{-# LANGUAGE DataKinds             #-}
{-# LANGUAGE DeriveAnyClass        #-}
{-# LANGUAGE DeriveGeneric         #-}
{-# LANGUAGE FlexibleContexts      #-}
{-# LANGUAGE FlexibleInstances     #-}
{-# LANGUAGE LambdaCase            #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE OverloadedStrings     #-}
{-# LANGUAGE RecordWildCards       #-}
{-# LANGUAGE StandaloneDeriving    #-}
{-# LANGUAGE TypeFamilies          #-}
{-# LANGUAGE TypeOperators         #-}
{-# LANGUAGE UndecidableInstances  #-}

-- | Module that deals with handling config options
module LintConfig (LintConfig(..), LintConfig', ConfigKind (..), patchConfig,stuffConfig,feedConfig) where

import           Universum

import           Data.Aeson            (FromJSON (parseJSON), Options (..),
                                        defaultOptions, eitherDecode)
import           Data.Aeson.Types      (genericParseJSON)
import qualified Data.ByteString.Char8 as C8
import qualified Data.ByteString.Lazy  as LB
import qualified Data.Map.Strict       as M
import           GHC.Generics          (Generic (Rep, from, to), K1 (..),
                                        M1 (..), (:*:) (..))
import           Types                 (Level)
import           Uris                  (SchemaSet,
                                        Substitution (DomainSubstitution))
import           WithCli.Pure          (Argument (argumentType, parseArgument))



data ConfigKind = Complete | Basic | Skeleton | Patch

-- | a field that must be given in configs for both server & standalone linter
type family ConfigField (f::ConfigKind) a where
  ConfigField Patch a = Maybe a
  ConfigField _ a = a

-- | a field that must be given for the standalone linter, but not the server
-- (usually because the server will infer them from its own config)
type family StandaloneField (f :: ConfigKind) a where
  StandaloneField Complete a = a
  StandaloneField Skeleton a = a
  StandaloneField _ a = Maybe a

-- | a field specific to a single world / assembly
type family WorldField (f :: ConfigKind) a where
  WorldField Complete a = a
  WorldField _ a = Maybe a

data LintConfig (f :: ConfigKind) = LintConfig
  { configScriptInject   :: ConfigField f (Maybe Text)
  -- ^ Link to Script that should be injected
  , configAssemblyTag    :: WorldField f Text
  -- ^ Assembly name (used for jitsiRoomAdminTag)
  , configAssemblies     :: StandaloneField f [Text]
  -- ^ list of all assembly slugs (used to lint e.g. world:// links)
  , configEventSlug      :: StandaloneField f Text
  -- ^ slug of this event (used e.g. to resolve world:// links)
  , configMaxLintLevel   :: ConfigField f Level
  -- ^ Maximum warn level allowed before the lint fails
  , configDontCopyAssets :: ConfigField f Bool
  -- ^ Don't copy map assets (mostly useful for development)
  , configAllowScripts   :: ConfigField f Bool
  -- ^ Allow defining custom scripts in maps
  , configUriSchemas     :: ConfigField f SchemaSet
  } deriving (Generic)

type LintConfig' = LintConfig Complete

deriving instance Show (LintConfig Complete)
deriving instance Show (LintConfig Skeleton)
deriving instance Show (LintConfig Patch)
instance NFData (LintConfig Basic)

aesonOptions :: Options
aesonOptions = defaultOptions
  { omitNothingFields = True
  , rejectUnknownFields = True
  , fieldLabelModifier = drop 6
  }

instance FromJSON (LintConfig Complete) where
  parseJSON = genericParseJSON aesonOptions

instance FromJSON (LintConfig Patch) where
  parseJSON = genericParseJSON aesonOptions

instance FromJSON (LintConfig Basic) where
  parseJSON = genericParseJSON aesonOptions



-- | generic typeclass for things that are "patchable"
class GPatch i m where
  gappend :: i p -> m p -> i p

-- generic instances. It's category theory, but with confusing names!
instance GPatch (K1 a k) (K1 a (Maybe k)) where
  gappend _ (K1 (Just k'))    = K1 k'
  gappend (K1 k) (K1 Nothing) = K1 k
  {-# INLINE gappend #-}

instance (GPatch i o, GPatch i' o')
    => GPatch (i :*: i') (o :*: o') where
  gappend (l :*: r) (l' :*: r') = gappend l l' :*: gappend r r'
  {-# INLINE gappend #-}

instance GPatch i o
    => GPatch (M1 _a _b i) (M1 _a' _b' o) where
  gappend (M1 x) (M1 y) = M1 (gappend x y)
  {-# INLINE gappend #-}


-- | A patch function. For (almost) and a :: * -> *,
-- take an a Identity and an a Maybe, then replace all appropriate
-- values in the former with those in the latter.
--
-- There isn't actually any useful reason for this function to be this
-- abstract, I just wanted to play around with higher kinded types for
-- a bit.
patch ::
  ( Generic (f Patch)
  , Generic (f Complete)
  , GPatch (Rep (f Complete))
    (Rep (f Patch))
  )
  => f Complete
  -> f Patch
  -> f Complete
patch x y = to (gappend (from x) (from y))

patchConfig
  :: LintConfig Complete
  -> Maybe (LintConfig Patch)
  -> LintConfig Complete
patchConfig config p = expandWorlds config'
  where
    config' = case p of
      Just p  -> patch config p
      Nothing -> config


-- | feed a basic server config
feedConfig
  :: LintConfig Basic
  -> [Text]
  -> Text
  -> LintConfig Skeleton
feedConfig LintConfig{..} worlds eventslug = expandWorlds $
  LintConfig
  { configAssemblies = worlds
  , configEventSlug = eventslug
  , .. }

-- | stuff a
stuffConfig :: LintConfig Skeleton -> Text -> LintConfig Complete
stuffConfig LintConfig{..} assemblyslug =
  LintConfig
  { configAssemblyTag = assemblyslug
  , ..}

class HasWorldList (a :: ConfigKind)
instance HasWorldList 'Complete
instance HasWorldList 'Skeleton

-- kinda sad that ghc can't solve these contraints automatically,
-- though i guess it also makes sense …
expandWorlds
  :: ( ConfigField a SchemaSet ~ SchemaSet
     , StandaloneField a [Text] ~ [Text]
     , StandaloneField a Text ~ Text
     , HasWorldList a)
  => LintConfig a -> LintConfig a
expandWorlds config = config { configUriSchemas = configUriSchemas' }
  where
    configUriSchemas' =
      M.insert "world:" [assemblysubsts] (configUriSchemas config)
    assemblysubsts =
      DomainSubstitution (M.fromList generated) ["map"]
      where generated = configAssemblies config
              <&> \slug -> (slug, "/_/general/maps.world.di.c3voc.de/assembly/"<>slug)

instance (FromJSON (LintConfig a)) => Argument (LintConfig a) where
  parseArgument str =
    case eitherDecode (LB.fromStrict $ C8.pack str) of
      Left _    -> Nothing
      Right res -> Just res

  argumentType Proxy = "LintConfig"