-- | Pure, in-memory tests for the EP-2 brute-force lockout and per-IP failure throttle
-- ('Shomei.Session.Authentication.Workflow.login' abuse protection). Every case runs through
-- 'Shomei.Test.InMemory.runInMemory' with no database or network, and asserts both the
-- returned 'Either' and the resulting lockout state read back from the 'World'.
--
-- The test config tightens the thresholds (3 failures per account, 5 per IP) so the loops are
-- short; the windowed-counting and cooldown semantics are otherwise the production defaults.
module Shomei.LockoutSpec (tests) where

import Data.IORef (IORef, modifyIORef', newIORef, readIORef)
import Data.Map.Strict qualified as Map
import Data.Text (Text)
import Data.Time (UTCTime (..), addUTCTime, fromGregorian)
import Effectful (Eff, IOE, liftIO, (:>))
import Effectful.Dispatch.Dynamic (interpose, passthrough, send)
import Shomei.Account.Email.Domain (Email, emailText, mkEmail)
import Shomei.Account.LoginId.Domain (LoginId, mkLoginId)
import Shomei.Account.Password.Domain (PlainPassword (..))
import Shomei.Authorization.Claims.Domain (Audience (..), Issuer (..))
import Shomei.Config (RateLimitConfig (..), ShomeiConfig (..), defaultRateLimitConfig, defaultShomeiConfig)
import Shomei.Error (AuthError (..))
import Shomei.Session.Authentication.Workflow (login, signup)
import Shomei.Session.Command (ClientContext (..), LoginCommand (..), SignupCommand (..))
import Shomei.Session.LoginAttempt.Domain (AccountKey (..), AccountLockout (..), ClientIp (..))
import Shomei.Session.LoginAttempt.Store (LoginAttemptStore (..))
import Shomei.Test.InMemory (World (..), emptyWorld, runInMemory)
import Test.Tasty (TestTree, testGroup)
import Test.Tasty.HUnit (assertBool, assertFailure, testCase, (@?=))

-- Fixtures -------------------------------------------------------------------

t0 :: UTCTime
t0 = UTCTime (fromGregorian 2026 1 1) 0

-- | Tightened thresholds: lock after 3 per-account failures, throttle after 5 per-IP failures.
cfg :: ShomeiConfig
cfg =
  (defaultShomeiConfig (Issuer "shomei") (Audience "shomei-clients"))
    { rateLimitConfig =
        defaultRateLimitConfig
          { maxFailedLoginsPerAccount = 3,
            maxFailedLoginsPerIp = 5
          }
    }

ip1, ip2 :: ClientIp
ip1 = ClientIp "10.0.0.1"
ip2 = ClientIp "10.0.0.2"

aliceEmail :: Email
aliceEmail = mkEmail' "alice@example.com"

unknownEmail :: Email
unknownEmail = mkEmail' "nobody@example.com"

strongPw :: PlainPassword
strongPw = PlainPassword "correct horse battery staple"

wrongPw :: PlainPassword
wrongPw = PlainPassword "totally the wrong password"

mkEmail' :: Text -> Email
mkEmail' t = case mkEmail t of
  Right e -> e
  Left err -> error ("bad test email: " <> show err)

keyOf :: Email -> AccountKey
keyOf e = AccountKey (emailText e)

ctxOf :: ClientIp -> Email -> ClientContext
ctxOf ip e = ClientContext ip (keyOf e)

badLogin :: IORef World -> ClientIp -> Email -> IO (Either AuthError ())
badLogin ref ip e = fmap (const ()) <$> runInMemory ref (login cfg (ctxOf ip e) (LoginCommand (either (error . show) id (mkLoginId (emailText e))) wrongPw))

goodLogin :: IORef World -> ClientIp -> Email -> IO (Either AuthError ())
goodLogin ref ip e = fmap (const ()) <$> runInMemory ref (login cfg (ctxOf ip e) (LoginCommand (either (error . show) id (mkLoginId (emailText e))) strongPw))

advanceClock :: IORef World -> UTCTime -> IO ()
advanceClock ref t = modifyIORef' ref (\w -> w {clock = t})

seedAlice :: IORef World -> IO ()
seedAlice ref = do
  r <- runInMemory ref (signup cfg (SignupCommand {loginId = either (error . show) id (mkLoginId (emailText aliceEmail)), email = Just aliceEmail, password = strongPw, displayName = Just "Alice"}))
  case r of
    Right _ -> pure ()
    Left e -> assertFailure ("seed signup failed: " <> show e)

isLocked :: World -> AccountKey -> Bool
isLocked w k = case Map.lookup k w.accountLockouts of
  Just lo -> maybe False (> t0) lo.lockedUntil
  Nothing -> False

