{-# LANGUAGE DeriveFunctor #-}
{-# LANGUAGE DeriveFoldable #-}
{-# LANGUAGE DeriveTraversable #-}
{-# LANGUAGE OverloadedStrings #-}

module Descript.Sugar.Data.Source
  ( Query (..)
  , AModule (..)
  , BModule (..)
  , Program (..)
  , Source (..)
  , mkSource
  , sourceToProgram
  , sourceBModule
  , sourceImportCtx
  ) where

import Descript.Sugar.Data.Reducer
import qualified Descript.Sugar.Data.Value.Reg as Reg
import Descript.Sugar.Data.Type
import Descript.Sugar.Data.Import
import Descript.Misc
import Data.Monoid
import Data.List
import Prelude hiding (mod)

-- | The "main" value in a program. A program is interpreted by reducing
-- its query - this reduced is the output of a program.
data Query an
  = Query
  { queryAnn :: an
  , queryVal :: Reg.Value an
  } deriving (Eq, Ord, Read, Show, Functor, Foldable, Traversable)

-- | Anonymous module - no scope. Defines how a program is interpreted.
-- When a module imports another, the other's 'AModule' is appended.
data AModule an
  = AModule
  { amoduleAnn :: an
  , recordCtx :: RecordCtx an
  , reduceCtx :: ReduceCtx an
  } deriving (Eq, Ord, Read, Show, Functor, Foldable, Traversable)

-- | A module with a scope and imports, which allows it to import other
-- modules.
data BModule an
  = BModule
  { bmoduleAnn :: an
  , importCtx :: ImportCtx an
  , amodule :: AModule an
  } deriving (Eq, Ord, Read, Show, Functor, Foldable, Traversable)

-- | Parsed from a source file and interpreted. To interpret, the query
-- is reduced using the module.
data Program an
  = Program
  { programAnn :: an
  , module' :: BModule an
  , query :: Query an
  } deriving (Eq, Ord, Read, Show, Functor, Foldable, Traversable)

-- | Every source file gets parsed into one of these.
data Source an
  = SourceModule (BModule an)
  | SourceProgram (Program an)
  deriving (Eq, Ord, Read, Show, Functor, Foldable, Traversable)

instance (Monoid an) => Monoid (AModule an) where
  mempty
    = AModule
    { amoduleAnn = mempty
    , recordCtx = mempty
    , reduceCtx = mempty
    }

  x `mappend` y
    = AModule
    { amoduleAnn = amoduleAnn x <> amoduleAnn y
    , recordCtx = recordCtx x <> recordCtx y
    , reduceCtx = reduceCtx x <> reduceCtx y
    }

instance Ann Source where
  getAnn (SourceModule mod) = getAnn mod
  getAnn (SourceProgram prog) = getAnn prog

instance Ann Program where
  getAnn = programAnn

instance Ann BModule where
  getAnn = bmoduleAnn

instance Ann AModule where
  getAnn = amoduleAnn

instance Ann Query where
  getAnn = queryAnn

instance Printable Source where
  aprintRec sub (SourceModule mod) = sub mod
  aprintRec sub (SourceProgram prog) = sub prog

instance Printable Program where
  aprintRec sub prog = pintercal "\n\n" $ filter (/= mempty)
    [ sub $ module' prog
    , sub $ query prog
    ]

instance Printable BModule where
  aprintRec sub mod = pintercal "\n\n" $ filter (/= mempty)
    [ sub $ importCtx mod
    , sub $ amodule mod
    ]

instance Printable AModule where
  aprintRec sub mod = pintercal "\n\n" $ filter (/= mempty)
    [ sub $ recordCtx mod
    , sub $ reduceCtx mod
    ]

instance Printable Query where
  aprintRec sub (Query _ val) = sub val <> "?"

instance (Show an) => Summary (Source an) where
  summaryRec = pprintSummaryRec

instance (Show an) => Summary (Program an) where
  summaryRec = pprintSummaryRec

instance (Show an) => Summary (BModule an) where
  summaryRec = pprintSummaryRec

instance (Show an) => Summary (AModule an) where
  summaryRec = pprintSummaryRec

instance (Show an) => Summary (Query an) where
  summaryRec = pprintSummaryRec

-- | Creates a source program if the query exists, or a source module if it doesn't.
mkSource :: an -> BModule an -> Maybe (Query an) -> Source an
mkSource _ mod Nothing = SourceModule mod
mkSource ann mod (Just qry) = SourceProgram $ Program ann mod qry

-- | If the source is a program, returns it.
-- If it's a module, returns 'Nothing'.
sourceToProgram :: Source an -> Maybe (Program an)
sourceToProgram (SourceModule _) = Nothing
sourceToProgram (SourceProgram prog) = Just prog

-- | The source's bound module.
sourceBModule :: Source an -> BModule an
sourceBModule (SourceModule mod) = mod
sourceBModule (SourceProgram prog) = module' prog

-- | Contains the source's module declaration and imports.
sourceImportCtx :: Source an -> ImportCtx an
sourceImportCtx = importCtx . sourceBModule