{-# OPTIONS_GHC -Wno-orphans #-}
module Info
  (Info (..),
   tagsFor, descFor, imagesFor, linksFor, updatesFor, compareFor, sortFor,
   Artist (..), Images' (..), Images, Image (..), Desc (..), DescField (..),
   Link (..), Update (..),
   GalleryInfo (..), GalleryFilters (..), ArtistFilter (..), NsfwFilter (..),
   IndexInfo (..),
   readArtistFilter, matchArtist, readNsfwFilter, matchNsfw, matchFilters,
   NoThumb (..), getThumb, thumbFile, pageFile,
   -- ** Reexports
   Date (..), Day (..), Text)
where

import Date
import Records

import Control.Applicative
import Control.Monad
import Control.Exception
import Data.Foldable (find)
import Data.Hashable (Hashable)
import Data.HashSet (HashSet)
import qualified Data.HashSet as HashSet
import qualified Data.Map.Strict as Map
import Data.Maybe (isJust, isNothing, fromMaybe, mapMaybe)
import Data.List (nub, sortBy)
import Data.Ord (comparing)
import Data.String (IsString)
import Data.Text (Text)
import qualified Data.Text as Text
import Data.YAML (FromYAML (..), (.:), (.:?), (.!=))
import qualified Data.YAML as YAML
import System.FilePath ((</>), takeBaseName, takeExtension, splitExtension)
import Data.Bifunctor (second)


data Info =
  Info {
    date        :: !Date,
    -- | extra sort key after date
    -- e.g. multiple things on the same day might have a,b,c in @sortEx@ to
    -- put them in the right order in the gallery
    sortEx      :: !Text,
    updates     :: ![Update],
    -- | if false, don't show updated emblem even if @updates@ is non-empty
    showUpdated :: !Bool,
    title       :: !Text,
    artist      :: !(Maybe Artist), -- nothing = me, obv
    nsfwOnly    :: !Bool,
    tags        :: ![Text],
    nsfwTags    :: ![Text],
    desc        :: !Desc,
    nsfwDesc    :: !Desc,
    bg          :: !(Maybe Text),
    images      :: !Images,
    thumb'      :: !(Maybe FilePath),
    links       :: ![Link],
    extras      :: ![FilePath]
  }
  deriving (Eq, Show)

data Desc =
    NoDesc
  | TextDesc !Text
  | LongDesc ![DescField]
  deriving (Eq, Show)

data DescField = DescField {name, text :: !Text}
  deriving (Eq, Show)

data Artist =
  Artist {
    name :: !Text,
    url  :: !(Maybe Text)
  }
  deriving (Eq, Show)

data Image =
  Image {
    label    :: !Text,
    path     :: !FilePath,
    download :: !(Maybe FilePath),
    nsfw     :: !Bool,
    warning  :: !(Maybe Text)
  }
  deriving (Eq, Show)

data Images' a =
    Uncat [a]         -- ^ uncategorised
  | Cat [(Text, [a])] -- ^ categorised
  deriving (Eq, Show, Functor, Foldable, Traversable)

type Images = Images' Image


data Link =
  Link {
    title :: !Text,
    url   :: !Text,
    nsfw  :: !Bool
  }
  deriving (Eq, Show)

data Update =
  Update {
    date       :: !Date,
    desc       :: !Text,
    nsfw       :: !Bool,
    ignoreSort :: !Bool
  }
  deriving (Eq, Ord, Show)

instance HasField "sfw" Image  Bool where getField = not . #nsfw
instance HasField "sfw" Link   Bool where getField = not . #nsfw
instance HasField "sfw" Update Bool where getField = not . #nsfw

instance HasField "all" (Images' a) [a] where
  getField (Uncat is) = is
  getField (Cat cats) = foldMap snd cats

filterImages :: (a -> Bool) -> Images' a -> Images' a
filterImages p (Uncat is) = Uncat $ filter p is
filterImages p (Cat cats) =
  Cat $ filter (not . null . snd) $ map (second $ filter p) cats

instance HasField "sfwImages" Info Images where
  getField = filterImages #sfw . #images
instance HasField "nsfwImages" Info Images where
  getField = filterImages #nsfw . #images
instance HasField "allNsfw" Info Bool where getField = null . #all . #sfwImages
instance HasField "allSfw" Info Bool where getField = null . #all . #nsfwImages
instance HasField "anySfw" Info Bool where getField = not . #allNsfw
instance HasField "anyNsfw" Info Bool where getField = not . #allSfw

