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

  data Entry = Entry {
    graphFile       :: String,
    category        :: Maybe String,
    defScope        :: Maybe String,
    defDescription  :: Maybe Description,
    instDescription :: Maybe Description,
    instances       :: Value
  } deriving (Show, Generic)

  instance FromJSON Entry where
    parseJSON (Object o) = Entry <$>
                           o .:  "graph-file" <*>
                           o .:? "category" <*>
                           o .:? "definition-scope" <*>
                           o .:? "definition-description" <*>
                           o .:? "instance-description" <*>
                           o .:  "instances"
    parseJSON _ = error "Unexpected yaml"

  type Title = String
  type Content = String

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

  instance FromJSON Description where
    parseJSON (Object o) = Description <$>
                           o .:? "fallback-lang" <*>
                           o .:  "fallback" <*>
                           o .:  "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 :: String -> Index -> Entry
  getEntryByFile file index = query (elems index) file where
    query :: [Entry] -> String -> Entry
    query [] _ = error $ "No entries left for " ++ file
    query (x:xs) file = if x.graphFile == file then x else query xs file