module TAP

import public Quox.Error

import Data.String
import Data.List.Elem
import Control.Monad.Reader
import Control.Monad.State

public export Info : Type
Info = List (String, String)

private
data Result = Tried Bool Info | Skip String | Todo String

private
record TestBase where
  constructor MakeTest
  label : String
  run   : IO Result


private
toLines1 : (String, String) -> List String
toLines1 (k, v) =
  let vs = lines v in
  if length vs == 1
     then ["\{k}: \{v}"]
     else "\{k}: |" :: map (indent 2) vs

private
toLines : Info -> List String
toLines [] = []
toLines xs = "---" :: concatMap toLines1 xs <+> ["..."]


public export interface ToInfo e where toInfo : e -> Info

export
All ToInfo es => ToInfo (OneOf es) where
  toInfo (One Here      value) = toInfo value
  toInfo (One (There x) value) = toInfo (One x value)

export ToInfo () where toInfo () = []

export
data Test = One TestBase | Group String (List Test)


export
testIO : (All ToInfo es, ToInfo a) => String -> ErrorT es IO a -> Test
testIO label act = One $ MakeTest label $ do
  case !(runErrorT act) of
       Left  err => pure $ Tried False $ toInfo err
       Right val => pure $ Tried True  $ toInfo val

export %inline
test : (All ToInfo es, ToInfo a) => String -> Lazy (Error es a) -> Test
test label val =
  testIO label $ MkErrorT $ primIO $ \w => MkIORes (runError val) w

export %inline
todoWith : String -> String -> Test
todoWith label reason = One $ MakeTest label $ pure $ Todo reason

export %inline
todo : String -> Test
todo label = todoWith label ""

export %inline
skipWith : String -> String -> Test
skipWith label reason = One $ MakeTest label $ pure $ Skip reason

export %inline
skip : String -> Test
skip label = skipWith label ""

infix 0 :-
export %inline
(:-) : String -> List Test -> Test
(:-) = Group



export
header : List a -> String
header tests = "1..\{show $ length tests}"


private
Runner : Type -> Type
Runner = ReaderT Nat IO

private
putIndentLines : List String -> Runner ()
putIndentLines xs = traverse_ (putStrLn . indent !ask) xs

private
isOk : Bool -> String
isOk b = if b then "ok" else "not ok"

private
toBool : Result -> Bool
toBool (Tried ok _) = ok
toBool _ = True


private
numbered : List a -> List (Nat, a)
numbered = go 1 where
  go : Nat -> List a -> List (Nat, a)
  go _ []        = []
  go i (x :: xs) = (i, x) :: go (S i) xs

private
run1' : (Nat, TestBase) -> Runner Bool
run1' (index, test) = do
  res <- liftIO test.run
  case res of
       Tried ok info => putIndentLines $
         "\{isOk ok} \{show index} - \{test.label}" ::
         toLines info
       Skip reason => putIndentLines $
         ["ok \{show index} - \{test.label}  # skip \{reason}"]
       Todo reason => putIndentLines $
         ["ok \{show index} - \{test.label}  # todo \{reason}"]
  pure $ toBool res

mutual
  private
  run' : (Nat, Test) -> Runner Bool
  run' (index, One test) = run1' (index, test)
  run' (index, Group label tests) = do
    putIndentLines ["# Subtest: \{label}"]
    res <- local (plus 4) $ runList tests
    putIndentLines ["\{isOk res} \{show index} - \{label}"]
    pure res

  private
  runList : List Test -> Runner Bool
  runList tests = do
    putIndentLines [header tests]
    all id <$> traverse run' (numbered tests)


export
run : List Test -> IO ()
run tests = do
  putStrLn "TAP version 14"
  ignore $ runReaderT 0 $ runList tests