Using the URL fragment/query args to determine which "sub app" to render, using initial URL to inform state

Main.elm

module Main exposing (main)

import Browser as B
import Browser.Navigation as BN
import Html as H
import Html.Attributes as HA
import Html.Events as HE
import Url as U


type alias Model =
    { selectedRobot : Maybe String }


type Msg
    = None


type alias Flags =
    {}


main =
    B.application
        { init = init
        , onUrlChange = \_ -> None
        , onUrlRequest = \_ -> None
        , subscriptions = \_ -> Sub.none
        , update = update
        , view = view
        }


init : Flags -> U.Url -> BN.Key -> ( Model, Cmd Msg )
init flags url key =
    ( { selectedRobot = url.fragment
      }
    , Cmd.none
    )


update : Msg -> Model -> ( Model, Cmd msg )
update msg model =
    ( model, Cmd.none )


type alias Robot =
    { name : String
    , host : String
    , load : ( Float, Float, Float )
    }


robots =
    [ Robot "Hector" "iad.domain" ( 6.54, 1.8, 1.2 )
    , Robot "Vargus" "dfw.domain" ( 1.2, 0.7, 0.7 )
    , Robot "Pharnup" "fra.domain" ( 4.1, 8.4, 3.6 )
    ]


view model =
    { title = "Dashboard"
    , body =
        [ case model.selectedRobot of
            Just name ->
                viewRobot name

            Nothing ->
                viewDashboard model
        ]
    }


viewDashboard model =
    H.div []
        [ H.node "style"
            []
            [ H.text style ]
        , H.h1 []
            [ H.text "Dashboard" ]
        , H.ul
            []
            (List.map
                (\{ name } ->
                    H.li []
                        [ H.a
                            [ HA.target "_blank", HA.href ("#" ++ name) ]
                            [ H.text name ]
                        ]
                )
                robots
            )
        ]


viewRobot name =
    H.div
        []
        (robots
            |> List.filter (\robot -> robot.name == name)
            |> List.map
                (\{ host, load } ->
                    let
                        ( l1, l5, l15 ) =
                            load
                    in
                    H.div
                        []
                        [ H.p [] [ H.text <| name ++ " on " ++ host ]
                        , H.p [] [ H.text <| "( " ++ String.fromFloat l1 ++ ", " ++ String.fromFloat l5 ++ ", " ++ String.fromFloat l15 ++ " )" ]
                        ]
                )
        )


style =
    """
"""