;; lib/js/transpile.sx — JS AST → SX AST
;;
;; Produces SX trees the existing CEK/VM can evaluate directly.
;; Reuses lib/js/runtime.sx shims for JS-specific semantics
;; (coercions, prototype lookup, abstract equality, etc.).
;;
;; Input AST node shapes (from lib/js/parser.sx):
;;   (js-num n)           (js-str s)         (js-bool b)
;;   (js-null)            (js-undef)
;;   (js-ident "name")
;;   (js-unop  op expr)
;;   (js-binop op l r)
;;   (js-member obj "key")       (js-index  obj expr)
;;   (js-call   fn (args...))
;;   (js-array  (elts...))       (js-object ({:key :value}...))
;;   (js-cond   c t f)
;;   (js-arrow  (params...) body)
;;   (js-assign op target rhs)
;;
;; Output is plain SX the evaluator can run, built with `list`/`cons`/
;; `make-symbol`. The entry point `js-eval-ast` calls `eval-expr` on
;; the transpiled tree.

;; ── tiny helpers ──────────────────────────────────────────────────

(define js-sym (fn (name) (make-symbol name)))
(define
  js-tag?
  (fn
    (ast tag)
    (and
      (= (type-of ast) "list")
      (not (empty? ast))
      (= (type-of (first ast)) "symbol")
      (= (symbol-name (first ast)) tag))))

(define js-ast-tag (fn (ast) (symbol-name (first ast))))

;; ── main dispatcher ───────────────────────────────────────────────

(define
  js-transpile
  (fn
    (ast)
    (cond
      ((= (type-of ast) "number") ast)
      ((= (type-of ast) "string") ast)
      ((= (type-of ast) "boolean") ast)
      ((= ast nil) ast)
      ((= (type-of ast) "list")
        (cond
          ((empty? ast) (list))
          ((js-tag? ast "js-num") (nth ast 1))
          ((js-tag? ast "js-str") (nth ast 1))
          ((js-tag? ast "js-bool") (nth ast 1))
          ((js-tag? ast "js-regex")
            (list (js-sym "js-regex-new") (nth ast 1) (nth ast 2)))
          ((js-tag? ast "js-null") nil)
          ((js-tag? ast "js-undef") (list (js-sym "quote") :js-undefined))
          ((js-tag? ast "js-ident") (js-transpile-ident (nth ast 1)))
          ((js-tag? ast "js-unop")
            (js-transpile-unop (nth ast 1) (nth ast 2)))
          ((js-tag? ast "js-binop")
            (js-transpile-binop (nth ast 1) (nth ast 2) (nth ast 3)))
          ((js-tag? ast "js-member")
            (js-transpile-member (nth ast 1) (nth ast 2)))
          ((js-tag? ast "js-index")
            (js-transpile-index (nth ast 1) (nth ast 2)))
          ((js-tag? ast "js-call")
            (js-transpile-call (nth ast 1) (nth ast 2)))
          ((js-tag? ast "js-array") (js-transpile-array (nth ast 1)))
          ((js-tag? ast "js-object") (js-transpile-object (nth ast 1)))
          ((js-tag? ast "js-cond")
            (js-transpile-cond (nth ast 1) (nth ast 2) (nth ast 3)))
          ((js-tag? ast "js-arrow")
            (js-transpile-arrow (nth ast 1) (nth ast 2)))
          ((js-tag? ast "js-program") (js-transpile-stmts (nth ast 1)))
          ((js-tag? ast "js-block") (js-transpile-stmts (nth ast 1)))
          ((js-tag? ast "js-exprstmt") (js-transpile (nth ast 1)))
          ((js-tag? ast "js-empty") nil)
          ((js-tag? ast "js-var")
            (js-transpile-var (nth ast 1) (nth ast 2)))
          ((js-tag? ast "js-if")
            (js-transpile-if-stmt (nth ast 1) (nth ast 2) (nth ast 3)))
          ((js-tag? ast "js-while")
            (js-transpile-while (nth ast 1) (nth ast 2)))
          ((js-tag? ast "js-do-while")
            (js-transpile-do-while (nth ast 1) (nth ast 2)))
          ((js-tag? ast "js-for")
            (js-transpile-for
              (nth ast 1)
              (nth ast 2)
              (nth ast 3)
              (nth ast 4)))
          ((js-tag? ast "js-for-of-in")
            (js-transpile-for-of-in
              (nth ast 1)
              (nth ast 2)
              (nth ast 3)
              (nth ast 4)))
          ((js-tag? ast "js-return") (js-transpile-return (nth ast 1)))
          ((js-tag? ast "js-break") (js-transpile-break))
          ((js-tag? ast "js-continue") (js-transpile-continue))
          ((js-tag? ast "js-funcdecl")
            (js-transpile-funcdecl (nth ast 1) (nth ast 2) (nth ast 3)))
          ((js-tag? ast "js-funcexpr")
            (js-transpile-funcexpr (nth ast 1) (nth ast 2) (nth ast 3)))
          ((js-tag? ast "js-assign")
            (js-transpile-assign (nth ast 1) (nth ast 2) (nth ast 3)))
          ((js-tag? ast "js-postfix")
            (js-transpile-postfix (nth ast 1) (nth ast 2)))
          ((js-tag? ast "js-prefix")
            (js-transpile-prefix (nth ast 1) (nth ast 2)))
          ((js-tag? ast "js-optchain-member")
            (js-transpile-optchain-member (nth ast 1) (nth ast 2)))
          ((js-tag? ast "js-optchain-index")
            (js-transpile-optchain-index (nth ast 1) (nth ast 2)))
          ((js-tag? ast "js-optchain-call")
            (js-transpile-optchain-call (nth ast 1) (nth ast 2)))
          ((js-tag? ast "js-switch")
            (js-transpile-switch (nth ast 1) (nth ast 2)))
          ((js-tag? ast "js-new")
            (js-transpile-new (nth ast 1) (nth ast 2)))
          ((js-tag? ast "js-class")
            (js-transpile-class (nth ast 1) (nth ast 2) (nth ast 3)))
          ((js-tag? ast "js-throw") (js-transpile-throw (nth ast 1)))
          ((js-tag? ast "js-try")
            (js-transpile-try (nth ast 1) (nth ast 2) (nth ast 3)))
          ((js-tag? ast "js-await")
            (list (js-sym "js-await-value") (js-transpile (nth ast 1))))
          ((js-tag? ast "js-funcdecl-async")
            (js-transpile-funcdecl-async
              (nth ast 1)
              (nth ast 2)
              (nth ast 3)))
          ((js-tag? ast "js-funcexpr-async")
            (js-transpile-funcexpr-async
              (nth ast 1)
              (nth ast 2)
              (nth ast 3)))
          ((js-tag? ast "js-arrow-async")
            (js-transpile-arrow-async (nth ast 1) (nth ast 2)))
          ((js-tag? ast "js-tpl") (js-transpile-tpl (nth ast 1)))
          (else
            (error (str "js-transpile: unknown AST tag: " (js-ast-tag ast))))))
      (else
        (error (str "js-transpile: unexpected value type: " (type-of ast)))))))

