;

@ServerlessScope(Scope.PUBLIC)
public class RestFieldCapabilitiesAction extends BaseRestHandler {

    private final Settings settings;
    private final CrossProjectModeDecider crossProjectModeDecider;

    public RestFieldCapabilitiesAction(Settings settings) {
        this.settings = settings;
        this.crossProjectModeDecider = new CrossProjectModeDecider(settings);
    }

    @Override
    public List<Route> routes() {
        return List.of(
            new Route(GET, "/_field_caps"),
            new Route(POST, "/_field_caps"),
            new Route(GET, "/{index}/_field_caps"),
            new Route(POST, "/{index}/_field_caps")
        );
    }

    @Override
    public String getName() {
        return "field_capabilities_action";
    }

    @Override
    public RestChannelConsumer prepareRequest(final RestRequest request, final NodeClient client) throws IOException {
        final FieldCapabilitiesRequest fieldRequest = new FieldCapabilitiesRequest();

        final boolean crossProjectEnabled = crossProjectModeDecider.crossProjectEnabled();
        if (crossProjectEnabled) {
            // Setting includeResolvedTo to always include index resolution data structure in the linked project responses,
            // in order to allow the coordinating node to call CrossProjectIndexResolutionValidator#validate
            fieldRequest.includeResolvedTo(true);
        }

        final String[] indices = Strings.splitStringByCommaToArray(request.param("index"));
        fieldRequest.indices(indices);

        if (crossProjectEnabled && fieldRequest.allowsCrossProject()) {
            var cpsIdxOpts = IndicesOptions.builder(fieldRequest.indicesOptions())
                .crossProjectModeOptions(new IndicesOptions.CrossProjectModeOptions(true))
                .build();
            fieldRequest.indicesOptions(cpsIdxOpts);
        }

        fieldRequest.indicesOptions(IndicesOptions.fromRequest(request, fieldRequest.indicesOptions()));
        fieldRequest.includeUnmapped(request.paramAsBoolean("include_unmapped", false));
        fieldRequest.includeEmptyFields(request.paramAsBoolean("include_empty_fields", true));
        fieldRequest.filters(request.paramAsStringArray("filters", Strings.EMPTY_ARRAY));
        fieldRequest.types(request.paramAsStringArray("types", Strings.EMPTY_ARRAY));
        request.withContentOrSourceParamParserOrNull(parser -> {
            if (parser != null) {
                PARSER.parse(parser, fieldRequest, null);
            }
        });
        if (request.hasParam("fields")) {
            if (fieldRequest.fields().length > 0) {
                throw new IllegalArgumentException(
                    "can't specify a request body and [fields]"
                        + " request parameter, either specify a request body or the"
                        + " [fields] request parameter"
                );
            }
            fieldRequest.fields(Strings.splitStringByCommaToArray(request.param("fields")));
        }
        return channel -> {
            RestCancellableNodeClient cancelClient = new RestCancellableNodeClient(client, request.getHttpChannel());
            cancelClient.fieldCaps(fieldRequest, new RestRefCountedChunkedToXContentListener<>(channel));
        };
    }

    private static final ParseField INDEX_FILTER_FIELD = new ParseField("index_filter");
    private static final ParseField RUNTIME_MAPPINGS_FIELD = new ParseField("runtime_mappings");
    private static final ParseField FIELDS_FIELD = new ParseField("fields");
    private static final ParseField PROJECT_ROUTING = new ParseField("project_routing");

    private static final ObjectParser<FieldCapabilitiesRequest, Void> PARSER = new ObjectParser<>("field_caps_request");

    static {
        PARSER.declareObject(FieldCapabilitiesRequest::indexFilter, (p, c) -> parseTopLevelQuery(p), INDEX_FILTER_FIELD);
        PARSER.declareObject(FieldCapabilitiesRequest::runtimeFields, (p, c) -> p.map(), RUNTIME_MAPPINGS_FIELD);
        PARSER.declareStringArray(fromList(String.class, FieldCapabilitiesRequest::fields), FIELDS_FIELD);
        PARSER.declareString(FieldCapabilitiesRequest::projectRouting, PROJECT_ROUTING);
    }
}