module Views.FilterView exposing (filterSidebar, applyFilters, parseFilterFromQuery, filterToQuery)

-- Local modules

import Messages exposing (Msg(..))
import Models exposing (Model, EventInstance, Filter, Day)


-- Core modules

import Regex


-- External modules

import Html exposing (Html, text, div, ul, li, span, i, h4)
import Html.Attributes exposing (class, classList, href)
import Html.Events exposing (onClick)
import Date.Extra exposing (Interval(..), equalBy)


applyFilters : Day -> Model -> List EventInstance
applyFilters day model =
    let
        types =
            List.map (\eventType -> eventType.slug)
                (if List.isEmpty model.filter.eventTypes then
                    model.eventTypes
                 else
                    model.filter.eventTypes
                )

        locations =
            List.map (\eventLocation -> eventLocation.slug)
                (if List.isEmpty model.filter.eventLocations then
                    model.eventLocations
                 else
                    model.filter.eventLocations
                )

        videoFilters =
            List.map (\filter -> filter.filter)
                (if List.isEmpty model.filter.videoRecording then
                    videoRecordingFilters
                 else
                    model.filter.videoRecording
                )

        filteredEventInstances =
            List.filter
                (\eventInstance ->
                    (Date.Extra.equalBy Month eventInstance.from day.date)
                        && (Date.Extra.equalBy Date.Extra.Day eventInstance.from day.date)
                        && List.member eventInstance.location locations
                        && List.member eventInstance.eventType types
                        && applyVideoRecordingFilters videoFilters eventInstance
                )
                model.eventInstances
    in
        filteredEventInstances


filterSidebar : Model -> Html Msg
filterSidebar model =
    div
        [ classList
            [ ( "col-sm-3", True )
            , ( "col-sm-push-9", True )
            , ( "schedule-sidebar", True )
            , ( "schedule-filter", True )
            , ( "sticky", True )
            ]
        ]
        [ h4 [] [ text "Filter" ]
        , div [ class "form-group" ]
            [ filterView "Type" model.eventTypes model.filter.eventTypes ToggleEventTypeFilter
            , filterView "Location" model.eventLocations model.filter.eventLocations ToggleEventLocationFilter
            , filterView "Video" videoRecordingFilters model.filter.videoRecording ToggleVideoRecordingFilter
            ]
        ]


notRecordedFilter : EventInstance -> Bool
notRecordedFilter eventInstance =
    eventInstance.videoRecording == False


recordedFilter : EventInstance -> Bool
recordedFilter eventInstance =
    eventInstance.videoRecording == True


hasRecordingFilter : EventInstance -> Bool
hasRecordingFilter eventInstance =
    eventInstance.videoUrl /= ""


videoRecordingFilters : List { name : String, slug : String, filter : EventInstance -> Bool }
videoRecordingFilters =
    [ { name = "Will not be recorded", slug = "not-to-be-recorded", filter = notRecordedFilter }
    , { name = "Will recorded", slug = "to-be-recorded", filter = recordedFilter }
    , { name = "Has recording", slug = "has-recording", filter = hasRecordingFilter }
    ]


applyVideoRecordingFilters : List (EventInstance -> Bool) -> EventInstance -> Bool
applyVideoRecordingFilters filters eventInstance =
    let
        results =
            List.map (\filter -> filter eventInstance) filters
    in
        List.member True results


filterView :
    String
    -> List { a | name : String }
    -> List { a | name : String }
    -> ({ a | name : String } -> Msg)
    -> Html Msg
filterView name possibleFilters currentFilters action =
    div []
        [ text (name ++ ":")
        , ul [] (List.map (\filter -> filterChoiceView filter currentFilters action) possibleFilters)
        ]


filterChoiceView :
    { a | name : String }
    -> List { a | name : String }
    -> ({ a | name : String } -> Msg)
    -> Html Msg
filterChoiceView filter currentFilters action =
    let
        active =
            List.member filter currentFilters

        notActive =
            not active
    in
        li []
            [ div
                [ classList
                    [ ( "btn", True )
                    , ( "btn-default", True )
                    , ( "filter-choice-active", active )
                    ]
                , onClick (action filter)
                ]
                [ span []
                    [ i [ classList [ ( "fa", True ), ( "fa-minus", active ), ( "fa-plus", notActive ) ] ] []
                    , text (" " ++ filter.name)
                    ]
                ]
            ]


findFilter : List { a | slug : String } -> String -> Maybe { a | slug : String }
findFilter modelItems filterSlug =
    List.head (List.filter (\x -> x.slug == filterSlug) modelItems)


getFilter : String -> List { a | slug : String } -> String -> List { a | slug : String }
getFilter filterType modelItems query =
    let
        filterMatch =
            query
                |> Regex.find (Regex.AtMost 1) (Regex.regex (filterType ++ "=([\\w,_-]+)&*"))
                |> List.concatMap .submatches
                |> List.head
                |> Maybe.withDefault Nothing
                |> Maybe.withDefault ""

        filterSlugs =
            String.split "," filterMatch
    in
        List.filterMap (\x -> findFilter modelItems x) filterSlugs


parseFilterFromQuery : String -> Model -> Filter
parseFilterFromQuery query model =
    let
        types =
            getFilter "type" model.eventTypes query

        locations =
            getFilter "location" model.eventLocations query

        videoFilters =
            getFilter "video" videoRecordingFilters query
    in
        { eventTypes = types
        , eventLocations = locations
        , videoRecording = videoFilters
        }


filterToQuery : Filter -> String
filterToQuery filter =
    let
        typePart =
            case String.join "," (List.map .slug filter.eventTypes) of
                "" ->
                    ""

                types ->
                    "type=" ++ types

        locationPart =
            case String.join "," (List.map .slug filter.eventLocations) of
                "" ->
                    ""

                locations ->
                    "location=" ++ locations

        videoPart =
            case String.join "," (List.map .slug filter.videoRecording) of
                "" ->
                    ""

                video ->
                    "video=" ++ video

        result =
            String.join "&" (List.filter (\x -> x /= "") [ typePart, locationPart, videoPart ])
    in
        "#" ++ result