instance HasField "sfwLinks" Info [Link] where
  getField = filter #sfw . #links
instance HasField "nsfwLinks" Info [Link] where
  getField = filter #nsfw . #links

instance HasField "sfwUpdates" Info [Update] where
  getField = filter #sfw . #updates
instance HasField "nsfwUpdates" Info [Update] where
  getField = filter #nsfw . #updates

instance HasField "thumb" Info (Maybe FilePath) where
  getField (Info {thumb', images}) =
    thumb' <|> #path <$> find #sfw (#all images)

instance HasField "mine"    Info Bool where getField = isNothing . #artist
instance HasField "notMine" Info Bool where getField = isJust    . #artist

instance HasField "latestDate" Info (Bool -> Date) where
  getField info@(Info {date=date₀}) nsfw =
    maximum $ date₀ : mapMaybe relDate (updatesFor nsfw info)
   where relDate (Update {date, ignoreSort}) = date <$ guard (not ignoreSort)

instance HasField "latestYear" Info (Bool -> Int) where
  getField info nsfw = #year $ #latestDate info nsfw


instance HasField "updated" Info (Bool -> Bool) where
  getField (Info {updates, showUpdated}) nsfw = showUpdated && updated
    where updated = if nsfw then not $ null updates else any #sfw updates

defDescKey :: Text
defDescKey = "about"

instance Semigroup Desc where
  NoDesc        <> d2            = d2
  d1            <> NoDesc        = d1
  (TextDesc t1) <> (TextDesc t2) = TextDesc $ t1 <> t2
  (LongDesc m1) <> (TextDesc t2) = LongDesc $ m1 <> [DescField defDescKey t2]
  (TextDesc t1) <> (LongDesc m2) = LongDesc $ [DescField defDescKey t1] <> m2
  (LongDesc m1) <> (LongDesc m2) = LongDesc $ merge m1 m2

merge :: [DescField] -> [DescField] -> [DescField]
merge fs1 fs2 = go fs1 [] fs2 where
  go first unused []     = first <> reverse unused
  go first unused (x:xs) =
    case insert first x of
      Just first' -> go first' unused     xs
      Nothing     -> go first  (x:unused) xs
  insert []     _ = Nothing
  insert (x:xs) y =
    if #name x == #name y then
      Just $ x {text = #text x <> #text y} : xs
    else
      (x :) <$> insert xs y

instance Monoid Desc where
  mempty = NoDesc
  mappend = (<>)

instance HasField "exists" Desc Bool where
  getField d = d /= NoDesc

descFor :: Bool -> Info -> Desc
descFor nsfw (Info {desc, nsfwDesc}) = if nsfw then desc <> nsfwDesc else desc

tagsFor :: Bool -> Info -> [Text]
tagsFor nsfw i = if nsfw then nub (#tags i <> #nsfwTags i) else #tags i

imagesFor :: Bool -> Info -> Images
imagesFor nsfw = if nsfw then #images else #sfwImages

linksFor :: Bool -> Info -> [Link]
linksFor nsfw = if nsfw then #links else #sfwLinks

updatesFor :: Bool -> Info -> [Update]
updatesFor nsfw = if nsfw then #updates else #sfwUpdates

compareFor :: Bool -> Info -> Info -> Ordering
compareFor nsfw = comparing \i -> (#latestDate i nsfw, #sortEx i, #title i)

sortFor :: Bool -> [Info] -> [Info]
sortFor = sortBy . compareFor


newtype NoThumb = NoThumb FilePath
  deriving stock Eq deriving anyclass Exception
instance Show NoThumb where show (NoThumb dir) = "no thumbnail for " ++ dir

getThumb :: FilePath -> Info -> FilePath
getThumb dir =
  maybe (throw $ NoThumb dir) (\t -> dir </> thumbFile t) . #thumb

thumbFile :: FilePath -> FilePath
thumbFile = addSuffix "_small"

pageFile :: FilePath -> FilePath
pageFile f
  | takeExtension f == ".gif" = f
  | otherwise                 = addSuffix "_med" f

addSuffix :: String -> FilePath -> FilePath
addSuffix suf path =
  let (pre, ext) = splitExtension path in
  pre ++ suf ++ ext


