mailbox/opensearch/src/main/java/org/apache/james/mailbox/opensearch/query/QueryConverter.java

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package org.apache.james.mailbox.opensearch.query;

import static org.opensearch.index.query.QueryBuilders.boolQuery;
import static org.opensearch.index.query.QueryBuilders.termsQuery;

import java.util.Collection;
import java.util.List;
import java.util.Optional;

import javax.inject.Inject;

import org.apache.james.mailbox.model.MailboxId;
import org.apache.james.mailbox.model.SearchQuery;
import org.apache.james.mailbox.opensearch.json.JsonMessageConstants;
import org.opensearch.index.query.BoolQueryBuilder;
import org.opensearch.index.query.QueryBuilder;

import com.google.common.collect.ImmutableList;

public class QueryConverter {


    private final CriterionConverter criterionConverter;

    @Inject
    public QueryConverter(CriterionConverter criterionConverter) {
        this.criterionConverter = criterionConverter;
    }

    public QueryBuilder from(Collection<MailboxId> mailboxIds, SearchQuery query) {
        BoolQueryBuilder boolQueryBuilder = boolQuery()
            .must(generateQueryBuilder(query));

        mailboxesQuery(mailboxIds).map(boolQueryBuilder::filter);
        return boolQueryBuilder;
    }

    private QueryBuilder generateQueryBuilder(SearchQuery searchQuery) {
        List<SearchQuery.Criterion> criteria = searchQuery.getCriteria();
        if (criteria.isEmpty()) {
            return criterionConverter.convertCriterion(SearchQuery.all());
        } else if (criteria.size() == 1) {
            return criterionConverter.convertCriterion(criteria.get(0));
        } else {
            return criterionConverter.convertCriterion(new SearchQuery.ConjunctionCriterion(SearchQuery.Conjunction.AND, criteria));
        }
    }

    private Optional<QueryBuilder> mailboxesQuery(Collection<MailboxId> mailboxIds) {
        if (mailboxIds.isEmpty()) {
            return Optional.empty();
        }
        ImmutableList<String> ids = mailboxIds.stream()
                .map(MailboxId::serialize)
                .collect(ImmutableList.toImmutableList());
        return Optional.of(termsQuery(JsonMessageConstants.MAILBOX_ID, ids));
    }

}