package bakeoff

import (
	"net/url"
	"regexp"
)

// Weight is what a first visit to a page downloads, apart from the shared
// CSS every app serves identically.
type Weight struct{ HTMLBytes, JSBytes int }

var scriptSrc = regexp.MustCompile(`<script\b[^>]*\bsrc="([^"]+)"`)

// PageWeight sums the page's HTML and every same-origin script it loads.
func PageWeight(s *Session, path string) (Weight, error) {
	html, err := s.get(path)
	if err != nil {
		return Weight{}, err
	}
	w := Weight{HTMLBytes: len(html)}
	for _, m := range scriptSrc.FindAllStringSubmatch(html, -1) {
		u, err := s.Base.Parse(m[1])
		if err != nil || u.Host != s.Base.Host {
			continue
		}
		js, err := s.get((&url.URL{Path: u.Path, RawQuery: u.RawQuery}).String())
		if err != nil {
			return Weight{}, err
		}
		w.JSBytes += len(js)
	}
	return w, nil
}