Method guessMimeType

app/src/main/java/eu/faircode/email/Helper.java:2920–2954

(String filename)

    }

    static String guessMimeType(String filename) {
        String type = null;

        String extension = Helper.getExtension(filename);
        if (extension != null) {
            extension = extension.toLowerCase(Locale.ROOT);

            if (extension.endsWith(")")) {
                int p = extension.lastIndexOf('(');
                if (p > 0 && p < extension.length() - 1)
                    if (TextUtils.isDigitsOnly(extension.substring(p + 1, extension.length() - 1)))
                        extension = extension.substring(0, p).trim();
            }

            type = MimeTypeMap.getSingleton().getMimeTypeFromExtension(extension);
        }

        if (TextUtils.isEmpty(type))
            if ("csv".equals(extension))
                return "text/csv";
            else if ("eml".equals(extension))
                return "message/rfc822";
            else if ("gpx".equals(extension))
                return "application/gpx+xml";
            else if ("log".equals(extension))
                return "text/plain";
            else if ("ovpn".equals(extension))
                return "application/x-openvpn-profile";
            else if ("mbox".equals(extension))
                return "application/mbox"; // https://tools.ietf.org/html/rfc4155
            else
                return "application/octet-stream";

        return type;
    }

    static String guessExtension(String mimeType) {
        String extension = null;