module Main where

import Prelude
import Effect (Effect)
import Halogen as H
import Halogen.Aff as HA
import Halogen.HTML as HH
import Halogen.HTML.Events as HE
import Halogen.VDom.Driver (runUI)

main :: Effect Unit
main = HA.runHalogenAff do
  body <- HA.awaitBody
  runUI component unit body

type State = { count :: Int }

data Action = Increment | Decrement

component :: forall q i o m. H.Component q i o m
component =
  H.mkComponent
    { initialState
    , render
    , eval: H.mkEval $ H.defaultEval { handleAction = handleAction }
    }

initialState :: forall i. i -> State
initialState _ = { count: 0 }

render :: forall m. State -> H.ComponentHTML Action () m
render state =
  HH.div_
    [ HH.button [ HE.onClick \_ -> Decrement ] [ HH.text "-" ]
    , HH.text (show state.count)
    , HH.button [ HE.onClick \_ -> Increment ] [ HH.text "+" ]
    ]

handleAction :: forall o m. Action -> H.HalogenM State Action () o m Unit
handleAction = case _ of
  Increment -> H.modify_ \st -> st { count = st.count + 1 }
  Decrement -> H.modify_ \st -> st { count = st.count - 1 }