WM.elm

module Main exposing (..)

import Color
import Element exposing (..)
import Element.Background as Background
import Element.Border as Border
import Element.Events as Events
import Element.Font as Font
import Html exposing (Html)


main =
    Html.program
        { view = view
        , update = update
        , init = init
        , subscriptions = \_ -> Sub.none
        }


view : Model -> Html Msg
view model =
    Element.layout
        [ Background.color Color.blue
        ]
    <|
        el
            [ width (px 500), height (px 500) ]
            (draw model.wm)


update : Msg -> Model -> ( Model, Cmd Msg )
update (Click int) model =
    ( { wm = split (toOrientation model.flip) int model.wm
      , flip = not model.flip
      }
    , Cmd.none
    )


toOrientation : Bool -> Orientation
toOrientation flip =
    if flip then
        Horizontal
    else
        Vertical


init : ( Model, Cmd Msg )
init =
    ( { wm = Panel [], flip = True }, Cmd.none )


type alias Model =
    { wm : WM, flip : Bool }


type Msg
    = Click Path


type Orientation
    = Horizontal
    | Vertical


type Direction
    = Left
    | Right


type alias Path =
    List Direction


type WM
    = Split Path Orientation WM WM
    | Panel Path


split : Orientation -> Path -> WM -> WM
split newSplitOrientation splitPath wm =
    -- NOTE: naive approach... O(n). we can follow the path and get O(log n)
    case wm of
        Panel path ->
            if splitPath == path then
                Split path
                    newSplitOrientation
                    (Panel (Left :: path))
                    (Panel (Right :: path))
            else
                Panel path

        Split path orientation left right ->
            -- trying to split a split -- just return out. no recursion.
            if splitPath == path then
                Split path orientation left right
            else
                Split path
                    orientation
                    (split newSplitOrientation splitPath left)
                    (split newSplitOrientation splitPath right)


draw : WM -> Element Msg
draw wm =
    case wm of
        Panel path ->
            el
                [ height fill
                , width fill
                , Border.width 1
                , Border.color Color.black
                , Border.solid
                , Events.onClick (Click path)
                ]
                Element.empty

        Split _ _ wm1 wm2 ->
            case o of
                Horizontal ->
                    row
                        [ height fill, width fill ]
                        [ draw wm1, draw wm2 ]

                Vertical ->
                    column
                        [ height fill, width fill ]
                        [ draw wm1, draw wm2 ]