[fix] Mail: add attachments, and embedded urls

duniter4j-core-shared/src/main/java/org/duniter/core/util/mail/MailContentBuilder.java

+package org.duniter.core.util.mail;
+
+import com.google.common.collect.Lists;
+import org.duniter.core.util.CollectionUtils;
+import org.duniter.core.util.Preconditions;
+import org.duniter.core.util.StringUtils;
+
+import javax.activation.DataHandler;
+import javax.activation.DataSource;
+import javax.activation.URLDataSource;
+import javax.mail.BodyPart;
+import javax.mail.MessagingException;
+import javax.mail.Multipart;
+import javax.mail.internet.MimeBodyPart;
+import javax.mail.internet.MimeMultipart;
+import java.net.MalformedURLException;
+import java.net.URL;
+import java.util.HashMap;
+import java.util.List;
+import java.util.UUID;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+/**
+ * Created by StrongMan on 25/05/14.
+ * See https://stackoverflow.com/questions/3902455/mail-multipart-alternative-vs-multipart-mixed
+ */
+public class MailContentBuilder {
+
+    private static final Pattern COMPILED_PATTERN_SRC_URL_SINGLE = Pattern.compile("src='([^']*)'",  Pattern.CASE_INSENSITIVE);
+    private static final Pattern COMPILED_PATTERN_SRC_URL_DOUBLE = Pattern.compile("src=\"([^\"]*)\"",  Pattern.CASE_INSENSITIVE);
+
+
+    public static List<URL> findUrls(String messageHtml) {
+        Preconditions.checkNotNull(messageHtml);
+        List<URL> urls = Lists.newArrayList();
+        urls.addAll(findUrls(messageHtml, COMPILED_PATTERN_SRC_URL_SINGLE));
+        urls.addAll(findUrls(messageHtml, COMPILED_PATTERN_SRC_URL_DOUBLE));
+        return urls;
+    }
+
+    /**
+     * Build an email message.
+     *
+     * The HTML may reference the embedded image (messageHtmlInline) using the filename. Any path portion is ignored to make my life easier
+     * e.g. If you pass in the image C:\Temp\dog.jpg you can use <img src="dog.jpg"/> or <img src="C:\Temp\dog.jpg"/> and both will work
+     *
+     * @param messageText
+     * @param messageHtml
+     * @param embeddedImages
+     * @param attachments
+     * @return
+     * @throws MessagingException
+     */
+    public Multipart build(String messageText, String messageHtml, List<URL> embeddedImages, List<URL> attachments) throws MessagingException {
+        final Multipart mpMixed = new MimeMultipart("mixed");
+        {
+            // alternative
+            final Multipart mpMixedAlternative = newChild(mpMixed, "alternative");
+            {
+                // Note: MUST RENDER HTML LAST otherwise iPad mail client only renders the last image and no email
+                addTextVersion(mpMixedAlternative,messageText);
+                addHtmlVersion(mpMixedAlternative,messageHtml, embeddedImages);
+            }
+            // attachments
+            addAttachments(mpMixed,attachments);
+        }
+
+        //msg.setText(message, "utf-8");
+        //msg.setContent(message,"text/html; charset=utf-8");
+        return mpMixed;
+    }
+
+    private Multipart newChild(Multipart parent, String alternative) throws MessagingException {
+        MimeMultipart child =  new MimeMultipart(alternative);
+        final MimeBodyPart mbp = new MimeBodyPart();
+        parent.addBodyPart(mbp);
+        mbp.setContent(child);
+        return child;
+    }
+
+    private void addTextVersion(Multipart mpRelatedAlternative, String messageText) throws MessagingException {
+        final MimeBodyPart textPart = new MimeBodyPart();
+        textPart.setContent(messageText, "text/plain");
+        mpRelatedAlternative.addBodyPart(textPart);
+    }
+
+    private void addHtmlVersion(Multipart parent, String messageHtml, List<URL> embedded) throws MessagingException {
+        // HTML version
+        final Multipart mpRelated = newChild(parent,"related");
+
+        // Get embedded URL from message
+        if (embedded == null) {
+            embedded = findUrls(messageHtml);
+        }
+
+        // Html
