server/protocols/jmap-draft/src/main/java/org/apache/james/jmap/draft/methods/MessageSender.java

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package org.apache.james.jmap.draft.methods;

import java.io.InputStream;

import jakarta.inject.Inject;
import jakarta.mail.MessagingException;

import org.apache.james.jmap.draft.send.MailSpool;
import org.apache.james.jmap.model.message.view.MessageFullViewFactory.MetaDataWithContent;
import org.apache.james.jmap.send.MailMetadata;
import org.apache.james.lifecycle.api.LifecycleUtil;
import org.apache.james.mailbox.MailboxSession;
import org.apache.james.mailbox.model.MessageId;
import org.apache.james.server.core.Envelope;
import org.apache.james.server.core.MailImpl;
import org.apache.james.server.core.MimeMessageSource;
import org.apache.mailet.Mail;

import com.google.common.annotations.VisibleForTesting;

import reactor.core.publisher.Mono;
import reactor.core.scheduler.Schedulers;

public class MessageSender {
    public static class MessageMimeMessageSource implements MimeMessageSource {
        private final String id;
        private final MetaDataWithContent message;

        public MessageMimeMessageSource(String id, MetaDataWithContent message) {
            this.id = id;
            this.message = message;
        }

        @Override
        public String getSourceId() {
            return id;
        }

        @Override
        public InputStream getInputStream() {
            return message.getContent();
        }

        @Override
        public long getMessageSize() {
            return message.getSize();
        }
    }

    private final MailSpool mailSpool;

    @Inject
    public MessageSender(MailSpool mailSpool) {
        this.mailSpool = mailSpool;
    }

    public Mono<Void> sendMessage(MetaDataWithContent message, Envelope envelope, MailboxSession session) {
        return Mono.usingWhen(Mono.fromCallable(() -> buildMail(message, envelope)),
            mail -> sendMessage(message.getMessageId(), mail, session),
            mail -> Mono.fromRunnable(() -> LifecycleUtil.dispose(mail)).subscribeOn(Schedulers.boundedElastic()));
    }

    @VisibleForTesting
    static Mail buildMail(MetaDataWithContent message, Envelope envelope) throws MessagingException {
        String name = message.getMessageId().serialize();
        MailImpl mail = MailImpl.builder()
            .name(name)
            .sender(envelope.getFrom().asOptional().orElseThrow(() -> new RuntimeException("Sender is mandatory")))
            .addRecipients(envelope.getRecipients())
            .build();
        mail.setMessageContent(new MessageMimeMessageSource(name, message));
        return mail;
    }

    public Mono<Void> sendMessage(MessageId messageId, Mail mail, MailboxSession session) {
        MailMetadata metadata = new MailMetadata(messageId, session.getUser().asString());
        return mailSpool.send(mail, metadata);
    }
}