; Phase 7 — rule-based optimization via maude-on-sx.
; Bridge round-trip: dag->term->dag is the identity on canonical (content-id) form.

; ---- linear chain a -> b -> c (b carries params) ----

(define
  mo-chain
  (artdag/build
    (list
      (list "a" "in" (list) {:v 5})
      (list "b" "blur" (list "a") {:radius 2})
      (list "c" "blur" (list "b") {:radius 3}))))
(define mo-c-id (artdag/dag-id mo-chain "c"))
(define mo-chain-rt (artdag/mb-roundtrip mo-chain mo-c-id))

(artdag-test
  "roundtrip: sink id preserved"
  (artdag/member? mo-c-id (keys (artdag/dag-nodes mo-chain-rt)))
  true)

(artdag-test
  "roundtrip: node count preserved"
  (artdag/node-count mo-chain-rt)
  3)

(artdag-test
  "roundtrip: sink op preserved"
  (artdag/node-op (artdag/dag-get mo-chain-rt mo-c-id))
  "blur")

(artdag-test
  "roundtrip: sink params preserved"
  (artdag/node-params (artdag/dag-get mo-chain-rt mo-c-id))
  {:radius 3})

(artdag-test
  "roundtrip: full reconstructed node equals original"
  (= (artdag/dag-get mo-chain-rt mo-c-id) (artdag/dag-get mo-chain mo-c-id))
  true)

; ---- term shape ----

(define mo-c-term (artdag/dag->term mo-chain mo-c-id))

(artdag-test "term: sink op is the maude operator" (mau/op mo-c-term) "blur")

(artdag-test
  "term: params recovered from meta"
  (artdag/term-params mo-c-term)
  {:radius 3})

(artdag-test
  "term: commutative flag recovered (false)"
  (artdag/term-commutative mo-c-term)
  false)

(artdag-test
  "term->entries: one entry per node"
  (len (artdag/term->entries mo-c-term))
  3)

; ---- commutative node: order-insensitive id survives round-trip ----

(define
  mo-comm
  (artdag/build
    (list
      (list "x" "src" (list) {})
      (list "y" "noise" (list) {})
      (list "z" "over" (list "x" "y") {} true))))
(define mo-z-id (artdag/dag-id mo-comm "z"))
(define mo-comm-rt (artdag/mb-roundtrip mo-comm mo-z-id))

(artdag-test
  "roundtrip comm: commutative id preserved"
  (artdag/member? mo-z-id (keys (artdag/dag-nodes mo-comm-rt)))
  true)

(artdag-test
  "term comm: commutative flag recovered (true)"
  (artdag/term-commutative (artdag/dag->term mo-comm mo-z-id))
  true)

; ---- diamond: shared subgraph re-collapses to one node ----

(define
  mo-diamond
  (artdag/build
    (list
      (list "a" "src" (list) {})
      (list "b" "blur" (list "a") {:radius 1})
      (list "c" "bright" (list "a") {:gain 2})
      (list "d" "over" (list "b" "c") {} true))))
(define mo-d-id (artdag/dag-id mo-diamond "d"))
(define mo-diamond-rt (artdag/mb-roundtrip mo-diamond mo-d-id))

(artdag-test
  "roundtrip diamond: shared node not duplicated"
  (artdag/node-count mo-diamond-rt)
  4)

(artdag-test
  "roundtrip diamond: sink id preserved"
  (artdag/member? mo-d-id (keys (artdag/dag-nodes mo-diamond-rt)))
  true)

(artdag-test
  "roundtrip diamond: shared src id preserved"
  (artdag/member?
    (artdag/dag-id mo-diamond "a")
    (keys (artdag/dag-nodes mo-diamond-rt)))
  true)