-- Copyright (c) 2014-present, Facebook, Inc.
-- All rights reserved.
--
-- This source code is distributed under the terms of a BSD license,
-- found in the LICENSE file.

{-# LANGUAGE CPP, OverloadedStrings, RebindableSyntax, MultiWayIf #-}
{-# LANGUAGE RecordWildCards #-}
module TestExampleDataSource (tests) where

import Haxl.Prelude as Haxl
import Prelude()

import Haxl.Core.Monad (unsafeLiftIO)
import Haxl.Core

import Test.HUnit
import Data.IORef
import Data.Maybe
import Control.Exception
import System.Environment
import System.FilePath

import ExampleDataSource
import LoadCache

testEnv :: IO (Env () ())
testEnv = do
  -- To use a data source, we need to initialize its state:
  exstate <- ExampleDataSource.initGlobalState

  -- And create a StateStore object containing the states we need:
  let st = stateSet exstate stateEmpty

  -- Create the Env:
  env <- initEnv st ()
  return env{ flags = (flags env){
    report = setReportFlag ReportFetchStats defaultReportFlags } }


tests = TestList [
  TestLabel "exampleTest" exampleTest,
  TestLabel "orderTest" orderTest,
  TestLabel "preCacheTest" preCacheTest,
  TestLabel "cachedComputationTest" cachedComputationTest,
  TestLabel "cacheResultTest" cacheResultTest,
  TestLabel "memoTest" memoTest,
  TestLabel "dataSourceExceptionTest" dataSourceExceptionTest,
  TestLabel "dumpCacheAsHaskell" dumpCacheTest,
  TestLabel "fetchError" fetchError
  ]

-- Let's test ExampleDataSource.

exampleTest :: Test
exampleTest = TestCase $ do
  env <- testEnv

  -- Run an example expression with two fetches:
  x <- runHaxl env $
     countAardvarks "abcabc" + (length <$> listWombats 3)

  assertEqual "runTests" x (2 + 3)

  -- Should be just one fetching round:
  Stats stats <- readIORef (statsRef env)
  putStrLn (ppStats (Stats stats))
  assertEqual "rounds" 1 (length stats)

  -- With two fetches:
  assertBool "reqs" $
    case stats of
       [FetchStats{..}] ->
         fetchDataSource == "ExampleDataSource" && fetchBatchSize == 2
       _otherwise -> False

-- Test side-effect ordering

orderTest = TestCase $ do
  env <- testEnv

  ref <- newIORef ([] :: [Int])

  let tick n = unsafeLiftIO (modifyIORef ref (n:))

  let left = do tick 1
                r <- countAardvarks "abcabc"
                tick 2
                return r

  let right = do tick 3
                 r <- length <$> listWombats 3
                 tick 4
                 return r

  x <- runHaxl env $ left + right
  assertEqual "TestExampleDataSource2" x (2 + 3)

  -- The order of the side effects is 1,3,2,4.  First we see 1, then
  -- left gets blocked, then we explore right, we see 3, then right
  -- gets blocked.  The data fetches are performed, then we see 2 and
  -- then 4.

  ys <- readIORef ref
  assertEqual "TestExampleDataSource: ordering" (reverse ys) [1,3,2,4]


preCacheTest = TestCase $ do
  env <- testEnv

  x <- runHaxl env $ do
    cacheRequest (CountAardvarks "xxx") (Right 3)
    cacheRequest (ListWombats 1000000) (Right [1,2,3])
    countAardvarks "xxx" + (length <$> listWombats 1000000)
  assertEqual "preCacheTest1" x (3 + 3)

  y <- Control.Exception.try $ runHaxl env $ do
    cacheRequest (CountAardvarks "yyy") $ except (NotFound "yyy")
    countAardvarks "yyy"
  assertBool "preCacheTest2" $
     case y of
       Left (NotFound "yyy") -> True
       _other -> False

-- Pretend CountAardvarks is a request computed by some Haxl code
cachedComputationTest = TestCase $ do
  env <- testEnv
  let env' = env { flags = (flags env){trace = 3} }

  let x = cachedComputation (CountAardvarks "ababa") $ do
        a <- length <$> listWombats 10
        b <- length <$> listWombats 20
        return (a + b)

  r <- runHaxl env' $ x + x + countAardvarks "baba"

  assertEqual "cachedComputationTest1" 62 r

  stats <- readIORef (statsRef env)
  assertEqual "fetches" 3 (numFetches stats)

cacheResultTest = TestCase $ do
  env <- testEnv
  ref <- newIORef 0
  let request = cacheResult (CountAardvarks "ababa") $ do
         modifyIORef ref (+1)
         readIORef ref
  r <- runHaxl env $ (+) <$> request <*> request
  assertEqual "cacheResult" 2 r


-- Pretend CountAardvarks is a request computed by some Haxl code
memoTest = TestCase $ do
  env <- testEnv
  let env' = env { flags = (flags env){trace = 3} }

  let x = memo (CountAardvarks "ababa") $ do
        a <- length <$> listWombats 10
        b <- length <$> listWombats 20
        return (a + b)

  r <- runHaxl env' $ x + x + countAardvarks "baba"

  assertEqual "memoTest1" 62 r

  stats <- readIORef (statsRef env)
  assertEqual "fetches" 3 (numFetches stats)

-- Test that the FetchError gets returned properly, and that we have
-- a failure logged in the stats.
fetchError = TestCase $ do
  env <- testEnv
  r <- runHaxl env $ Haxl.try $
    (++) <$> listWombats 1000000 <*> listWombats 1000001
  assertBool "fetchError1" $ case r of
    Left FetchError{} -> True
    Right _ -> False
  Stats stats <- readIORef (statsRef env)
  assertEqual "fetchError2" 2 (sum [ fetchFailures | FetchStats{..} <- stats ])

dataSourceExceptionTest = TestCase $ do
  env <- testEnv

  r <- runHaxl env $ Haxl.try $ countAardvarks "BANG"
  assertBool "exception1" $
    case r of
      Left (ErrorCall "BANG") -> True
      _ -> False
  r <- runHaxl env $ Haxl.try $ countAardvarks "BANG2"
  assertBool "exception2" $
    case r of
      Left (ErrorCall "BANG2") -> True
      _ -> False

  -- In this test, BANG3 is an asynchronous exception (ThreadKilled),
  -- so we should see that instead of the exception on the left.
  -- Furthermore, it doesn't get caught by Haxl.try, and we have to
  -- catch it outside of runHaxl.
  env <- testEnv
  r <- Control.Exception.try $ runHaxl env $ Haxl.try $
          (length <$> listWombats 100) + countAardvarks "BANG3"
  print r
  assertBool "exception3" $
    case (r :: Either AsyncException (Either SomeException Int)) of
       Left ThreadKilled -> True
       _ -> False

-- Test that we can load the cache from a dumped copy of it, and then dump it
-- again to get the same result.
dumpCacheTest = TestCase $ do
  env <- testEnv
  runHaxl env loadCache
  str <- runHaxl env dumpCacheAsHaskell
  lcPath <-loadCachePath
  loadcache <- readFile lcPath
  -- The order of 'cacheRequest ...' calls is nondeterministic and
  -- differs among GHC versions, so we sort the lines for comparison.
  assertEqual "dumpCacheAsHaskell" (sort $ lines loadcache) (sort $ lines str)
  where
    loadCachePath = do
      lcEnv <- lookupEnv "LOADCACHE"
      return $ fromMaybe (dropFileName __FILE__ </> "LoadCache.txt") lcEnv