;; lib/host/tests/execute.sx — the EXECUTE-fold (lib/host/execute.sx): a second interpreter
;; over the SAME seq/alt/each composition algebra as the render-fold, proving the algebra is
;; domain-agnostic (plans/composition-objects.md step 7). Leaves are effects; the fold
;; returns an effect log. Reuses compose.sx's when-predicates / field resolver / each source.

(define host-ex-pass 0)
(define host-ex-fail 0)
(define host-ex-fails (list))
(define host-ex-test
  (fn (name actual expected)
    (if (= actual expected)
      (set! host-ex-pass (+ host-ex-pass 1))
      (begin
        (set! host-ex-fail (+ host-ex-fail 1))
        (append! host-ex-fails {:name name :actual actual :expected expected})))))

;; the verbs of an effect log, in order (effect records are {:verb :args}).
(define ex-verbs (fn (effects) (map (fn (e) (get e :verb)) effects)))
(define ex-args  (fn (effects) (map (fn (e) (get e :args)) effects)))

;; -- seq: steps in order --
(host-ex-test "seq runs effects in order"
  (ex-verbs (host/exec-run (quote (seq (effect a) (effect b) (effect c))) {}))
  (list "a" "b" "c"))
(host-ex-test "nested seq flattens in order"
  (ex-verbs (host/exec-run (quote (seq (effect a) (seq (effect b) (effect c)) (effect d))) {}))
  (list "a" "b" "c" "d"))

;; -- alt + when: branch (reusing the render-fold's predicate set) --
(host-ex-test "alt runs the first branch whose when holds"
  (ex-verbs (host/exec-run (quote (alt (when (has "auth") (effect publish)) (else (effect hold)))) {"auth" "y"}))
  (list "publish"))
(host-ex-test "alt falls through to else when no when holds"
  (ex-verbs (host/exec-run (quote (alt (when (has "auth") (effect publish)) (else (effect hold)))) {}))
  (list "hold"))
(host-ex-test "alt eq predicate branches on a context value"
  (ex-verbs (host/exec-run (quote (alt (when (eq "role" "admin") (effect grant)) (else (effect deny)))) {"role" "admin"}))
  (list "grant"))

;; -- each: for-each over the (reused) source, with field resolution from the item --
(host-ex-test "each runs the body per item (for-each)"
  (ex-verbs (host/exec-run (quote (each (items {:email "a"} {:email "b"}) (effect notify))) {}))
  (list "notify" "notify"))
(host-ex-test "effect args resolve (field K) from the current item"
  (ex-args (host/exec-run (quote (each (items {:email "a@x"} {:email "b@x"}) (effect notify (field :email)))) {}))
  (list (list "a@x") (list "b@x")))
(host-ex-test "effect args resolve (field K) from the context, and literals pass through"
  (ex-args (host/exec-run (quote (seq (effect log (field :who) "done"))) {"who" "alice"}))
  (list (list "alice" "done")))

;; -- robustness: non-effect leaves / unknown heads produce no effects --
(host-ex-test "a non-list node yields no effects"
  (host/exec-run "bare" {}) (list))
(host-ex-test "an unknown combinator head yields no effects"
  (host/exec-run (quote (frobnicate 1 2)) {}) (list))

;; -- the KEYSTONE: ONE control skeleton, folded TWO ways. Same alt+when, same context, the
;; SAME branch is chosen (both use host/comp--pred?); render emits HTML, execute emits an
;; effect. The composition algebra is domain-agnostic — render and behaviour are two folds. --
(host-ex-test "same skeleton folds two ways — render picks the branch, execute picks the SAME branch (authed)"
  (let ((ctx {"auth" "y"}))
    (list (host/comp-render (quote (alt (when (has "auth") (text "<b>in</b>")) (else (text "out")))) ctx)
          (ex-verbs (host/exec-run (quote (alt (when (has "auth") (effect enter)) (else (effect leave)))) ctx))))
  (list "<b>in</b>" (list "enter")))
(host-ex-test "same skeleton folds two ways — the else branch agrees across folds (anon)"
  (let ((ctx {}))
    (list (host/comp-render (quote (alt (when (has "auth") (text "<b>in</b>")) (else (text "out")))) ctx)
          (ex-verbs (host/exec-run (quote (alt (when (has "auth") (effect enter)) (else (effect leave)))) ctx))))
  (list "out" (list "leave")))

;; -- a small workflow: validate -> (branch on status) -> notify each recipient. Proves the
;; behaviour model is just an execute-fold over a composition object. --
(host-ex-test "a publish workflow runs as one execute-fold over the composition"
  (ex-verbs
    (host/exec-run
      (quote (seq
               (effect validate (field :slug))
               (alt (when (eq "status" "ready") (effect publish (field :slug)))
                    (else (effect hold (field :slug))))
               (each (items {:to "a"} {:to "b"}) (effect notify (field :to)))))
      {"slug" "post-1" "status" "ready"}))
  (list "validate" "publish" "notify" "notify"))

(define host-ex-tests-run!
  (fn ()
    {:total (+ host-ex-pass host-ex-fail)
     :passed host-ex-pass :failed host-ex-fail :fails host-ex-fails}))