;; ── Identifier lookup ─────────────────────────────────────────────

;; `undefined` in JS is really a global binding. If the parser emits
;; (js-undef) we handle that above. A bare `undefined` ident also maps
;; to the same sentinel.
(define
  js-transpile-ident
  (fn
    (name)
    (cond
      ((= name "undefined") (list (js-sym "quote") :js-undefined))
      (else (js-sym name)))))

;; ── Unary ops ─────────────────────────────────────────────────────

(define
  js-transpile-unop
  (fn
    (op arg)
    (let
      ((a (js-transpile arg)))
      (cond
        ((= op "-") (list (js-sym "js-neg") a))
        ((= op "+") (list (js-sym "js-pos") a))
        ((= op "!") (list (js-sym "js-not") a))
        ((= op "~") (list (js-sym "js-bitnot") a))
        ((= op "typeof") (list (js-sym "js-typeof") a))
        ((= op "void") (list (js-sym "quote") :js-undefined))
        (else (error (str "js-transpile-unop: unsupported op: " op)))))))

;; ── Binary ops ────────────────────────────────────────────────────

(define
  js-transpile-binop
  (fn
    (op l r)
    (cond
      ((= op "+")
        (list (js-sym "js-add") (js-transpile l) (js-transpile r)))
      ((= op "-")
        (list (js-sym "js-sub") (js-transpile l) (js-transpile r)))
      ((= op "*")
        (list (js-sym "js-mul") (js-transpile l) (js-transpile r)))
      ((= op "/")
        (list (js-sym "js-div") (js-transpile l) (js-transpile r)))
      ((= op "%")
        (list (js-sym "js-mod") (js-transpile l) (js-transpile r)))
      ((= op "**")
        (list (js-sym "js-pow") (js-transpile l) (js-transpile r)))
      ((= op "===")
        (list (js-sym "js-strict-eq") (js-transpile l) (js-transpile r)))
      ((= op "!==")
        (list (js-sym "js-strict-neq") (js-transpile l) (js-transpile r)))
      ((= op "==")
        (list (js-sym "js-loose-eq") (js-transpile l) (js-transpile r)))
      ((= op "!=")
        (list (js-sym "js-loose-neq") (js-transpile l) (js-transpile r)))
      ((= op "<")
        (list (js-sym "js-lt") (js-transpile l) (js-transpile r)))
      ((= op ">")
        (list (js-sym "js-gt") (js-transpile l) (js-transpile r)))
      ((= op "<=")
        (list (js-sym "js-le") (js-transpile l) (js-transpile r)))
      ((= op ">=")
        (list (js-sym "js-ge") (js-transpile l) (js-transpile r)))
      ((= op "&&")
        (list
          (js-sym "js-and")
          (js-transpile l)
          (list (js-sym "fn") (list) (js-transpile r))))
      ((= op "||")
        (list
          (js-sym "js-or")
          (js-transpile l)
          (list (js-sym "fn") (list) (js-transpile r))))
      ((= op "instanceof")
        (list (js-sym "js-instanceof") (js-transpile l) (js-transpile r)))
      ((= op "in")
        (list (js-sym "js-in") (js-transpile l) (js-transpile r)))
      ((= op "??")
        (list
          (js-sym "let")
          (list (list (js-sym "_a") (js-transpile l)))
          (list
            (js-sym "if")
            (list
              (js-sym "or")
              (list (js-sym "=") (js-sym "_a") nil)
              (list (js-sym "js-undefined?") (js-sym "_a")))
            (js-transpile r)
            (js-sym "_a"))))
      (else (error (str "js-transpile-binop: unsupported op: " op))))))