instance FromYAML Info where
  parseYAML = YAML.withMap "info" \m ->
    Info <$>  m .:  "date"
         <*>  m .:? "sort"         .!= ""
         <*> (m .:? "updates" >>= updateList)
         <*>  m .:? "show-updated" .!= True
         <*>  m .:  "title"
         <*>  m .:? "artist"
         <*>  m .:? "nsfw-only" .!= False
         <*>  m .:? "tags"      .!= []
         <*>  m .:? "nsfw-tags" .!= []
         <*>  m .:? "desc"      .!= NoDesc
         <*>  m .:? "nsfw-desc" .!= NoDesc
         <*>  m .:? "bg"
         <*>  m .:  "images"
         <*>  m .:? "thumb"
         <*>  m .:? "links"  .!= []
         <*>  m .:? "extras" .!= []

instance FromYAML Artist where
  parseYAML y = justName y <|> withUrl y where
    justName = YAML.withStr "name" \name -> pure $ Artist {name, url = Nothing}
    withUrl  = YAML.withMap "full info" \m ->
      Artist <$> m .: "name" <*> m .:? "url"

instance FromYAML Desc where
  parseYAML y = textDesc y <|> mapDesc y where
    textDesc = YAML.withStr "text" $ pure . TextDesc
    mapDesc  = fmap LongDesc . parseYAML

instance FromYAML DescField where parseYAML = withPair DescField

imageList :: YAML.Node YAML.Pos -> YAML.Parser [Image]
imageList y = pure <$> unlabelledImage y <|> parseYAML y

instance FromYAML Image where
  parseYAML y = unlabelledImage y <|> labelled y where
    labelled = withPairM \label -> unlabelledImage' (Just label)

unlabelledImage :: YAML.Node YAML.Pos -> YAML.Parser Image
unlabelledImage = unlabelledImage' Nothing

unlabelledImage' :: Maybe Text -> YAML.Node YAML.Pos -> YAML.Parser Image
unlabelledImage' label' y = asStr y <|> asObj y
 where
  asStr = YAML.withStr "path" \(Text.unpack -> path) ->
    let label = fromMaybe (pathToLabel path) label' in
    pure $ Image {label, path, download = Nothing,
                  nsfw = False, warning = Nothing}
  asObj = YAML.withMap "image info" \m -> do
    path     <- m .:  "path"
    download <- m .:? "download"
    nsfw     <- m .:? "nsfw" .!= False
    warning  <- m .:? "warning"
    let label = fromMaybe (pathToLabel path) label'
    pure $ Image {label, path, download, nsfw, warning}
  pathToLabel = Text.pack . gapToSpace . takeBaseName
  gapToSpace = map \case '-' -> ' '; '_' -> ' '; c -> c

instance FromYAML Images where
  parseYAML y = Uncat <$> imageList y
            <|> Cat   <$> YAML.withSeq "list of categories" fromPairs y
    where fromPairs = traverse $ withPairM \label -> fmap (label,) . imageList

instance FromYAML Link where
  parseYAML =
    withPairM \title rest -> asStr title rest <|> asObj title rest
   where
    asStr title = YAML.withStr "url" \url ->
      pure $ Link {title, url, nsfw = False}
    asObj title = YAML.withMap "link info" \m -> do
      url  <- m .:  "url"
      nsfw <- m .:? "nsfw" .!= False
      pure $ Link {title, url, nsfw}


updateList :: Maybe (YAML.Node YAML.Pos) -> YAML.Parser [Update]
updateList =
  maybe (pure []) $ YAML.withMap "updates" $ traverse asEither . Map.toList
 where
  asEither (date', rest) = do
    date <- parseYAML date'
    asDesc date rest <|> asObj date rest
  asDesc date = YAML.withStr "desc" \desc ->
    pure $ Update {date, desc, nsfw = False, ignoreSort = False}
  asObj date = YAML.withMap "update info" \m -> do
    desc       <- m .:  "desc"
    nsfw       <- m .:? "nsfw"        .!= False
    ignoreSort <- m .:? "ignore-sort" .!= False
    pure $ Update {date, desc, nsfw, ignoreSort}


data GalleryInfo =
  GalleryInfo {
    title   :: !Text,
    desc    :: !Text,
    prefix  :: !FilePath,
    filters :: !GalleryFilters,
    hidden  :: !(HashSet Text) -- ^ tags to initially hide
  }
  deriving (Eq, Show)

instance HasField "nsfw" GalleryInfo Bool where
  getField g = #nsfw (#filters g) /= NoNsfw