-- | Record every 'LoginAttemptStore' operation a workflow issues, then forward it unchanged to
-- the in-memory interpreter underneath.
--
-- 'interpose' replaces the handler of an effect that is already in the stack, for the duration
-- of the wrapped action. Sending the operation again from inside the handler dispatches to the
-- /upstream/ (original) handler rather than recursing, and 'passthrough' forwards the
-- operations this wrapper does not care about. The point is to observe which operations were
-- issued: the in-memory 'ClearAccountLockout' is a @Map.delete@, so a clear of an absent key
-- leaves the 'World' identical to no clear at all and cannot be detected by reading state.
recordAttemptOps :: (LoginAttemptStore :> es, IOE :> es) => IORef [Text] -> Eff es a -> Eff es a
recordAttemptOps traceRef = interpose \env -> \case
  ClearAccountLockout k -> do
    liftIO (modifyIORef' traceRef ("ClearAccountLockout" :))
    send (ClearAccountLockout k)
  op -> passthrough env op

-- | Run a successful login, returning the 'LoginAttemptStore' operations it issued.
tracedGoodLogin :: IORef World -> ClientIp -> Email -> IO (Either AuthError (), [Text])
tracedGoodLogin ref ip e = do
  traceRef <- newIORef []
  r <-
    runInMemory
      ref
      (recordAttemptOps traceRef (login cfg (ctxOf ip e) (LoginCommand (either (error . show) id (mkLoginId (emailText e))) strongPw)))
  ops <- readIORef traceRef
  pure (fmap (const ()) r, ops)

-- Tests ----------------------------------------------------------------------

tests :: TestTree
tests =
  testGroup
    "Shomei.Lockout"
    [ testLocksAfterN,
      testLockedSameGenericError,
      testUnknownAndWrongIndistinguishable,
      testUnlockAfterCooldown,
      testSuccessClearsCounter,
      testPerIpThrottle,
      testNoLockoutIssuesNoClear,
      testStandingLockoutStillCleared
    ]

-- | The round-trip saving of MasterPlan 6 EP-1 M2: a login on an account with no lockout row
-- must not issue the DELETE at all. Lockouts are rare, so the unconditional clear this
-- replaces cost a wasted database round-trip on virtually every successful login.
testNoLockoutIssuesNoClear :: TestTree
testNoLockoutIssuesNoClear = testCase "a successful login with no standing lockout issues no ClearAccountLockout" do
  ref <- newIORef (emptyWorld t0)
  seedAlice ref
  (ok, ops) <- tracedGoodLogin ref ip1 aliceEmail
  ok @?= Right ()
  assertBool
    ("expected no ClearAccountLockout, got: " <> show ops)
    (notElem "ClearAccountLockout" ops)

-- | The other half of the same change: when a lockout row does exist, the clear still happens.
-- Three failures lock alice; advancing past the cooldown lets the correct password through, and
-- that login must delete the (now expired) row exactly as the unconditional version did.
testStandingLockoutStillCleared :: TestTree
testStandingLockoutStillCleared = testCase "a successful login with a standing lockout still issues ClearAccountLockout" do
  ref <- newIORef (emptyWorld t0)
  seedAlice ref
  _ <- badLogin ref ip1 aliceEmail
  _ <- badLogin ref ip1 aliceEmail
  _ <- badLogin ref ip1 aliceEmail
  advanceClock ref (addUTCTime (16 * 60) t0)
  (ok, ops) <- tracedGoodLogin ref ip1 aliceEmail
  ok @?= Right ()
  assertBool
    ("expected a ClearAccountLockout, got: " <> show ops)
    (elem "ClearAccountLockout" ops)
  w <- readIORef ref
  assertBool "the lockout row is gone" (not (Map.member (keyOf aliceEmail) w.accountLockouts))

testLocksAfterN :: TestTree
testLocksAfterN = testCase "account locks after N failed logins" do
  ref <- newIORef (emptyWorld t0)
  seedAlice ref
  r1 <- badLogin ref ip1 aliceEmail
  r2 <- badLogin ref ip1 aliceEmail
  r3 <- badLogin ref ip1 aliceEmail
  r1 @?= Left InvalidCredentials
  r2 @?= Left InvalidCredentials
  r3 @?= Left InvalidCredentials
  w <- readIORef ref
  assertBool "alice's account is locked after 3 failures" (isLocked w (keyOf aliceEmail))
  case Map.lookup (keyOf aliceEmail) w.accountLockouts of
    Just lo -> lo.lockedUntil @?= Just (addUTCTime (15 * 60) t0)
    Nothing -> assertFailure "expected a lockout row for alice"

