{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE TypeApplications #-}

module Minilang.ServerSpec where

import Control.Monad (void)
import Data.Aeson (FromJSON, eitherDecode, encode)
import Data.Bifunctor (first)
import Data.ByteString (isInfixOf, toStrict)
import qualified Data.ByteString as BS
import qualified Data.ByteString.Base64.Lazy as Base64
import Data.ByteString.Lazy (ByteString)
import qualified Data.ByteString.Lazy as LBS
import Data.Data (Proxy (..))
import Data.String (fromString)
import qualified Data.Text.Lazy as LT
import Data.Text.Lazy.Encoding (decodeUtf8)
import Minilang.API (Challenge (..), Score, User (..), defaultChallenges, newToken)
import Minilang.App (makeEnv)
import Minilang.Server (serveAPI)
import Network.Wai (Application)
import Network.Wai.Test (SResponse)
import System.Random (StdGen, mkStdGen64)
import Test.Hspec (Spec, it)
import Test.Hspec.Wai (WaiSession, get, matchBody, request, shouldRespondWith, with)
import Test.Hspec.Wai.Matcher (MatchBody (..))

spec :: Spec
spec = with (app testSeed) $ do
  let (token, gen) = first Base64.encode (newToken testSeed)
      alice = encode $ User "alice"

  it "GET / returns 'index.html'" $ do
    get "/"
      `shouldRespondWith` 200
        { matchBody = MatchBody $ \_ actual ->
            if "<html>" `isInfixOf` toStrict actual
              then Nothing
              else Just "Expected HTML content"
        }

  it "GET /api/leaderboard returns empty list of scores" $ do
    get "/api/leaderboard"
      `shouldRespondWith` 200 {matchBody = arrayOfLengthOf (Proxy @Score) 2}

  it "POST /api/register returns registration token given user is not registered" $ do
    postJSON "/api/register" alice
      `shouldRespondWith` 201
        { matchBody = MatchBody $ \_ t ->
            if t == encode (decodeUtf8 token)
              then
                Nothing
              else Just ("Expected token " ++ show token ++ ", but got " ++ show t)
        }

  it "POST /api/register returns 400 given user is already registered" $ do
    void $ postJSON "/api/register" alice

    postJSON "/api/register" alice
      `shouldRespondWith` 400

  it "GET /api/challenge returns next challenge given user is registered" $ do
    let expected = LT.unpack $ decodeUtf8 $ encode $ Challenge {level = 0, expr = "x"}
    postJSON "/api/register" alice
      `shouldRespondWith` 201

    get ("/api/challenge?token=" <> LBS.toStrict token)
      `shouldRespondWith` fromString expected

  it "GET /api/challenge returns 400 given user is not registered" $
    get ("/api/challenge?token=" <> LBS.toStrict token)
      `shouldRespondWith` 400

  it "POST /api/challenge returns 200 given challenge response is correct" $ do
    let response = "\"x\""
    void $ postJSON "/api/register" alice

    postJSON ("/api/challenge?token=" <> LBS.toStrict token) response
      `shouldRespondWith` 200

  it "POST /api/challenge returns 400 given challenge response is incorrect" $ do
    let response = "\"y\""
    void $ postJSON "/api/register" alice

    postJSON ("/api/challenge?token=" <> LBS.toStrict token) response
      `shouldRespondWith` 400

  it "POST /api/challenge returns 400 given user is not registered" $ do
    let response = "\"x\""

    postJSON ("/api/challenge?token=" <> LBS.toStrict token) response
      `shouldRespondWith` 400

  it "POST /api/challenge returns 400 given wrong token" $ do
    let response = "\"x\""
        otherToken = Base64.encode $ fst $ newToken gen

    postJSON ("/api/challenge?token=" <> LBS.toStrict otherToken) response
      `shouldRespondWith` 400

  it "GET /api/challenge returns next level challenge after successful POST" $ do
    let expected = LT.unpack $ decodeUtf8 $ encode $ Challenge {level = 1, expr = "y"}

    void $ postJSON "/api/register" alice
    void $ postJSON ("/api/challenge?token=" <> LBS.toStrict token) "\"x\""

    get ("/api/challenge?token=" <> LBS.toStrict token)
      `shouldRespondWith` fromString expected

  it "GET /api/challenge returns same challenge after failed POST" $ do
    let expected = LT.unpack $ decodeUtf8 $ encode $ head defaultChallenges

    void $ postJSON "/api/register" alice
    void $ postJSON ("/api/challenge?token=" <> LBS.toStrict token) "\"y\""

    get ("/api/challenge?token=" <> LBS.toStrict token)
      `shouldRespondWith` fromString expected

postJSON :: BS.ByteString -> ByteString -> WaiSession () SResponse
postJSON url = request "POST" url [("Content-Type", "application/json")]

arrayOfLengthOf :: forall elem proxy. (FromJSON elem) => proxy elem -> Int -> MatchBody
arrayOfLengthOf _ len = MatchBody $ \_ actual ->
  case eitherDecode actual of
    Right (scores :: [elem]) ->
      if length scores == len
        then Nothing
        else Just $ "Expected array of length " ++ show len ++ ", but got " ++ show (length scores)
    Left err -> Just $ "Failed to decode JSON: " ++ err

app :: StdGen -> IO Application
app g = do
  env <- makeEnv g defaultChallenges
  pure $ serveAPI env

testSeed :: StdGen
testSeed = mkStdGen64 42