;; ── Member / index ────────────────────────────────────────────────

(define
  js-transpile-member
  (fn (obj key) (list (js-sym "js-get-prop") (js-transpile obj) key)))

(define
  js-transpile-index
  (fn
    (obj idx)
    (list (js-sym "js-get-prop") (js-transpile obj) (js-transpile idx))))

;; ── Call ──────────────────────────────────────────────────────────

;; JS `f(a, b, c)` → `(f a b c)` after transpile. Works for both
;; identifier calls and computed callee (arrow fn, member access).
(define
  js-transpile-call
  (fn
    (callee args)
    (cond
      ((and (js-tag? callee "js-member") (not (js-has-spread? args)))
        (let
          ((recv (js-transpile (nth callee 1))) (key (nth callee 2)))
          (list
            (js-sym "js-invoke-method")
            recv
            key
            (js-transpile-args args))))
      ((and (js-tag? callee "js-index") (not (js-has-spread? args)))
        (let
          ((recv (js-transpile (nth callee 1)))
            (key (js-transpile (nth callee 2))))
          (list
            (js-sym "js-invoke-method-dyn")
            recv
            key
            (js-transpile-args args))))
      ((js-tag? callee "js-member")
        (let
          ((recv (js-transpile (nth callee 1))) (key (nth callee 2)))
          (list
            (js-sym "js-invoke-method")
            recv
            key
            (js-transpile-args args))))
      ((js-tag? callee "js-index")
        (let
          ((recv (js-transpile (nth callee 1)))
            (key (js-transpile (nth callee 2))))
          (list
            (js-sym "js-invoke-method-dyn")
            recv
            key
            (js-transpile-args args))))
      (else
        (list
          (js-sym "js-call-plain")
          (js-transpile callee)
          (js-transpile-args args))))))

;; ── Array literal ─────────────────────────────────────────────────

(define
  js-transpile-new
  (fn
    (callee args)
    (list
      (js-sym "js-new-call")
      (js-transpile callee)
      (cons (js-sym "list") (map js-transpile args)))))

;; ── Object literal ────────────────────────────────────────────────

;; Build a dict by `(dict)` + `dict-set!` inside a `let` that yields
;; the dict as its final expression. This keeps keys in JS insertion
;; order and allows computed values.
(define
  js-transpile-array
  (fn
    (elts)
    (if
      (js-has-spread? elts)
      (cons
        (js-sym "js-array-spread-build")
        (map
          (fn
            (e)
            (if
              (js-tag? e "js-spread")
              (list (js-sym "list") "js-spread" (js-transpile (nth e 1)))
              (list (js-sym "list") "js-value" (js-transpile e))))
          elts))
      (cons (js-sym "list") (map js-transpile elts)))))

;; ── Conditional ───────────────────────────────────────────────────

(define
  js-has-spread?
  (fn
    (lst)
    (cond
      ((empty? lst) false)
      ((js-tag? (first lst) "js-spread") true)
      (else (js-has-spread? (rest lst))))))

;; ── Arrow function ────────────────────────────────────────────────

(define
  js-transpile-args
  (fn
    (args)
    (if
      (js-has-spread? args)
      (cons
        (js-sym "js-array-spread-build")
        (map
          (fn
            (e)
            (if
              (js-tag? e "js-spread")
              (list (js-sym "list") "js-spread" (js-transpile (nth e 1)))
              (list (js-sym "list") "js-value" (js-transpile e))))
          args))
      (cons (js-sym "list") (map js-transpile args)))))

;; ── Assignment ────────────────────────────────────────────────────

;; `a = b` on an ident → (set! a b).
;; `a += b` on an ident → (set! a (js-add a b)).
;; `obj.k = v` / `obj[k] = v` → (js-set-prop obj "k" v).
(define
  js-transpile-object
  (fn
    (entries)
    (list
      (js-sym "let")
      (list (list (js-sym "_obj") (list (js-sym "dict"))))
      (cons
        (js-sym "begin")
        (append
          (map
            (fn
              (entry)
              (list
                (js-sym "dict-set!")
                (js-sym "_obj")
                (get entry :key)
                (js-transpile (get entry :value))))
            entries)
          (list (js-sym "_obj")))))))

(define
  js-transpile-cond
  (fn
    (c t f)
    (list
      (js-sym "if")
      (list (js-sym "js-to-boolean") (js-transpile c))
      (js-transpile t)
      (js-transpile f))))

(define
  js-transpile-arrow
  (fn
    (params body)
    (let
      ((param-syms (js-build-param-list params))
        (inits (js-param-init-forms params))
        (body-tr
          (if
            (and (list? body) (js-tag? body "js-block"))
            (list
              (js-sym "call/cc")
              (list
                (js-sym "fn")
                (list (js-sym "__return__"))
                (cons
                  (js-sym "begin")
                  (append
                    inits
                    (append
                      (js-collect-funcdecls (nth body 1))
                      (js-transpile-stmt-list (nth body 1)))))))
            (if
              (empty? inits)
              (js-transpile body)
              (cons
                (js-sym "begin")
                (append inits (list (js-transpile body))))))))
      (list (js-sym "fn") param-syms body-tr))))

