OK now I understand. You want to have all-in-one package 
I don't know how you want to apply all resources back into the DOM after unzipping in the browser but I assume you need to change the original HTML to
(a) remove references to that resources so browser won't load them
(b) save those references for later processing (applying to correct DOM nodes), e.g. replace <img src="..."> to <img zipped-src="...">
(c) somewhere save path to the resources you will need to package and serve for this page
(d) insert HTML/JavaScript snippet to download the zip file with resources
(e) when browser asks for the zip file you will need to know which resources you have to package, here applies the point (c), and additionally you need to process
1, CSS files and replace references to the images (with base64 strings containing image data (which seem to me now as the easiest possibility)) ?
2, JS files and somehow do the same
Also be careful because many resources are loaded from the theme, which is different web application, so you need to know how to access those files on the disk.
It's challenging but hopefully not impossible
EDIT: this you can try to implement with the servlet filter placed inside the portal web application.
-- tom
I don't know how you want to apply all resources back into the DOM after unzipping in the browser but I assume you need to change the original HTML to
(a) remove references to that resources so browser won't load them
(b) save those references for later processing (applying to correct DOM nodes), e.g. replace <img src="..."> to <img zipped-src="...">
(c) somewhere save path to the resources you will need to package and serve for this page
(d) insert HTML/JavaScript snippet to download the zip file with resources
(e) when browser asks for the zip file you will need to know which resources you have to package, here applies the point (c), and additionally you need to process
1, CSS files and replace references to the images (with base64 strings containing image data (which seem to me now as the easiest possibility)) ?
2, JS files and somehow do the same
Also be careful because many resources are loaded from the theme, which is different web application, so you need to know how to access those files on the disk.
It's challenging but hopefully not impossible
EDIT: this you can try to implement with the servlet filter placed inside the portal web application.
-- tom