org.apache.james.jmap.utils.MimeMessageBodyGenerator Maven / Gradle / Ivy

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package org.apache.james.jmap.utils;

import java.io.IOException;
import java.util.Optional;

import javax.activation.DataHandler;
import javax.inject.Inject;
import javax.mail.MessagingException;
import javax.mail.Multipart;
import javax.mail.internet.MimeBodyPart;
import javax.mail.internet.MimeMessage;
import javax.mail.internet.MimeMultipart;
import javax.mail.util.ByteArrayDataSource;

import org.apache.james.mime4j.dom.field.ContentTypeField;

import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Preconditions;

public class MimeMessageBodyGenerator {
    public static final String MIXED = "mixed";
    public static final String EMPTY_TEXT = "";

    private final HtmlTextExtractor htmlTextExtractor;

    @Inject
    @VisibleForTesting
    MimeMessageBodyGenerator(HtmlTextExtractor htmlTextExtractor) {
        this.htmlTextExtractor = htmlTextExtractor;
    }

    public MimeMessage from(MimeMessage messageHoldingHeaders, Optional plainText, Optional htmlText) throws MessagingException {
        Preconditions.checkNotNull(messageHoldingHeaders);
        Preconditions.checkNotNull(plainText);
        Preconditions.checkNotNull(htmlText);
        if (htmlText.isPresent()) {
            messageHoldingHeaders.setContent(generateMultipart(htmlText.get(), plainText));
        } else {
            messageHoldingHeaders.setText(plainText.orElse(EMPTY_TEXT));
        }
        return messageHoldingHeaders;
    }

    private Multipart generateMultipart(String htmlText, Optional plainText) throws MessagingException {
        try {
            Multipart multipart = new MimeMultipart(MIXED);
            addTextPart(multipart, htmlText, "text/html");
            addTextPart(multipart, retrievePlainTextMessage(plainText, htmlText), ContentTypeField.TYPE_TEXT_PLAIN);
            return multipart;
        } catch (IOException e) {
            throw new MessagingException("Cannot read specified content", e);
        }
    }

    private Multipart addTextPart(Multipart multipart, String text, String contentType) throws MessagingException, IOException {
        MimeBodyPart textReasonPart = new MimeBodyPart();
        textReasonPart.setDataHandler(
            new DataHandler(
                new ByteArrayDataSource(
                    text,
                    contentType + "; charset=UTF-8")));
        multipart.addBodyPart(textReasonPart);
        return multipart;
    }

    private String retrievePlainTextMessage(Optional plainText, String htmlText) {
        return plainText.orElseGet(() -> htmlTextExtractor.toPlainText(htmlText));
    }

}