;; ── End-to-end entry points ───────────────────────────────────────

;; Transpile + eval a single JS expression string.
(define
  js-transpile-tpl
  (fn
    (parts)
    (cond
      ((empty? parts) (list (quote quote) ""))
      ((= (len parts) 1)
        (list (js-sym "js-to-string") (js-transpile (first parts))))
      (else
        (cons (js-sym "js-template-concat") (js-transpile-tpl-parts parts))))))

;; Transpile a JS expression string to SX source text (for inspection
;; in tests). Useful for asserting the exact emitted tree.
(define
  js-transpile-tpl-parts
  (fn
    (parts)
    (if
      (empty? parts)
      (list)
      (cons
        (js-transpile (first parts))
        (js-transpile-tpl-parts (rest parts))))))

(define
  js-transpile-assign
  (fn
    (op target rhs)
    (cond
      ((js-tag? target "js-ident")
        (let
          ((name (nth target 1)))
          (let
            ((sxname (js-sym name)))
            (cond
              ((= op "=") (list (js-sym "set!") sxname (js-transpile rhs)))
              (else
                (list
                  (js-sym "set!")
                  sxname
                  (js-compound-update op sxname (js-transpile rhs))))))))
      ((js-tag? target "js-member")
        (list
          (js-sym "js-set-prop")
          (js-transpile (nth target 1))
          (nth target 2)
          (js-compound-update-or-plain
            op
            (js-transpile target)
            (js-transpile rhs))))
      ((js-tag? target "js-index")
        (list
          (js-sym "js-set-prop")
          (js-transpile (nth target 1))
          (js-transpile (nth target 2))
          (js-compound-update-or-plain
            op
            (js-transpile target)
            (js-transpile rhs))))
      (else (error "js-transpile-assign: unsupported target")))))

(define
  js-compound-update
  (fn
    (op lhs-expr rhs-expr)
    (cond
      ((= op "+=") (list (js-sym "js-add") lhs-expr rhs-expr))
      ((= op "-=") (list (js-sym "js-sub") lhs-expr rhs-expr))
      ((= op "*=") (list (js-sym "js-mul") lhs-expr rhs-expr))
      ((= op "/=") (list (js-sym "js-div") lhs-expr rhs-expr))
      ((= op "%=") (list (js-sym "js-mod") lhs-expr rhs-expr))
      ((= op "**=") (list (js-sym "js-pow") lhs-expr rhs-expr))
      ((= op "&&=")
        (list
          (js-sym "if")
          (list (js-sym "js-to-boolean") lhs-expr)
          rhs-expr
          lhs-expr))
      ((= op "||=")
        (list
          (js-sym "if")
          (list (js-sym "js-to-boolean") lhs-expr)
          lhs-expr
          rhs-expr))
      ((= op "??=")
        (list
          (js-sym "if")
          (list
            (js-sym "or")
            (list (js-sym "=") lhs-expr nil)
            (list (js-sym "js-undefined?") lhs-expr))
          rhs-expr
          lhs-expr))
      (else (error (str "js-compound-update: unsupported op: " op))))))

(define
  js-compound-update-or-plain
  (fn
    (op lhs-expr rhs-expr)
    (cond
      ((= op "=") rhs-expr)
      (else (js-compound-update op lhs-expr rhs-expr)))))

(define
  js-transpile-prefix
  (fn
    (op target)
    (let
      ((delta (if (= op "++") 1 -1)))
      (cond
        ((js-tag? target "js-ident")
          (let
            ((name (nth target 1)))
            (let
              ((sxname (js-sym name)))
              (list
                (js-sym "set!")
                sxname
                (list
                  (js-sym "+")
                  (list (js-sym "js-to-number") sxname)
                  delta)))))
        ((js-tag? target "js-member")
          (let
            ((obj-sx (js-transpile (nth target 1))) (key (nth target 2)))
            (list
              (js-sym "js-set-prop")
              obj-sx
              key
              (list
                (js-sym "+")
                (list
                  (js-sym "js-to-number")
                  (list (js-sym "js-get-prop") obj-sx key))
                delta))))
        ((js-tag? target "js-index")
          (let
            ((obj-sx (js-transpile (nth target 1)))
              (key-sx (js-transpile (nth target 2))))
            (list
              (js-sym "js-set-prop")
              obj-sx
              key-sx
              (list
                (js-sym "+")
                (list
                  (js-sym "js-to-number")
                  (list (js-sym "js-get-prop") obj-sx key-sx))
                delta))))
        (else (error "js-transpile-prefix: unsupported target"))))))