data GalleryFilters =
  GalleryFilters {
    nsfw   :: !NsfwFilter,
    artist :: !ArtistFilter,
    require, exclude :: !(HashSet Text)
  }
  deriving (Eq, Show)

data NsfwFilter = NoNsfw | OnlyNsfw | AllN deriving (Eq, Show)

readNsfwFilter :: (IsString str, Eq str, Alternative f) => str -> f NsfwFilter
readNsfwFilter "no"   = pure NoNsfw
readNsfwFilter "only" = pure OnlyNsfw
readNsfwFilter "all"  = pure AllN
readNsfwFilter _      = empty

matchNsfw :: NsfwFilter -> Info -> Bool
matchNsfw NoNsfw   i = #anySfw  i && not (#nsfwOnly i)
matchNsfw OnlyNsfw i = #anyNsfw i
matchNsfw AllN     _ = True

instance FromYAML NsfwFilter where
  parseYAML = YAML.withStr "nsfw filter" readNsfwFilter


data ArtistFilter = Me | NotMe | AllA deriving (Eq, Show)

readArtistFilter :: (IsString str, Eq str, Alternative f)
                 => str -> f ArtistFilter
readArtistFilter "me"     = pure Me
readArtistFilter "not-me" = pure NotMe
readArtistFilter "all"    = pure AllA
readArtistFilter _        = empty

matchArtist :: ArtistFilter -> Info -> Bool
matchArtist Me    = #mine
matchArtist NotMe = #notMine
matchArtist AllA  = const True

noFilters :: GalleryFilters
noFilters =
  GalleryFilters {nsfw = AllN, artist = AllA, require = [], exclude = []}

matchFilters :: GalleryFilters -> Info -> Bool
matchFilters (GalleryFilters {nsfw, artist, require, exclude}) i =
  matchNsfw nsfw i && matchArtist artist i &&
  all (\t -> HashSet.member t tags) require &&
  all (\t -> not $ HashSet.member t tags) exclude
 where tags = HashSet.fromList $ #tags i


instance FromYAML GalleryInfo where
  parseYAML = YAML.withMap "gallery info" \m ->
    GalleryInfo <$> m .:  "title"
                <*> m .:  "desc"
                <*> m .:  "prefix"
                <*> m .:? "filters" .!= noFilters
                <*> m .:? "hidden"  .!= mempty

instance FromYAML GalleryFilters where
  parseYAML = YAML.withMap "gallery filters" \m ->
    GalleryFilters <$> m .:? "nsfw"    .!= AllN
                   <*> m .:? "artist"  .!= AllA
                   <*> m .:? "require" .!= []
                   <*> m .:? "exclude" .!= []

instance FromYAML ArtistFilter where
  parseYAML = YAML.withStr "artist filter" readArtistFilter


data IndexInfo =
  IndexInfo {
    title     :: !Text,
    desc      :: !Text,
    galleries :: ![GalleryInfo],
    links     :: ![Link],
    footer    :: !(Maybe Text)
  }
  deriving Show

instance FromYAML IndexInfo where
  parseYAML = YAML.withMap "index info" \m ->
    IndexInfo <$> m .:  "title"
              <*> m .:  "desc"
              <*> m .:? "galleries" .!= []
              <*> m .:? "links"     .!= []
              <*> m .:? "footer"


data Pair a b = Pair !a !b

instance (FromYAML a, FromYAML b) => FromYAML (Pair a b) where
  parseYAML = YAML.withMap "single-pair map" \m ->
    case Map.toList m of
      [(a, b)] -> Pair <$> parseYAML a <*> parseYAML b
      _        -> fail "expected exactly one pair"

withPairM :: (FromYAML a, FromYAML b)
          => (a -> b -> YAML.Parser c)
          -> (YAML.Node YAML.Pos -> YAML.Parser c)
withPairM k y = parseYAML y >>= \(Pair a b) -> k a b

withPair :: (FromYAML a, FromYAML b)
         => (a -> b -> c)
         -> (YAML.Node YAML.Pos -> YAML.Parser c)
withPair f = withPairM \a b -> pure $ f a b


instance {-# OVERLAPPING #-} FromYAML String where
  parseYAML y = Text.unpack <$> parseYAML y

instance (FromYAML a, Eq a, Hashable a) => FromYAML (HashSet a) where
  parseYAML y = HashSet.fromList <$> parseYAML y