;; Erlang evaluator tests — sequential expressions.

(define er-eval-test-count 0)
(define er-eval-test-pass 0)
(define er-eval-test-fails (list))

(define
  eev-deep=
  (fn
    (a b)
    (cond
      (and (= (type-of a) "dict") (= (type-of b) "dict"))
      (let
        ((ka (sort (keys a))) (kb (sort (keys b))))
        (and (= ka kb) (every? (fn (k) (eev-deep= (get a k) (get b k))) ka)))
      (and (= (type-of a) "list") (= (type-of b) "list"))
      (and
        (= (len a) (len b))
        (every? (fn (i) (eev-deep= (nth a i) (nth b i))) (range 0 (len a))))
      :else (= a b))))

(define
  er-eval-test
  (fn
    (name actual expected)
    (set! er-eval-test-count (+ er-eval-test-count 1))
    (if
      (eev-deep= actual expected)
      (set! er-eval-test-pass (+ er-eval-test-pass 1))
      (append! er-eval-test-fails {:actual actual :expected expected :name name}))))

(define ev erlang-eval-ast)
(define nm (fn (v) (get v :name)))

;; ── literals ──────────────────────────────────────────────────────
(er-eval-test "int" (ev "42") 42)
(er-eval-test "zero" (ev "0") 0)
(er-eval-test "float" (ev "3.14") 3.14)
(er-eval-test "string" (ev "\"hi\"") "hi")
(er-eval-test "atom" (nm (ev "ok")) "ok")
(er-eval-test "atom true" (nm (ev "true")) "true")
(er-eval-test "atom false" (nm (ev "false")) "false")

;; ── arithmetic ────────────────────────────────────────────────────
(er-eval-test "add" (ev "1 + 2") 3)
(er-eval-test "sub" (ev "5 - 3") 2)
(er-eval-test "mul" (ev "4 * 3") 12)
(er-eval-test "div-real" (ev "10 / 4") 2.5)
(er-eval-test "div-int" (ev "10 div 3") 3)
(er-eval-test "rem" (ev "10 rem 3") 1)
(er-eval-test "div-neg" (ev "-10 div 3") -3)
(er-eval-test "precedence" (ev "1 + 2 * 3") 7)
(er-eval-test "parens" (ev "(1 + 2) * 3") 9)
(er-eval-test "unary-neg" (ev "-(1 + 2)") -3)
(er-eval-test "unary-neg int" (ev "-7") -7)

;; ── comparison ────────────────────────────────────────────────────
(er-eval-test "lt true" (nm (ev "1 < 2")) "true")
(er-eval-test "gt false" (nm (ev "1 > 2")) "false")
(er-eval-test "le equal" (nm (ev "2 =< 2")) "true")
(er-eval-test "ge equal" (nm (ev "2 >= 2")) "true")
(er-eval-test "eq" (nm (ev "2 == 2")) "true")
(er-eval-test "neq" (nm (ev "1 /= 2")) "true")
(er-eval-test "exact-eq same" (nm (ev "1 =:= 1")) "true")
(er-eval-test "exact-neq int" (nm (ev "1 =:= 2")) "false")
(er-eval-test "=/= true" (nm (ev "1 =/= 2")) "true")
(er-eval-test "atom-eq" (nm (ev "ok == ok")) "true")
(er-eval-test "atom-neq" (nm (ev "ok == error")) "false")

;; ── logical ───────────────────────────────────────────────────────
(er-eval-test "and tt" (nm (ev "true and true")) "true")
(er-eval-test "and tf" (nm (ev "true and false")) "false")
(er-eval-test "or tf" (nm (ev "true or false")) "true")
(er-eval-test
  "andalso short"
  (nm (ev "false andalso Neverref"))
  "false")
(er-eval-test
  "orelse short"
  (nm (ev "true orelse Neverref"))
  "true")
(er-eval-test "not true" (nm (ev "not true")) "false")
(er-eval-test "not false" (nm (ev "not false")) "true")