(define
  js-transpile-postfix
  (fn
    (op target)
    (let
      ((delta (if (= op "++") 1 -1)))
      (cond
        ((js-tag? target "js-ident")
          (let
            ((name (nth target 1)))
            (let
              ((sxname (js-sym name)))
              (list
                (js-sym "let")
                (list
                  (list
                    (js-sym "__js_old__")
                    (list (js-sym "js-to-number") sxname)))
                (list
                  (js-sym "set!")
                  sxname
                  (list (js-sym "+") (js-sym "__js_old__") delta))
                (js-sym "__js_old__")))))
        ((js-tag? target "js-member")
          (let
            ((obj-sx (js-transpile (nth target 1))) (key (nth target 2)))
            (list
              (js-sym "let")
              (list
                (list (js-sym "__js_obj__") obj-sx)
                (list
                  (js-sym "__js_old__")
                  (list
                    (js-sym "js-to-number")
                    (list (js-sym "js-get-prop") (js-sym "__js_obj__") key))))
              (list
                (js-sym "js-set-prop")
                (js-sym "__js_obj__")
                key
                (list (js-sym "+") (js-sym "__js_old__") delta))
              (js-sym "__js_old__"))))
        ((js-tag? target "js-index")
          (let
            ((obj-sx (js-transpile (nth target 1)))
              (key-sx (js-transpile (nth target 2))))
            (list
              (js-sym "let")
              (list
                (list (js-sym "__js_obj__") obj-sx)
                (list (js-sym "__js_key__") key-sx)
                (list
                  (js-sym "__js_old__")
                  (list
                    (js-sym "js-to-number")
                    (list
                      (js-sym "js-get-prop")
                      (js-sym "__js_obj__")
                      (js-sym "__js_key__")))))
              (list
                (js-sym "js-set-prop")
                (js-sym "__js_obj__")
                (js-sym "__js_key__")
                (list (js-sym "+") (js-sym "__js_old__") delta))
              (js-sym "__js_old__"))))
        (else (error "js-transpile-postfix: unsupported target"))))))

(define
  js-transpile-switch
  (fn
    (discr cases)
    (let
      ((discr-sym (js-sym "__discr__"))
        (matched-sym (js-sym "__matched__"))
        (break-sym (js-sym "__break__")))
      (list
        (js-sym "call/cc")
        (list
          (js-sym "fn")
          (list break-sym)
          (list
            (js-sym "let")
            (list
              (list discr-sym (js-transpile discr))
              (list matched-sym false))
            (js-transpile-switch-clauses cases discr-sym matched-sym)))))))

(define
  js-transpile-switch-clauses
  (fn
    (cases discr-sym matched-sym)
    (let
      ((forms (list)))
      (for-each
        (fn
          (c)
          (let
            ((kind (nth c 0)))
            (cond
              ((= kind "case")
                (let
                  ((val (nth c 1)) (body (nth c 2)))
                  (append!
                    forms
                    (list
                      (js-sym "when")
                      (list
                        (js-sym "or")
                        matched-sym
                        (list
                          (js-sym "js-strict-eq")
                          discr-sym
                          (js-transpile val)))
                      (js-transpile-switch-body-block matched-sym body)))))
              ((= kind "default")
                (let
                  ((body (nth c 2)))
                  (append!
                    forms
                    (list
                      (js-sym "when")
                      matched-sym
                      (js-transpile-switch-body-block matched-sym body))))))))
        cases)
      (let
        ((def-body nil))
        (for-each
          (fn
            (c)
            (when (= (nth c 0) "default") (set! def-body (nth c 2))))
          cases)
        (when
          (not (= def-body nil))
          (append!
            forms
            (list
              (js-sym "when")
              (list (js-sym "not") matched-sym)
              (js-transpile-switch-body-block matched-sym def-body)))))
      (cons (js-sym "begin") forms))))

(define
  js-transpile-switch-body-block
  (fn
    (matched-sym body)
    (let
      ((forms (list (list (js-sym "set!") matched-sym true))))
      (for-each (fn (stmt) (append! forms (js-transpile stmt))) body)
      (cons (js-sym "begin") forms))))

(define
  js-transpile-for-of-in
  (fn
    (iter-kind ident iter-ast body-ast)
    (let
      ((ident-sym (js-sym ident))
        (iter-sx (js-transpile iter-ast))
        (body-sx (js-transpile body-ast))
        (items-sym (js-sym "__js_items__")))
      (list
        (js-sym "call/cc")
        (list
          (js-sym "fn")
          (list (js-sym "__break__"))
          (list
            (js-sym "let")
            (list
              (list
                items-sym
                (if
                  (= iter-kind "of")
                  (list (js-sym "js-iterable-to-list") iter-sx)
                  (list (js-sym "js-object-keys") iter-sx))))
            (list
              (js-sym "for-each")
              (list
                (js-sym "fn")
                (list ident-sym)
                (list
                  (js-sym "call/cc")
                  (list
                    (js-sym "fn")
                    (list (js-sym "__continue__"))
                    body-sx)))
              items-sym)))))))

(define
  js-param-sym
  (fn
    (p)
    (cond
      ((string? p) (js-sym p))
      ((and (list? p) (js-tag? p "js-param")) (js-sym (nth p 1)))
      ((and (list? p) (js-tag? p "js-rest")) (js-sym (nth p 1)))
      (else (js-sym p)))))

(define
  js-build-param-list
  (fn
    (params)
    (cond
      ((empty? params) (list))
      ((and (list? (first params)) (js-tag? (first params) "js-rest"))
        (list (js-sym "&rest") (js-sym (nth (first params) 1))))
      (else
        (cons
          (js-param-sym (first params))
          (js-build-param-list (rest params)))))))

