Support for multiple body parts

app/src/main/java/eu/faircode/email/MessageHelper.java

@@ -1221,78 +1221,90 @@ public class MessageHelper {
     }
 
     class MessageParts {
-        private Part plain = null;
-        private Part html = null;
+        private List<Part> plain = new ArrayList<>();
+        private List<Part> html = new ArrayList<>();
         private List<AttachmentPart> attachments = new ArrayList<>();
         private ArrayList<String> warnings = new ArrayList<>();
 
         Boolean isPlainOnly() {
-            if (plain == null && html == null)
+            if (plain.size() + html.size() == 0)
                 return null;
-            return (html == null);
+            return (html.size() == 0);
         }
 
         Long getBodySize() throws MessagingException {
-            Part part = (html == null ? plain : html);
-            if (part == null)
-                return null;
-            int size = part.getSize();
-            if (size < 0)
-                return null;
-            else
-                return (long) size;
+            Long size = null;
+
+            List<Part> all = new ArrayList<>();
+            all.addAll(plain);
+            all.addAll(html);
+            for (Part p : all) {
+                int s = p.getSize();
+                if (s >= 0)
+                    if (size == null)
+                        size = (long) s;
+                    else
+                        size += (long) s;
+            }
+            return size;
         }
 
         String getHtml(Context context) throws MessagingException, IOException {
-            if (plain == null && html == null) {
+            if (plain.size() + html.size() == 0) {
                 Log.i("No body part");
                 return null;
             }
 
-            String result;
-            Part part = (html == null ? plain : html);
-            if (part.getSize() > MAX_MESSAGE_SIZE) {
-                warnings.add(context.getString(R.string.title_insufficient_memory));
-                return null;
-            }
+            StringBuilder sb = new StringBuilder();
 
-            try {
-                Object content = part.getContent();
-                Log.i("Content class=" + (content == null ? null : content.getClass().getName()));
+            for (Part part : html.size() > 0 ? html : plain) {
+                if (part.getSize() > MAX_MESSAGE_SIZE) {
+                    warnings.add(context.getString(R.string.title_insufficient_memory));
+                    return null;
+                }
+
+                String result;
+
+                try {
+                    Object content = part.getContent();
+                    Log.i("Content class=" + (content == null ? null : content.getClass().getName()));
+
+                    if (content == null) {
+                        warnings.add(context.getString(R.string.title_no_body));
+                        return null;
+                    }
 
-                if (content == null) {
-                    warnings.add(context.getString(R.string.title_no_body));
+                    if (content instanceof String)
+                        result = (String) content;
+                    else if (content instanceof InputStream)
+                        // Typically com.sun.mail.util.QPDecoderStream
+                        result = Helper.readStream((InputStream) content, StandardCharsets.UTF_8.name());
+                    else
+                        result = content.toString();
+                } catch (IOException | FolderClosedException | MessageRemovedException ex) {
+                    throw ex;
+                } catch (Throwable ex) {
+                    Log.w(ex);
+                    warnings.add(Log.formatThrowable(ex, false));
                     return null;
                 }
 
-                if (content instanceof String)
-                    result = (String) content;
-                else if (content instanceof InputStream)
-                    // Typically com.sun.mail.util.QPDecoderStream
-                    result = Helper.readStream((InputStream) content, StandardCharsets.UTF_8.name());
-                else
-                    result = content.toString();
-            } catch (IOException | FolderClosedException | MessageRemovedException ex) {
-                throw ex;
-            } catch (Throwable ex) {
-                Log.w(ex);
-                warnings.add(Log.formatThrowable(ex, false));
-                return null;
-            }
+                try {
+                    ContentType ct = new ContentType(part.getContentType());
+                    String charset = ct.getParameter("charset");
+                    if (UnknownCharsetProvider.charsetForMime(charset) == null)
+                        warnings.add(context.getString(R.string.title_no_charset, charset));
+                } catch (ParseException ex) {
+                    Log.e(ex);
+                }
 
-            try {
-                ContentType ct = new ContentType(part.getContentType());
-                String charset = ct.getParameter("charset");
-                if (UnknownCharsetProvider.charsetForMime(charset) == null)
-                    warnings.add(context.getString(R.string.title_no_charset, charset));
-            } catch (ParseException ex) {
-                Log.e(ex);
-            }
+                if (part.isMimeType("text/plain"))
+                    result = "<div>" + HtmlHelper.formatPre(result) + "</div>";
 
-            if (part == plain)
-                result = "<div>" + HtmlHelper.formatPre(result) + "</div>";
+                sb.append(result);
+            }
 
-            return result;
+            return sb.toString();
         }
 
         List<AttachmentPart> getAttachmentParts() {
@@ -1637,14 +1649,11 @@ public class MessageHelper {
                         contentType = new ContentType(Helper.guessMimeType(filename));
                 }
 
-                if (!Part.ATTACHMENT.equalsIgnoreCase(disposition) &&
-                        TextUtils.isEmpty(filename) &&
-                        ((parts.plain == null && "text/plain".equalsIgnoreCase(contentType.getBaseType())) ||
-                                (parts.html == null && "text/html".equalsIgnoreCase(contentType.getBaseType())))) {
-                    if ("text/html".equalsIgnoreCase(contentType.getBaseType()))
-                        parts.html = part;
-                    else
-                        parts.plain = part;
+                if (!Part.ATTACHMENT.equalsIgnoreCase(disposition) && TextUtils.isEmpty(filename)) {
+                    if ("text/plain".equalsIgnoreCase(contentType.getBaseType()))
+                        parts.plain.add(part);
+                    else if ("text/html".equalsIgnoreCase(contentType.getBaseType()))
+                        parts.html.add(part);
                 } else {
                     AttachmentPart apart = new AttachmentPart();
                     apart.disposition = disposition;