Find data:image in email html body, decode, embed and replacing them with <img src="cid:...", return the new html body

gistfile1.txt

    private String replaceImgPattern(ImageHtmlEmail imageHtmlEmail, String html) {
        Matcher matcher = IMG_PATTERN.matcher(html);

        // Used to name the embedded images
        int i = 0;
        while (matcher.find()) {
            // in the RegEx we have the <src> element as second "group"
            String srcAttribute = matcher.group(2);

            if (srcAttribute.startsWith("data:image")) {
                // This extracts the encoded part
                String bytes = StringUtils.substringAfter(srcAttribute, ",");
                // This extracts the data type from the long base64 string (i.e. 'data:image/jpeg;base64,/9j/4AAQSkZJRgABA...')
                String type = StringUtils.substringBetween(srcAttribute, ":", ";");

                if (StringUtils.isBlank(bytes) || StringUtils.isBlank(type)) {
                    logger.warn("Skipping base64 encoded image because of incomplete data, bytes or type were not found");
                    continue;
                }
                byte[] decoded = Base64.getDecoder().decode(bytes);
                logger.debug("Creating ByteArrayDataSource for a base64 encoded image of {} bytes and type {}", decoded.length, type);
                ByteArrayDataSource bads = new ByteArrayDataSource(decoded, type);

                try {
                    String cid = imageHtmlEmail.embed(bads, String.valueOf(i));
//                    String cid = email.embed(tempFile);
                    String replacement = "cid:" + cid;
                    logger.debug("Embedded just decoded base64 encoded image, its cid is {} and was named {}, replacing the encoded one with this now", cid, i);
                    html = StringUtils.replace(html, srcAttribute, replacement);
                } catch (EmailException ex) {
                    logger.error("The embedding has failed, its name would have been " + i, ex);
                }
            }
            i++;
        }

        return html;
    }