{-# LANGUAGE LambdaCase        #-}
{-# LANGUAGE NoImplicitPrelude #-}
{-# LANGUAGE OverloadedStrings #-}
module Decoder
  ( decoderTests
  ) where

import           Prelude                    (Char, Eq, Int, Show, String, print,
                                             (==))

import           Control.Applicative        (liftA3, pure, (<$>))
import           Control.Category           ((.))
import           Control.Monad              (Monad, (>=>), (>>=))
import           Control.Monad.Except       (throwError)

import           Test.Tasty                 (TestTree, testGroup)
import           Test.Tasty.HUnit           (Assertion, assertBool, assertEqual,
                                             assertFailure, testCase, (@?=))

import           Data.Bool                  (Bool (..))
import qualified Data.ByteString            as BS
import qualified Data.Either                as Either
import           Data.Function              (const, ($))
import           Data.Functor.Alt           ((<!>))
import qualified Data.Sequence              as Seq
import           Data.Tagged                (untag)
import           Data.Text                  (Text)

import qualified Natural                    as N

import           Waargonaut.Generic         (mkDecoder)

import           Waargonaut.Decode.Internal (ZipperMove (BranchFail),
                                             ppCursorHistory, unCursorHistory')

import qualified Waargonaut.Decode          as D
import qualified Waargonaut.Decode.Error    as D

import           Types.Common               (imageDecodeSuccinct, parseBS,
                                             testImageDataType)

decoderTests :: TestTree
decoderTests = testGroup "Decoding"
  [ testCase "Image (test1.json)" decodeTest1Json
  , testCase "[Int]" decodeTest2Json
  , testCase "(Char,String,[Int])" decodeTest3Json
  , testCase "Fail with Bad Key" decodeTestBadObjKey
  , testCase "Fail with Missing Key" decodeTestMissingObjKey
  , testCase "Enum and throwError" decodeTestEnumError
  , testCase "Using Alt" decodeAlt
  , testCase "Using Alt (Error) - Records BranchFail" decodeAltError
  , testCase "List Decoder" listDecoder
  , testCase "NonEmpty List Decoder" nonEmptyDecoder
  ]

nonEmptyDecoder :: Assertion
nonEmptyDecoder = do
  let
    dec = D.runPureDecode (D.nonempty D.int) parseBS . D.mkCursor

    ok = "[1]"
    notOkay = "[]"

    badElem = "[1, \"fred\"]"

  assertBool "NonEmpty Decoder - fail! non-empty list decoder BROKEN. Start panicking" (Either.isRight (dec ok))
  assertBool "NonEmpty Decoder - empty list shouldn't succeed" (Either.isLeft (dec notOkay))
  assertBool "NonEmpty Decoder - invalid element decoder accepted" (Either.isLeft (dec badElem))

listDecoder :: Assertion
listDecoder = do
  let
    dec = D.runPureDecode (D.list D.int) parseBS . D.mkCursor

    ok = "[1,2,3]"
    okE = "[]"

    badShape = "{}"
    badElem = "[\"fred\", \"susan\"]"

  assertBool "List Decoder - fail! List Decoder BROKEN. Start panicking." (Either.isRight (dec ok))
  assertBool "List Decoder - empty list fail" (Either.isRight (dec okE))
  assertBool "List Decoder - move down should return empty list" (Either.isRight (dec badShape))
  assertBool "List Decoder - invalid element decoder accepted" (Either.isLeft (dec badElem))

decodeTestMissingObjKey :: Assertion
decodeTestMissingObjKey = do
  let
    j = "{\"foo\":33}"

    d = D.withCursor $ D.down >=> D.fromKey "bar" D.int

  r <- D.runDecode d parseBS (D.mkCursor j)

  Either.either
    (\(e, _) -> assertBool "Incorrect Error - Expected KeyDecodeFailed" (e == D.KeyNotFound "bar") )
    (\_ -> assertFailure "Expected Error!")
    r

decodeTestBadObjKey :: Assertion
decodeTestBadObjKey = do
  let
    j = "{33:33}"

    d = D.withCursor $ D.down >=> D.fromKey "foo" D.int

  r <- D.runDecode d parseBS (D.mkCursor j)

  Either.either
    (\(e, _) -> assertBool "Incorrect Error - Expected KeyDecodeFailed" (e == D.KeyDecodeFailed) )
    (\_ -> assertFailure "Expected Error!")
    r

decodeTest1Json :: Assertion
decodeTest1Json = D.runPureDecode imageDecodeSuccinct parseBS . D.mkCursor
  <$> BS.readFile "test/json-data/test1.json"
  >>= Either.either failWithHistory (assertEqual "Image Decode Failed" testImageDataType)
  where
    failWithHistory (err, hist) = do
      print err
      print (ppCursorHistory hist)
      assertFailure "Decode Failed :("

decodeTest2Json :: Assertion
decodeTest2Json = assertBool "[Int] Decode Success" . Either.isRight
  $ D.runPureDecode listDecode parseBS (D.mkCursor "[23,44]")
  where
    listDecode :: Monad f => D.Decoder f [Int]
    listDecode = untag mkDecoder

decodeTest3Json :: Assertion
decodeTest3Json = assertBool "(Char,String,[Int]) Decode Success" . Either.isRight
  $ D.runPureDecode decoder parseBS (D.mkCursor "[\"a\",\"fred\",1,2,3,4]")
  where
    decoder :: Monad f => D.Decoder f (Char,String,[Int])
    decoder = D.withCursor $ D.down >=> \fstElem -> liftA3 (,,)
      (D.focus D.unboundedChar fstElem)
      (D.moveRight1 fstElem >>= D.focus D.string)
      (D.moveRightN (N.successor' (N.successor' N.zero')) fstElem >>= D.rightwardSnoc [] D.int)

data MyEnum
  = A
  | B
  | C
  deriving (Eq, Show)

decodeMyEnum :: Monad f => D.Decoder f MyEnum
decodeMyEnum = D.text >>= \case
  "a" -> pure A
  "b" -> pure B
  "c" -> pure C
  _   -> throwError (D.ConversionFailure "MyEnum")

decodeTestEnumError :: Assertion
decodeTestEnumError = D.runDecode decodeMyEnum parseBS (D.mkCursor "\"WUT\"")
  >>= Either.either
    (\(e, _) -> assertBool "Incorrect Error!" (e == D.ConversionFailure "MyEnum"))
    (const (assertFailure "Should not succeed"))

decodeEitherAlt :: Monad f => D.Decoder f (Either.Either Text Int)
decodeEitherAlt = (Either.Left <$> D.text) <!> (Either.Right <$> D.int)

decodeAlt :: Assertion
decodeAlt = do
  t <- D.runDecode decodeEitherAlt parseBS (D.mkCursor "\"FRED\"")
  i <- D.runDecode decodeEitherAlt parseBS (D.mkCursor "33")

  t @?= Either.Right (Either.Left "FRED")
  i @?= Either.Right (Either.Right 33)

decodeAltError :: Assertion
decodeAltError = D.runDecode decodeEitherAlt parseBS (D.mkCursor "{\"foo\":33}")
  >>= Either.either
                 (\(_,h) -> assertBool "BranchFail error not found in history" $
                 case Seq.viewr (unCursorHistory' h) of
                   _ Seq.:> (BranchFail _, _) -> True
                   _                          -> False

                 )
                 (\_ -> assertFailure "Alt Error Test should fail")