{-# LANGUAGE DerivingVia #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE StandaloneDeriving #-}

module Zettel.Types
  ( Combine (..),
    UseCombine (..),
    ZettelId (..),
    ZettelCat (..),
    ZettelTag (..),
    ZettelMetadata (..),
    Zettel (..),
    ZettelGraph (..),
  )
where

import Text.Pandoc.Builder (ToMetaValue (..))
import Text.Pandoc.Definition (Block (..), Caption (..), Inline (..), Meta (..), MetaValue (..), Pandoc (..), Row (..), TableBody (..), TableFoot (..), TableHead (..))
import Text.Pandoc.Walk (Walkable (..))

class Combine a where
  cappend :: a -> a -> a
  cempty :: a

newtype UseCombine a = UC a

instance (Monoid a) => Combine (UseCombine a) where
  cappend (UC a) (UC b) = UC $ a <> b
  cempty = UC mempty

deriving via (UseCombine Text) instance Combine Text

deriving via (UseCombine Pandoc) instance Combine Pandoc

deriving via (UseCombine [a]) instance Combine [a]

instance Combine (Maybe a) where
  cappend Nothing a = a
  cappend a _ = a

  cempty = Nothing

-- | The ZettelId is just Text, however, it should also be possible to convert
-- it to a list of the ID split up into it's parts.
newtype ZettelId = ZettelId {unZettelId :: Text}
  deriving (Show, Eq, Ord, IsString, ToString, Semigroup, Monoid, ToMetaValue)
  deriving (Combine) via (UseCombine ZettelId)

newtype ZettelTag = ZettelTag {unZettelTag :: Text}
  deriving (Show, Eq, Ord, IsString, ToString, Semigroup, Monoid, ToMetaValue)
  deriving (Combine) via (UseCombine ZettelId)

newtype ZettelCat = ZettelCat {unZettelCat :: Text}
  deriving (Show, Eq, Ord, IsString, ToString, Semigroup, Monoid, ToMetaValue)
  deriving (Combine) via (UseCombine ZettelId)

data ZettelMetadata = ZettelMetadata
  { -- | Optional creation date of the Zettel.
    zettelCreationDate :: Maybe Text,
    -- | Optional last modified date of the Zettel.
    zettelModifiedDate :: Maybe Text,
    -- | Optional tags.
    zettelTags :: [ZettelTag],
    -- | Optional Category
    zettelCats :: [ZettelCat],
    -- | Author
    zettelAuthor :: Maybe Text
  }
  deriving (Show, Eq)

instance Combine ZettelMetadata where
  cappend (ZettelMetadata c m t a b) (ZettelMetadata c' m' t' a' b') =
    ZettelMetadata (cappend c c') (cappend m m') (cappend t t') (cappend a a') (cappend b b')

  cempty = ZettelMetadata cempty cempty cempty cempty cempty

data Zettel = Zettel
  { -- | The title of the Zettel, which should also be present in the body,
    -- however, this is useful to gather metadata about the Zettel.
    zettelTitle :: ![Inline],
    -- | Zettel metadata which is mostly optional.
    zettelMetadata :: ZettelMetadata,
    -- | The text body of the Zettel, which is stored as a Pandoc document to
    -- make it easy to export to other documents.
    zettelBody :: Pandoc,
    zettelNext :: [ZettelId],
    zettelPrev :: [ZettelId]
  }
  deriving (Show, Eq)

instance Combine Zettel where
  cappend (Zettel b c d e f) (Zettel b' c' d' e' f') =
    Zettel (cappend b b') (cappend c c') (cappend d d') (cappend e e') (cappend f f')

  cempty = Zettel cempty cempty cempty cempty cempty

walkMZettel ::
  (Walkable a Pandoc, Monad m, Applicative m, Functor m) =>
  (a -> m a) ->
  Zettel ->
  m Zettel
walkMZettel f b = do
  res <- walkM f (zettelBody b)
  return b {zettelBody = res}

queryZettel ::
  (Walkable a Pandoc, Monoid c) => (a -> c) -> Zettel -> c
queryZettel f = query f . zettelBody

instance Walkable Block Zettel where
  walkM = walkMZettel
  query = queryZettel

instance Walkable Meta Zettel where
  walkM = walkMZettel
  query = queryZettel

instance Walkable [Block] Zettel where
  walkM = walkMZettel
  query = queryZettel

instance Walkable Pandoc Zettel where
  walkM = walkMZettel
  query = queryZettel

instance Walkable Inline Zettel where
  walkM = walkMZettel
  query = queryZettel

instance Walkable MetaValue Zettel where
  walkM = walkMZettel
  query = queryZettel

instance Walkable [Inline] Zettel where
  walkM = walkMZettel
  query = queryZettel

data ZettelGraph = ZettelGraph
  { unZettelGraph :: Map ZettelId Zettel,
    zettelGraphBib :: Maybe Pandoc
  }
  deriving (Show, Eq)

walkMZettelGraph ::
  (Walkable a Pandoc, Walkable a Zettel, Monad m, Applicative m, Functor m) =>
  (a -> m a) ->
  ZettelGraph ->
  m ZettelGraph
walkMZettelGraph f b = do
  res <- traverse (walkM f) (unZettelGraph b)
  newBib <- traverse (walkM f) (zettelGraphBib b)
  return $ ZettelGraph res newBib

queryZettelGraph ::
  (Monoid a1, Walkable a2 Zettel, Walkable a2 Pandoc) =>
  (a2 -> a1) ->
  ZettelGraph ->
  a1
queryZettelGraph f g = query f (unZettelGraph g) <> maybe mempty (query f) (zettelGraphBib g)

instance Walkable Block ZettelGraph where
  walkM = walkMZettelGraph
  query = queryZettelGraph

instance Walkable Meta ZettelGraph where
  walkM = walkMZettelGraph
  query = queryZettelGraph

instance Walkable [Block] ZettelGraph where
  walkM = walkMZettelGraph
  query = queryZettelGraph

instance Walkable Pandoc ZettelGraph where
  walkM = walkMZettelGraph
  query = queryZettelGraph

instance Walkable Inline ZettelGraph where
  walkM = walkMZettelGraph
  query = queryZettelGraph

instance Walkable MetaValue ZettelGraph where
  walkM = walkMZettelGraph
  query = queryZettelGraph

instance Walkable [Inline] ZettelGraph where
  walkM = walkMZettelGraph
  query = queryZettelGraph

-- instance Walkable ZettelGraph