testLockedSameGenericError :: TestTree
testLockedSameGenericError = testCase "locked account returns the same generic error (even with correct password)" do
  ref <- newIORef (emptyWorld t0)
  seedAlice ref
  _ <- badLogin ref ip1 aliceEmail
  _ <- badLogin ref ip1 aliceEmail
  _ <- badLogin ref ip1 aliceEmail
  -- Even the CORRECT password is refused while locked, with the identical generic error.
  locked <- goodLogin ref ip1 aliceEmail
  locked @?= Left InvalidCredentials

testUnknownAndWrongIndistinguishable :: TestTree
testUnknownAndWrongIndistinguishable = testCase "unknown email and wrong password are indistinguishable and both count toward lockout" do
  ref <- newIORef (emptyWorld t0)
  seedAlice ref
  -- Failures against an email with NO account still lock that key and return the generic error.
  u1 <- badLogin ref ip1 unknownEmail
  u2 <- badLogin ref ip1 unknownEmail
  u3 <- badLogin ref ip1 unknownEmail
  u1 @?= Left InvalidCredentials
  u3 @?= Left InvalidCredentials
  -- A wrong password against the real account returns the identical generic error.
  wrong <- badLogin ref ip2 aliceEmail
  wrong @?= u2
  w <- readIORef ref
  assertBool "the unknown-email key is locked after 3 failures" (isLocked w (keyOf unknownEmail))

testUnlockAfterCooldown :: TestTree
testUnlockAfterCooldown = testCase "account unlocks after the cooldown elapses" do
  ref <- newIORef (emptyWorld t0)
  seedAlice ref
  _ <- badLogin ref ip1 aliceEmail
  _ <- badLogin ref ip1 aliceEmail
  _ <- badLogin ref ip1 aliceEmail
  wLocked <- readIORef ref
  assertBool "alice is locked immediately after the failures" (isLocked wLocked (keyOf aliceEmail))
  -- Advance the clock past lockedUntil (lockoutDuration default = 15 min) and the window.
  advanceClock ref (addUTCTime (16 * 60) t0)
  ok <- goodLogin ref ip1 aliceEmail
  ok @?= Right ()
  w <- readIORef ref
  assertBool "the lockout row is cleared after a successful login" (not (Map.member (keyOf aliceEmail) w.accountLockouts))

testSuccessClearsCounter :: TestTree
testSuccessClearsCounter = testCase "successful login clears the failure counter" do
  ref <- newIORef (emptyWorld t0)
  seedAlice ref
  -- One short of the lock threshold (2 of 3), then a correct login.
  _ <- badLogin ref ip1 aliceEmail
  _ <- badLogin ref ip1 aliceEmail
  ok <- goodLogin ref ip1 aliceEmail
  ok @?= Right ()
  wAfter <- readIORef ref
  assertBool "no lockout row after the successful login" (not (Map.member (keyOf aliceEmail) wAfter.accountLockouts))
  -- A subsequent single failure must NOT lock (the success reset the counter).
  _ <- badLogin ref ip1 aliceEmail
  w <- readIORef ref
  assertBool "a single failure after a success does not lock" (not (isLocked w (keyOf aliceEmail)))

testPerIpThrottle :: TestTree
testPerIpThrottle = testCase "per-IP failure throttle trips across different accounts" do
  ref <- newIORef (emptyWorld t0)
  -- Fail logins against 5 distinct (unregistered) emails from one IP: 5 failures, none of
  -- which individually locks an account, but together they trip the per-IP throttle (5).
  let spread = map (\u -> mkEmail' (u <> "@example.com")) ["u1", "u2", "u3", "u4", "u5"]
  results <- traverse (badLogin ref ip1) spread
  assertBool "the 5 spread failures each return the generic error" (all (== Left InvalidCredentials) results)
  -- The next attempt from the SAME IP is throttled.
  throttled <- badLogin ref ip1 (mkEmail' "u6@example.com")
  throttled @?= Left TooManyRequests
  -- The SAME attempt from a DIFFERENT IP returns the ordinary generic error, not 429.
  other <- badLogin ref ip2 (mkEmail' "u6@example.com")
  other @?= Left InvalidCredentials