javadev / pt-backend

final class TemplateEngine {

    private static final String ALL_SYMBOLS = "([\\s\\S]+?)";

    private static final Map<String, String> TEMPLATE_SETTINGS = new HashMap<>();

    static {

        TEMPLATE_SETTINGS.put("evaluate", "\\{\\{" + ALL_SYMBOLS + "\\}\\}");

    }

    interface Template<F> {

        String apply(F arg);

    }

    static final class TemplateImpl<K, V> implements Template<Map<K, V>> {

        private final String template;

        TemplateImpl(String template) {

            this.template = template;

        }

        @Override

        public String apply(Map<K, V> value) {

            final String evaluate = TEMPLATE_SETTINGS.get("evaluate");

            String result = template;

            for (final Map.Entry<K, V> element : value.entrySet()) {

                result =

                        java.util.regex.Pattern.compile(

                                        evaluate.replace(

                                                ALL_SYMBOLS,

                                                "\\s*"

                                                        + java.util.regex.Pattern.quote(

                                                                String.valueOf(element.getKey()))

                                                        + "\\s*"))

                                .matcher(result)

                                .replaceAll(String.valueOf(element.getValue()));

            }

            return result;

        }

    }

    static <K, V> TemplateEngine.Template<Map<K, V>> template(final String template) {

        return new TemplateImpl<>(template);