# emit_spawn.ludic — spawn / despawn / self(), and seeding a component's fields
# from its declared defaults plus any per-spawn overrides.

fn emit_init_component(e: ptr, comp: ptr, rec: Node) -> void {
  let me = itoa(MAX_ENT)
  let c = find_comp(comp)
  if ptr_is_null(c) { perr(sconcat("spawn: unknown property ", comp)) }
  let hp = nreg();  emit("  ");  emit(hp);  emit(" = getelementptr inbounds [");  emit(me);  emit(" x i8], ptr @H_");  emit(comp);  emit(", i32 0, i32 ");  emit(e);  emit("\n")
  emit("  store i8 1, ptr ");  emit(hp);  emit("\n")
  let slot = nreg()
  emit("  ");  emit(slot);  emit(" = getelementptr inbounds [");  emit(me);  emit(" x %Cmp_");  emit(comp);  emit("], ptr @S_");  emit(comp);  emit(", i32 0, i32 ");  emit(e);  emit("\n")
  # defaults
  let f = 0
  while f < len(c.kids) {
    let fd = c.kids[f]
    let addr = nreg()
    emit("  ");  emit(addr);  emit(" = getelementptr inbounds %Cmp_");  emit(comp);  emit(", ptr ");  emit(slot);  emit(", i32 0, i32 ");  emit(itoa(f));  emit("\n")
    let lt = llty(fd.ty)
    let v = "0"
    if streq(lt, "ptr") { v = "null" }
    if not ptr_is_null(fd.a) { let dv = emit_expr(fd.a);  v = dv.code }
    emit("  store ");  emit(lt);  emit(" ");  emit(v);  emit(", ptr ");  emit(addr);  emit("\n")
    f = f + 1
  }
  # per-spawn overrides
  if not ptr_is_null(rec) {
    let j = 0
    while j < len(rec.kids) {
      let fi = rec.kids[j]
      let fidx = field_index(c, fi.s)
      if fidx >= 0 {
        let addr = nreg()
        emit("  ");  emit(addr);  emit(" = getelementptr inbounds %Cmp_");  emit(comp);  emit(", ptr ");  emit(slot);  emit(", i32 0, i32 ");  emit(itoa(fidx));  emit("\n")
        let dv = emit_expr(fi.a)
        emit("  store ");  emit(llty(field_type(c, fi.s)));  emit(" ");  emit(dv.code);  emit(", ptr ");  emit(addr);  emit("\n")
      }
      j = j + 1
    }
  }
  # @OnAttach(Property) runs once the property is attached and seeded
  let ab = onattach_body(comp)
  if not ptr_is_null(ab) {
    let save = nloc
    let vslot = emit_alloca("ptr")
    emit("  store ptr ");  emit(slot);  emit(", ptr ");  emit(vslot);  emit("\n")
    loc_push(comp, vslot, comp)
    emit_block(ab)
    nloc = save
  }
}

# bind each of a model's properties to entity `e`'s component storage, so an
# @OnSpawn hook body can address them by name (like a query binding for one entity).
fn emit_bind_props(model: Node, e: ptr) -> void {
  let me = itoa(MAX_ENT)
  let c = 0
  while c < len(model.kids) {
    let pname = model.kids[c].s
    let slot = nreg()
    emit("  ");  emit(slot);  emit(" = getelementptr inbounds [");  emit(me);  emit(" x %Cmp_");  emit(pname);  emit("], ptr @S_");  emit(pname);  emit(", i32 0, i32 ");  emit(e);  emit("\n")
    let vslot = emit_alloca("ptr")
    emit("  store ptr ");  emit(slot);  emit(", ptr ");  emit(vslot);  emit("\n")
    loc_push(pname, vslot, pname)
    c = c + 1
  }
}

fn emit_spawn(st: Node) -> void {
  let e = emit_bind("call i32 @L_alloc()")
  let ak = find_arch_id(st.s)
  if ak > 0 {
    let me = itoa(MAX_ENT)
    let kp = nreg();  emit("  ");  emit(kp);  emit(" = getelementptr inbounds [");  emit(me);  emit(" x i32], ptr @L_kind, i32 0, i32 ");  emit(e);  emit("\n")
    emit("  store i32 ");  emit(itoa(ak));  emit(", ptr ");  emit(kp);  emit("\n")
    let arch = find_arch(st.s)
    let c = 0
    while c < len(arch.kids) {
      let cn = arch.kids[c].s
      let rec = ptr_null()
      let i = 0
      while i < len(st.kids) { if streq(st.kids[i].s, cn) { rec = st.kids[i].a };  i = i + 1 }
      emit_init_component(e, cn, rec)
      c = c + 1
    }
    let ob = onspawn_body(st.s)                 # @OnSpawn(Model) hook runs after init
    if not ptr_is_null(ob) {
      let save = nloc
      emit_bind_props(arch, e)
      emit_block(ob)
      nloc = save
    }
  } else {
    let i = 0
    while i < len(st.kids) { emit_init_component(e, st.kids[i].s, st.kids[i].a);  i = i + 1 }
  }
}

fn emit_despawn(st: Node) -> void {
  let v = emit_expr(st.a)
  # @OnDespawn: dispatch on the entity's kind and run the matching model's hook
  if len(g_ondespawn) > 0 {
    let me = itoa(MAX_ENT)
    let kp = nreg();  emit("  ");  emit(kp);  emit(" = getelementptr inbounds [");  emit(me);  emit(" x i32], ptr @L_kind, i32 0, i32 ");  emit(v.code);  emit("\n")
    let kind = emit_bind(sconcat("load i32, ptr ", kp))
    let i = 0
    while i < len(g_ondespawn) {
      let mname = g_ondespawn[i].s
      let c = emit_bind(sconcat("icmp eq i32 ", sconcat(kind, sconcat(", ", itoa(find_arch_id(mname))))))
      let yes = lbl("dh");  let no = lbl("dhn")
      emit("  br i1 ");  emit(c);  emit(", label %");  emit(yes);  emit(", label %");  emit(no);  emit("\n")
      emit(yes);  emit(":\n  call void @on_despawn_");  emit(mname);  emit("(i32 ");  emit(v.code);  emit(")\n")
      emit("  br label %");  emit(no);  emit("\n");  emit(no);  emit(":\n")
      i = i + 1
    }
  }
  emit("  call void @L_free_entity(i32 ");  emit(v.code);  emit(")\n")
}