/// <summary>View rendering context for myWebLog</summary>
[<AutoOpen>]
module MyWebLog.ViewContext

open Microsoft.AspNetCore.Antiforgery
open MyWebLog.ViewModels

/// <summary>The rendering context for this application</summary>
[<NoComparison; NoEquality>]
type AppViewContext = {
    /// <summary>The web log for this request</summary>
    WebLog: WebLog

    /// <summary>The ID of the current user</summary>
    UserId: WebLogUserId option

    /// <summary>The title of the page being rendered</summary>
    PageTitle: string

    /// <summary>The subtitle for the page</summary>
    Subtitle: string option

    /// <summary>The anti-Cross Site Request Forgery (CSRF) token set to use when rendering a form</summary>
    Csrf: AntiforgeryTokenSet option

    /// <summary>The page list for the web log</summary>
    PageList: DisplayPage array

    /// <summary>Categories and post counts for the web log</summary>
    Categories: DisplayCategory array

    /// <summary>Tag mappings</summary>
    TagMappings: TagMap array

    /// <summary>The URL of the page being rendered</summary>
    CurrentPage: string

    /// <summary>User messages</summary>
    Messages: UserMessage array

    /// <summary>The generator string for the rendered page</summary>
    Generator: string

    /// <summary>The payload for this page (see other properties that wrap this one)</summary>
    Payload: obj

    /// <summary>The content of a page (wrapped when rendering the layout)</summary>
    Content: string

    /// <summary>Whether the current user is an author</summary>
    IsAuthor: bool

    /// <summary>Whether the current user is an editor (implies author)</summary>
    IsEditor: bool

    /// <summary>Whether the current user is a web log administrator (implies author and editor)</summary>
    IsWebLogAdmin: bool

    /// <summary>Whether the current user is an installation administrator (implies all web log rights)</summary>
    IsAdministrator: bool

    /// <summary>Whether the current page is the home page of the web log</summary>
    IsHome: bool

    /// <summary>Whether the current page is a category archive page</summary>
    IsCategory: bool

    /// <summary>Whether the current page is a category archive home page</summary>
    IsCategoryHome: bool

    /// <summary>Whether the current page is a tag archive page</summary>
    IsTag: bool

    /// <summary>Whether the current page is a tag archive home page</summary>
    IsTagHome: bool

    /// <summary>Whether the current page is a single post</summary>
    IsPost: bool

    /// <summary>Whether the current page is a static page</summary>
    IsPage: bool

    /// <summary>The slug for a category or tag</summary>
    Slug: string option
} with

    /// <summary>Whether there is a user logged on</summary>
    member this.IsLoggedOn = Option.isSome this.UserId

    /// <summary>The payload for this page as a <c>DisplayPage</c></summary>
    member this.Page =
        this.Payload :?> DisplayPage

    /// <summary>The payload for this page as a <c>PostDisplay</c></summary>
    member this.Posts =
        this.Payload :?> PostDisplay
    
    /// <summary>The model for this view (prior versions used <c>model</c> for the v3 <c>payload</c>)</summary>
    member this.Model =
        this.Payload

    /// <summary>An empty view context</summary>
    static member Empty =
        { WebLog          = WebLog.Empty
          UserId          = None
          PageTitle       = ""
          Subtitle        = None
          Csrf            = None
          PageList        = [||]
          Categories      = [||]
          TagMappings     = [||]
          CurrentPage     = ""
          Messages        = [||]
          Generator       = ""
          Payload         = obj ()
          Content         = ""
          IsAuthor        = false
          IsEditor        = false
          IsWebLogAdmin   = false
          IsAdministrator = false
          IsHome          = false
          IsCategory      = false
          IsCategoryHome  = false
          IsTag           = false
          IsTagHome       = false
          IsPost          = false
          IsPage          = false
          Slug            = None }