;; lib/host/static.sx — serve the client kernel + assets so the blog can boot the
;; SX-htmx hypermedia engine (web/engine.sx) and run as a SPA. The native
;; http-listen host reads files with the `file-read` primitive (no perform), so
;; GET /static/** maps to a file under the static root (default "shared/static",
;; resolved against the server cwd — mount ./shared/static there in the container).
;; Depends on lib/dream/types.sx (dream-response/-html-status/-param) + router.

(define host/static-root "shared/static")
(define host/static-use-root! (fn (r) (set! host/static-root r)))

;; content-type by file extension; default to octet-stream.
(define host/static--ctype
  (fn (path)
    (cond
      ((ends-with? path ".js")    "application/javascript; charset=utf-8")
      ((ends-with? path ".mjs")   "application/javascript; charset=utf-8")
      ((ends-with? path ".css")   "text/css; charset=utf-8")
      ((ends-with? path ".json")  "application/json; charset=utf-8")
      ((ends-with? path ".map")   "application/json; charset=utf-8")
      ((ends-with? path ".svg")   "image/svg+xml")
      ((ends-with? path ".png")   "image/png")
      ((ends-with? path ".woff2") "font/woff2")
      ((ends-with? path ".wasm")  "application/wasm")
      (true                       "application/octet-stream"))))

;; reject empty, absolute, or traversal paths.
(define host/static--safe?
  (fn (rel)
    (and (> (len rel) 0)
         (not (starts-with? rel "/"))
         (not (string-contains? rel "..")))))

;; Serve one asset by its path relative to the static root. file-read THROWS on a
;; missing file, so gate on file-exists? first and return a 404 instead.
(define host/static-serve
  (fn (rel)
    (if (not (host/static--safe? rel))
      (dream-html-status 403 "Forbidden")
      (let ((path (str host/static-root "/" rel)))
        (if (not (file-exists? path))
          (dream-html-status 404 "Not Found")
          (dream-response 200
            {:content-type (host/static--ctype rel)
             :cache-control "public, max-age=3600"}
            (file-read path)))))))

;; Route group: GET /static/** -> file under the static root. A plain route LIST
;; (like host/feed-routes); host/serve combines + flattens the groups itself.
(define host/static-routes
  (list
    (dream-get "/static/**"
      (fn (req) (host/static-serve (dream-param req "**"))))))