{-# LANGUAGE NoImplicitPrelude #-}
{-# LANGUAGE OverloadedStrings #-}

-- | App update logic
module Biz.Ibb.Move
  ( move
  -- * Server interactions
  , fetchPeople
  )
where

import           Alpha
import           Biz.Ibb.Core    as Core
import           Network.RemoteData
import           Data.Aeson
import           JavaScript.Web.XMLHttpRequest  ( Request(..)
                                                , Method(GET)
                                                , RequestData(NoData)
                                                , contents
                                                , xhrByteString
                                                )
import           Miso
import           Miso.String

move :: Action -> Model -> Effect Action Model
move Nop             m = noEff m
move (HandleRoute u) m = m { uri = u } <# pure Nop
move (ChangeRoute u) m = m <# do
  pushURI u >> pure Nop
move FetchPeople    m = m <# (SetPeople </ fetchPeople)
move (SetPeople ps) m = noEff m { people = ps }

fetchPeople :: IO (WebData [Core.Person])
fetchPeople = do
  mjson <- contents </ xhrByteString req
  case mjson of
    Nothing -> pure $ Failure "could not read from server"
    Just a ->
      pure $ fromEither $ either (Left . ms) pure $ eitherDecodeStrict a
 where
  req = Request { reqMethod          = GET
                -- FIXME: can replace this hardcoding with a function?
                , reqURI             = "/api/people"
                , reqLogin           = Nothing
                , reqHeaders         = []
                , reqWithCredentials = False
                , reqData            = NoData
                }