module Client.Features.Teacher.Home.State

open Elmish
open Domain
open Client.Features
open Client.Features.Teacher.Home.Types

/// `role` decides whether the Admin-only "Пользователи" tab is shown/loaded —
/// Teacher and Admin otherwise share this exact same page (see DESIGN.md §2:
/// Admin = Teacher + user management).
let init (role: Role) : Model * Cmd<Msg> =
    let questionsModel, questionsCmd = Teacher.Questions.State.init ()
    let testsModel, testsCmd = Teacher.Tests.State.init ()

    let usersCmd =
        match role with
        | Admin -> Cmd.map UsersMsg (Cmd.ofMsg Admin.Users.Types.LoadUsers)
        | Teacher
        | Student -> Cmd.none

    { Tab = QuestionsTab
      Role = role
      Questions = questionsModel
      Tests = testsModel
      Users = Admin.Users.Types.empty },
    Cmd.batch [ Cmd.map QuestionsMsg questionsCmd; Cmd.map TestsMsg testsCmd; usersCmd ]

let update (token: string option) (msg: Msg) (model: Model) : Model * Cmd<Msg> =
    match msg with
    | SwitchTab tab -> { model with Tab = tab }, Cmd.none
    | QuestionsMsg(Teacher.Questions.Types.TopicCreated topic as subMsg) ->
        let m, cmd = Teacher.Questions.State.update token subMsg model.Questions

        { model with
            Questions = m
            // Questions and Tests keep independent `Topics` lists (own VSA
            // slices, own `LoadTopics` on init) — a topic created in one
            // must be mirrored into the other, or the quiz question-picker
            // never sees topics added after the page first loaded.
            Tests = { model.Tests with Topics = model.Tests.Topics @ [ topic ] } },
        Cmd.map QuestionsMsg cmd
    | QuestionsMsg subMsg ->
        let m, cmd = Teacher.Questions.State.update token subMsg model.Questions
        { model with Questions = m }, Cmd.map QuestionsMsg cmd
    | TestsMsg subMsg ->
        let m, cmd = Teacher.Tests.State.update token subMsg model.Tests
        { model with Tests = m }, Cmd.map TestsMsg cmd
    | UsersMsg subMsg ->
        let m, cmd = Admin.Users.State.update token subMsg model.Users
        { model with Users = m }, Cmd.map UsersMsg cmd