(define
  js-param-init-forms
  (fn
    (params)
    (cond
      ((empty? params) (list))
      ((and (list? (first params)) (js-tag? (first params) "js-param"))
        (let
          ((nm (js-sym (nth (first params) 1)))
            (dv (js-transpile (nth (first params) 2))))
          (cons
            (list
              (js-sym "set!")
              nm
              (list
                (js-sym "if")
                (list
                  (js-sym "or")
                  (list (js-sym "=") nm nil)
                  (list
                    (js-sym "=")
                    nm
                    (list (js-sym "quote") :js-undefined)))
                dv
                nm))
            (js-param-init-forms (rest params)))))
      (else (js-param-init-forms (rest params))))))

(define
  js-transpile-stmts
  (fn
    (stmts)
    (let
      ((hoisted (js-collect-funcdecls stmts)))
      (let
        ((rest-stmts (js-transpile-stmt-list stmts)))
        (cons (js-sym "begin") (append hoisted rest-stmts))))))

(define
  js-collect-funcdecls
  (fn
    (stmts)
    (cond
      ((empty? stmts) (list))
      ((and (list? (first stmts)) (js-tag? (first stmts) "js-funcdecl"))
        (cons
          (js-transpile-funcdecl
            (nth (first stmts) 1)
            (nth (first stmts) 2)
            (nth (first stmts) 3))
          (js-collect-funcdecls (rest stmts))))
      (else (js-collect-funcdecls (rest stmts))))))

(define
  js-transpile-optchain-member
  (fn
    (obj-ast name)
    (list (js-sym "js-optchain-get") (js-transpile obj-ast) name)))

(define
  js-transpile-optchain-index
  (fn
    (obj-ast key-ast)
    (list
      (js-sym "js-optchain-get")
      (js-transpile obj-ast)
      (js-transpile key-ast))))

(define
  js-transpile-optchain-call
  (fn
    (callee-ast args)
    (list
      (js-sym "js-optchain-call")
      (js-transpile callee-ast)
      (js-transpile-args args))))

(define
  js-transpile-stmt-list
  (fn
    (stmts)
    (cond
      ((empty? stmts) (list))
      ((and (list? (first stmts)) (js-tag? (first stmts) "js-funcdecl"))
        (cons nil (js-transpile-stmt-list (rest stmts))))
      (else
        (cons
          (js-transpile (first stmts))
          (js-transpile-stmt-list (rest stmts)))))))

(define
  js-transpile-var
  (fn (kind decls) (cons (js-sym "begin") (js-vardecl-forms decls))))

(define
  js-vardecl-forms
  (fn
    (decls)
    (cond
      ((empty? decls) (list))
      (else
        (let
          ((d (first decls)))
          (cond
            ((js-tag? d "js-vardecl")
              (cons
                (list
                  (js-sym "define")
                  (js-sym (nth d 1))
                  (js-transpile (nth d 2)))
                (js-vardecl-forms (rest decls))))
            ((js-tag? d "js-vardecl-obj")
              (let
                ((names (nth d 1))
                  (rhs (js-transpile (nth d 2)))
                  (tmp-sym (js-sym "__destruct__")))
                (cons
                  (list (js-sym "define") tmp-sym rhs)
                  (js-vardecl-obj-forms
                    names
                    tmp-sym
                    (js-vardecl-forms (rest decls))))))
            ((js-tag? d "js-vardecl-arr")
              (let
                ((names (nth d 1))
                  (rhs (js-transpile (nth d 2)))
                  (tmp-sym (js-sym "__destruct__")))
                (cons
                  (list (js-sym "define") tmp-sym rhs)
                  (js-vardecl-arr-forms
                    names
                    tmp-sym
                    0
                    (js-vardecl-forms (rest decls))))))
            (else (error "js-vardecl-forms: unexpected decl"))))))))

(define
  js-vardecl-obj-forms
  (fn
    (names tmp-sym tail)
    (cond
      ((empty? names) tail)
      ((= (first names) nil)
        (js-vardecl-obj-forms (rest names) tmp-sym tail))
      ((and (list? (first names)) (= (first (first names)) "rename"))
        (cons
          (list
            (js-sym "define")
            (js-sym (nth (first names) 2))
            (list (js-sym "js-get-prop") tmp-sym (nth (first names) 1)))
          (js-vardecl-obj-forms (rest names) tmp-sym tail)))
      ((and (list? (first names)) (= (first (first names)) "rest"))
        (js-vardecl-obj-forms (rest names) tmp-sym tail))
      (else
        (cons
          (list
            (js-sym "define")
            (js-sym (first names))
            (list (js-sym "js-get-prop") tmp-sym (first names)))
          (js-vardecl-obj-forms (rest names) tmp-sym tail))))))

(define
  js-vardecl-arr-forms
  (fn
    (names tmp-sym i tail)
    (cond
      ((empty? names) tail)
      ((= (first names) nil)
        (js-vardecl-arr-forms (rest names) tmp-sym (+ i 1) tail))
      ((and (list? (first names)) (= (first (first names)) "rest"))
        (cons
          (list
            (js-sym "define")
            (js-sym (nth (first names) 1))
            (list
              (js-sym "js-list-slice")
              tmp-sym
              i
              (list (js-sym "len") tmp-sym)))
          tail))
      (else
        (cons
          (list
            (js-sym "define")
            (js-sym (first names))
            (list (js-sym "js-get-prop") tmp-sym i))
          (js-vardecl-arr-forms (rest names) tmp-sym (+ i 1) tail))))))

