# census.ludic - making one (a slot reused before a new one, a look, a name, a start on its own
# ground out of the players' sight where that can be had), a post's fixed person, and leaving
export function npc_spawn(npc_st: mut NpcState, kind: int) -> NpcPerson {
  if npc_st.np_n >= npc_st.np_max or kind < 0 or kind >= NPCK_COUNT { return null }
  var p: NpcPerson = null
  for i in 0 .. len(npc_st.np_walkers) {
    if not npc_st.np_walkers[i].active {
      p = npc_st.np_walkers[i]
      break
    }
  }
  @alloc_ok("a walker for each of np_max at most; one who left is reused")
  if p == null {
    if len(npc_st.np_walkers) >= npc_st.np_max { return null }
    p = new NpcPerson
    p.slot = len(npc_st.np_walkers)
    push(npc_st.np_walkers, p)
  }
  np_fresh(p, kind, npc_between(npc_st, 1, 99999))
  p.name = npc_pick_name(npc_st, p.body)
  let k = NpcKinds[kind]
  p.leg = npc_between(npc_st, 0, 3)
  p.seed = npc_rnd(npc_st) * 40.0
  p.out_h = k.leave_lo + npc_rnd(npc_st) * (k.leave_hi - k.leave_lo)
  p.yaw = npc_rnd(npc_st) * NP_TAU
  if k.start != null {
    let start = k.start
    start(p)
  } else { npc_start_near(npc_st, p, NpcWorld.origin_x(), NpcWorld.origin_z(), 6.0, 30.0) }
  if not NpcWorld.active(p.x, p.z) { return null }   # nobody is born outside every zone; the slot waits
  p.active = true
  npc_st.np_n += 1
  NpcWorld.born(p)
  npc_plan(npc_st, p)
  return p
}

function np_fresh(p: NpcPerson, kind: int, look: int) -> void {
  p.kind = kind
  p.id = NpcWorld.next_id()
  p.look = look
  p.body = NpcWorld.body_of(look)
  p.fixed = false
  p.said = -1
  p.near = 0
  p.goal = -1
  p.subj = -1
  p.note = -1
  p.note_h = 0.0
  p.flags = 0
  p.stalk = false
  p.stall = 0.0
  p.stall_max = 0.0
  p.fails = 0
  p.phase = 0.0
  p.home_face = false
  p.heard = false
  p.act = NPCA_IDLE
  p.act_t = 0.0
  p.speed = 0.0
  p.via_on = false
}

# its own ground: a spot r0 .. r1 from (cx, cz), tried a few times for one no player is within 60 m
# of, else near the place's origin; that is home, where it stands and faces
export function npc_start_near(npc_st: mut NpcState, p: NpcPerson, cx: float, cz: float, r0: float, r1: float) -> void {
  var x = NpcWorld.origin_x()
  var z = NpcWorld.origin_z()
  var ok = false
  for t in 0 .. 8 {
    if not npc_spot_near(npc_st, cx, cz, r0, r1) { continue }
    x = npc_st.np_px
    z = npc_st.np_pz
    ok = true
    if npc_near(npc_st, x, z) > 60.0 { break }
  }
  if not ok and npc_spot_near(npc_st, x, z, 10.0, 45.0) {
    x = npc_st.np_px
    z = npc_st.np_pz
  }
  npc_set_at(p, x, z)
}

# put it down at (x, z) as its home, stood still
export function npc_set_at(p: NpcPerson, x: float, z: float) -> void {
  p.x = x
  p.z = z
  p.y = NpcWorld.ground(x, z)
  p.hx = x
  p.hz = z
  p.tx = x
  p.tz = z
}

# somebody fixed at a post (a vendor behind the counter): never walks, never counted, never leaves,
# turns to a player within its kind's notice and back to `yaw` when they go
export function npc_place(npc_st: mut NpcState, kind: int, x: float, z: float, yaw: float, name: string, look: int) -> NpcPerson {
  let p = new NpcPerson
  p.slot = len(npc_st.np_posts)
  np_fresh(p, kind, look)
  p.fixed = true
  p.name = name
  p.seed = float(p.slot) * 0.9
  p.stance = yaw
  p.yaw = yaw
  npc_set_at(p, x, z)
  p.active = true
  push(npc_st.np_posts, p)
  NpcWorld.born(p)
  npc_do(npc_st, p, NPCA_IDLE, 3600.0)
  return p
}

export function npc_retire(npc_st: mut NpcState, p: NpcPerson) -> void {
  if not p.active { return }
  p.active = false
  if not p.fixed and npc_st.np_n > 0 { npc_st.np_n -= 1 }
  np_left(npc_st, p.name)
  NpcWorld.gone(p)
}