{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE TypeFamilies #-}

module Tests.Helpers
  ( module Tests.Helpers
  , module Test.Tasty
  )
where

import Data.Algorithm.DiffContext (getContextDiff, prettyContextDiff)
import Org.Builder (Many)
import Org.Parser
import Org.Parser.Objects (Marked (..))
import Org.Types (OrgDocument, OrgElementData, Properties)
import Test.Tasty
import Test.Tasty.HUnit
import Text.Megaparsec (eof)
import Text.Megaparsec.Error (errorBundlePretty)
import Text.Pretty.Simple
import Text.PrettyPrint (render, text)

{- | This class is mainly used for the tests cases.
@Parsed m a@ is the "monad-stripped" version of parse
tree with which we can compare in the test cases.
-}
class Parsable m a where
  type Parsed m a
  parse' :: m a -> Text -> Either OrgParseError (Parsed m a)

instance Parsable OrgParser a where
  type Parsed OrgParser a = a
  parse' p = parseOrg defaultOrgOptions (p <* eof) ""

instance Parsable (Marked OrgParser) a where
  type Parsed (Marked OrgParser) a = a
  parse' p = parse' (getParser p)

instance PrettyFormable Properties where
  type PrettyForm Properties = Properties
  prettyForm = id

instance Parsable OrgParser OrgDocument where
  type Parsed OrgParser OrgDocument = OrgDocument
  parse' p = parseOrg defaultOrgOptions (p <* eof) ""

instance PrettyFormable OrgDocument where
  type PrettyForm OrgDocument = OrgDocument
  prettyForm = id

class PrettyFormable a where
  type PrettyForm a
  prettyForm :: a -> PrettyForm a

instance PrettyFormable (Many a) where
  type PrettyForm (Many a) = [a]
  prettyForm = toList

instance PrettyFormable OrgElementData where
  type PrettyForm OrgElementData = OrgElementData
  prettyForm = id

prettyParse :: (Parsable m a, PrettyFormable (Parsed m a), Show (PrettyForm (Parsed m a))) => m a -> Text -> IO ()
prettyParse parser txt =
  case parse' parser txt of
    Left e -> putStrLn $ errorBundlePretty e
    Right x -> pPrint $ prettyForm x

infix 1 =?>

(=?>) :: a -> b -> (a, Either () b)
x =?> y = (x, Right y)

infix 1 =!>

(=!>) :: a -> () -> (a, Either () c)
x =!> y = (x, Left y)

infix 4 =:

(=:) :: (Eq a, Show a) => TestName -> (a, a) -> TestTree
(=:) name (x, y) = testCase name (x @?= y)

infix 4 ~:

(~:) ::
  HasCallStack =>
  (Parsable m a, PrettyFormable (Parsed m a), Eq (Parsed m a), Show (Parsed m a)) =>
  TestName ->
  m a ->
  [(Text, Either () (Parsed m a))] ->
  TestTree
(~:) name parser cases =
  testGroup name $
    flip (`zipWith` [1 ..]) cases $ \(i :: Int) (txt, ref) ->
      testCase (name <> " " <> show i) $
        case parse' parser txt of
          Left e
            | isRight ref -> assertFailure $ errorBundlePretty e
            | otherwise -> pure ()
          Right x
            | Right ref' <- ref ->
                unless (x == ref') do
                  let reflines = map toString $ lines (toStrict $ pShow ref')
                      gotlines = map toString $ lines (toStrict $ pShow x)
                      diff = getContextDiff 3 reflines gotlines
                      pdiff = prettyContextDiff (text "Test reference") (text "Parsed") text diff
                  assertFailure (render pdiff)
            | otherwise ->
                assertFailure $
                  "Should not parse, but parsed as:\n" <> show x