# ============================================================================
# tiled_spawn.ludic — Tiled P4 (#72) opt-in entity spawning. Split from
# tiled.ludic because it stands on the reflection ABI (world_spawn / world_set /
# world_field_id …), which the compiler emits only for a game (has_ecs); so this
# fragment is spliced only when a Tiled program is itself a game. A plain tool
# that reads maps never references the world table.
# ============================================================================
# ---- opt-in entity spawning ------------------------------------------------
# set an int field named `fname` on entity e wherever it exists (any prop the
# entity carries) — the by-name bridge from object properties to components.
function tiled_apply_field(e: int, fname: pointer, v: int) -> void {
  let np = world_prop_count()
  var pi = 0
  while pi < np {
    if world_has(e, pi) == 1 {
      let fid = world_field_id(pi, fname)
      if fid >= 0 { world_set(e, pi, fid, v) }
    }
    pi += 1
  }
}

# spawn a Ludic entity of `model_name` from an object: its Position (if the model
# has one) takes the object's x/y, and each object custom property sets a like-
# named int/bool component field. Returns the entity, or -1 if the model is
# unknown. Opt-in — the core load never calls this.
function tiled_spawn_object(m: Tmap, obj: Val, model_name: pointer) -> int {
  let mid = world_model_id(model_name)
  if mid < 0 { return -1 }
  let e = world_spawn(mid)
  let pp = world_prop_id("Position")
  if pp >= 0 and world_has(e, pp) == 1 {
    let fx = world_field_id(pp, "x")
    let fy = world_field_id(pp, "y")
    if fx >= 0 { world_set(e, pp, fx, value_as_int(value_get(obj, "x"))) }
    if fy >= 0 { world_set(e, pp, fy, value_as_int(value_get(obj, "y"))) }
  }
  let props = value_get(obj, "properties")
  var i = 0
  while i < value_count(props) {
    let p = value_at(props, i)
    tiled_apply_field(e, value_as_str(value_get(p, "name")), tiled_prop_int(obj, value_as_str(value_get(p, "name"))))
    i += 1
  }
  return e
}

# spawn every object on `layer` as `model_name` (opt-in). Returns the count.
function tiled_spawn_layer(m: Tmap, layer: int, model_name: pointer) -> int {
  var n = 0
  let c = tmap_object_count(m, layer)
  var i = 0
  while i < c { if tiled_spawn_object(m, tmap_object(m, layer, i), model_name) >= 0 { n += 1 };  i += 1 }
  return n
}