-- SPDX-FileCopyrightText: 2023 David Mosbach <david.mosbach@campus.lmu.de>
--
-- SPDX-License-Identifier: AGPL-3.0-or-later

{-# Language DuplicateRecordFields,
    NoFieldSelectors,
    OverloadedRecordDot,
    OverloadedStrings,
    DeriveGeneric #-}

module Index where

  import Control.Applicative hiding (empty)
  import GHC.Generics (Generic)
  import Data.Map
  import Data.Maybe (fromMaybe, fromJust)
  import Data.Text (Text)
  import YamlParser
  
  type Index = Map Text Entry

  data Entry = Entry {
    graphFile       :: Text,
    category        :: Maybe Text,
    defScope        :: Maybe Text,
    defDescription  :: Maybe Description,
    instDescription :: Maybe Description,
    instances       :: YAMLNode
  } deriving Show

  instance FromYAML' Entry where
    fromYAML (Mapping mapping _ _ _ _) = Entry
                                         <$> mapping <|  "graph-file"
                                         <*> mapping <|? "category"
                                         <*> mapping <|? "definition-scope"
                                         <*> mapping <|? "definition-description"
                                         <*> mapping <|? "instance-description"
                                         <*> mapping <|  "instances"
    -- parseJSON _ = error "Unexpected yaml"

  type Title = Text
  type Content = Text

  data Description = Description {
    fallbackLang :: Maybe Text,
    fallback     :: (Maybe Title, Maybe Content),
    translations :: Map Text (Maybe Title, Maybe Content)
  } deriving Show

  instance FromYAML' Description where
    fromYAML (Mapping mapping _ _ _ _) = Description
                                         <$> mapping <|? "fallback-lang"
                                         <*> mapping <|  "fallback"
                                         <*> mapping <|  "translations"

  english = "en-eu";

  getDefDescription :: Entry -> (Maybe Title, Maybe Content)
  getDefDescription entry = let description = fromJust entry.defDescription
                                def = description.fallback
                            in  findWithDefault def english description.translations
  getInstDescription :: Entry -> (Maybe Title, Maybe Content)
  getInstDescription entry = let description = fromJust entry.instDescription
                                 def = description.fallback
                             in  findWithDefault def english description.translations

  getEntryByFile :: Text -> Index -> Entry
  getEntryByFile file index = query (elems index) file where
    query :: [Entry] -> Text -> Entry
    query [] _ = error $ "No entries left for " ++ show file
    query (x:xs) file = if x.graphFile == file then x else query xs file