# mounted.ludic - which components the last frame showed, and one's model: an editor's questions of a
# running game's interface (devlink's ui_screen and ui_model), asked on request and never a frame.

# the class names of the components mounted in the last build, in tree order (every root the frame
# drew, a node at a time) and each once, into the caller's list
@alloc_ok("an inspector's question: the caller's list grows to the most classes shown at once")
export function ui_mounted(ui_st: UiState, out: []string) -> void {
  List.clear(out)
  for r in 0 .. len(ui_st.fb_roots) { mt_walk(ui_st, ui_st.fb_roots[r], out) }
  for i in 0 .. len(ui_st.in_list) {            # a mounted one the walk did not meet, in the order made
    let it = ui_st.in_list[i]
    if it.seen == ui_st.in_build { mt_add(out, it.cls.name) }
  }
}
@alloc_ok("an inspector's question: the caller's list grows to the most classes shown at once")
function mt_walk(ui_st: UiState, n: UiNode, out: []string) -> void {
  if n == null { return }
  for i in 0 .. len(ui_st.in_list) {
    let it = ui_st.in_list[i]
    if it.seen == ui_st.in_build and it.key == n.key { mt_add(out, it.cls.name) }
  }
  for c in 0 .. len(n.children) { mt_walk(ui_st, n.children[c], out) }
}
@alloc_ok("an inspector's question: the caller's list grows to the most classes shown at once")
function mt_add(out: []string, name: string) -> void {
  for i in 0 .. len(out) {
    if out[i] == name { return }
  }
  push(out, name)
}
# the model of the first mounted instance of `cls` (the Val its class's model() fills), or null: read
# it now, as the next frame fills the same object again
export function ui_model_of(ui_st: UiState, cls: string) -> Val {
  for i in 0 .. len(ui_st.in_list) {
    let it = ui_st.in_list[i]
    if it.seen == ui_st.in_build and it.cls != null and it.cls.name == cls { return it.model }
  }
  return null
}