module Calculator exposing (..)

import Html exposing (..)
import Html.Attributes exposing (..)
import Html.Events exposing (..)

import NumberInput
import Select

type Tax = Net | Gross

ctShow ct = case ct of
  Gross -> "Brutto"
  Net -> "Netto"

type alias Model =
  { tax : Select.Model Tax
  , bundlePrice : NumberInput.Model Float
  , bundleSize : NumberInput.Model Int
  }

init bundlePrice = Model
  (Select.init ctShow ctShow Net [Net, Gross])
  (NumberInput.fromFloat bundlePrice)
  (NumberInput.fromInt 1)

getResult model taxGroup =
  case (NumberInput.get model.bundlePrice, NumberInput.get model.bundleSize) of
    (Just bundlePrice, Just bundleSize) ->
      Just <| roundTo 2 <|
        if Select.get model.tax == Gross then
          (bundlePrice / toFloat bundleSize) / (1 + taxGroup.percentage)
        else
          bundlePrice / toFloat bundleSize
    _ ->
      Nothing


type Msg
  = SetTax String
  | SetBundlePrice String
  | SetBundleSize String

update msg model = case msg of
  SetTax key ->
    { model | tax = Select.update key model.tax }
  SetBundlePrice str ->
    { model | bundlePrice = NumberInput.update str model.bundlePrice }
  SetBundleSize str ->
    { model | bundleSize = NumberInput.update str model.bundleSize }

view model taxGroup =
  let
    mainPart =
      [ text "("
      , input
        [ class "formula-input", placeholder "Gebindepreis"
        , value <| NumberInput.show model.bundlePrice
        , onInput SetBundlePrice
        ]
        []
      , text " ÷ "
      , input
        [ class "formula-input", placeholder "Gebindegröße"
        , value <| NumberInput.show model.bundleSize
        , onInput SetBundleSize
        ]
        []
      , text ") "
      ]
    taxPart =
      [ text " ÷ "
      , input
        [ class "formula-input"
        , disabled True
        , value <| String.fromFloat <| 1 + taxGroup.percentage
        ]
        []
      ]
    resultPart =
      [ text " = "
      , input
        [ class "formula-input"
        , disabled True
        , value <| Maybe.withDefault "?" <| Maybe.map String.fromFloat <| getResult model taxGroup
        ]
        []
      ]
  in
    fieldset []
      [ legend [] [ text "Preisrechner" ]
      , div [] <| List.concat <| List.filterMap identity
        [ Just mainPart
        , if Select.get model.tax == Gross then Just taxPart else Nothing
        , Just resultPart
        ]
      , div [ class "form-input" ]
        [ label [ for "calculator-tax" ] [ text "Gebindepreis ist" ]
        , Select.view [] SetTax model.tax
        ]
      ]

roundTo places x = toFloat (round <| x * 10 ^ places) / 10 ^ places