{-# LANGUAGE OverloadedLists #-}
module Gyehoek.Test.Stack.VM where

import Test.Tasty (TestTree, testGroup)
import Test.Tasty.HUnit
import Gyehoek.Stack.Syntax
import Gyehoek.Stack.VM qualified as Sut
import Data.List (List)
import Gyehoek.Jalmot


evalsTo :: List Obj -> Program -> Assertion
evalsTo rs p = runJalmotUnsafe (Sut.eval p) @?= rs

test_root = testGroup "stack machine"
  [ testCase "immediate halt" do
      evalsTo [ObjImm (ImmInt 3)] [stkP|
        (define $start
          (return 0))
      |]
  , testCase "lit int" do
      evalsTo [ObjImm (ImmInt 3)] [stkP|
        (define $start
          (push! 3)
          (return 1))
      |]
  -- , testCase "return constant" do
  --     evalsTo [ObjImm (ImmInt 123)] [stkP|
  --       (define ($start %ktail)
  --         (tail-call $silly %ktail))
  --       (define ($silly %ktail)
  --         (tail-call %ktail 123))
  --     |]
  -- , testCase "identity continuation" do
  --     evalsTo [ObjImm (ImmInt 45)] [stkP|
  --       (define ($start %ktail)
  --         (push! %ktail)
  --         (tail-call $id 45))
  --       (define ($id %x)
  --         (pop! %ktail)
  --         (tail-call %ktail %x))
  --     |]
  -- , testCase "identity function" do
  --     evalsTo [ObjImm (ImmInt 45)] [stkP|
  --       (define ($start %ktail)
  --         (tail-call $id 45 %ktail))
  --       (define ($id %x %ktail)
  --         (tail-call %ktail %x))
  --     |]
  -- , testCase "square" do
  --     evalsTo [ObjImm (ImmInt 16)] [stkP|
  --       (define ($start %ktail)
  --         (tail-call $square 4 %ktail))
  --       (define ($square %x %ktail)
  --         (prim %x2 (* %x %x))
  --         (tail-call %ktail %x2))
  --     |]
  -- , testCase "factorial" do
  --     let hsfac (n :: Int) = foldr (*) (1) [1..n]
  --     let fac (n :: Int) = [stkP|
  --           (define ($fac %n %ktail)
  --             (prim %x0 (zero? %n))
  --             (if %x0
  --               (then (tail-call %ktail 1))
  --               (else (push! %n)
  --                     (push! %ktail)
  --                     (prim %x1 (- %n 1))
  --                     (tail-call $fac %x1 $fac-k0))))
  --           (define ($fac-k0 %x2)
  --             (pop! %ktail)
  --             (pop! %n)
  --             (prim %x3 (* %x2 %n))
  --             (tail-call %ktail %x3))
  --           (define ($start %ktail)
  --             (tail-call $fac #{n} %ktail))
  --         |]
  --     evalsTo [ObjImm (ImmInt 1)] $ fac 0
  --     evalsTo [ObjImm (ImmInt 1)] $ fac 1
  --     evalsTo [ObjImm (ImmInt 720)] $ fac 6
  --     -- 20 is the greatest `n` for which n! ≤ maxBount @Int
  --     evalsTo [ObjImm (ImmInt 2432902008176640000)] $ fac 20
  ]