+        final MimeBodyPart htmlPart = new MimeBodyPart();
+        HashMap<String,String> cids = new HashMap<String, String>();
+        htmlPart.setContent(replaceUrlWithCids(messageHtml,cids), "text/html");
+        mpRelated.addBodyPart(htmlPart);
+
+        // Inline images
+        addImagesInline(mpRelated, embedded, cids);
+    }
+
+    private void addImagesInline(Multipart parent, List<URL> embedded, HashMap<String,String> cids) throws MessagingException {
+        if (embedded != null) {
+            for (URL img : embedded) {
+                final MimeBodyPart htmlPartImg = new MimeBodyPart();
+                DataSource htmlPartImgDs = new URLDataSource(img);
+                htmlPartImg.setDataHandler(new DataHandler(htmlPartImgDs));
+                String fileName = img.getFile();
+                fileName = getFileName(fileName);
+                String newFileName = cids.get(fileName);
+                boolean imageNotReferencedInHtml = newFileName == null;
+                if (imageNotReferencedInHtml) continue;
+                // Gmail requires the cid have <> around it
+                htmlPartImg.setHeader("Content-ID", "<"+newFileName+">");
+                htmlPartImg.setDisposition(BodyPart.INLINE);
+                parent.addBodyPart(htmlPartImg);
+            }
+        }
+    }
+
+    private void addAttachments(Multipart parent, List<URL> attachments) throws MessagingException {
+        if (attachments != null)
+        {
+            for (URL attachment : attachments)
+            {
+                final MimeBodyPart mbpAttachment = new MimeBodyPart();
+                DataSource htmlPartImgDs = new URLDataSource(attachment);
+                mbpAttachment.setDataHandler(new DataHandler(htmlPartImgDs));
+                String fileName = attachment.getFile();
+                fileName = getFileName(fileName);
+                mbpAttachment.setDisposition(BodyPart.ATTACHMENT);
+                mbpAttachment.setFileName(fileName);
+                parent.addBodyPart(mbpAttachment);
+            }
+        }
+    }
+
+    public String replaceUrlWithCids(String html, HashMap<String,String> cids)
+    {
+        html = replaceUrlWithCids(html, COMPILED_PATTERN_SRC_URL_SINGLE, "src='cid:@cid'", cids);
+        html = replaceUrlWithCids(html, COMPILED_PATTERN_SRC_URL_DOUBLE, "src=\"cid:@cid\"", cids);
+        return html;
+    }
+
+    private String replaceUrlWithCids(String html, Pattern pattern, String replacement, HashMap<String,String> cids) {
+        Matcher matcher = pattern.matcher(html);
+        StringBuffer sb = new StringBuffer();
+        while (matcher.find()) {
+            String fileName = matcher.group(1);
+            // Disregarding file path, so don't clash your filenames!
+            fileName = getFileName(fileName);
+            // A cid must start with @ and be globally unique
+            String cid = "@" + UUID.randomUUID() + "_" + fileName;
+            if (cids.containsKey(fileName))
+                cid = cids.get(fileName);
+            else
+                cids.put(fileName,cid);
+            matcher.appendReplacement(sb,replacement.replace("@cid",cid));
+        }
+        matcher.appendTail(sb);
+        html = sb.toString();
+        return html;
+    }
+
+    private String getFileName(String fileName) {
+        if (fileName.contains("/"))
+            fileName = fileName.substring(fileName.lastIndexOf("/")+1);
+        return fileName;
+    }
+
+
+    private static List<URL> findUrls(String messageHtml, Pattern pattern) {
+        List<URL> urls = Lists.newArrayList();
+        Matcher matcher = pattern.matcher(messageHtml);
+        while (matcher.find()) {
+            String src = matcher.group(1);
+            try {
+                URL url = new URL(src);
+                urls.add(url);
+            } catch (MalformedURLException e) {
+                // Skip
+            }
+        }
+        return urls;
+    }
+}
\ No newline at end of file