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 * 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   *
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 * 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    *
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 * under the License.                                           *
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package org.apache.james.jmap.draft.methods;

import static org.apache.james.util.ReactorUtils.context;

import javax.inject.Inject;

import org.apache.james.core.Username;
import org.apache.james.jmap.api.filtering.FilteringManagement;
import org.apache.james.jmap.draft.model.GetFilterRequest;
import org.apache.james.jmap.draft.model.GetFilterResponse;
import org.apache.james.jmap.draft.model.MethodCallId;
import org.apache.james.jmap.draft.model.SetError;
import org.apache.james.mailbox.MailboxSession;
import org.apache.james.metrics.api.MetricFactory;
import org.apache.james.util.MDCBuilder;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.google.common.base.Preconditions;

import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;

public class GetFilterMethod implements Method {
    private static final Logger LOGGER = LoggerFactory.getLogger(GetFilterMethod.class);

    private static final Method.Request.Name METHOD_NAME = Method.Request.name("getFilter");
    private static final Method.Response.Name RESPONSE_NAME = Method.Response.name("filter");

    private final MetricFactory metricFactory;
    private final FilteringManagement filteringManagement;

    @Inject
    private GetFilterMethod(MetricFactory metricFactory, FilteringManagement filteringManagement) {
        this.metricFactory = metricFactory;
        this.filteringManagement = filteringManagement;
    }

    @Override
    public Request.Name requestHandled() {
        return METHOD_NAME;
    }

    @Override
    public Class<? extends JmapRequest> requestType() {
        return GetFilterRequest.class;
    }

    @Override
    public Flux<JmapResponse> process(JmapRequest request, MethodCallId methodCallId, MailboxSession mailboxSession) {
        Preconditions.checkNotNull(request);
        Preconditions.checkNotNull(methodCallId);
        Preconditions.checkNotNull(mailboxSession);
        Preconditions.checkArgument(request instanceof GetFilterRequest);

        GetFilterRequest filterRequest = (GetFilterRequest) request;

        return Flux.from(metricFactory.decoratePublisherWithTimerMetric(JMAP_PREFIX + METHOD_NAME.getName(),
            process(methodCallId, mailboxSession, filterRequest)
                .subscriberContext(context("GET_FILTER", MDCBuilder.ofValue(MDCBuilder.ACTION, "GET_FILTER")))));
    }

    private Mono<JmapResponse> process(MethodCallId methodCallId, MailboxSession mailboxSession, GetFilterRequest request) {
        return retrieveFilter(methodCallId, mailboxSession.getUser())
            .onErrorResume(e -> {
                LOGGER.warn("Failed to retrieve filter", e);

                return Mono.just(unKnownError(methodCallId));
            });
    }

    private Mono<JmapResponse> retrieveFilter(MethodCallId methodCallId, Username username) {
        return Mono.from(filteringManagement.listRulesForUser(username))
            .map(rules -> GetFilterResponse.builder()
                .rules(rules.getRules())
                .build())
            .map(getFilterResponse -> JmapResponse.builder()
                .methodCallId(methodCallId)
                .response(getFilterResponse)
                .responseName(RESPONSE_NAME)
                .build());
    }

    private JmapResponse unKnownError(MethodCallId methodCallId) {
        return JmapResponse.builder()
            .methodCallId(methodCallId)
            .responseName(RESPONSE_NAME)
            .response(ErrorResponse.builder()
                .type(SetError.Type.ERROR.asString())
                .description("Failed to retrieve filter")
                .build())
            .build();
    }
}