(define
  js-transpile-if-stmt
  (fn
    (c t e)
    (let
      ((c-tr (list (js-sym "js-to-boolean") (js-transpile c)))
        (t-tr (if (= t nil) nil (js-transpile t))))
      (if
        (= e nil)
        (list (js-sym "if") c-tr t-tr nil)
        (list (js-sym "if") c-tr t-tr (js-transpile e))))))

(define
  js-transpile-while
  (fn
    (c body)
    (list
      (js-sym "call/cc")
      (list
        (js-sym "fn")
        (list (js-sym "__break__"))
        (list
          (js-sym "letrec")
          (list
            (list
              (js-sym "__loop__")
              (list
                (js-sym "fn")
                (list)
                (list
                  (js-sym "if")
                  (list (js-sym "js-to-boolean") (js-transpile c))
                  (list
                    (js-sym "begin")
                    (list
                      (js-sym "call/cc")
                      (list
                        (js-sym "fn")
                        (list (js-sym "__continue__"))
                        (js-transpile body)))
                    (list (js-sym "__loop__")))
                  nil))))
          (list (js-sym "__loop__")))))))

(define
  js-transpile-do-while
  (fn
    (body c)
    (list
      (js-sym "call/cc")
      (list
        (js-sym "fn")
        (list (js-sym "__break__"))
        (list
          (js-sym "letrec")
          (list
            (list
              (js-sym "__loop__")
              (list
                (js-sym "fn")
                (list)
                (list
                  (js-sym "begin")
                  (list
                    (js-sym "call/cc")
                    (list
                      (js-sym "fn")
                      (list (js-sym "__continue__"))
                      (js-transpile body)))
                  (list
                    (js-sym "if")
                    (list (js-sym "js-to-boolean") (js-transpile c))
                    (list (js-sym "__loop__"))
                    nil)))))
          (list (js-sym "__loop__")))))))

(define
  js-transpile-for
  (fn
    (init cond-ast step body)
    (let
      ((init-form (if (= init nil) nil (js-transpile init)))
        (cond-form
          (if
            (= cond-ast nil)
            (list (js-sym "quote") true)
            (list (js-sym "js-to-boolean") (js-transpile cond-ast))))
        (step-form (if (= step nil) nil (js-transpile step)))
        (body-tr (js-transpile body)))
      (list
        (js-sym "begin")
        (if (= init-form nil) nil init-form)
        (list
          (js-sym "call/cc")
          (list
            (js-sym "fn")
            (list (js-sym "__break__"))
            (list
              (js-sym "letrec")
              (list
                (list
                  (js-sym "__loop__")
                  (list
                    (js-sym "fn")
                    (list)
                    (list
                      (js-sym "if")
                      cond-form
                      (list
                        (js-sym "begin")
                        (list
                          (js-sym "call/cc")
                          (list
                            (js-sym "fn")
                            (list (js-sym "__continue__"))
                            body-tr))
                        (if (= step-form nil) nil step-form)
                        (list (js-sym "__loop__")))
                      nil))))
              (list (js-sym "__loop__")))))))))

(define
  js-transpile-return
  (fn
    (e)
    (list
      (js-sym "__return__")
      (if (= e nil) (list (js-sym "quote") :js-undefined) (js-transpile e)))))

(define js-transpile-break (fn () (list (js-sym "__break__") nil)))

(define js-transpile-continue (fn () (list (js-sym "__continue__") nil)))

(define
  js-transpile-funcdecl
  (fn
    (name params body)
    (list
      (js-sym "define")
      (js-sym name)
      (js-transpile-funcexpr name params body))))

(define
  js-transpile-class
  (fn
    (name parent methods)
    (let
      ((ctor-method (js-find-ctor methods))
        (instance-methods (js-filter-methods methods "instance"))
        (name-sym (js-sym name)))
      (let
        ((ctor-body (if (= ctor-method nil) (if parent (js-default-ctor-with-super parent) (js-default-ctor-noop)) (js-transpile-funcexpr name (nth ctor-method 3) (nth ctor-method 4)))))
        (cons
          (js-sym "begin")
          (append
            (list (list (js-sym "define") name-sym ctor-body))
            (list (list (js-sym "js-reset-ctor-proto!") name-sym))
            (if
              parent
              (list
                (list
                  (js-sym "dict-set!")
                  (list (js-sym "js-get-ctor-proto") name-sym)
                  "__proto__"
                  (list (js-sym "js-get-ctor-proto") (js-sym parent))))
              (list))
            (map
              (fn
                (m)
                (let
                  ((mname (nth m 2))
                    (mparams (nth m 3))
                    (mbody (nth m 4)))
                  (list
                    (js-sym "dict-set!")
                    (list (js-sym "js-get-ctor-proto") name-sym)
                    mname
                    (js-transpile-funcexpr mname mparams mbody))))
              instance-methods)
            (list
              (list
                (js-sym "dict-set!")
                (list (js-sym "js-get-ctor-proto") name-sym)
                "constructor"
                name-sym))))))))

