(** Source element context validation checker.
    Validates that source attributes are appropriate for the parent context. *)

type parent_context =
  | Picture
  | Video
  | Audio
  | Other

type state = {
  mutable context_stack : parent_context list;
}

let create () = {
  context_stack = [];
}

let reset state =
  state.context_stack <- []

let current_context state =
  match state.context_stack with
  | ctx :: _ -> ctx
  | [] -> Other

let start_element state ~element collector =
  match element.Element.tag with
  | Tag.Html `Picture ->
    state.context_stack <- Picture :: state.context_stack
  | Tag.Html `Video ->
    state.context_stack <- Video :: state.context_stack
  | Tag.Html `Audio ->
    state.context_stack <- Audio :: state.context_stack
  | Tag.Html `Source ->
    let ctx = current_context state in
    (match ctx with
     | Video | Audio ->
       (* These attributes are only valid on source in picture, not audio/video *)
       Attr_utils.check_disallowed_attrs
         ~element:"source" ~collector ~attrs:element.raw_attrs
         ["srcset"; "sizes"; "width"; "height"]
     | Picture | Other -> ())
  | _ -> ()

let end_element state ~tag _collector =
  match tag with
  | Tag.Html (`Picture | `Video | `Audio) ->
    (match state.context_stack with
     | _ :: rest -> state.context_stack <- rest
     | [] -> ())
  | _ -> ()

let checker = Checker.make ~create ~reset ~start_element ~end_element ()