;; Phase 16 — Exception handling unit tests.

(hk-test
  "catch — success path returns the action result"
  (hk-deep-force
    (hk-run
      "main = catch (return 42) (\\(SomeException m) -> return 0)"))
  (list "IO" 42))

(hk-test
  "catch — error caught, handler receives message"
  (hk-deep-force
    (hk-run
      "main = catch (error \"boom\") (\\(SomeException m) -> return m)"))
  (list "IO" "boom"))

(hk-test
  "try — success returns Right v"
  (hk-deep-force
    (hk-run "main = try (return 42)"))
  (list "IO" (list "Right" 42)))

(hk-test
  "try — error returns Left (SomeException msg)"
  (hk-deep-force
    (hk-run "main = try (error \"oops\")"))
  (list "IO" (list "Left" (list "SomeException" "oops"))))

(hk-test
  "handle — flip catch — caught error message"
  (hk-deep-force
    (hk-run
      "main = handle (\\(SomeException m) -> return m) (error \"hot\")"))
  (list "IO" "hot"))

(hk-test
  "throwIO + catch — handler sees the SomeException"
  (hk-deep-force
    (hk-run
      "main = catch (throwIO (SomeException \"bang\")) (\\(SomeException m) -> return m)"))
  (list "IO" "bang"))

(hk-test
  "throwIO + try — Left side"
  (hk-deep-force
    (hk-run
      "main = try (throwIO (SomeException \"x\"))"))
  (list "IO" (list "Left" (list "SomeException" "x"))))

(hk-test
  "evaluate — pure value returns IO v"
  (hk-deep-force
    (hk-run "main = evaluate (1 + 2 + 3)"))
  (list "IO" 6))

(hk-test
  "evaluate — error surfaces as catchable exception"
  (hk-deep-force
    (hk-run
      "main = catch (evaluate (error \"deep\")) (\\(SomeException m) -> return m)"))
  (list "IO" "deep"))

(hk-test
  "nested catch — inner handler runs first"
  (hk-deep-force
    (hk-run
      "main = catch (catch (error \"inner\") (\\(SomeException m) -> error (m ++ \"-rethrown\"))) (\\(SomeException m) -> return m)"))
  (list "IO" "inner-rethrown"))

(hk-test
  "catch chain — handler can succeed inside IO"
  (hk-deep-force
    (hk-run
      "main = do { x <- catch (error \"e1\") (\\(SomeException m) -> return 100); return (x + 1) }"))
  (list "IO" 101))

(hk-test
  "try then bind on Right"
  (hk-deep-force
    (hk-run
      "branch (Right v) = return (v * 2)
branch (Left _) = return 0
main = do { r <- try (return 21); branch r }"))
  (list "IO" 42))

(hk-test
  "try then bind on Left"
  (hk-deep-force
    (hk-run
      "branch (Right _) = return \"ok\"
branch (Left (SomeException m)) = return m
main = do { r <- try (error \"failed\"); branch r }"))
  (list "IO" "failed"))

(hk-test
  "catch — handler can use closed-over IORef"
  (hk-deep-force
    (hk-run
      "import qualified Data.IORef as IORef
main = do
  r <- IORef.newIORef 0
  catch (error \"x\") (\\(SomeException m) -> IORef.writeIORef r 7)
  v <- IORef.readIORef r
  return v"))
  (list "IO" 7))