function assetsUrl(path) for jetbrick-template

AssetsUrlFunctions.java

import java.io.File;
import java.io.FilenameFilter;
import java.util.HashMap;
import java.util.Map;
import javax.servlet.ServletContext;
import jetbrick.template.runtime.JetPageContext;
import jetbrick.template.web.JetWebContext;

public class AssetsUrlFunctions {
    private static Map<String, String> mapping = new HashMap<String, String>(128);

    public static String assetsUrl(JetPageContext ctx, String path) {
        String url = mapping.get(path);
        if (url != null) {
            return url;
        }

        ServletContext sc = (ServletContext) ctx.getContext().get(JetWebContext.SERVLET_CONTEXT);
        url = "/assets/" + path;

        File file = new File(sc.getRealPath(url));
        if (!file.exists()) {
            int pos = file.getName().lastIndexOf(".");
            if (pos > 0) {
                final String nameWithoutExt = file.getName().substring(0, pos);
                final String ext = file.getName().substring(pos);
                File[] files = file.getParentFile().listFiles(new FilenameFilter() {
                    @Override
                    public boolean accept(File dir, String name) {
                        return name.startsWith(nameWithoutExt + "-") && name.endsWith(ext);
                    }
                });
                if (files != null && files.length > 0) {
                    url = url.replaceFirst("([^/\\\\]+)$", files[0].getName());
                }
            }
        }
        url = sc.getContextPath() + url;
        mapping.put(path, url);
        return url;
    }
}