module Schema
  ( Schema,
    viewSchema,
    schemaTable,
    schemaForm,
  )
where

#ifdef ghcjs_HOST_OS
import Data.Text qualified as T
#endif
import Control.Applicative ((<|>))
import Data.Aeson qualified as A
import Data.Aeson.Key qualified as AK
import Data.Aeson.KeyMap qualified as AM
import Data.List
import Data.Map qualified as M
import Data.Maybe
import Data.Scientific (fromFloatDigits)
import Data.Set qualified as S
import Form qualified as F
import Miso
import Miso.String (MisoString, fromMisoString, intercalate, toMisoString)
import Route
import Safe

data Schema = Schema
  { id :: MisoString,
    schema :: MisoString,
    properties :: M.Map MisoString Property,
    required :: S.Set MisoString,
    title :: MisoString,
    type_ :: MisoString
  }
  deriving (Show, Eq)

instance A.FromJSON Schema where
  parseJSON = A.withObject "Schema" $ \v ->
    Schema
      <$> v A..: "$id"
      <*> v A..: "$schema"
      <*> v A..: "properties"
      <*> v A..: "required"
      <*> v A..: "title"
      <*> v A..: "type"

#ifdef ghcjs_HOST_OS
instance A.FromJSONKey MisoString where
  parseJSON = fromMisoString @T.Text <$> parseJSON
#endif

data Property
  = Type MisoString
  | Reference MisoString
  | Union [MisoString]
  deriving (Show, Eq)

instance A.FromJSON Property where
  parseJSON = A.withObject "Property" $ \v ->
    (Type <$> v A..: "type")
      <|> (Reference <$> v A..: "$ref")
      <|> (fmap Union $ traverse (A..: "type") =<< v A..: "oneOf")

viewSchema :: Schema -> View action
viewSchema schema =
  ol_ [] $
    ( \(k, v) ->
        li_ [] $
          [ text (toMisoString k),
            text ":",
            text
              ( case v of
                  Type v -> toMisoString v
                  Reference v -> "reference to " <> toMisoString v
                  Union vs -> Miso.String.intercalate " or " vs
              ),
            text (if k `S.member` schema.required then "" else "?")
          ]
    )
      <$> (M.toList schema.properties)

schemaTable :: MisoString -> Schema -> [A.Object] -> View action
schemaTable collection schema values =
  table_ [] [thead, tbody]
  where
    thead =
      thead_ [] $
        [ tr_ [] $
            [ th_ [] [text (toMisoString k)]
              | k <- M.keys schema.properties
            ]
        ]
    tbody =
      tbody_ [] $
        [ tr_
            []
            [ td_ [] $
                [ case (k, getO (AK.fromText (fromMisoString k)) value) of
                    ("$fileName", A.String fn) ->
                      a_
                        [ href_
                            (routeToMisoString (EditValue collection (toMisoString fn)))
                        ]
                        [ text (toMisoString fn)
                        ]
                    (_, v) ->
                      text $
                        case v of
                          A.String s -> toMisoString s
                          _ -> toMisoString (A.encode v)
                ]
              | k <- M.keys schema.properties
            ]
          | value <- values
        ]

