Method onPurgeFolder

app/src/main/java/eu/faircode/email/Core.java:3161–3224

(Context context, JSONArray jargs, EntityAccount account, EntityFolder folder, IMAPFolder ifolder)

    }

    private static void onPurgeFolder(Context context, JSONArray jargs, EntityAccount account, EntityFolder folder, IMAPFolder ifolder) throws MessagingException {
        // Delete all messages from folder
        try {
            DB db = DB.getInstance(context);
            List<Long> busy = db.message().getBusyUids(folder.id, new Date().getTime());

            Message[] imessages = ifolder.getMessages();
            Log.i(folder.name + " purge=" + imessages.length + " busy=" + busy.size());

            FetchProfile fp = new FetchProfile();
            fp.add(UIDFolder.FetchProfileItem.UID);
            ifolder.fetch(imessages, fp);

            List<Message> idelete = new ArrayList<>();
            for (Message imessage : imessages)
                try {
                    long uid = ifolder.getUID(imessage);
                    if (!busy.contains(uid))
                        idelete.add(imessage);
                } catch (MessageRemovedException ex) {
                    Log.w(ex);
                }

            EntityLog.log(context, folder.name + " purging=" + idelete.size() + "/" + imessages.length);
            if (account.isYahooJp()) {
                for (Message imessage : new ArrayList<>(idelete))
                    try {
                        imessage.setFlag(Flags.Flag.DELETED, true);
                    } catch (MessagingException mex) {
                        Log.w(mex);
                        idelete.remove(imessage);
                    }
            } else {
                SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
                int chunk_size = prefs.getInt("chunk_size", DEFAULT_CHUNK_SIZE);

                Flags flags = new Flags(Flags.Flag.DELETED);
                List<Message> iremove = new ArrayList<>();
                for (List<Message> list : Helper.chunkList(idelete, chunk_size))
                    try {
                        ifolder.setFlags(list.toArray(new Message[0]), flags, true);
                    } catch (MessagingException ex) {
                        Log.w(ex);
                        for (Message imessage : list)
                            try {
                                imessage.setFlag(Flags.Flag.DELETED, true);
                            } catch (MessagingException mex) {
                                Log.w(mex);
                                iremove.add(imessage);
                            }
                    }

                for (Message imessage : iremove)
                    idelete.remove(imessage);
            }
            Log.i(folder.name + " purge deleted");
            expunge(context, ifolder, idelete);
        } catch (Throwable ex) {