;; ── tuples & lists ────────────────────────────────────────────────
(er-eval-test "tuple tag" (get (ev "{1, 2, 3}") :tag) "tuple")
(er-eval-test "tuple len" (len (get (ev "{1, 2, 3}") :elements)) 3)
(er-eval-test "tuple elem" (nth (get (ev "{10, 20}") :elements) 1) 20)
(er-eval-test "empty tuple" (len (get (ev "{}") :elements)) 0)
(er-eval-test "nested tuple"
  (nm (nth (get (ev "{ok, error}") :elements) 0)) "ok")
(er-eval-test "nil list" (get (ev "[]") :tag) "nil")
(er-eval-test "list head" (get (ev "[1, 2, 3]") :head) 1)
(er-eval-test
  "list tail tail head"
  (get (get (get (ev "[1, 2, 3]") :tail) :tail) :head)
  3)

;; ── list ops ──────────────────────────────────────────────────────
(er-eval-test "++ head" (get (ev "[1, 2] ++ [3]") :head) 1)
(er-eval-test "++ last"
  (get (get (get (ev "[1, 2] ++ [3]") :tail) :tail) :head) 3)

;; ── block ─────────────────────────────────────────────────────────
(er-eval-test "block last wins" (ev "begin 1, 2, 3 end") 3)
(er-eval-test "bare body" (ev "1, 2, 99") 99)

;; ── match + var ───────────────────────────────────────────────────
(er-eval-test "match bind-and-use" (ev "X = 5, X + 1") 6)
(er-eval-test "match sequential" (ev "X = 1, Y = 2, X + Y") 3)
(er-eval-test
  "rebind equal ok"
  (ev "X = 5, X = 5, X") 5)

;; ── if ────────────────────────────────────────────────────────────
(er-eval-test "if picks first" (ev "if true -> 1; true -> 2 end") 1)
(er-eval-test
  "if picks second"
  (nm (ev "if 1 > 2 -> bad; true -> good end"))
  "good")
(er-eval-test
  "if with guard"
  (ev "X = 5, if X > 0 -> 1; true -> 0 end")
  1)

;; ── pattern matching ─────────────────────────────────────────────
(er-eval-test "match atom literal" (nm (ev "ok = ok, done")) "done")
(er-eval-test "match int literal" (ev "5 = 5, 42") 42)
(er-eval-test "match tuple bind"
  (ev "{ok, V} = {ok, 99}, V") 99)
(er-eval-test "match tuple nested"
  (ev "{A, {B, C}} = {1, {2, 3}}, A + B + C") 6)
(er-eval-test "match cons head"
  (ev "[H|T] = [1, 2, 3], H") 1)
(er-eval-test "match cons tail head"
  (ev "[_, H|_] = [1, 2, 3], H") 2)
(er-eval-test "match nil"
  (ev "[] = [], 7") 7)
(er-eval-test "match wildcard always"
  (ev "_ = 42, 7") 7)
(er-eval-test "match var reuse equal"
  (ev "X = 5, X = 5, X") 5)

;; ── case ─────────────────────────────────────────────────────────
(er-eval-test "case bind" (ev "case 5 of N -> N end") 5)
(er-eval-test "case tuple"
  (ev "case {ok, 42} of {ok, V} -> V end") 42)
(er-eval-test "case cons"
  (ev "case [1, 2, 3] of [H|_] -> H end") 1)
(er-eval-test "case fallthrough"
  (ev "case error of ok -> 1; error -> 2 end") 2)
(er-eval-test "case wildcard"
  (nm (ev "case x of ok -> ok; _ -> err end"))
  "err")
(er-eval-test "case guard"
  (ev "case 5 of N when N > 0 -> pos; _ -> neg end")
  (er-mk-atom "pos"))
(er-eval-test "case guard fallthrough"
  (ev "case -3 of N when N > 0 -> pos; _ -> neg end")
  (er-mk-atom "neg"))
(er-eval-test "case bound re-match"
  (ev "X = 5, case 5 of X -> same; _ -> diff end")
  (er-mk-atom "same"))
(er-eval-test "case bound re-match fail"
  (ev "X = 5, case 6 of X -> same; _ -> diff end")
  (er-mk-atom "diff"))
(er-eval-test "case nested tuple"
  (ev "case {ok, {value, 42}} of {ok, {value, V}} -> V end")
  42)
(er-eval-test "case multi-clause"
  (ev "case 2 of 1 -> one; 2 -> two; _ -> other end")
  (er-mk-atom "two"))
(er-eval-test "case leak binding"
  (ev "case {ok, 7} of {ok, X} -> X end + 1")
  8)

(define
  er-eval-test-summary
  (str "eval " er-eval-test-pass "/" er-eval-test-count))