schemaForm :: Schema -> F.Form A.Object A.Object
schemaForm schema =
  fmap mergeJson . sequence . catMaybes $
    ( \((AK.fromText . fromMisoString) -> k, v) ->
        case v of
          Type "string" ->
            Just $
              if toMisoString (AK.toText k) `S.member` schema.required
                then
                  AM.singleton k
                    <$> ( F.mapValues (getO k) (setO k) $
                            fmap (A.String . fromMisoString) . F.mapValues fromJson toJson $
                              F.inputText (toMisoString (AK.toString k))
                        )
                else
                  AM.singleton k
                    <$> ( F.mapValues (getO k) (setO k)
                            $ fmap (maybe A.Null (A.String . fromMisoString))
                              . F.mapValues fromJson toJson
                            $ F.optional (F.inputText (toMisoString (AK.toString k)))
                        )
          Type "number" ->
            Just $
              if toMisoString (AK.toText k) `S.member` schema.required
                then
                  AM.singleton k
                    <$> ( F.mapValues (getO k) (setO k) $
                            fmap ((A.Number . fromFloatDigits)) . F.mapValues fromJson toJson $
                              F.inputNumber (toMisoString (AK.toString k))
                        )
                else
                  AM.singleton k
                    <$> ( F.mapValues (getO k) (setO k)
                            $ fmap (maybe A.Null (A.Number . fromFloatDigits))
                              . F.mapValues fromJson toJson
                            $ F.optional (F.inputNumber (toMisoString (AK.toString k)))
                        )
          Reference _ -> Nothing
          Union (map F.stringToTypeName -> typeStrings) ->
            let inputFromOutput = \case
                  A.String x -> pure (F.StringType, M.singleton F.StringType (toMisoString x))
                  A.Number x -> pure (F.NumberType, M.singleton F.NumberType (toMisoString (show x)))
                  _ -> fail ""
                inputFromInput = A.fromJSON
                inputDef =
                  ( fromMaybe F.StringType (headMay typeStrings),
                    M.empty
                  )
             in Just $
                  if toMisoString (AK.toText k) `S.member` schema.required
                    then
                      AM.singleton k
                        <$> ( fmap A.toJSON $
                                F.mapValues (getInput k inputFromOutput inputFromInput inputDef) (setInput k A.toJSON) $
                                  F.inputUnion (toMisoString (AK.toString k)) typeStrings
                            )
                    else
                      AM.singleton k
                        <$> ( fmap A.toJSON $
                                F.mapValues (getInput k inputFromOutput inputFromInput inputDef) (setInput k A.toJSON) $
                                  F.optional (F.inputUnion (toMisoString (AK.toString k)) typeStrings)
                            )
          _ -> Nothing
    )
      <$> (M.toList schema.properties)

mergeJson :: [A.Object] -> A.Object
mergeJson = foldl' mergeObject AM.empty

mergeObject :: A.Object -> A.Object -> A.Object
mergeObject kvs kvs' = AM.union kvs kvs'

fromJson :: A.Value -> MisoString
fromJson (A.String x) = toMisoString x
fromJson _ = ""

toJson :: MisoString -> A.Value -> A.Value
toJson x _ = A.String (fromMisoString x)

getO :: AK.Key -> A.Object -> A.Value
getO k kvs = fromMaybe A.Null (AM.lookup k kvs)

setO :: AK.Key -> A.Value -> A.Object -> A.Object
setO k v kvs = AM.insert k v kvs

-- | Used in `mapValues (getInput ...) (setInput ..)`.
--
-- Suppose *input" is an `A.Object`, this function is concerned with getting a sub-form model from within that object, given a *key* and the *subform's type*.
--
-- The input model can be in three different states:
--
-- - (1) The input object has been converted from an output model, no modification has been done on it. The value in question corresponds to the output model, which may be different from the corresponding form value.
-- - (2) The input object had been modified, and so the value in question conforms structurally to the input value.
-- - (3) The input object is in an undefined state, ie. this should not happen.
--
-- The first three arguments `(A.Value -> A.Result i)`, `(A.Value -> A.Result i)`, `i` correspond to these cases and are tested for in order of (2), (1), (3).
getInput ::
  AK.Key ->
  (A.Value -> A.Result i) ->
  (A.Value -> A.Result i) ->
  i ->
  A.Object ->
  i
getInput k f1 f2 f3 kvs =
  let v = getO k kvs
   in case f2 v <|> f1 v of
        A.Error _ -> f3
        A.Success x -> x

setInput :: AK.Key -> (i -> A.Value) -> i -> A.Object -> A.Object
setInput k f i kvs =
  setO k (f i) kvs