{-# LANGUAGE GeneralizedNewtypeDeriving #-}
{-# LANGUAGE MultiParamTypeClasses      #-}
{-# LANGUAGE FunctionalDependencies     #-}
{-# LANGUAGE CPP                        #-}
#if __GLASGOW_HASKELL__ >= 800
{-# LANGUAGE TemplateHaskellQuotes      #-}
#else
{-# LANGUAGE QuasiQuotes                #-}
{-# LANGUAGE TemplateHaskell            #-}
#endif

module Text.RE.Types.REOptions where

import           Data.Hashable
import qualified Data.HashMap.Strict        as HM
import           Data.String
import           Language.Haskell.TH
import           Language.Haskell.TH.Syntax

-- | the default API uses these simple, universal RE options,
-- which get auto-converted into the apropriate 'REOptions_' actually
-- as apropriate the chosen back end
data SimpleREOptions
  = MultilineSensitive        -- ^ case-sensitive with ^ and $ matching the start and end of a line
  | MultilineInsensitive      -- ^ case-insensitive with ^ and $ matsh the start and end of a line
  | BlockSensitive            -- ^ case-sensitive with ^ and $ matching the start and end of the input text
  | BlockInsensitive          -- ^ case-insensitive with ^ and $ matching the start and end of the input text
  deriving (Bounded,Enum,Eq,Ord,Show)

-- | we need to use this in the quasi quoters to specify @SimpleREOptions@
-- selected by the quasi quoter
instance Lift SimpleREOptions where
  lift sro = case sro of
    MultilineSensitive    -> conE 'MultilineSensitive
    MultilineInsensitive  -> conE 'MultilineInsensitive
    BlockSensitive        -> conE 'BlockSensitive
    BlockInsensitive      -> conE 'BlockInsensitive

-- | the general options for an RE are dependent on which back end is
-- being used and are parameterised over the @RE@ type for the back end,
-- and its @CompOption@ and @ExecOption@ types (the compile-time and
-- execution time options, respectively); each back end will define an
-- @REOptions@ type that fills out these three type parameters with the
-- apropriate types
data REOptions_ r c e =
  REOptions
    { optionsMacs :: !(Macros r)    -- ^ the available TestBench RE macros
    , optionsComp :: !c             -- ^ the back end compile-time options
    , optionsExec :: !e             -- ^ the back end execution-time options
    }
  deriving (Show)

-- | a number of types can be used to encode @REOptions@, each of which
-- can be made a member of this class.
class IsOption o r c e |
    e -> r, c -> e , e -> c, r -> c, c -> r, r -> e where
  -- | convert the @o@ type into an @REOptions r c e@
  makeREOptions :: o -> REOptions_ r c e

-- | @MacroID@ is just a wrapped @String@ type with an @IsString@
-- instance
newtype MacroID =
    MacroID { getMacroID :: String }
  deriving (IsString,Ord,Eq,Show)

-- | @MacroID@ is used with @HM.HashMap@ to build macro lookup tables
instance Hashable MacroID where
  hashWithSalt i = hashWithSalt i . getMacroID

-- | our macro tables are parameterised over the backend @RE@ type and
-- and just associate each @MacroID@ with an @RE@
type Macros r = HM.HashMap MacroID r

-- | a macro table containing no entries
emptyMacros :: Macros r
emptyMacros = HM.empty