;; _hyperscript integration — wire _="..." attributes to compiled SX
;;
;; Entry points:
;;   (hs-handler src)       — compile source to callable (fn (me) ...)
;;   (hs-activate! el)      — activate hyperscript on a single element
;;   (hs-boot!)             — scan DOM, activate all _="..." elements
;;   (hs-boot-subtree! root) — activate within a subtree (for HTMX swaps)

;; ── Compile source to a handler function ────────────────────────
;; Returns a function (fn (me) ...) that can be called with a DOM element.
;; Uses eval-expr-cek to turn the SX data structure into a live closure.

(begin
  (define
    hs-collect-vars
    (fn
      (sx)
      (define vars (list))
      (define
        reserved
        (list
          (quote me)
          (quote it)
          (quote event)
          (quote you)
          (quote yourself)))
      (define
        walk
        (fn
          (node)
          (when
            (list? node)
            (when
              (and
                (> (len node) 1)
                (= (first node) (quote set!))
                (symbol? (nth node 1)))
              (let
                ((name (nth node 1)))
                (when
                  (and
                    (not (some (fn (v) (= v name)) vars))
                    (not (some (fn (v) (= v name)) reserved)))
                  (set! vars (cons name vars)))))
            (for-each walk node))))
      (walk sx)
      vars))
  (define
    hs-handler
    (fn
      (src)
      (let
        ((sx (hs-to-sx-from-source src)))
        (let
          ((extra-vars (hs-collect-vars sx)))
          (do
            (for-each
              (fn (v) (eval-expr-cek (list (quote define) v nil)))
              extra-vars)
            (let
              ((guarded (list (quote guard) (list (quote _e) (list (quote true) (list (quote if) (list (quote and) (list (quote list?) (quote _e)) (list (quote =) (list (quote first) (quote _e)) "hs-return")) (list (quote nth) (quote _e) 1) (list (quote raise) (quote _e))))) sx)))
              (eval-expr-cek
                (list
                  (quote fn)
                  (list (quote me))
                  (list
                    (quote let)
                    (list (list (quote it) nil) (list (quote event) nil))
                    guarded))))))))))

;; ── Activate a single element ───────────────────────────────────
;; Reads the _="..." attribute, compiles, and executes with me=element.
;; Marks the element to avoid double-activation.

(define
  hs-activate!
  (fn
    (el)
    (let
      ((src (dom-get-attr el "_")) (prev (dom-get-data el "hs-script")))
      (when
        (and src (not (= src prev)))
        (hs-log-event! "hyperscript:init")
        (dom-set-data el "hs-script" src)
        (dom-set-data el "hs-active" true)
        (dom-set-attr el "data-hyperscript-powered" "true")
        (let ((handler (hs-handler src))) (handler el))))))

;; ── Boot: scan entire document ──────────────────────────────────
;; Called once at page load. Finds all elements with _ attribute,
;; compiles their hyperscript, and activates them.

(define
  hs-deactivate!
  (fn
    (el)
    (let
      ((unlisteners (or (dom-get-data el "hs-unlisteners") (list))))
      (for-each (fn (u) (when u (u))) unlisteners)
      (dom-set-data el "hs-unlisteners" (list))
      (dom-set-data el "hs-active" false)
      (dom-set-data el "hs-script" nil))))

;; ── Boot subtree: for dynamic content ───────────────────────────
;; Called after HTMX swaps or dynamic DOM insertion.
;; Only activates elements within the given root.

(define
  hs-boot!
  (fn
    ()
    (let
      ((elements (dom-query-all (host-get (host-global "document") "body") "[_]")))
      (for-each (fn (el) (hs-activate! el)) elements))))

(define
  hs-boot-subtree!
  (fn
    (root)
    (let
      ((elements (dom-query-all root "[_]")))
      (for-each (fn (el) (hs-activate! el)) elements))
    (when (dom-get-attr root "_") (hs-activate! root))))