(define
  js-find-ctor
  (fn
    (methods)
    (cond
      ((empty? methods) nil)
      ((and (js-tag? (first methods) "js-method") (= (nth (first methods) 1) "instance") (= (nth (first methods) 2) "constructor"))
        (first methods))
      (else (js-find-ctor (rest methods))))))

(define
  js-filter-methods
  (fn
    (methods kind)
    (cond
      ((empty? methods) (list))
      ((and (js-tag? (first methods) "js-method") (= (nth (first methods) 1) kind) (not (= (nth (first methods) 2) "constructor")))
        (cons (first methods) (js-filter-methods (rest methods) kind)))
      (else (js-filter-methods (rest methods) kind)))))

(define
  js-default-ctor-noop
  (fn
    ()
    (list
      (js-sym "fn")
      (list (js-sym "&rest") (js-sym "__args__"))
      (list
        (js-sym "let")
        (list (list (js-sym "this") (list (js-sym "js-this"))))
        :js-undefined))))

(define
  js-default-ctor-with-super
  (fn
    (parent)
    (list
      (js-sym "fn")
      (list (js-sym "&rest") (js-sym "__args__"))
      (list
        (js-sym "let")
        (list (list (js-sym "this") (list (js-sym "js-this"))))
        (list
          (js-sym "js-call-with-this")
          (js-sym "this")
          (js-sym parent)
          (js-sym "__args__"))))))

(define
  js-transpile-throw
  (fn (e) (list (js-sym "raise") (js-transpile e))))

(define
  js-transpile-try
  (fn
    (body catch-part finally-part)
    (let
      ((body-tr (js-transpile body)))
      (let
        ((with-catch (cond ((= catch-part nil) body-tr) (else (let ((pname (nth catch-part 0)) (cbody (nth catch-part 1))) (list (js-sym "guard") (list (if (= pname nil) (js-sym "__exc__") (js-sym pname)) (list (js-sym "else") (js-transpile cbody))) body-tr))))))
        (cond
          ((= finally-part nil) with-catch)
          (else
            (list
              (js-sym "let")
              (list (list (js-sym "__try_result__") with-catch))
              (js-transpile finally-part)
              (js-sym "__try_result__"))))))))

(define
  js-transpile-funcexpr
  (fn
    (name params body)
    (let
      ((param-syms (js-build-param-list params))
        (inits (js-param-init-forms params))
        (body-forms
          (if
            (and (list? body) (js-tag? body "js-block"))
            (let
              ((hoisted (js-collect-funcdecls (nth body 1))))
              (append hoisted (js-transpile-stmt-list (nth body 1))))
            (list (js-transpile body)))))
      (list
        (js-sym "fn")
        param-syms
        (list
          (js-sym "let")
          (list (list (js-sym "this") (list (js-sym "js-this"))))
          (list
            (js-sym "call/cc")
            (list
              (js-sym "fn")
              (list (js-sym "__return__"))
              (cons (js-sym "begin") (append inits body-forms)))))))))

(define
  js-transpile-funcexpr-async
  (fn
    (name params body)
    (let
      ((param-syms (js-build-param-list params))
        (inits (js-param-init-forms params))
        (body-forms
          (if
            (and (list? body) (js-tag? body "js-block"))
            (let
              ((hoisted (js-collect-funcdecls (nth body 1))))
              (append hoisted (js-transpile-stmt-list (nth body 1))))
            (list (js-transpile body)))))
      (list
        (js-sym "fn")
        param-syms
        (list
          (js-sym "let")
          (list (list (js-sym "this") (list (js-sym "js-this"))))
          (list
            (js-sym "js-async-wrap")
            (list
              (js-sym "fn")
              (list)
              (list
                (js-sym "call/cc")
                (list
                  (js-sym "fn")
                  (list (js-sym "__return__"))
                  (cons (js-sym "begin") (append inits body-forms)))))))))))

(define
  js-transpile-funcdecl-async
  (fn
    (name params body)
    (list
      (js-sym "define")
      (js-sym name)
      (js-transpile-funcexpr-async name params body))))

(define
  js-transpile-arrow-async
  (fn
    (params body)
    (let
      ((param-syms (js-build-param-list params))
        (inits (js-param-init-forms params))
        (body-tr
          (if
            (and (list? body) (js-tag? body "js-block"))
            (list
              (js-sym "call/cc")
              (list
                (js-sym "fn")
                (list (js-sym "__return__"))
                (cons
                  (js-sym "begin")
                  (append
                    inits
                    (append
                      (js-collect-funcdecls (nth body 1))
                      (js-transpile-stmt-list (nth body 1)))))))
            (if
              (empty? inits)
              (js-transpile body)
              (cons
                (js-sym "begin")
                (append inits (list (js-transpile body))))))))
      (list
        (js-sym "fn")
        param-syms
        (list (js-sym "js-async-wrap") (list (js-sym "fn") (list) body-tr))))))

(define
  js-eval
  (fn
    (src)
    (let
      ((result (eval-expr (js-transpile (js-parse (js-tokenize src))))))
      (js-drain-microtasks!)
      result)))

(define js-compile-expr (fn (src) (js-transpile (js-parse-expr src))))