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package org.apache.james.mailbox.store;

import javax.inject.Inject;

import org.apache.james.core.Username;
import org.apache.james.mailbox.MailboxManager;
import org.apache.james.mailbox.MailboxSession;
import org.apache.james.mailbox.MessageManager;
import org.apache.james.mailbox.Role;
import org.apache.james.mailbox.SystemMailboxesProvider;
import org.apache.james.mailbox.exception.MailboxNotFoundException;
import org.apache.james.mailbox.model.MailboxMetaData;
import org.apache.james.mailbox.model.MailboxPath;
import org.apache.james.mailbox.model.search.MailboxQuery;
import org.apache.james.mailbox.model.search.PrefixedWildcard;

import com.github.fge.lambdas.Throwing;
import com.github.fge.lambdas.functions.ThrowingFunction;
import com.google.common.annotations.VisibleForTesting;

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

public class SystemMailboxesProviderImpl implements SystemMailboxesProvider {

    private final MailboxManager mailboxManager;

    @Inject
    @VisibleForTesting
    public SystemMailboxesProviderImpl(MailboxManager mailboxManager) {
        this.mailboxManager = mailboxManager;
    }

    @Override
    public Flux<MessageManager> getMailboxByRole(Role aRole, Username username) {
        MailboxSession session = mailboxManager.createSystemSession(username);
        MailboxPath mailboxPath = MailboxPath.forUser(username, aRole.getDefaultMailbox());

        return Mono.fromCallable(() -> mailboxManager.getMailbox(mailboxPath, session))
            .flux()
            .onErrorResume(MailboxNotFoundException.class, e -> searchMessageManagerByMailboxRole(aRole, username));

    }

    private boolean hasRole(Role aRole, MailboxPath mailBoxPath) {
        return Role.from(mailBoxPath.getName())
            .map(aRole::equals)
            .orElse(false);
    }

    private Flux<MessageManager> searchMessageManagerByMailboxRole(Role aRole, Username username) {
        MailboxSession session = mailboxManager.createSystemSession(username);
        ThrowingFunction<MailboxPath, MessageManager> loadMailbox = path -> mailboxManager.getMailbox(path, session);
        MailboxQuery mailboxQuery = MailboxQuery.privateMailboxesBuilder(session)
            .expression(new PrefixedWildcard(aRole.getDefaultMailbox()))
            .build();
        return mailboxManager.search(mailboxQuery, session)
            .map(MailboxMetaData::getPath)
            .filter(path -> hasRole(aRole, path))
            .map(Throwing.function(loadMailbox).sneakyThrow());
    }
}