Qit.Cells

module Qit.Cells exposing (Config, config, withSelectionChange, withId, Model, init, update, view, Message)

{-| Cells
@docs Config, config, withSelectionChange, withId, Model, init, update, view, Message
-}

import Color
import List
import Task

import Element exposing (..)
import Element.Attributes exposing (..)
import Element.Events exposing (..)

import Qit.Style exposing (Style(..))

-- TODO move content events
-- TODO replicate content events
-- TODO select row/col
-- TODO multi-select
-- TODO cleanup exposed API

-- TODO inline edit -> is this really needed?

{-| Placeholder
-}
type Config model style msg row col = 
    Config (InternalConfig model style msg row col)

type alias InternalConfig model style msg row col =
    { style : Style -> style
    , lift : Message row col -> msg
    , rows : model -> List row
    , cols : model -> List col
    , rowHeader : row -> String
    , colHeader : col -> String
    , cell : model -> row -> col -> String
    , id : String
    , onSelectionChange : Maybe msg
    }

{-| Placeholder
-}
config: (Style -> style) -> (Message row col -> msg) -> (model -> List row) -> (model -> List col) -> (row -> String) -> (col -> String) -> (model -> row -> col -> String) -> Config model style msg row col
config style lift rows cols rowHeader colHeader cell =
    Config ({ style = style
            , lift = lift
            , rows = rows
            , cols = cols
            , rowHeader = rowHeader
            , colHeader = colHeader
            , cell = cell
            , id = "cells"
            , onSelectionChange = Nothing
            })

{-| Placeholder
-}
withSelectionChange: Message -> (Config model style Message row col) -> Config model style Message row col
withSelectionChange message (Config config) =
    Config { config | onSelectionChange = Just message}

{-| Placeholder
-}
withId: String -> (Config model style Message row col) -> Config model style Message row col
withId id (Config config) =
    Config { config | id = id }

{-| Placeholder
-}
type alias Model row col =
    { selected : Maybe (row, col)
    }

{-| Placeholder
-}
init : Model row col
init = Model Nothing

{-| Placeholder
-}
type Message row col = SelectCell (row, col)

{-| Placeholder
-}
update: Config model style msg row col -> Model row col -> Message row col -> (Model row col, Cmd msg)
update (Config config) model message =
    case message of
        SelectCell cell -> 
            { model | selected = Just cell } !
                ( case config.onSelectionChange of
                    Just onSelectionChange -> [ Task.succeed onSelectionChange |> Task.perform identity ]
                    Nothing -> []
                )

{-| Placeholder
-}
view: Config model style msg row col -> Model row col -> model -> Element style variation msg
view (Config config) cellModel model =
    el (config.style None) [width (percent 100)] (
        column (config.style None) []
            ( columnHeaders config model :: columnData config cellModel model )
    )

columnHeaders config model =
    row (config.style None) []
        ( x config :: (config.cols model |> List.map (columnHeader config model))
        )

x config = el (config.style CellHeader) [width (px 128), height (px 24)] empty

columnHeader config model c =
    el (config.style CellHeader) [width (px 128), height (px 24)]
        ( text (config.colHeader c) )

columnData config cellModel model =
    config.rows model |> List.map 
        (\r ->
            row (config.style None) []
                ( rowHeader config cellModel model r ::
                  rowData config cellModel model r
                )
        )

rowHeader config cellModel model r =
     el (config.style CellHeader) [width (px 128), height (px 24)]
        ( text (config.rowHeader r) )

rowData config cellModel model r =
    config.cols model |> List.map
        ( \c ->
            if Just (r, c) == cellModel.selected then
                el (config.style SelectedCellData) [width (px 128), height (px 24), paddingRight 8, paddingLeft 8, onClick <| config.lift <| SelectCell (r, c)]
                            ( text (config.cell model r c) )
            else
                el (config.style CellData) [width (px 128), height (px 24), paddingRight 8, paddingLeft 8, onClick <| config.lift <| SelectCell (r, c)]
                            ( text (config.cell model r c) )
        )