{-
   - This file is part of `typers`.
   -
   - `typers` is free software: you can redistribute it and/or modify
   - it under the terms of the GNU Affero Public License as published by
   - the Free Software Foundation, either version 3 of the License, or
   - (at your option) any later version.
   -
   - `typers` is distributed in the hope that it will be useful,
   - but WITHOUT ANY WARRANTY; without even the implied warranty of
   - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   - GNU Affero Public License for more details.
   -
   - You should have received a copy of the GNU Affero Public License
   - along with `typers`.  If not, see <https://www.gnu.org/licenses/>.
-}


module Main exposing (..)

import Array exposing (..)
import Base exposing (..)
import Browser
import Css
import Css.Global exposing (body, everything, global, selector)
import Data exposing (..)
import Html
import Html.Styled exposing (..)
import Html.Styled.Attributes exposing (..)
import Html.Styled.Events exposing (onClick, onInput)
import Random
import Styles exposing (styledButton, styledInput, styledTextBox, wordStyle)
import Task
import Time
import Utils exposing (flip, isJust, isNothing)
import Views exposing (..)


main =
    Browser.document
        { init = init
        , view = \m -> { title = "typers", body = [ view m |> toUnstyled ] }
        , update = update
        , subscriptions = subscriptions
        }


subscriptions : Model -> Sub Msg
subscriptions model =
    Sub.none


stringsToWords : List String -> List Word
stringsToWords ls =
    List.map (flip Word <| Todo) ls


generateWords : Config -> Cmd Msg
generateWords config =
    Random.generate LoadWords (randomParagraph config)


defaultModel : Model
defaultModel =
    Model Nothing Nothing Array.empty Nothing defaultConfig 0 "" False


init : () -> ( Model, Cmd Msg )
init _ =
    ( defaultModel
    , generateWords defaultConfig
    )


setStartTime : Cmd Msg
setStartTime =
    Task.perform Started Time.now


setEndTime : Cmd Msg
setEndTime =
    Task.perform Finished Time.now


firstWord : Model -> Bool
firstWord model =
    String.length model.inputBox == 1 && model.currentWord == 0


lastWord : Model -> Bool
lastWord model =
    model.currentWord == model.config.length - 1


wordEnded : String -> Bool
wordEnded s =
    String.endsWith " " s


handleWordEnded : Model -> ( Model, Cmd Msg )
handleWordEnded model =
    let
        s =
            model.inputBox

        current =
            Array.get model.currentWord model.words |> Maybe.withDefault (Word "" Todo)

        currentContent =
            current.content

        prevWordStatus =
            if s == currentContent then
                Correct

            else
                Wrong

        newWords =
            Array.set model.currentWord { current | status = prevWordStatus } model.words

        newModel =
            { model | inputBox = "", words = newWords, currentWord = model.currentWord + 1 }

        cmd =
            if lastWord model then
                setEndTime

            else
                Cmd.none
    in
    ( newModel, cmd )


update : Msg -> Model -> ( Model, Cmd Msg )
update msg model =
    case msg of
        Started t ->
            ( { model | begin = Just t }
            , Cmd.none
            )

        Finished t ->
            ( { model | end = Just t }
            , Cmd.none
            )

        LoadWords ls ->
            ( { model | words = Array.fromList <| stringsToWords ls }
            , Cmd.none
            )

        InputChanged s ->
            let
                cmd =
                    if firstWord model && isNothing model.begin then
                        setStartTime

                    else if s == currentContents model && lastWord model then
                        setEndTime

                    else
                        Cmd.none

                inpStat =
                    String.startsWith s (currentContents model)
            in
            ( { model | inputBox = s, inputCorrect = inpStat }
            , cmd
            )

        WordLengthChanged n ->
            let
                oldConfig =
                    model.config

                newConfig =
                    { oldConfig | length = n }
            in
            ( { defaultModel | config = newConfig }
            , generateWords newConfig
            )

        Redo ->
            let
                oldConfig =
                    model.config

                newModel =
                    { defaultModel | config = oldConfig }
            in
            ( newModel, generateWords oldConfig )

        NextWord ->
            if isJust model.end then
                ( model, Cmd.none )

            else
                handleWordEnded model

        _ ->
            ( model
            , Cmd.none
            )


toPara : Array Word -> Int -> String -> Html Msg
toPara words current content =
    words
        |> Array.map (\w -> span [ css [ wordStyle w.status ] ] [ text w.content ])
        |> Array.set current (span [ css [ wordStyle CurrentWord ] ] [ text content ])
        |> Array.toList
        |> List.intersperse (span [] [ text " " ])
        |> styledTextBox []


currentContents : Model -> String
currentContents model =
    Array.get model.currentWord model.words
        |> Maybe.map .content
        |> Maybe.withDefault ""


view : Model -> Html Msg
view model =
    div
        []
        [ div
            [ style "width" "95%"
            , style "max-width" "650px"
            , style "margin" "15% auto auto auto"
            ]
            [ div
                [ style "width" "100%"
                ]
                [ viewWordLengthOptions
                , div
                    [ style "float" "right" ]
                    [ styledButton [ onClick Redo ] [ text "redo" ] ]
                ]
            , div []
                [ toPara model.words model.currentWord (currentContents model)
                , div []
                    [ text "> "
                    , styledInput model.inputCorrect [ onInput handleInputChanged, value model.inputBox ] []
                    ]
                ]
            , div [] [ viewStats model ]
            , global [ selector "li:not(:last-child)::after" [ Css.property "content" "' · '" ] ]
            , global [ selector "*,*:focus,*:hover" [ Css.property "outline" "none" ] ]
            , global [ everything [ Css.fontFamily Css.monospace, Css.fontSize (Css.px 18) ] ]
            ]
        , div
            [ style "position" "absolute"
            , style "bottom" "0"
            , style "left" "50%"
            , style "transform" "translate(-50%)"
            ]
            [ viewFooter ]
        ]


handleInputChanged : String -> Msg
handleInputChanged s =
    if wordEnded s then
        NextWord

    else
        InputChanged s